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Sample records for gaba benzodiazepine receptors

  1. A Unified Model of the GABA(A) Receptor Comprising Agonist and Benzodiazepine Binding Sites

    DEFF Research Database (Denmark)

    Kongsbak, Kristine Grønning; Bergmann, Rikke; Sørensen, Pernille Louise

    2013-01-01

    We present a full-length a1b2c2 GABA receptor model optimized for agonists and benzodiazepine (BZD) allosteric modulators. We propose binding hypotheses for the agonists GABA, muscimol and THIP and for the allosteric modulator diazepam (DZP). The receptor model is primarily based on the glutamate...

  2. Regulation of GABA and benzodiazepine receptors following neurotoxin-induced striatal and medial forebrain bundle lesions

    International Nuclear Information System (INIS)

    Pan, H.S.I.

    1985-01-01

    GABA, a major inhibitory transmitter, is used by many projection neurons of the striatum. To investigate the role of GABA in striatal function, the GABA receptor complex was studied after lesions of the striatum or the nigrostriatal neurons. Quantitative receptor autoradiography using thaw-mounted tissue slices was developed for the study of GABA and benzodiazepine (BDZ) receptors. With the technique established, binding to GABA and BDZ receptors after unilateral striatal kainate lesions was examined. Subsequently, changes in GABA and BDZ receptors were studied following the destruction of dopaminergic nigrostriatal cells by unilateral 6-hydroxydopamine lesion of the medial forebrain bundle. In summary, quantitative receptor autoradiography allowed the detection of GABA and BDZ receptor changes in multiple small areas in each lesioned brain. This technique made it feasible to carry out kinetic saturation, and competition studies using less than 1 mg of tissue. The data suggest that dopamine is functionally inhibitory on striatopallidal neurons but is functionally excitatory on striatoentopeduncular and striatonigral cells which in turn inhibit the thalamus. This quantitative autoradiographic technique can be generalized to study other transmitter receptors and can be combined with 2-deoxyglucose uptake studies

  3. The benzodiazepine/GABA receptor complex during severe ethanol intoxication and withdrawal in the rat

    International Nuclear Information System (INIS)

    Hemmingsen, R.; Braestrup, C.; Nielsen, M.; Barry, D.I.

    1982-01-01

    The benzodiazepine/GABA (gammaaminobutyric acid) receptor complex was investigated during severe ethanol intoxication and withdrawal in the rat. The intragastric intubation technique was used to establish physical ethanol dependence in the animals. Cerebral cortex from male Wistar rats was studied 1) after 31/2 days of severe ethanol intoxication, 2) during the ethanol withdrawal reaction and 3) in a control group. The effect of GABA-ergic activation by muscimol and THIP (4,5,6,7-tetrahydroisoxazole(5,4-c)pyridin-3-01) on 3 H-diazepam binding was unchanged during ethanol intoxication and withdrawal, as was the affinity constant (Ksub(D)) and the maximal number of binding sites (Bsub(max)) for 3 H-flunitrazepam. In conclusion, the benzodiazepine/GABA receptor complex is unlikely to play any causual part in physical ethanol dependence. (author)

  4. GABA and benzodiazepine receptors in the gerbil brain after transient ischemia: demonstration by quantitative receptor autoradiography

    International Nuclear Information System (INIS)

    Onodera, H.; Sato, G.; Kogure, K.

    1987-01-01

    Quantitative receptor autoradiography was used to measure the binding of gamma-aminobutyric acid (GABA) and benzodiazepine receptors after ischemia by means of transient occlusion of bilateral common carotid arteries in the gerbil. [ 3 H]Muscimol was used to label the GABAA receptors and [ 3 H]flunitrazepam to label central type benzodiazepine receptors. In the superolateral convexities of the frontal cortices, [ 3 H]muscimol binding was increased in 60% of the animals killed 3 days after ischemia, and decreased in 67% of the animals killed 27 days after ischemia. Twenty-seven days after ischemia, [ 3 H]flunitrazepam binding in the substantia nigra pars reticulata increased to 252% of the control, though the increase in [ 3 H]muscimol binding was not significant. In the dorsolateral region of the caudate putamen, marked neuronal necrosis and depletion of both [ 3 H]muscimol and [ 3 H]flunitrazepam binding sites were observed 27 days after ischemia, the ventromedial region being left intact. In spite of the depletion of pyramidal cells in the CA1 region of the hippocampus, both [ 3 H]muscimol and [ 3 H]flunitrazepam binding sites were preserved 27 days after ischemia. Since our previous study revealed that adenosine A1 binding sites were depleted in the CA1 subfield of the hippocampus after ischemia correlating with neuronal damage, GABAA and benzodiazepine receptors may not be distributed predominantly on the pyramidal cells in the CA1 region

  5. A Review of the Updated Pharmacophore for the Alpha 5 GABA(A Benzodiazepine Receptor Model

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    Terry Clayton

    2015-01-01

    Full Text Available An updated model of the GABA(A benzodiazepine receptor pharmacophore of the α5-BzR/GABA(A subtype has been constructed prompted by the synthesis of subtype selective ligands in light of the recent developments in both ligand synthesis, behavioral studies, and molecular modeling studies of the binding site itself. A number of BzR/GABA(A α5 subtype selective compounds were synthesized, notably α5-subtype selective inverse agonist PWZ-029 (1 which is active in enhancing cognition in both rodents and primates. In addition, a chiral positive allosteric modulator (PAM, SH-053-2′F-R-CH3 (2, has been shown to reverse the deleterious effects in the MAM-model of schizophrenia as well as alleviate constriction in airway smooth muscle. Presented here is an updated model of the pharmacophore for α5β2γ2 Bz/GABA(A receptors, including a rendering of PWZ-029 docked within the α5-binding pocket showing specific interactions of the molecule with the receptor. Differences in the included volume as compared to α1β2γ2, α2β2γ2, and α3β2γ2 will be illustrated for clarity. These new models enhance the ability to understand structural characteristics of ligands which act as agonists, antagonists, or inverse agonists at the Bz BS of GABA(A receptors.

  6. Modulation of acetylcholine release from rat striatal slices by the GABA/benzodiazepine receptor complex

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    Supavilai, P.; Karobath, M.

    1985-02-04

    GABA, THIP and muscimol enhance spontaneous and inhibit electrically induced release of tritium labelled compounds from rat striatal slices which have been pre-labelled with /sup 3/H-choline. Baclofen is inactive in this model. Muscimol can inhibit electrically induced release of tritiated material by approximately 75% with half maximal effects at 2 ..mu..M. The response to muscimol can be blocked by the GABA antagonists bicuculline methobromide, picrotoxin, anisatin, R 5135 and CPTBO (cyclopentylbicyclophosphate). Drugs which act on the benzodiazepine receptor (BR) require the presence of muscimol to be effective and they modulate the effects of muscimol in a bidirectional manner. Thus BR agonists enhance and inverse BR agonists attenuate the inhibitory effects of muscimol on electrically induced release. Ro15-1788, a BR antagonist, does not modulate the inhibitory effects of muscimol but antagonizes the actions of clonazepam, a BR agonist, and of DMCM, an inverse BR agonist. These results demonstrate that a GABA/benzodiazepine receptor complex can modulate acetylcholine release from rat striatal slices in vitro. 24 references, 3 figures, 5 table.

  7. GABA receptor imaging

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    Lee, Jong Doo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA{sub A}-receptor that allows chloride to pass through a ligand gated ion channel and GABA{sub B}-receptor that uses G-proteins for signaling. The GABA{sub A}-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA{sub A}-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with {sup 11}C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, {sup 18}F-fluoroflumazenil (FFMZ) has been developed to overcome {sup 11}C's short half-life. {sup 18}F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1{sup 1}C-FMZ PET instead of {sup 18}F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA{sub A} receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

  8. GABA receptor imaging

    International Nuclear Information System (INIS)

    Lee, Jong Doo

    2007-01-01

    GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA A -receptor that allows chloride to pass through a ligand gated ion channel and GABA B -receptor that uses G-proteins for signaling. The GABA A -receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA A -receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with 11 C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, 18 F-fluoroflumazenil (FFMZ) has been developed to overcome 11 C's short half-life. 18 F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1 1 C-FMZ PET instead of 18 F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA A receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas

  9. Interactions of pyrethroid insecticides with GABA sub A and peripheral-type benzodiazepine receptors

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    Devaud, L.L.

    1988-01-01

    Pyrethroid insecticides are potent proconvulsants in the rat. All pyrethroids evincing proconvulsant activity elicited a similar 25-30% maximal reduction of seizure threshold. The Type II pyrethroids were the most potent proconvulsants with 1R{alpha}S, cis cypermethrin having an ED{sub 50} value of 6.3 nmol/kg. The proconvulsant activity of both Type I and Type II pyrenthroids was blocked by pretreatment with PK 11195, the peripheral-type benzodiazepine receptor (PTBR) antagonist. In contrast, phenytoin did not antagonize the proconvulsant activity of either deltamethrin or permethrin. Pyrethroids displaced the specific binding of ({sup 3}H)Ro5-4864 to rat brain membranes with a significant correlation between the log EC{sub 50} values for their activities as proconvulsants and the log IC{sub 50} values for their inhibition of ({sup 3}H)Ro5-4864 binding. Both Ro5-4864 and pyrethroid insecticides were found to influence specific ({sup 35}S)TBPS binding in a GABA-dependent manner. PK 11195 and the Type II pyrethroid, deltamethrin antagonized the Ro5-4864-induced modulation of ({sup 35}S)TBPS binding. Pyrethroid insecticides, Ro5-4864 and veratridine influenced GABA-gated {sup 36}Chloride influx. Moreover, the Type II pyrethroids elicited an increase in {sup 36}chloride influx in the absence of GABA-stimulation. Both of these actions were antagonized by PK 11195 and tetrodotoxin.

  10. Species dependent dual modulation of the benzodiazepine/GABA receptor chloride channel by dihydroergosine

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    Pericic, D.; Tvrdeic, A. (Rudjer Boskovic Institute, Zagreb (Yugoslavia))

    1990-01-01

    Dihydroergosine enhanced the incidence of bicuculline induced convulsions in female rats, while 100 mg/kg of dihydroergosine given to female mice made 45% convulsive dose of bicuculline to be subconvulsive. The same dose of dihydroergosine enhanced in mice the latency of bicuculline-induced convulsions. Although, in in vitro experiments dihydroergosine showed very weak ability to prevent the binding of {sup 3}H-muscimol, the drug was able to diminish and to augment the IC{sub 50} of bicuculline and GABA when added to crude synaptosomal pellet of the rat and mouse brain respectively. Lower concentrations of dihydroergosine stimulated and higher inhibited {sup 3}H-TBOB binding to the crude synaptosomal pellet of the rat brain. In the preparation of mouse brain dihydroergosine produced only inhibition of {sup 3}H-TBOB binding. Only slight quantitative differences were observed in bicuculline-induced stimulation and in GABA- and diazepam-induced inhibition of {sup 3}H-TBOB binding between the two species. The results suggest that the opposite species-dependent effects of dihydroergosine on bicuculline-induced convulsions are due to the ability of this drug to modulate species-dependently the benzodiazepine/GABA receptor chloride channel complex.

  11. Pharmacological and biochemical properties of the benzodiazepine-GABA receptor in codfish brain in comparison with mammalian brain

    International Nuclear Information System (INIS)

    Deng, L.

    1989-01-01

    The GABA receptor of codfish brain is encoded by an ancestral gene of the mammalian GABA receptor based on phylogenetic studies. The mammalian GABA receptor consists of at least two subunits (β and α) which could be photoaffinity labeled by the GABA agonist [ 3 H]muscimol (57 kDa) and the benzodiazepine (BZ) agonist [ 3 H]flunitrazepam (52 kDa), respectively. In contrast, electrophoresis of codfish GABA receptor photoaffinity labeled by the same ligands showed a single radioactive peak on sodium dodecyl surface polyarcylamide gel, giving rise to a relative molecular weight of 56-57 kDa equivalent to the β subunit of 57 kDa in mammals. The homogeneity of purified receptor using benzodiazepine (Ro 7-1986/1) affinity chromatography was further verified by two-dimensional gel electrophoresis based on isoelectric point and molecular weight, in addition to a single band on a silver stained gel and specific activity. The receptor density and affinity constant for [ 3 H]muscimol and [ 3 H]flunitrazepam are comparable to those in bovine, rate, and human brain

  12. GABA receptors and benzodiazepine binding sites modulate hippocampal acetylcholine release in vivo

    NARCIS (Netherlands)

    Moor, E; de Boer, P; Westerink, B.H.C.

    1998-01-01

    In the present study, the regulation of acetylcholine release from the ventral hippocampus by gamma-aminobutyric acid (GABA) was investigated in vivo. GABA receptor agonists and antagonists were administered locally in the medial septum and the adjacent vertical limb of the diagonal band of Broca,

  13. SPECT imaging of GABA{sub A}/benzodiazepine receptors and cerebral perfusion in mild cognitive impairment

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    Pappata, Sabina; Varrone, Andrea; Vicidomini, Caterina; Sansone, Valeria; Comerci, Marco; Panico, Maria Rosaria; Quarantelli, Mario [CNR, Institute of Biostructure and Bioimaging, Naples (Italy); Milan, Graziella; De Falco, Caterina; Lore, Elisa; Postiglione, Alfredo [University ' ' Federico II' ' , Department of Clinical and Experimental Medicine, Naples (Italy); Iavarone, Alessandro [Neurologic and Stroke Unit, CTO Hospital, Naples (Italy); Salvatore, Marco [CNR, Institute of Biostructure and Bioimaging, Naples (Italy); University ' ' Federico II' ' , Department of Biomorphological and Functional Sciences, Naples (Italy)

    2010-06-15

    The involvement of neocortical and limbic GABA{sub A}/benzodiazepine (BZD) receptors in Alzheimer's disease (AD) is controversial and mainly reported in advanced stages. The status of these receptors in the very early stages of AD is unclear and has not been explored in vivo. Our aims were to investigate in vivo the integrity of cerebral cortical GABA{sub A}/BZD receptors in subjects with amnestic mild cognitive impairment (MCI) and to compare possible receptor changes to those in cerebral perfusion. [{sup 123}I]Iomazenil and [{sup 99m}Tc]HMPAO SPECT images were acquired in 16 patients with amnestic MCI and in 14 normal elderly control subjects (only [{sup 123}I]iomazenil imaging in 5, only [{sup 99m}Tc]HMPAO imaging in 4, and both [{sup 123}I]iomazenil and [{sup 99m}Tc]HMPAO imaging in 5). Region of interest (ROI) analysis and voxel-based analysis were performed with cerebellar normalization. Neither ROI analysis nor voxel-based analysis showed significant [{sup 123}I]iomazenil binding changes in MCI patients compared to control subjects, either as a whole group or when considering only those patients with MCI that converted to AD within 2 years of clinical follow-up. In contrast, the ROI analysis revealed significant hypoperfusion of the precuneus and posterior cingulate cortex in the whole group of MCI patients and in MCI converters as compared to control subjects. Voxel-based analysis showed similar results. These results indicate that in the very early stages of AD, neocortical and limbic neurons/synapses expressing GABA{sub A}/BZD receptors are essentially preserved. They suggest that in MCI patients functional changes precede neuronal/synaptic loss in neocortical posterior regions and that [{sup 99m}Tc]HMPAO rCBF imaging is more sensitive than [{sup 123}I]iomazenil GABA{sub A}/BZD receptor imaging in detecting prodromal AD. (orig.)

  14. Yokukansan enhances pentobarbital-induced sleep in socially isolated mice: possible involvement of GABA(A)-benzodiazepine receptor complex.

    Science.gov (United States)

    Egashira, Nobuaki; Nogami, Ai; Iwasaki, Katsunori; Ishibashi, Ayumi; Uchida, Naoki; Takasaki, Kotaro; Mishima, Kenichi; Nishimura, Ryoji; Oishi, Ryozo; Fujiwara, Michihiro

    2011-01-01

    In the present study, we investigated the effect of the Kampo medicine Yokukansan (YKS) on pentobarbital-induced sleep in group-housed and socially isolated mice. Socially isolated mice showed shorter sleeping time than the group-housed mice. YKS (300 mg/kg, p.o.) prolonged the pentobarbital-induced sleeping time in socially isolated mice without affecting pentobarbital sleep in group-housed mice. The prolongation of sleeping time by YKS was reversed by bicuculline (3 mg/kg, i.p.) and flumazenil (3 mg/kg, i.p.), but not WAY100635. These findings suggest that the GABA(A)-benzodiazepine receptor complex, but not 5-HT(1A) receptors, is involved in the reversal effect of YKS on the decrease of pentobarbital sleep by social isolation.

  15. Functional characterization of the 1,5-benzodiazepine clobazam and its major active metabolite N-desmethylclobazam at human GABA(A receptors expressed in Xenopus laevis oocytes.

    Directory of Open Access Journals (Sweden)

    Harriet Hammer

    Full Text Available The 1,5-benzodiazepine clobazam is indicated for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome in patients 2 years of age or older in the United States, and for treatment of anxiety and various forms of epilepsy elsewhere. Clobazam has been reported to exhibit different in vivo adverse effects and addiction liability profile than the classic 1,4-benzodiazepines. In this study, it was investigated whether the in vitro pharmacological properties of clobazam and its major active metabolite N-desmethylclobazam could explain some of these clinical differences. The functional properties of the two 1,5-benzodiazepines were characterized at the human γ-aminobutyric acid type A receptor (GABA(AR subtypes α1β2γ(2S, α2β2γ(2S, α3β2γ(2S, α5β2γ(2S and α6β2δ expressed in Xenopus laevis oocytes by use of two-electrode voltage-clamp electrophysiology and compared to those exhibited by the 1,4-benzodiazepine clonazepam. All three compounds potentiated GABA EC20-evoked responses through the α(1,2,3,5β2γ(2S GABA(ARs in a reversible and concentration-dependent manner, with each displaying similar EC50 values at the four subtypes. Furthermore, the degrees of potentiation of the GABA EC20 currents through the four receptors mediated by saturating modulator concentrations did not differ substantially for any of the three benzodiazepines. The three compounds were substantially less potent (200-3900 fold as positive allosteric modulators at the α6β2δ GABA(AR than at the α(1,2,3,5β2γ(2S receptors. Interestingly, however, clobazam and especially N-desmethylclobazam were highly efficacious potentiators of α6β2δ receptor signaling. Although this activity component is unlikely to contribute to the in vivo effects of clobazam/N-desmethylclobazam, the 1,5-benzodiazepine could constitute an interesting lead for novel modulators targeting this low-affinity binding site in GABAARs. In conclusion, the non

  16. Affinities and densities of high-affinity [3H]muscimol (GABA-A) binding sites and of central benzodiazepine receptors are unchanged in autopsied brain tissue from cirrhotic patients with hepatic encephalopathy

    International Nuclear Information System (INIS)

    Butterworth, R.F.; Lavoie, J.; Giguere, J.F.; Pomier-Layrargues, G.

    1988-01-01

    The integrity of GABA-A receptors and of central benzodiazepine receptors was evaluated in membrane preparations from prefrontal cortex and caudate nuclei obtained at autopsy from nine cirrhotic patients who died in hepatic coma and an equal number of age-matched control subjects. Histopathological studies revealed Alzheimer Type II astrocytosis in all cases in the cirrhotic group; controls were free from neurological, psychiatric or hepatic diseases. Binding to GABA-A receptors was studied using [ 3 H]muscimol as radioligand. The integrity of central benzodiazepine receptors was evaluated using [ 3 H]flunitrazepam and [ 3 H]Ro15-1788. Data from saturation binding assays was analyzed by Scatchard plot. No modifications of either affinities (Kd) or densities (Bmax) of [ 3 H]muscimol of central benzodiazepine binding sites were observed. These findings do not support recent suggestions that alterations of either high-affinity GABA or benzodiazepine receptors play a significant role in the pathogenesis of hepatic encephalopathy

  17. Triton X-100 inhibits agonist-induced currents and suppresses benzodiazepine modulation of GABA(A) receptors in Xenopus oocytes

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Ebert, Bjarke; Klaerke, Dan

    2009-01-01

    Changes in lipid bilayer elastic properties have been proposed to underlie the modulation of voltage-gated Na(+) and L-type Ca(2+) channels and GABA(A) receptors by amphiphiles. The amphiphile Triton X-100 increases the elasticity of lipid bilayers at micromolar concentrations, assessed from its...... effects on gramicidin channel A appearance rate and lifetime in artificial lipid bilayers. In the present study, the pharmacological action of Triton-X 100 on GABA(A) receptors expressed in Xenopus laevis oocytes was examined. Triton-X 100 inhibited GABA(A) alpha(1)beta(3)gamma(2S) receptor currents...... in a noncompetitive, time- and voltage-dependent manner and increased the apparent rate and extent of desensitization at 10 muM, which is 30 fold below the critical micelle concentration. In addition, Triton X-100 induced picrotoxin-sensitive GABA(A) receptor currents and suppressed allosteric modulation...

  18. The brain GABA-benzodiazepine receptor alpha-5 subtype in autism spectrum disorder: a pilot [(11)C]Ro15-4513 positron emission tomography study.

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    Mendez, Maria Andreina; Horder, Jamie; Myers, Jim; Coghlan, Suzanne; Stokes, Paul; Erritzoe, David; Howes, Oliver; Lingford-Hughes, Anne; Murphy, Declan; Nutt, David

    2013-05-01

    GABA (gamma-amino-butyric-acid) is the primary inhibitory neurotransmitter in the human brain. It has been proposed that the symptoms of autism spectrum disorders (ASDs) are the result of deficient GABA neurotransmission, possibly including reduced expression of GABAA receptors. However, this hypothesis has not been directly tested in living adults with ASD. In this preliminary investigation, we used Positron Emission Tomography (PET) with the benzodiazepine receptor PET ligand [(11)C]Ro15-4513 to measure α1 and α5 subtypes of the GABAA receptor levels in the brain of three adult males with well-characterized high-functioning ASD compared with three healthy matched volunteers. We found significantly lower [(11)C]Ro15-4513 binding throughout the brain of participants with ASD (p < 0.0001) compared with controls. Planned region of interest analyses also revealed significant reductions in two limbic brain regions, namely the amygdala and nucleus accumbens bilaterally. Further analysis suggested that these results were driven by lower levels of the GABAA α5 subtype. These results provide initial evidence of a GABAA α5 deficit in ASD and support further investigations of the GABA system in this disorder. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Euphorbia hirta reverses chronic stress-induced anxiety and mediates its action through the GABA(A) receptor benzodiazepine receptor-Cl(-) channel complex.

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    Anuradha, H; Srikumar, B N; Shankaranarayana Rao, B S; Lakshmana, M

    2008-01-01

    Chronic stress is known to result in impairment of learning and memory and precipitate several affective disorders including depression and anxiety. Drugs of natural origin are known to possess several effects on the central nervous system and are emerging as promising alternative therapies. In this context, the hydroalcoholic extract of Euphorbia hirta (Eh) was evaluated for anxiolytic property in chronically stressed rats subjected to elevated plus maze (EPM) and open field test (OFT). Eh treatment (200 mg/kg, p.o.; seven days) showed marked anti-anxiety activity in chronic immobilization stress. In contrast, the forced swim stress-induced anxiety was only partially decreased by Eh. Co-treatment of rats with flumazenil (0.5 mg/kg, i.p.), bicuculline (1 mg/kg, i.p.) or picrotoxin (1 mg/kg, i.p.) resulted in a significant reduction of anxiolytic effect of Eh indicating that its actions are mediated through GABA(A) receptor-benzodiazepine receptor-Cl(-) channel complex. Thus, our studies indicate that Eh is a potential anxiolytic drug, which might be beneficial in the treatment of stress-induced anxiety disorders.

  20. The GABA-A benzodiazepine receptor complex: Role of pet and spect in neurology and psychiatry; Der GABA-A-benzodiazepinrezeptorkomplex: Rolle von PET und SPECT in Neurologie und Psychiatrie

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    Juengling, F.D. [Abt. fuer Nuklearmedizin, Radiologie III, Universitaetsklinik Ulm (Germany); Schaefer, M.; Heinz, A. [Klinik fuer Psychiatrie und Psychotherapie, Charite, Humboldt-Univ. zu Berlin (Germany)

    2002-09-01

    Nuclear medicine imaging techniques such as positron emission tomography (PET) and single photon emission tomography (SPECT) for selective depiction of GABA-A-benzodiazepine receptor (GBZR) binding are complementary investigations in the diagnostic process of neurological and psychiatric disorders. This review summarizes the current knowledge about options and limitations of PET and SPECT for in vivo diagnostics in neurology and psychiatry. The growing importance of GBZR-imaging for the understanding of pathophysiology and pharmacological treatment in different psychiatric syndromes is discussed. (orig.) [German] Mit der Entwicklung selektiver Liganden fuer den GABA-A-Benzodiazepinrezeptorkomplex (GBZR) hat die nuklearmedizinische Bildgebung mittels positronen-emissionstomographie (PET) und single-photon-emissionscomputertomographie (SPECT) einen festen Stellenwert fuer Klinik und Forschung in der Neurologie und Psychiatrie erlangt. Die vorliegende Ueberblicksarbeit fasst den aktuellen Wissensstand von Anwendungsmoeglichkeiten und -grenzen der nuklearmedizinischen Bildgebung der GBZR in vivo zusammen und beleuchtet ihren klinischen Nutzen. Die wachsende Bedeutung fuer das Verstaendnis der Pathophysiologie und pharmakotherapeutischer Konzepte unterschiedlicher psychiatrischer Erkrankungen wird herausgestellt. (orig.)

  1. GABA-B receptor activation and conflict behavior

    International Nuclear Information System (INIS)

    Ketelaars, C.E.J.; Bollen, E.L.; Rigter, H.; Bruinvels, J.

    1988-01-01

    Baclofen and oxazepam enhance extinction of conflict behavior in the Geller-Seifter test while baclofen and diazepam release punished behavior in Vogel's conflict test. In order to investigate the possibility that the effect of the selective GABA-B receptor agonist baclofen is mediated indirectly via the GABA-A/benzodiazepine receptor complex, the effect of pretreatment of rats with baclofen on [ 3 H]-diazepam binding to washed and unwashed cortical and cerebellar membranes of rats has been studied. Baclofen pretreatment increase Bmax in washed cerebellar membranes when bicuculline was present in the incubation mixture. No effect was seen in cortical membranes. The present results render it unlikely that the effect of baclofen on extinction of conflict behavior and punished drinking is mediated via the GABA-A/benzodiazepine receptor complex. 50 references, 1 figure, 4 tables

  2. The Anticonvulsant Activity of a Flavonoid-Rich Extract from Orange Juice Involves both NMDA and GABA-Benzodiazepine Receptor Complexes

    Directory of Open Access Journals (Sweden)

    Rita Citraro

    2016-09-01

    Full Text Available The usage of dietary supplements and other natural products to treat neurological diseases has been growing over time, and accumulating evidence suggests that flavonoids possess anticonvulsant properties. The aim of this study was to examine the effects of a flavonoid-rich extract from orange juice (OJe in some rodent models of epilepsy and to explore its possible mechanism of action. The genetically audiogenic seizures (AGS-susceptible DBA/2 mouse, the pentylenetetrazole (PTZ-induced seizures in ICR-CD1 mice and the WAG/Rij rat as a genetic model of absence epilepsy with comorbidity of depression were used. Our results demonstrate that OJe was able to exert anticonvulsant effects on AGS-sensible DBA/2 mice and to inhibit PTZ-induced tonic seizures, increasing their latency. Conversely, it did not have anti-absence effects on WAG/Rij rats. Our experimental findings suggest that the anti-convulsant effects of OJe are likely mediated by both an inhibition of NMDA receptors at the glycine-binding site and an agonistic activity on benzodiazepine-binding site at GABAA receptors. This study provides evidences for the antiepileptic activity of OJe, and its results could be used as scientific basis for further researches aimed to develop novel complementary therapy for the treatment of epilepsy in a context of a multitarget pharmacological strategy.

  3. Stability of solubilized benzodiazepine receptors

    NARCIS (Netherlands)

    Janssen, M.J; Ensing, K; de Zeeuw, R.A

    1997-01-01

    According to the observations of other researchers, benzodiazepine receptors solubilized with sodium deoxycholate are unstable, but stability can be improved by exchanging deoxycholate for Triton X-100. In our experiments we conclude that the choice of detergent is not the restrictive factor for the

  4. On the benzodiazepine binding pocket in GABAA receptors.

    Science.gov (United States)

    Berezhnoy, Dmytro; Nyfeler, Yves; Gonthier, Anne; Schwob, Hervé; Goeldner, Maurice; Sigel, Erwin

    2004-01-30

    Benzodiazepines are used for their sedative/hypnotic, anxiolytic, muscle relaxant, and anticonvulsive effects. They exert their actions through a specific high affinity binding site on the major inhibitory neurotransmitter receptor, the gamma-aminobutyric acid, type A (GABA(A)) receptor channel, where they act as positive allosteric modulators. To start to elucidate the relative positioning of benzodiazepine binding site ligands in their binding pocket, GABA(A) receptor residues thought to reside in the site were individually mutated to cysteine and combined with benzodiazepine analogs carrying substituents reactive to cysteine. Direct apposition of such reactive partners is expected to lead to an irreversible site-directed reaction. We describe here the covalent interaction of alpha(1)H101C with a reactive group attached to the C-7 position of diazepam. This interaction was studied at the level of radioactive ligand binding and at the functional level using electrophysiological methods. Covalent reaction occurs concomitantly with occupancy of the binding pocket. It stabilizes the receptor in its allosterically stimulated conformation. Covalent modification is not observed in wild type receptors or when using mutated alpha(1)H101C-containing receptors in combination with the reactive ligand pre-reacted with a sulfhydryl group, and the modification rate is reduced by the binding site ligand Ro15-1788. We present in addition evidence that gamma(2)Ala-79 is probably located in the access pathway of the ligand to its binding pocket.

  5. Characterization of astrocytic and neuronal benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bender, A.S.

    1988-01-01

    Primary cultures of astrocytes and neurons express benzodiazepine receptors. Neuronal benzodiazepine receptors were of high-affinity, K{sub D} values were 7.5-43 nM and the densities of receptors (B{sub max}) were 924-4131 fmol/mg protein. Astrocytes posses a high-affinity benzodiazepine receptor, K{sub D} values were 6.6-13 nM. The B{sub max} values were 6,033-12,000 fmol/mg protein. The pharmacological profile of the neuronal benzodiazepine receptor was that of the central-type benzodiazepine receptor, where clonazepam has a high-affinity and Ro 5-4864 (4{prime}-chlorodiazepam) has a low-affinity. Whereas astrocytic benzoidazepine receptor was characteristic of the so called peripheral-type benzodiazepine receptors, which shows a high-affinity towards Ro 5-4863, and a low-affinity towards clonazepam. The astrocytic benzodiazepine receptors was functionally correlated with voltage dependent calcium channels, since dihydropyridines and benzodiazepines interacted with ({sup 3}H) diazepam and ({sup 3}H) nitrendipine receptors with the same rank order of potency, showing a statistically significant correlation. No such correlation was observed in neurons.

  6. Daily rhythms of benzodiazepine receptor numbers in frontal lobe and cerebellum of the rat

    International Nuclear Information System (INIS)

    Brennan, M.J.W.; Volicer, L.; Moore-Ede, M.C.; Borsook, D.

    1985-01-01

    Behavioral, biochemical and neurophysiological evidence suggests that gamma-aminobutyric acid (GABA) may play an important role in the neural control of circadian rhythms. Central receptors for benzodiazepines are functionally coupled to GABA receptors and appear to mediate behavioral effects of exogenous benzodiazepines. The binding of 3 H-flunitrazepam to synaptic plasma membranes prepared from various regions of rat brain was examined at 6-hour intervals over a 36-hour period. Prominent daily rhythms in receptor number (Bmax) were observed in the frontal lobe and the cerebellum but not in the temporoparietal regions, hypothalamus or medulla/pons. Binding was highest during periods of sleep/low activity with a significant decrease occurring just prior to waking. These results suggest that daily fluctuations in benzodiazepine receptor numbers may be related to the temporal control of sleep/wake and muscle activity cycles. 23 references, 1 figure, 1 table

  7. Actions of insecticides on the insect GABA receptor complex

    Energy Technology Data Exchange (ETDEWEB)

    Bermudez, I.; Hawkins, C.A.; Taylor, A.M.; Beadle, D.J. (School of Biological and Molecular Sciences, Oxford Polytechnic, Headington, Oxford (England))

    1991-01-01

    The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using (35S)t-butylbicyclophosphorothionate (( 35S)TBPS) binding and voltage-clamp techniques. Specific binding of (35S)TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 {plus minus} 2.9 nM and a Bmax value of 1770 {plus minus} 40 fmol/mg protein. (35S)TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of (35S)TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on (35S)TBPS binding. These results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current.

  8. Actions of insecticides on the insect GABA receptor complex

    International Nuclear Information System (INIS)

    Bermudez, I.; Hawkins, C.A.; Taylor, A.M.; Beadle, D.J.

    1991-01-01

    The actions of insecticides on the insect gamma-aminobutyric acid (GABA) receptor were investigated using [35S]t-butylbicyclophosphorothionate [( 35S]TBPS) binding and voltage-clamp techniques. Specific binding of [35S]TBPS to a membrane homogenate derived from the brain of Locusta migratoria locusts is characterised by a Kd value of 79.3 ± 2.9 nM and a Bmax value of 1770 ± 40 fmol/mg protein. [35S]TBPS binding is inhibited by mM concentrations of barbiturates and benzodiazepines. In contrast dieldrin, ivermectin, lindane, picrotoxin and TBPS are inhibitors of [35S]TBPS binding at the nanomolar range. Bicuculline, baclofen and pyrethroid insecticides have no effect on [35S]TBPS binding. These results are similar to those obtained in electrophysiological studies of the current elicited by GABA in both Locusta and Periplaneta americana central neurones. Noise analysis of the effects of lindane, TBPS, dieldrin and picrotoxin on the cockroach GABA responses reveals that these compounds decrease the variance of the GABA-induced current but have no effect on its mean open time. All these compounds, with the exception of dieldrin, significantly decrease the conductance of GABA-evoked single current

  9. Analysis of subcomponents of the gamma-aminobutyric acid/benzodiazepine receptor macromolecular complex in mammalian central nervous system

    International Nuclear Information System (INIS)

    McCabe, R.T.

    1987-01-01

    Since the presence of endogenous gamma-aminobutyric acid (GABA) may affect benzodiazepine binding to tissue sections in autoradiographic studies, a protocol designed to check for this influence has been investigated. [ 3 H]Flunitrazepam (1 nM) was used to label benzodiazepine receptors for autoradiographic localization. Bicuculline was added to the incubation medium of an additional set of tissue sections to antagonize any potential effect of endogenous GABA. Binding in these sections was compared to that occurring in another set in which excess GABA was added to create further GABA enhancement. Binding was also compared to adjacent sections which were treated similarly but also preincubated in distilled-deionized water to burst the cells by osmotic shock and eliminate endogenous GABA, thereby preventing any effect on benzodiazepine binding. The results indicated that endogenous GABA is indeed present in the slide-mounted tissue sections and is affecting benzodiazepine receptor binding differentially in various regions of the brain depending on the density of GABAergic innervation. Scatchard analysis of saturation data demonstrated that the alteration in BZ binding due to GABA was a result of a change in the affinity rather than number of receptors present

  10. GABA(A receptor α subunits differentially contribute to diazepam tolerance after chronic treatment.

    Directory of Open Access Journals (Sweden)

    Christiaan H Vinkers

    Full Text Available Within the GABA(A-receptor field, two important questions are what molecular mechanisms underlie benzodiazepine tolerance, and whether tolerance can be ascribed to certain GABA(A-receptor subtypes.We investigated tolerance to acute anxiolytic, hypothermic and sedative effects of diazepam in mice exposed for 28-days to non-selective/selective GABA(A-receptor positive allosteric modulators: diazepam (non-selective, bretazenil (partial non-selective, zolpidem (α(1 selective and TPA023 (α(2/3 selective. In-vivo binding studies with [(3H]flumazenil confirmed compounds occupied CNS GABA(A receptors.Chronic diazepam treatment resulted in tolerance to diazepam's acute anxiolytic, hypothermic and sedative effects. In mice treated chronically with bretazenil, tolerance to diazepam's anxiolytic and hypothermic, but not sedative, effects was seen. Chronic zolpidem treatment resulted in tolerance to diazepam's hypothermic effect, but partial anxiolytic tolerance and no sedative tolerance. Chronic TPA023 treatment did not result in tolerance to diazepam's hypothermic, anxiolytic or sedative effects.OUR DATA INDICATE THAT: (i GABA(A-α(2/α(3 subtype selective drugs might not induce tolerance; (ii in rodents quantitative and temporal variations in tolerance development occur dependent on the endpoint assessed, consistent with clinical experience with benzodiazepines (e.g., differential tolerance to antiepileptic and anxiolytic actions; (iii tolerance to diazepam's sedative actions needs concomitant activation of GABA(A-α(1/GABA(A-α(5 receptors. Regarding mechanism, in-situ hybridization studies indicated no gross changes in expression levels of GABA(A α(1, α(2 or α(5 subunit mRNA in hippocampus or cortex. Since selective chronic activation of either GABA(A α(2, or α(3 receptors does not engender tolerance development, subtype-selective GABA(A drugs might constitute a promising class of novel drugs.

  11. Anaesthetic impairment of immune function is mediated via GABA(A receptors.

    Directory of Open Access Journals (Sweden)

    Daniel W Wheeler

    2011-02-01

    Full Text Available GABA(A receptors are members of the Cys-loop family of neurotransmitter receptors, proteins which are responsible for fast synaptic transmission, and are the site of action of wide range of drugs. Recent work has shown that Cys-loop receptors are present on immune cells, but their physiological roles and the effects of drugs that modify their function in the innate immune system are currently unclear. We are interested in how and why anaesthetics increase infections in intensive care patients; a serious problem as more than 50% of patients with severe sepsis will die. As many anaesthetics act via GABA(A receptors, the aim of this study was to determine if these receptors are present on immune cells, and could play a role in immunocompromising patients.We demonstrate, using RT-PCR, that monocytes express GABA(A receptors constructed of α1, α4, β2, γ1 and/or δ subunits. Whole cell patch clamp electrophysiological studies show that GABA can activate these receptors, resulting in the opening of a chloride-selective channel; activation is inhibited by the GABA(A receptor antagonists bicuculline and picrotoxin, but not enhanced by the positive modulator diazepam. The anaesthetic drugs propofol and thiopental, which can act via GABA(A receptors, impaired monocyte function in classic immunological chemotaxis and phagocytosis assays, an effect reversed by bicuculline and picrotoxin.Our results show that functional GABA(A receptors are present on monocytes with properties similar to CNS GABA(A receptors. The functional data provide a possible explanation as to why chronic propofol and thiopental administration can increase the risk of infection in critically ill patients: their action on GABA(A receptors inhibits normal monocyte behaviour. The data also suggest a potential solution: monocyte GABA(A receptors are insensitive to diazepam, thus the use of benzodiazepines as an alternative anesthetising agent may be advantageous where infection is a life

  12. Anaesthetic impairment of immune function is mediated via GABA(A) receptors.

    Science.gov (United States)

    Wheeler, Daniel W; Thompson, Andrew J; Corletto, Federico; Reckless, Jill; Loke, Justin C T; Lapaque, Nicolas; Grant, Andrew J; Mastroeni, Pietro; Grainger, David J; Padgett, Claire L; O'Brien, John A; Miller, Nigel G A; Trowsdale, John; Lummis, Sarah C R; Menon, David K; Beech, John S

    2011-02-24

    GABA(A) receptors are members of the Cys-loop family of neurotransmitter receptors, proteins which are responsible for fast synaptic transmission, and are the site of action of wide range of drugs. Recent work has shown that Cys-loop receptors are present on immune cells, but their physiological roles and the effects of drugs that modify their function in the innate immune system are currently unclear. We are interested in how and why anaesthetics increase infections in intensive care patients; a serious problem as more than 50% of patients with severe sepsis will die. As many anaesthetics act via GABA(A) receptors, the aim of this study was to determine if these receptors are present on immune cells, and could play a role in immunocompromising patients. We demonstrate, using RT-PCR, that monocytes express GABA(A) receptors constructed of α1, α4, β2, γ1 and/or δ subunits. Whole cell patch clamp electrophysiological studies show that GABA can activate these receptors, resulting in the opening of a chloride-selective channel; activation is inhibited by the GABA(A) receptor antagonists bicuculline and picrotoxin, but not enhanced by the positive modulator diazepam. The anaesthetic drugs propofol and thiopental, which can act via GABA(A) receptors, impaired monocyte function in classic immunological chemotaxis and phagocytosis assays, an effect reversed by bicuculline and picrotoxin. Our results show that functional GABA(A) receptors are present on monocytes with properties similar to CNS GABA(A) receptors. The functional data provide a possible explanation as to why chronic propofol and thiopental administration can increase the risk of infection in critically ill patients: their action on GABA(A) receptors inhibits normal monocyte behaviour. The data also suggest a potential solution: monocyte GABA(A) receptors are insensitive to diazepam, thus the use of benzodiazepines as an alternative anesthetising agent may be advantageous where infection is a life

  13. Mitochondrial benzodiazepine receptors regulate steroid biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mukhin, A.G.; Papadopoulos, V.; Costa, E.; Krueger, K.E. (Georgetown Univ. School of Medicine, Washington, DC (USA))

    1989-12-01

    Recent observations on the steroid synthetic capability within the brain open the possibility that benzodiazepines may influence steroid synthesis in nervous tissue through interactions with peripheral-type benzodiazepine recognition sites, which are highly expressed in steroidogenic cells and associated with the outer mitochondrial membrane. To examine this possibility nine molecules that exhibit a greater than 10,000-fold difference in their affinities for peripheral-type benzodiazepine binding sites were tested for their effects on a well-established steroidogenic model system, the Y-1 mouse adrenal tumor cell line. 4{prime}-Chlorodiazepam, PK 11195, and PK 14067 stimulated steroid production by 2-fold in Y-1 cells, whereas diazepam, flunitrazepam, zolpidem, and PK 14068 displayed a lower (1.2- to 1.5-fold) maximal stimulation. In contrast, clonazepam and flumazenil did not stimulate steroid synthesis. The potencies of these compounds to inhibit {sup 3}H-labeled PK 11195 binding to peripheral-type benzodiazepine recognition sites correlated with their potencies to stimulate steroid production. Similar findings were observed in bovine and rat adrenocortical cell preparations. These results suggest that ligands of the peripheral-type benzodiazepine recognition site acting on this mitochondrial receptor can enhance steroid production. This action may contribute specificity to the pharmacological profile of drugs preferentially acting on the benzodiazepine recognition site associated with the outer membrane of certain mitochondrial populations.

  14. Early ontogeny of the central benzodiazepine receptor in human embryos and fetuses

    Energy Technology Data Exchange (ETDEWEB)

    Hebebrand, J.; Hofmann, D.; Reichelt, R.; Schnarr, S.; Knapp, M.; Propping, P.; Foedisch, H.J.

    1988-01-01

    The early ontogeny of the central benzodiazepine receptor (BZR) was investigated in human embryos and fetuses between 7 and 26 weeks of gestation. Brain tissue was gained from terminated pregnancies or spontaneous abortions. Binding studies, which were performed with /sup 3/H-flunitrazepam (FNZ), revealed that specific benzodiazepine binding is already detectable at an embryonal age of 7 weeks post conception. Binding at this early stage can be displaced potently by clonazepam and the inverse agonist ..beta..-CCE. Additionally, /sup 3/H-FNZ binding is enhanced by GABA. Thus, benzodiazepine binding is of the central type. Receptor density increases steeply in whole brain between weeks 8 and 11 of gestation. In frontal cortex receptor density increases gradually between weeks 12 and 26 of gestation. No specific fetal disease entity (including trisomy 21) was consistently associated with exceptionally high or low B/sub max/-values.

  15. Allosteric ligands and their binding sites define γ-aminobutyric acid (GABA) type A receptor subtypes.

    Science.gov (United States)

    Olsen, Richard W

    2015-01-01

    GABAA receptors (GABA(A)Rs) mediate rapid inhibitory transmission in the brain. GABA(A)Rs are ligand-gated chloride ion channel proteins and exist in about a dozen or more heteropentameric subtypes exhibiting variable age and brain regional localization and thus participation in differing brain functions and diseases. GABA(A)Rs are also subject to modulation by several chemotypes of allosteric ligands that help define structure and function, including subtype definition. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABA(A)Rs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Two classes of pharmacologically important allosteric modulatory ligand binding sites reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site and the high-affinity, relevant to intoxication, ethanol site. The benzodiazepine site is specific for certain GABA(A)R subtypes, mainly synaptic, while the ethanol site is found at a modified benzodiazepine site on different, extrasynaptic, subtypes. In the transmembrane domain are allosteric modulatory ligand sites for diverse chemotypes of general anesthetics: the volatile and intravenous agents, barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are endogenous positive allosteric modulators. X-ray crystal structures of prokaryotic and invertebrate pentameric ligand-gated ion channels, and the mammalian GABA(A)R protein, allow homology modeling of GABA(A)R subtypes with the various ligand sites located to suggest the structure and function of these proteins and their pharmacological modulation. © 2015 Elsevier Inc. All rights reserved.

  16. The residence time of GABA(A)Rs at inhibitory synapses is determined by direct binding of the receptor α1 subunit to gephyrin

    DEFF Research Database (Denmark)

    Mukherjee, Jayanta; Kretschmannova, Karla; Gouzer, Geraldine

    2011-01-01

    The majority of fast synaptic inhibition in the brain is mediated by benzodiazepine-sensitive α1-subunit-containing GABA type A receptors (GABA(A)Rs); however, our knowledge of the mechanisms neurons use to regulate their synaptic accumulation is rudimentary. Using immunoprecipitation, we demonst...

  17. Decrease in benzodiazepine receptor binding in a patient with Angelman syndrome detected by iodine-123 iomazenil and single-photon emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Odano, Ikuo [Dept. of Radiology, Niigata Univ. School of Medicine, Niigata (Japan); Anezaki, Toshiharu [Dept. of Neurology, Brain Research Inst., Niigata Univ., Niigata (Japan); Ohkubo, Masaki [Dept. of Radiology, Niigata Univ. School of Medicine, Niigata (Japan); Yonekura, Yoshiharu [Nihon Medi-Physics Co. Ltd., Hyogo (Japan); Onishi, Yoshihiro [Biomedical Imaging Research Center, Fukui Medical School, Fukui (Japan); Inuzuka, Takashi [Dept. of Neurology, Brain Research Inst., Niigata Univ., Niigata (Japan); Takahashi, Makoto [Dept. of Radiology, Niigata Univ. School of Medicine, Niigata (Japan); Tsuji, Shoji [Dept. of Neurology, Brain Research Inst., Niigata Univ., Niigata (Japan)

    1996-05-01

    A receptor mapping technique using iodine-123 iomazenil and single-photon emission tomography (SPET) was employed to examine benzodiazepine receptor binding in a patient with Angelman syndrome (AS). AS is characterized by developmental delay, seizures, inappropriate laughter and ataxic movement. In this entity there is a cytogenic deletion of the proximal long arm of chromosome 15q11-q13, where the gene encoding the GABA{sub A} receptor {beta}3 subunit (GABRB3) is located. Since the benzodiazepine receptor is constructed as a receptor-ionophore complex that contains the GABA{sub A} receptor, it is a suitable marker for GABA-ergic synapsis. To determine whether benzodiazepine receptor density, which indirectly indicates changes in GABA{sub A} receptor density, is altered in the brain in patients with AS, we investigated a 27-year-old woman with AS using {sup 123}I-iomazenil and SPET. Receptor density was quantitatively assessed by measuring the binding potential using a simplified method. Regional cerebral blood flow was also measured with N-isopropyl-p-[{sup 123}]iodoamphetamine. We demonstrated that benzodiazepine receptor density is severely decreased in the cerebellum, and mildly decreased in the frontal and temporal cortices and basal ganglia, a result which is considered to indicate decreased GABA{sub A} receptor density in these regions. Although the deletion of GABRB3 was not observed in the present study, we indirectly demonstrated the disturbance of inhibitory neurotransmission mediated by the GABA{sub A} receptor in the investigated patient. {sup 123}I-iomazenil with SPET was useful to map benzodiazepine receptors, which indicate GABA{sub A} receptor distribution and their density. (orig.)

  18. Diazepam-bound GABAA receptor models identify new benzodiazepine binding-site ligands

    Science.gov (United States)

    Richter, Lars; de Graaf, Chris; Sieghart, Werner; Varagic, Zdravko; Mörzinger, Martina; de Esch, Iwan J P; Ecker, Gerhard F; Ernst, Margot

    2012-01-01

    Benzodiazepines exert their anxiolytic, anticonvulsant, muscle-relaxant and sedative-hypnotic properties by allosterically enhancing the action of GABA at GABAA receptors via their benzodiazepine-binding site. Although these drugs have been used clinically since 1960, the molecular basis of this interaction is still not known. By using multiple homology models and an un biased docking protocol, we identified a binding hypothesis for the diazepam-bound structure of the benzodiazepine site, which was confirmed by experimental evidence. Moreover, two independent virtual screening approaches based on this structure identified known benzodiazepine-site ligands from different structural classes and predicted potential new ligands for this site. Receptor-binding assays and electrophysiological studies on recombinant receptors confirmed these predictions and thus identified new chemotypes for the benzodiazepine-binding site. Our results support the validity of the diazepam-bound structure of the benzodiazepine-binding pocket, demonstrate its suitability for drug discovery and pave the way for structure-based drug design. PMID:22446838

  19. Bioassay-guided isolation of apigenin with GABA-benzodiazepine activity from Tanacetum parthenium

    DEFF Research Database (Denmark)

    Jäger, Anna Katharina; Krydsfeldt, Katrine; Rasmussen, Hasse Bonde

    2009-01-01

    was fractionated by VLC on silica and preparative C18 HPLC. Each step was monitored with the GABA(A)-benzodiazepine bioassay. The fractionation led to the isolation of apigenin, which may be responsible for CNS-effects of T. parthenium extracts. Copyright (c) 2009 John Wiley & Sons, Ltd....

  20. Novel agents acting on GABA2 receptors: potential cognitive enhancers

    International Nuclear Information System (INIS)

    Chebib, M.

    2001-01-01

    γ- Aminobutyric acid (GABA) is a low molecular weight ammo acid found throughout the central and peripheral nervous systems. It is a very flexible molecule and thus can attain a number of low-energy conformations which are recognised by a series of enzymes, receptors and transporter systems. This article will concentrate on the effects of GABA C as the major inhibitory neurotransmitter in the brain. GABA C receptors belong to the superfamily of ligand-gated ion channels that include nicotinic acetylcholine, GABA A , strychnine-sensitive glycine, and serotonin type 3 receptors. The compound outlined in this article provide us with novel leads for the design and development of compounds that may be selective for GABA receptors. Such compounds will help in the study of GABA C receptors both in vitro and in vivo, providing an insight into the role these receptors play in the brain

  1. Repeated swim stress alters brain benzodiazepine receptors measured in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Weizman, R.; Weizman, A.; Kook, K.A.; Vocci, F.; Deutsch, S.I.; Paul, S.M.

    1989-06-01

    The effects of repeated swim stress on brain benzodiazepine receptors were examined in the mouse using both an in vivo and in vitro binding method. Specific in vivo binding of (/sup 3/H)Ro15-1788 to benzodiazepine receptors was decreased in the hippocampus, cerebral cortex, hypothalamus, midbrain and striatum after repeated swim stress (7 consecutive days of daily swim stress) when compared to nonstressed mice. In vivo benzodiazepine receptor binding was unaltered after repeated swim stress in the cerebellum and pons medulla. The stress-induced reduction in in vivo benzodiazepine receptor binding did not appear to be due to altered cerebral blood flow or to an alteration in benzodiazepine metabolism or biodistribution because there was no difference in (14C)iodoantipyrine distribution or whole brain concentrations of clonazepam after repeated swim stress. Saturation binding experiments revealed a change in both apparent maximal binding capacity and affinity after repeated swim stress. Moreover, a reduction in clonazepam's anticonvulsant potency was also observed after repeated swim stress (an increase in the ED50 dose for protection against pentylenetetrazol-induced seizures), although there was no difference in pentylenetetrazol-induced seizure threshold between the two groups. In contrast to the results obtained in vivo, no change in benzodiazepine receptor binding kinetics was observed using the in vitro binding method. These data suggest that environmental stress can alter the binding parameters of the benzodiazepine receptor and that the in vivo and in vitro binding methods can yield substantially different results.

  2. Repeated swim stress alters brain benzodiazepine receptors measured in vivo

    International Nuclear Information System (INIS)

    Weizman, R.; Weizman, A.; Kook, K.A.; Vocci, F.; Deutsch, S.I.; Paul, S.M.

    1989-01-01

    The effects of repeated swim stress on brain benzodiazepine receptors were examined in the mouse using both an in vivo and in vitro binding method. Specific in vivo binding of [ 3 H]Ro15-1788 to benzodiazepine receptors was decreased in the hippocampus, cerebral cortex, hypothalamus, midbrain and striatum after repeated swim stress (7 consecutive days of daily swim stress) when compared to nonstressed mice. In vivo benzodiazepine receptor binding was unaltered after repeated swim stress in the cerebellum and pons medulla. The stress-induced reduction in in vivo benzodiazepine receptor binding did not appear to be due to altered cerebral blood flow or to an alteration in benzodiazepine metabolism or biodistribution because there was no difference in [14C]iodoantipyrine distribution or whole brain concentrations of clonazepam after repeated swim stress. Saturation binding experiments revealed a change in both apparent maximal binding capacity and affinity after repeated swim stress. Moreover, a reduction in clonazepam's anticonvulsant potency was also observed after repeated swim stress [an increase in the ED50 dose for protection against pentylenetetrazol-induced seizures], although there was no difference in pentylenetetrazol-induced seizure threshold between the two groups. In contrast to the results obtained in vivo, no change in benzodiazepine receptor binding kinetics was observed using the in vitro binding method. These data suggest that environmental stress can alter the binding parameters of the benzodiazepine receptor and that the in vivo and in vitro binding methods can yield substantially different results

  3. Characteristics of benzodiazepine receptors in rats differing in predisposition to experimental alcoholism

    International Nuclear Information System (INIS)

    Burov, Yu.V.; Maiskii, A.I.; Yukhananov, R.Yu.

    1986-01-01

    This paper studies the number and affinity of benzodiazepine receptors for diazepam in the cerebral cortex and hippocampus of rats differently predisposed to the development of experimental alcoholism. Ethanol was injected once intraperitoneally, in a dose of 2.5 g/kg. Control animals received the same volume of physiological saline. Bound and free N-methyl-tritium-diazepam were separated by means of GF/B filters. The characteristics of benzodiazepine receptors are shown in rats differing in predisposition to the development of experimental alcoholism and in rats during voluntary chronic alcoholization. It is shown that weakening of functional acitivity of the GABA-benzodiazepam complex in animals predisposed to the development of experimental alcoholism is one of the neurochemical mechanisms of development of the abstinence syndrome

  4. A novel GABA(A) alpha 5 receptor inhibitor with therapeutic potential.

    Science.gov (United States)

    Ling, István; Mihalik, Balázs; Etherington, Lori-An; Kapus, Gábor; Pálvölgyi, Adrienn; Gigler, Gábor; Kertész, Szabolcs; Gaál, Attila; Pallagi, Katalin; Kiricsi, Péter; Szabó, Éva; Szénási, Gábor; Papp, Lilla; Hársing, László G; Lévay, György; Spedding, Michael; Lambert, Jeremy J; Belelli, Delia; Barkóczy, József; Volk, Balázs; Simig, Gyula; Gacsályi, István; Antoni, Ferenc A

    2015-10-05

    Novel 2,3-benzodiazepine and related isoquinoline derivatives, substituted at position 1 with a 2-benzothiophenyl moiety, were synthesized to produce compounds that potently inhibited the action of GABA on heterologously expressed GABAA receptors containing the alpha 5 subunit (GABAA α5), with no apparent affinity for the benzodiazepine site. Substitutions of the benzothiophene moiety at position 4 led to compounds with drug-like properties that were putative inhibitors of extra-synaptic GABAA α5 receptors and had substantial blood-brain barrier permeability. Initial characterization in vivo showed that 8-methyl-5-[4-(trifluoromethyl)-1-benzothiophen-2-yl]-1,9-dihydro-2H-[1,3]oxazolo[4,5-h][2,3]benzodiazepin-2-one was devoid of sedative, pro-convulsive or motor side-effects, and enhanced the performance of rats in the object recognition test. In summary, we have discovered a first-in-class GABA-site inhibitor of extra-synaptic GABAA α5 receptors that has promising drug-like properties and warrants further development. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. GABA(A) receptor- and GABA transporter polymorphisms and risk for essential tremor

    DEFF Research Database (Denmark)

    Thier, S; Kuhlenbäumer, G; Lorenz, D

    2011-01-01

    Background:  Clinical features and animal models of essential tremor (ET) suggest gamma-aminobutyric acid A receptor (GABA(A) R) subunits and GABA transporters as putative candidate genes. Methods:  A total of 503 ET cases and 818 controls were investigated for an association between polymorphisms...... in 15 GABA(A) R and four GABA transporter genes and ET. Results:  Nine nominally significant tagging SNPs (P values from 4.9 × 10(-2) to 5.2 × 10(-4) ) were found in the hypothesis generation stage. Five SNPs were followed up in a second verification stage but failed to reach significance. (P values...... from 0.30 to 0.77). Discussion:  In our samples, no evidence of association between GABA(A) R and GABA transporter genes with ET was detected. Further studies are necessary to clarify the role of these genes in ET....

  6. Hyperalgesic effect induced by barbiturates, midazolam and ethanol: pharmacological evidence for GABA-A receptor involvement

    Directory of Open Access Journals (Sweden)

    M.A.K.F. Tatsuo

    1997-02-01

    Full Text Available The involvement of GABA-A receptors in the control of nociception was studied using the tail-flick test in rats. Non-hypnotic doses of the barbiturates phenobarbital (5-50 mg/kg, pentobarbital (17-33 mg/kg, and thiopental (7.5-30 mg/kg, of the benzodiazepine midazolam (10 mg/kg or of ethanol (0.4-1.6 g/kg administered by the systemic route reduced the latency for the tail-flick response, thus inducing a 'hyperalgesic' state in the animals. In contrast, non-convulsant doses of the GABA-A antagonist picrotoxin (0.12-1.0 mg/kg administered systemically induced an increase in the latency for the tail-flick response, therefore characterizing an 'antinociceptive' state. Previous picrotoxin (0.12 mg/kg treatment abolished the hyperalgesic state induced by effective doses of the barbiturates, midazolam or ethanol. Since phenobarbital, midazolam and ethanol reproduced the described hyperalgesic effect of GABA-A-specific agonists (muscimol, THIP, which is specifically antagonized by the GABA-A antagonist picrotoxin, our results suggest that GABA-A receptors are tonically involved in the modulation of nociception in the rat central nervous system

  7. Benzodiazepine modulation of partial agonist efficacy and spontaneously active GABAA receptors supports an allosteric model of modulation

    OpenAIRE

    Downing, Scott S; Lee, Yan T; Farb, David H; Gibbs, Terrell T

    2005-01-01

    Benzodiazepines (BZDs) have been used extensively for more than 40 years because of their high therapeutic index and low toxicity. Although BZDs are understood to act primarily as allosteric modulators of GABAA receptors, the mechanism of modulation is not well understood.The applicability of an allosteric model with two binding sites for γ-aminobutyric acid (GABA) and one for a BZD-like modulator was investigated.This model predicts that BZDs should enhance the efficacy of partial agonists.C...

  8. Benzodiazepine receptors: Labeling in intact animals with [3H] flunitrazepam

    International Nuclear Information System (INIS)

    Chang, R.S.L.; Snyder, S.H.

    1978-01-01

    [ 3 H] Flunitrazepam appears to label specific benzodiazepine receptors in vitro after i.v. injection in mice. Benzodiazepine potencies in reducing [ 3 H] flunitrazepam binding in vitro corresponds to pharmacological potencies and parallel relative affinities for [ 3 H] flunitrazepam binding sites in isolated brain membranes. However, 50% occupation of [ 3 H]-flunitrazepam sites by benzodiazepines in vivo requires concentrations of the drugs about 1000 times higher than their Ksub(i) values for the binding sites in vitro. In pharmacologically active doses sodium pentobarbital, strychnine, picrotoxin and bicuculline fail to influence [ 3 H] flunitrazepam binding in vivo. (Auth.)

  9. Temporal development of GABA agonist induced alterations in ultrastructure and GABA receptor expression in cultured cerebellar granule cells

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Belhage, B; Schousboe, A

    1987-01-01

    The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays...... exposed to THIP (150 microM) for 3 hr low affinity GABA receptors were induced. These findings show that the effect of THIP on the ultrastructure composition and GABA receptor expression in cultured cerebellar granule cells may be interrelated and moreover it is likely that the turn-over of GABA receptors...

  10. Blockade of alcohol's amnestic activity in humans by an alpha5 subtype benzodiazepine receptor inverse agonist.

    Science.gov (United States)

    Nutt, David J; Besson, Marie; Wilson, Susan J; Dawson, Gerard R; Lingford-Hughes, Anne R

    2007-12-01

    Alcohol produces many subjective and objective effects in man including pleasure, sedation, anxiolysis, plus impaired eye movements and memory. In human volunteers we have used a newly available GABA-A/benzodiazepine receptor inverse agonist that is selective for the alpha5 subtype (a5IA) to evaluate the role of this subtype in mediating these effects of alcohol on the brain. After pre-treatment with a5IA, we found almost complete blockade of the marked impairment caused by alcohol (mean breath concentration 150mg/100ml) of word list learning and partial but non-significant reversal of subjective sedation without effects on other measures such as intoxication, liking, and slowing of eye movements. This action was not due to alterations in alcohol kinetics and so provides the first proof of concept that selectively decreasing GABA-A receptor function at a specific receptor subtype can offset some actions of alcohol in humans. It also supports growing evidence for a key role of the alpha5 subtype in memory. Inverse agonists at other GABA-A receptor subtypes may prove able to reverse other actions of alcohol, and so offer a new approach to understanding the actions of alcohol in the human brain and in the treatment of alcohol related disorders in humans.

  11. Imaging of a glioma using peripheral benzodiazepine receptor ligands

    Energy Technology Data Exchange (ETDEWEB)

    Starosta-Rubinstein, S.; Ciliax, B.J.; Penney, J.B.; McKeever, P.; Young, A.B.

    1987-02-01

    Two types of benzodiazepine receptors have been demonstrated in mammalian tissues, one which is localized on neuronal elements in brain and the other, on glial cells and in peripheral tissues such as kidney. In vivo administration of /sup 3/H-labeled PK 11195 (1-(2-chlorophenyl-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide) or (/sup 3/H)flunitrazepam with 5 mg of clonazepam per kg to rats with intracranial C6 gliomas resulted in high levels of tritiated-drug binding to the tumor as shown by quantitative autoradiography. Pharmacological studies indicated that the bound drugs labeled the peripheral benzodiazepine binding site. Binding to the peripheral benzodiazepine site was confirmed primarily to malignant cells with little binding to adjacent normal brain tissue or to necrotic tissue. Tumor cell binding was completely inhibited by preadministration of the peripheral benzodiazepine blocking agent PK 11195 at 5 mg/kg. The centrally selective benzodiazepine ligand clonazepam had no effect on PK 11195 binding to the tumor cells. When binding to other tumor cell lines grown in nude mice and nude athymic rats was evaluated, little or no peripheral benzodiazepine binding was detected on human pheochromocytoma (RN1) and neuroblastoma (SK-N-MC, SK-N-SH) tumor cells, respectively. However, high densities of peripheral benzodiazepine binding sites were observed on tumors derived from a human glioma cell line (ATCC HTB 14, U-87 MG). The presence of high concentrations of specific peripheral benzodiazepine receptors on glial tumors suggests that human primary central nervous system tumors could be imaged and diagnosed using peripheral benzodiazepine ligands labeled with positron- or gamma-emitting isotopes.

  12. Effects of the benzodiazepine receptor antagonist flumazenil in hepatic encephalopathy in humans.

    Science.gov (United States)

    Bansky, G; Meier, P J; Riederer, E; Walser, H; Ziegler, W H; Schmid, M

    1989-09-01

    If increased gamma-aminobutyric acid (GABA)-mediated neurotransmission contributes to the mediation of hepatic encephalopathy, it may be possible to induce ameliorations of the syndrome by pharmacologically antagonizing a component of the GABA/benzodiazepine receptor complex. To test this possibility we administered the benzodiazepine receptor antagonist flumazenil by intravenous injection to 14 patients with hepatic encephalopathy complicating cirrhosis. Flumazenil administration induced variable and transient, but distinct, improvements of the mental status in 71% of the patients. The degree of encephalopathy improved from stage IV to stage II in 4 patients and from stage IV to stage III in 2 patients. The mental status of all patients with less advanced encephalopathy (3 with stage III, 1 with stage II) also improved, but these responses were clinically less impressive. The arousal effect occurred within minutes after the injection and lasted for 1 to 2 h. Furthermore, it was associated with a significant increase of the mean electroencephalographic frequency from 4.2 to 5.2 cycle/s. Of the 8 patients who were ultimately discharged from the hospital, 7 had responded to flumazenil. No patient who died within 48 h of receiving flumazenil had shown any arousal effect. These findings strongly favor a prominent pathogenetic role of increased GABAergic tone in hepatic encephalopathy in humans and suggest that a positive response to flumazenil might be of prognostic value in predicting short-term survival in encephalopathic patients with liver disease.

  13. Benzodiazepine receptor antagonists for acute and chronic hepatic encephalopathy

    DEFF Research Database (Denmark)

    Als-Nielsen, B; Kjaergard, L L; Gluud, C

    2001-01-01

    The pathogenesis of hepatic encephalopathy is unknown. It has been suggested that liver failure leads to the accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition which may progress to coma. Several trials have assessed benzodiazepine receptor...

  14. The contribution of endogenous benzodiazepine receptor ligands to the pathogenesis of hepatic encephalopathy

    Energy Technology Data Exchange (ETDEWEB)

    Basile, A.S. (National Institutes of Health, Betheda, MD (USA))

    1991-02-01

    The involvement of the gamma-aminobutyric acid A(GABAA) receptor complex in the pathogenesis of hepatic encephalopathy (HE) was examined in galactosamine-treated rabbits with HE caused by fulminant hepatic failure. Radioligand binding to the constituent components of the GABAA receptor complex was unchanged in rabbits with HE. However, partially purified extracts from encephalopathic rabbit brain were approximately three times more potent in inhibiting ({sup 3}H)Ro 15-1788 binding to benzodiazepine (BZ) receptors than extracts from control rabbits. The inhibition of radioligand binding to the BZ receptor produced by these extracts was competitive and reversible and was significantly enhanced by GABA. Further purification of these extracts by high-performance liquid chromatography (HPLC) indicated that the inhibitory activity was localized in several peaks, some of which had retention times corresponding to 1,4-benzodiazepine standards. The presence of diazepam in these extracts was confirmed using mass spectroscopy. Both mass spectroscopic and radiometric techniques demonstrated that the concentration of diazepam in brain extracts from encephalopathic rabbits was approximately 4 times greater than control extracts. These findings link the presence of BZ receptor agonists to the development of a neuropathological condition, thereby providing a rational basis for the use of BZ receptor antagonists in the management of HE in man.

  15. INSIGHTS INTO FUNCTIONAL PHARMACOLOGY OF α1 GABAA RECEPTORS: HOW MUCH DOES PARTIAL ACTIVATION AT THE BENZODIAZEPINE SITE MATTER?

    OpenAIRE

    Joksimović, Srđan; Varagic, Zdravko; Kovačević, Jovana; Van Linn, Michael; Milić, Marija; Rallapalli, Sundari; Timić, Tamara; Sieghart, Werner; Cook, James M.; Savić, Miroslav M.

    2013-01-01

    Synthesis of ligands inactive or low-active at α1 GABAA receptors has become the key concept for development of novel, more tolerable benzodiazepine (BZ)-like drugs. WYS8, a remarkably (105 times) α1-subtype selective partial positive modulator, may serve as a pharmacological tool for refining the role of α1 GABAA receptors in mediation of BZs’ effects. Here, the effects of WYS8 on GABA-induced currents and on diazepam-induced potentiation of recombinant BZ-sensitive GABAA receptors were stud...

  16. Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

    Science.gov (United States)

    Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nabekura, J; Noguchi, K; Akaike, N; Witt, M R; Nielsen, M

    1997-06-25

    Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

  17. Radioligands for PET studies of central benzodiazepine receptors and PK (peripheral benzodiazepine) binding sites -current status

    International Nuclear Information System (INIS)

    Pike, V.W.; Osman, S.; Shah, F.; Turton, D.R.; Waters, S.L.; Crouzel, C.; Nutt, D.J.

    1993-01-01

    The status of the radiochemical development and biological evaluation of radioligands for PET studies of central benzodiazepine (BZ) receptors and the so-called peripheral benzodiazepine binding sites, here discriminated and referred to as PK binding sites, is reviewed against current pharmacological knowledge, indicating those agents with present value and those with future potential. Practical recommendations are given for the preparation of two useful radioligands for PET studies, [N-methyl- 11 C]flumazenil for central BZ receptors, and [N-methyl- 11 C]PK 11195 for PK binding sites. Quality assurance and plasma metabolite analysis are also reviewed for these radioligands and practical recommendations are given on methodology for their performance. (Author)

  18. Benzodiazepines

    Science.gov (United States)

    ... with amnesia, hostility, irritability, and vivid or disturbing dreams. Affect on body Benzodiazepines slow down the central nervous system and may cause sleepiness. Drugs causing similar effects Alcohol, barbiturates, sleeping pills, and GHB Overdose effects ...

  19. GABA agonist promoted formation of low affinity GABA receptors on cerebellar granule cells is restricted to early development

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, Gert Helge; Schousboe, A

    1988-01-01

    The ability of the GABA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) to promote formation of low affinity GABA receptors on cerebellar granule cells was tested using primary cultures of these neurons. Granule cells were exposed to THIP (150 microM) for 6 hr after......, respectively, 4, 7, 10 and 14 days in culture. It was found that THIP treatment of 4- and 7-day-old cultures led to formation of low affinity GABA receptors, whereas such receptors could not be detected after THIP treatment in the older cultures (10 and 14 days) in spite of the fact that these cultured granule...... cells expressed a high density of high affinity GABA receptors. It is concluded that the ability of THIP to promote formation of low affinity GABA receptors on cerebellar granule cells is restricted to an early developmental period....

  20. Chronic stress in Lizards: Studies on the Behavior and Benzodiazepine Receptors in Liolaemus koslowskyi and Cnemidophorus tergolaevigatus.

    Science.gov (United States)

    Soloaga, Alejandra; Pueta, Mariana; Cruz, Félix Benjamín; Kembro, Jackelyn Melissa; Marin, Raul Hector

    2016-12-01

    Behavioral and physiological adaptive responses of animals facing chronic exposure to a single stressor may allow them to overcome its negative effects for future exposures to similar stressful situations. At chemical level, the GABA A /benzodiazepine complex is considered one of the main receptor systems involved in the modulation of stress-induced responses. Here, we describe the behavioral responses of two different lizard species, Liolaemus koslowskyi and Cnemidophorus tergolaevigatus exposed to three potential chronic stressful treatments: (a) high temperature, (b) forced swimming, and (c) simulated predator. Additionally, we aimed to determine in those lizards whether the central-type benzodiazepine receptor (CBR; an allosteric modulator site of the GABA A receptor) is related to adaptive responses to those stressful stimulations. Our results revealed that the simulated predator was the stress condition that showed the largest difference in behavioral responses between the two species, resembling previously described strategies in nature. The basal affinity of CBRs (obtained from undisturbed animals) showed differences between both species, and the simulated predator was the only stressor that altered the affinity of CBRs. L. koslowskyi CBRs showed a decreased receptor affinity, whereas C. tergolaevigatus showed an increased receptor affinity in comparison to their respective control groups. We show for the first time the effects of different types of stressors upon behavioral responses and CBR biochemical parameters in two lizard species. Our findings suggest a potential GABA/benzodiazepine role in the ability of lizards to cope with a repeated exposure to a stressful (e.g., predator) condition. © 2017 Wiley Periodicals, Inc.

  1. GABA regulates the rat hypothalamic-pituitary-adrenocortical axis via different GABA-A receptor alpha-subtypes

    DEFF Research Database (Denmark)

    Mikkelsen, Jens D; Bundzikova, Jana; Larsen, Marianne Hald

    2008-01-01

    dependent on the composition of the GABA-A receptor subunits through which they act. We show here that positive modulators of alpha(1)-subtype containing GABA-A receptors with zolpidem (10 mg/kg) increase HPA activity in terms of increase in plasma corticosterone and induction of Fos in the PVN, whereas...

  2. Allosteric modulation of retinal GABA receptors by ascorbic acid

    Science.gov (United States)

    Calero, Cecilia I.; Vickers, Evan; Moraga Cid, Gustavo; Aguayo, Luis G.; von Gersdorff, Henrique; Calvo, Daniel J.

    2011-01-01

    Summary Ionotropic γ-aminobutyric acid receptors (GABAA and GABAC) belong to the cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA-puff evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ρ1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereospecific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two cys-loop cysteines and histidine 141, all located in the ρ1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. PMID:21715633

  3. In vivo neurochemical evidence that newly synthesised GABA activates GABA(B), but not GABA(A), receptors on dopaminergic nerve endings in the nucleus accumbens of freely moving rats.

    NARCIS (Netherlands)

    Saigusa, T.; Aono, Y.; Sekino, R.; Uchida, T.; Takada, K.; Oi, Y.; Koshikawa, N.; Cools, A.R.

    2012-01-01

    GABA released from accumbal GABAergic interneurons plays an inhibitory role in the regulation of dopamine efflux through GABA(B) and GABA(A) receptors located on accumbal dopaminergic nerve endings. The cytosolic newly synthesised GABA alters vesicular GABA levels and, accordingly, the amount of

  4. Functional modulation of cerebral gamma-aminobutyric acidA receptor/benzodiazepine receptor/chloride ion channel complex with ethyl beta-carboline-3-carboxylate: Presence of independent binding site for ethyl beta-carboline-3-carboxylate

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, J.; Kuriyama, K. (Kyoto Prefectural Univ. of Medicine (Japan))

    1990-05-01

    Effect of ethyl beta-carboline-3-carboxylate (beta-CCE) on the function of gamma-aminobutyric acid (GABA)A receptor/benzodiazepine receptor/chloride ion channel complex was studied. Beta-CCE noncompetitively and competitively inhibited (3H)flunitrazepam binding to benzodiazepine receptor, but not (3H)muscimol binding to GABAA receptor as well as t-(3H)butylbicycloorthobenzoate (( 3H) TBOB) binding to chloride ion channel, in particulate fraction of the mouse brain. Ro15-1788 also inhibited competitively (3H) flunitrazepam binding. On the other hand, the binding of beta-(3H)CCE was inhibited noncompetitively and competitively by clonazepam and competitively by Ro15-1788. In agreement with these results, benzodiazepines-stimulated (3H)muscimol binding was antagonized by beta-CCE and Ro15-1788. Gel column chromatography for the solubilized fraction from cerebral particulate fraction by 0.2% sodium deoxycholate (DOC-Na) in the presence of 1 M KCl indicated that beta-(3H)CCE binding site was eluted in the same fraction (molecular weight, 250,000) as the binding sites for (3H)flunitrazepam, (3H)muscimol and (3H)TBOB. GABA-stimulated 36Cl- influx into membrane vesicles prepared from the bovine cerebral cortex was stimulated and attenuated by flunitrazepam and beta-CCE, respectively. These effects of flunitrazepam and beta-CCE on the GABA-stimulated 36Cl- influx were antagonized by Ro15-1788. The present results suggest that the binding site for beta-CCE, which resides on GABAA receptor/benzodiazepine receptor/chloride ion channel complex, may be different from that for benzodiazepine. Possible roles of beta-CCE binding site in the allosteric inhibitions on benzodiazepine binding site as well as on the functional coupling between chloride ion channel and GABAA receptor are also suggested.

  5. GABA(B), not GABA(A) receptors play a role in cortical postictal refractoriness

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Kubová, Hana

    2015-01-01

    Roč. 88, Jan 2015 (2015), s. 99-102 ISSN 0028-3908 R&D Projects: GA MŠk(CZ) LH11015; GA ČR(CZ) GAP302/10/0971; GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : cortical seizures * postictal refractoriness * GABA receptors * pharmacology Subject RIV: FH - Neurology Impact factor: 4.936, year: 2015

  6. Editing modifies the GABA(A) receptor subunit alpha3

    DEFF Research Database (Denmark)

    Ohlson, Johan; Pedersen, Jakob Skou; Haussler, David

    2007-01-01

    to find selectively edited sites and combined it with bioinformatic techniques that find stem-loop structures suitable for editing. We present here the first verified editing candidate detected by this screening procedure. We show that Gabra-3, which codes for the alpha3 subunit of the GABA(A) receptor...

  7. Low nanomolar GABA effects at extrasynaptic a4ß1/ß3delta GABAA receptor subtypes indicate a different binding mode for GABA at these receptors

    DEFF Research Database (Denmark)

    Karim, Nasiara; Wellendorph, Petrine; Absalom, Nathan

    2012-01-01

    Ionotropic GABA(A) receptors are a highly heterogenous population of receptors assembled from a combination of multiple subunits. The aims of this study were to characterize the potency of GABA at human recombinant d-containing extrasynaptic GABA(A) receptors expressed in Xenopus oocytes using...... the two-electrode voltage clamp technique, and to investigate, using site-directed mutagenesis, the molecular determinants for GABA potency at a4ß3d GABA(A) receptors. a4/d-Containing GABA(A) receptors displayed high sensitivity to GABA, with mid-nanomolar concentrations activating a4ß1d (EC(50)=24n......M) and a4ß3d (EC(50)=12nM) receptors. In the majority of oocytes expressing a4ß3d subtypes, GABA produced a biphasic concentration-response curve, and activated the receptor with low and high concentrations (EC(50)(1)=16nM; EC(50)(2)=1.2µM). At a4ß2d, GABA had low micromolar activity (EC(50)=1µ...

  8. Gamma-aminobutyric acid-modulated benzodiazepine binding sites in bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Lummis, S.C.R.; Johnston, G.A.R. (Univ. of Sydney, New South Wales (Australia)); Nicoletti, G. (Royal Melbourne Inst. of Tech. (Australia)); Holan, G. (CSIRO, Melbourne (Australia))

    1991-01-01

    Benzodiazepine binding sites, which were once considered to exist only in higher vertebrates, are here demonstrated in the bacteria E. coli. The bacterial ({sup 3}H)diazepam binding sites are modulated by GABA; the modulation is dose dependent and is reduced at high concentrations. The most potent competitors of E.Coli ({sup 3}H)diazepam binding are those that are active in displacing ({sup 3}H)benzodiazepines from vertebrate peripheral benzodiazepine binding sites. These vertebrate sites are not modulated by GABA, in contrast to vertebrate neuronal benzodiazepine binding sites. The E.coli benzodiazepine binding sites therefore differ from both classes of vertebrate benzodiazepine binding sites; however the ligand spectrum and GABA-modulatory properties of the E.coli sites are similar to those found in insects. This intermediate type of receptor in lower species suggests a precursor for at least one class of vertebrate benzodiazepine binding sites may have existed.

  9. The flavone hispidulin, a benzodiazepine receptor ligand with positive allosteric properties, traverses the blood–brain barrier and exhibits anticonvulsive effects

    OpenAIRE

    Kavvadias, Dominique; Sand, Philipp; Youdim, Kuresh A; Qaiser, M Zeeshan; Rice-Evans, Catherine; Baur, Roland; Sigel, Erwin; Rausch, Wolf-Dieter; Riederer, Peter; Schreier, Peter

    2004-01-01

    The functional characterization of hispidulin (4′,5,7-trihydroxy-6-methoxyflavone), a potent benzodiazepine (BZD) receptor ligand, was initiated to determine its potential as a modulator of central nervous system activity.After chemical synthesis, hispidulin was investigated at recombinant GABAA/BZD receptors expressed by Xenopus laevis oocytes. Concentrations of 50 nM and higher stimulated the GABA-induced chloride currents at tested receptor subtypes (α1−3,5,6β2γ2S) indicating positive allo...

  10. Temporal development of GABA agonist induced alterations in ultrastructure and GABA receptor expression in cultured cerebellar granule cells

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Belhage, B; Schousboe, A

    1987-01-01

    The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays. It was f......The temporal development of the effect of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) on the ultrastructure composition and GABA receptor expression in cerebellar granule cells was investigated by quantitative electron microscopy (morphometric analysis) and GABA binding assays....... It was found that the cytoplasmic density of smooth endoplasmic reticulum was decreased, while the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles and coated vesicles was greatly enhanced after exposure of the cells to THIP (150 microM) for only 1 hr. In cerebellar granule cells...

  11. GABA-A Receptor Modulation and Anticonvulsant, Anxiolytic, and Antidepressant Activities of Constituents from Artemisia indica Linn

    Directory of Open Access Journals (Sweden)

    Imran Khan

    2016-01-01

    Full Text Available Artemisia indica, also known as “Mugwort,” has been widely used in traditional medicines. However, few studies have investigated the effects of nonvolatile components of Artemisia indica on central nervous system’s function. Fractionation of Artemisia indica led to the isolation of carnosol, ursolic acid, and oleanolic acid which were evaluated for their effects on GABA-A receptors in electrophysiological studies in Xenopus oocytes and were subsequently investigated in mouse models of acute toxicity, convulsions (pentylenetetrazole induced seizures, depression (tail suspension and forced swim tests, and anxiety (elevated plus maze and light/dark box paradigms. Carnosol, ursolic acid, and oleanolic acid were found to be positive modulators of α1β2γ2L GABA-A receptors and the modulation was antagonized by flumazenil. Carnosol, ursolic acid, and oleanolic acid were found to be devoid of any signs of acute toxicity (50–200 mg/kg but elicited anticonvulsant, antidepressant, and anxiolytic activities. Thus carnosol, ursolic acid, and oleanolic acid demonstrated CNS activity in mouse models of anticonvulsant, antidepressant, and anxiolysis. The anxiolytic activity of all three compounds was ameliorated by flumazenil suggesting a mode of action via the benzodiazepine binding site of GABA-A receptors.

  12. Effects of Antecedent GABA A Receptor Activation on Counterregulatory Responses to Exercise in Healthy Man.

    Science.gov (United States)

    Hedrington, Maka S; Tate, Donna B; Younk, Lisa M; Davis, Stephen N

    2015-09-01

    The aim of this study was to determine whether antecedent stimulation of γ-aminobutyric acid (GABA) A receptors with the benzodiazepine alprazolam can blunt physiologic responses during next-day moderate (90 min) exercise in healthy man. Thirty-one healthy individuals (16 male/15 female aged 28 ± 1 year, BMI 23 ± 3 kg/m(2)) were studied during separate, 2-day protocols. Day 1 consisted of morning and afternoon 2-h hyperinsulinemic-euglycemic or hypoglycemic clamps with or without 1 mg alprazolam given 30 min before a clamp. Day 2 consisted of 90-min euglycemic cycling exercise at 50% VO2max. Despite similar euglycemia (5.3 ± 0.1 mmol/L) and insulinemia (46 ± 6 pmol/L) during day 2 exercise studies, GABA A activation with alprazolam during day 1 euglycemia resulted in significant blunting of plasma epinephrine, norepinephrine, glucagon, cortisol, and growth hormone responses. Lipolysis (glycerol, nonesterified fatty acids) and endogenous glucose production during exercise were also reduced, and glucose infusion rates were increased following prior euglycemia with alprazolam. Prior hypoglycemia with alprazolam resulted in further reduction of glucagon and cortisol responses during exercise. We conclude that prior activation of GABA A pathways can play a significant role in blunting key autonomous nervous system, neuroendocrine, and metabolic physiologic responses during next-day exercise in healthy man. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  13. Association Between Benzodiazepine Receptor Agonists and Snoring Among Women in the Nurses' Health Study.

    Science.gov (United States)

    Lin, Brian M; Hu, Frank B; Curhan, Gary C

    2017-02-01

    Snoring is highly prevalent among adults. The use of benzodiazepine receptor agonists is also common, with higher prevalence of use with more advanced age. Benzodiazepine receptor agonists cause muscle relaxation, which may affect muscle tone and airway dynamics and thereby increase snoring. Previous studies examining the association between use of benzodiazepine receptor agonists and snoring were underpowered to detect clinically meaningful differences or did not report the magnitude of association. To investigate the association between use of benzodiazepine receptor agonists and snoring in women. Women aged 62 to 86 years provided information on snoring and covariates of interest in the 2008 survey of the Nurses' Health Study, a cross-sectional cohort study of female registered nurses in the United States. Potential effect modification of the association between use of benzodiazepine receptor agonists and snoring by age, body mass index, waist circumference, smoking, alcohol consumption, and physical activity was explored. Logistic regression was used to adjust for potential confounders. Data analysis was conducted from November 2015 to March 2016. Self-reported habitual snoring, defined as a few nights a week or more. Of 52 504 participants (mean [SD] age, 72.4 [6.7] years), 14 831 (28.2%) reported habitual snoring. There was a slightly higher prevalence of benzodiazepine receptor agonist use among habitual snorers (11.4%) compared with nonhabitual snorers (10.6%) (absolute difference, 0.8%; 95% CI, 0.2%-1.4%). After multivariable adjustment, use of benzodiazepine receptor agonists was not associated with snoring (odds ratio, 1.01; 95% CI, 0.95-1.07) compared with women who did not use benzodiazepine receptor agonists. Although there was no significant interaction with smoking, there were higher odds of snoring with use of benzodiazepine receptor agonists among current smokers (odds ratio, 1.34; 95% CI, 1.04-1.73). Use of benzodiazepine receptor agonists is

  14. Biochemical study of multiple drug recognition sites on central benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Trifiletti, R.R.

    1986-01-01

    The benzodiazepine receptor complex of mammalian brain possesses recognition sites which mediate (at least in part) the pharmacologic actions of the 1,4-benzodiazepines and barbiturates. Evidence is provided suggesting the existence of least seven distinct drug recognition sites on this complex. Interactions between the various recognition sites have been explored using radioligand binding techniques. This information is utilized to provide a comprehensive scheme for characterizing receptor-active drugs on an anxiolytic-anticonvulsant/proconvulsant continuum using radioligand binding techniques, as well as a comprehensive program for identifying potential endogenous receptor-active substances. Further evidence is provided here supporting the notion of benzodiazepine recognition site heterogeneity. Classical 1,4-benzodiazepines do not appear to differentiate two populations of benzodiazepine receptors in an equilibrium sense, but appear to do so in a kinetic sense. An apparent physical separation of the two receptor subtypes can be achieved by differential solubilization. The benzodiazepine binding subunit can be identified by photoaffinity labeling with the benzodiazepine agonist (/sup 3/H)flunitrazepan. Conditions for reproducible partial proteolytic mapping of (/sup 3/H)flunitrazepam photoaffinity labeled receptors are established. From these maps, it is concluded that there are probably no major differences in the primary sequence of the benzodiazepine binding subunit in various regions of the rat central nervous system.

  15. Bromine-75-labeled 1,4-benzodiazepines: potential agents for the mapping of benzodiazepine receptors in vivo: concise communication

    Energy Technology Data Exchange (ETDEWEB)

    Scholl, H.; Kloster, G.; Stoecklin, G.

    1983-05-01

    We have prepared four different 1,4-benzodiazepines, labeled at C-7 with the 1.6-hr positron emitter Br-75 or the 57-hr gamma emitter Br-77, as potential radio-pharmaceuticals for the mapping of cerebral benzodiazepine receptor areas. The triazene method was used and optimized. Yields at the no-carrier-added level were 20%. (7-/sup 75/Br)-5-(2-flophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepine-2-one (Br-75 BFB) was isolated with a minimum specific activity of 20,000 Ci/mmole. Biodistribution in mice shows that BFB is taken up rapidly by the brain and is retained there at useful concentrations for significant periods of time. The maximum uptake is observed at 0.25 min. Brain-to-blood concentration ratios are larger than 2 during the interval (0.25 to 10 min) investigated.

  16. The benzodiazepine diazepam potentiates responses of α1β2γ2 γ-aminobutyric acid type A receptors activated by either γ-aminobutyric acid or allosteric agonists

    Science.gov (United States)

    Li, Ping; Eaton, Megan M.; Steinbach, Joe Henry; Akk, Gustav

    2013-01-01

    Background The γ-aminobutyric acid type A receptor is target for several anesthetics, anticonvulsants, anxiolytics and sedatives. Neurosteroids, barbiturates and etomidate both potentiate responses to γ-aminobutyric acid (GABA) and allosterically activate the receptor. We examined the ability of a benzodiazepine, diazepam, to potentiate responses to allosteric agonists. Methods The γ-aminobutyric acid type A receptors were expressed in human embryonic kidney 293 cells, and studied using whole-cell and single-channel patch clamp. The receptors were activated by the orthosteric agonist GABA, and allosteric agonists pentobarbital, etomidate and alfaxalone. Results Diazepam is equally potent at enhancing responses to orthosteric and allosteric agonists. Diazepam EC50s were 25±4, 26±6, 33±6, and 26±3 nM for receptors activated by GABA, pentobarbital, etomidate, and alfaxalone, respectively (mean±S.D., 5–6 cells at each condition). Mutations to the benzodiazepine-binding site (α1(H101C), γ2(R144C), γ2(R197C)) reduced or removed potentiation for all agonists, and an inverse agonist at the benzodiazepine site reduced responses to all agonists. Single-channel data elicited by GABA demonstrate that in the presence of 1 μM diazepam the prevalence of the longest open-time component is increased from 13±7 (mean±S.D., n=5 patches) to 27±8 % (n=3 patches) and the rate of channel closing is decreased from 129±28 s−1 to 47±6 s−1 (mean±S.D.) Conclusions We conclude that benzodiazepines do not act by enhancing affinity of the orthosteric site for GABA but rather by increasing channel gating efficacy. The results also demonstrate the presence of significant interactions between allosteric activators and potentiators, raising a possibility of effects on dosage requirements or changes in side effects. PMID:23407108

  17. Gamma-aminobutyric acid (GABA) and pentobarbital induce different conformational rearrangements in the GABA A receptor alpha1 and beta2 pre-M1 regions.

    Science.gov (United States)

    Mercado, Jose; Czajkowski, Cynthia

    2008-05-30

    Gamma-aminobutyric acid (GABA) binding to GABA(A) receptors (GABA(A)Rs) triggers conformational movements in the alpha(1) and beta(2) pre-M1 regions that are associated with channel gating. At high concentrations, the barbiturate pentobarbital opens GABA(A)R channels with similar conductances as GABA, suggesting that their open state structures are alike. Little, however, is known about the structural rearrangements induced by barbiturates. Here, we examined whether pentobarbital activation triggers movements in the GABA(A)R pre-M1 regions. Alpha(1)beta(2) GABA(A)Rs containing cysteine substitutions in the pre-M1 alpha(1) (K219C, K221C) and beta(2) (K213C, K215C) subunits were expressed in Xenopus oocytes and analyzed using two-electrode voltage clamp. The cysteine substitutions had little to no effect on GABA and pentobarbital EC(50) values. Tethering chemically diverse thiol-reactive methanethiosulfonate reagents onto alpha(1)K219C and alpha(1)K221C affected GABA- and pentobarbital-activated currents differently, suggesting that the pre-M1 structural elements important for GABA and pentobarbital current activation are distinct. Moreover, pentobarbital altered the rates of cysteine modification by methanethiosulfonate reagents differently than GABA. For alpha(1)K221Cbeta(2) receptors, pentobarbital decreased the rate of cysteine modification whereas GABA had no effect. For alpha(1)beta(2)K215C receptors, pentobarbital had no effect whereas GABA increased the modification rate. The competitive GABA antagonist SR-95531 and a low, non-activating concentration of pentobarbital did not alter their modification rates, suggesting that the GABA- and pentobarbital-mediated changes in rates reflect gating movements. Overall, the data indicate that the pre-M1 region is involved in both GABA- and pentobarbital-mediated gating transitions. Pentobarbital, however, triggers different movements in this region than GABA, suggesting their activation mechanisms differ.

  18. Benzodiazepine receptor binding in vivo with (/sup 3/)-Ro 15-1788

    Energy Technology Data Exchange (ETDEWEB)

    Goeders, N.E.; Kuhar, M.J.

    1985-07-29

    In vivo benzodiazepine receptor binding has generally been studied by ex vivo techniques. In this investigation, the authors identify the conditions where (/sup 3/H)-Ro 15-1788 labels benzodiazepine receptors by true in vivo binding, i.e. where workable specific to nonspecific ratios are obtained in intact tissues without homogenization or washing. (/sup 3/H)-Flunitrazepam and (/sup 3/H)-clonazepam did not exhibit useful in vivo receptor binding. 39 references, 5 figures, 1 table.

  19. Physiology and physiopathology of central type Benzodiazepine receptors: Study in the monkey and in human brain using positron emission tomography

    International Nuclear Information System (INIS)

    Hantraye, P.

    1987-01-01

    A new non-invasive technique that allows to study in a living subject central type benzodiazepine receptors is developed. A combined approach is applied using a specific positron-emitting radiotracer for the in vivo labelling of the receptors and positron emission tomography allowing, by external detection, a quantitative determination of tissue radioactivity. The radioligand used for the in vivo labelling of benzodiazepine receptors is the antagonist RO 15-1788 labelled with carbon 11. The various stages of the study are described: in vivo characterization in the monkey of central type benzodiazepine receptors; characterization of central type benzodiazepine receptors in human brain using selective molecules for the BZ1 benzodiazepine subclass; demonstration of the heterogeneity of central type benzodiazepine receptors in the brain; study of pathological alteration of benzodiazepine receptors in experimental epilepsy [fr

  20. Molecular basis of the alternative recruitment of GABA(A) versus glycine receptors through gephyrin

    DEFF Research Database (Denmark)

    Maric, Hans-Michael; Kasaragod, Vikram Babu; Hausrat, Torben Johann

    2014-01-01

    γ-Aminobutyric acid type A and glycine receptors (GABA(A)Rs, GlyRs) are the major inhibitory neurotransmitter receptors and contribute to many synaptic functions, dysfunctions and human diseases. GABA(A)Rs are important drug targets regulated by direct interactions with the scaffolding protein ge...

  1. An analytic study of central benzodiazepine receptor in the surgically resected tissues of patients with intractable localization-related epilepsy. Quantitative analysis using 125I-iomazenil autoradiography

    International Nuclear Information System (INIS)

    Doi, Toshiaki; Matsuda, Kazumi; Mihara, Tadahiro; Yagi, Kazuichi; Seino, Masakazu

    1998-01-01

    The authors report a quantitative autoradiographic analysis of benzodiazepine receptors using the partial inverse agonist 125 I-iomazenil in surgically resected tissues of 27 patients with intractable partial epilepsies. Pathological diagnosis of these tissues was; 14 mesial temporal sclerosis (MTS), 8 dysembryoplastic neuroepithelial tumor (DNT), 4 cortical dysplasia (CD) and 1 angioma. In MTS patients, the density of benzodiazepine receptors decreased in CA1, CA3 and CA4. The layers of gyrus dentatus were displaced with a thick and high density band. These findings were similar to simultaneous GABA-A stain findings. The decrease of receptor in each hippocampal structure highly correlated to the degree of cell loss in CA1, CA3 and CA4. The receptors were almost absent in the main lesions of DNT and angioma, and showed irregular distributions in the cortex around these lesions. The receptor densities of CD were parallel to Palmini's pathological grading. Nine cases were analyzed using 123 I-iomazenil SPECT before surgery after obtaining informed consent. Eight of them revealed marked low accumulations in the areas corresponding to the epileptogenic foci. We conclude that our results support histochemically the clinical availability of 123 I-iomazenil SPECT as a non-invasive technique for detecting the changes in benzodiazepine receptor densities in patients with partial epilepsies. (author)

  2. INSIGHTS INTO FUNCTIONAL PHARMACOLOGY OF α1 GABAA RECEPTORS: HOW MUCH DOES PARTIAL ACTIVATION AT THE BENZODIAZEPINE SITE MATTER?

    Science.gov (United States)

    Joksimović, Srđan; Varagic, Zdravko; Kovačević, Jovana; Van Linn, Michael; Milić, Marija; Rallapalli, Sundari; Timić, Tamara; Sieghart, Werner; Cook, James M.; Savić, Miroslav M.

    2013-01-01

    Synthesis of ligands inactive or low-active at α1 GABAA receptors has become the key concept for development of novel, more tolerable benzodiazepine (BZ)-like drugs. WYS8, a remarkably (105 times) α1-subtype selective partial positive modulator, may serve as a pharmacological tool for refining the role of α1 GABAA receptors in mediation of BZs’ effects. Here, the effects of WYS8 on GABA-induced currents and on diazepam-induced potentiation of recombinant BZ-sensitive GABAA receptors were studied in more detail. In addition, the behavioral profile of WYS8 (0.2, 1 and 10 mg/kg i.p.), on its own and in combination with diazepam, was tested in the spontaneous locomotor activity, elevated plus maze, grip strength, rotarod and pentylenetetrazole tests. WYS8, applied at an in vivo attainable concentration of 100 nM, reduced the stimulation of GABA currents by 1 μM diazepam by 57% at α1β3γ2, but not at α2β3γ2, α3β3γ2, or α5β3γ2 GABAA receptors. The administration of WYS8 alone induced negligible behavioral consequences. When combined with diazepam, WYS8 caused a reduced sedation, muscle relaxation and anticonvulsant activity, as compared to this BZ alone, whereas ataxia was preserved, and the anxiolytic effect of 2 mg/kg diazepam was unmasked. Hence, a partial instead of full activation at α1 GABAA receptors did not necessarily result in the attenuation of the effects assumed to be mediated by activation of these receptors, or in the full preservation of the effects mediated by activation of other GABAA receptors. Thus, the role of α1 GABAA receptors appears more complex than that proposed by genetic studies. PMID:23685860

  3. Potentiating action of propofol at GABAA receptors of retinal bipolar cells

    DEFF Research Database (Denmark)

    Yue, Lan; Xie, An; Bruzik, Karol S

    2011-01-01

    Purpose. Propofol (2,6-diisopropyl phenol), a widely used systemic anesthetic, is known to potentiate GABA(A) receptor activity in a number of CNS neurons and to produce changes in electroretinographically recorded responses of the retina. However, little is known about propofol's effects...... on specific retinal neurons. The authors investigated the action of propofol on GABA-elicited membrane current responses of retinal bipolar cells, which have both GABA(A) and GABA(C) receptors. Methods. Single, enzymatically dissociated bipolar cells obtained from rat retina were treated with propofol...

  4. Autoradiographic localization of benzodiazepine receptors in the rat kidney

    International Nuclear Information System (INIS)

    Beaumont, K.; Healy, D.P.; Fanestil, D.D.

    1984-01-01

    The localization of benzodiazepine (BZD) receptors in the rat kidney was studied by autoradiography after in vitro labeling of kidney slices with flunitrazepam. The affinity, density, and rank order of displacement of [ 3 H]-flunitrazepam by several BZDs (RO 5-4864 > diazepam > clonazepam) demonstrated that binding was to BZD receptors of the peripheral type. In autoradiograms obtained with tritium-sensitive film, a high density of silver grains was obtained in the outer medulla, with lower densities in the cortex. Binding was absent from the inner medulla (papilla). In higher resolution autoradiograms obtained with an emulsion-coated cover slip procedure, silver grains were seen to be concentrated over a tubular element in both outer medulla and cortex, identifiable by morphology and distribution as the thick ascending limb of the loop of Henle and the distal convoluted tubule. The identity of the labeled tubules was confirmed by immunofluorescent localization in adjacent slices of Tamm-Horsfall protein, a specific marker for these segments of tubules. Investigation of the effects of peripherally specific BZDs such as RO 5-4864 on distal tubule function is indicated

  5. Autoradiographic localization of benzodiazepine receptors in the rat kidney

    Energy Technology Data Exchange (ETDEWEB)

    Beaumont, K.; Healy, D.P.; Fanestil, D.D.

    1984-11-01

    The localization of benzodiazepine (BZD) receptors in the rat kidney was studied by autoradiography after in vitro labeling of kidney slices with flunitrazepam. The affinity, density, and rank order of displacement of (/sup 3/H)-flunitrazepam by several BZDs (RO 5-4864 > diazepam > clonazepam) demonstrated that binding was to BZD receptors of the peripheral type. In autoradiograms obtained with tritium-sensitive film, a high density of silver grains was obtained in the outer medulla, with lower densities in the cortex. Binding was absent from the inner medulla (papilla). In higher resolution autoradiograms obtained with an emulsion-coated cover slip procedure, silver grains were seen to be concentrated over a tubular element in both outer medulla and cortex, identifiable by morphology and distribution as the thick ascending limb of the loop of Henle and the distal convoluted tubule. The identity of the labeled tubules was confirmed by immunofluorescent localization in adjacent slices of Tamm-Horsfall protein, a specific marker for these segments of tubules. Investigation of the effects of peripherally specific BZDs such as RO 5-4864 on distal tubule function is indicated.

  6. GABA agonist induced changes in ultrastructure and GABA receptor expression in cerebellar granule cells is linked to hyperpolarization of the neurons

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, Gert Helge; Schousboe, A

    1990-01-01

    GABA has been shown to exert a neurotrophic like activity by enhancing the morphological and functional maturation of neurons. Mechanisms involved in this effect of GABA are largely unknown but since GABA has been shown to mediate a hyperpolarizing action on neurons it can be assumed...... that this action might be important. In order to investigate this possibility, the ability to mimic the trophic actions of GABA of different agents known to influence the membrane potential or the GABA gated chloride channels was studied. Hence, GABA receptor expression as well as the ultrastructure of cerebellar...... granule cells were monitored after exposure of the cells in culture to either bromide, valinomycin or picrotoxin. It was found that cells which at early developmental stages (4 days in culture) were exposed to bromide or valinomycin expressed low affinity GABA receptors similar to cells treated...

  7. Urinary and brain beta-carboline-3-carboxylates as potent inhibitors of brain benzodiazepine receptors.

    OpenAIRE

    Braestrup, C; Nielsen, M; Olsen, C E

    1980-01-01

    Benzodiazepines probably exert their anxiolytic, hypnotic, and anticonvulsant effects by interacting with brain-specific high-affinity benzodiazepine receptors. In searching for possible endogenous ligands for these receptors we have purified a compound 10(7)-fold from human urine by extractions, treatment with hot ethanol, and column chromatography. The compound was identified as beta-carboline-3-carboxylic acid ethyl ester (IIc) by mass spectrometry, NMR spectrometry, and synthesis; IIc was...

  8. Modeling Starburst cells' GABA(B) receptors and their putative role in motion sensitivity.

    Science.gov (United States)

    Grzywacz, Norberto M; Zucker, Charles L

    2006-07-15

    Neal and Cunningham (Neal, M. J., and J. R. Cunningham. 1995. J. Physiol. (Lond.). 482:363-372) showed that GABA(B) agonists and glycinergic antagonists enhance the light-evoked release of retinal acetylcholine. They proposed that glycinergic cells inhibit the cholinergic Starburst amacrine cells and are in turn inhibited by GABA through GABA(B) receptors. However, as recently shown, glycinergic cells do not appear to have GABA(B) receptors. In contrast, the Starburst amacrine cell has GABA(B) receptors in a subpopulation of its varicosities. We thus propose an alternate model in which GABA(B)-receptor activation reduces the release of ACh from some dendritic compartments onto a glycinergic cell, which then feeds back and inhibits the Starburst cell. In this model, the GABA necessary to make these receptors active comes from the Starburst cell itself, making them autoreceptors. Computer simulations of this model show that it accounts quantitatively for the Neal and Cunningham data. We also argue that GABA(B) receptors could work to increase the sensitivity to motion over other stimuli.

  9. GABA-BZD Receptor Modulating Mechanism of Panax quinquefolius against 72-hours Sleep Deprivation Induced Anxiety like Behavior: Possible Roles of Oxidative Stress, Mitochondrial Dysfunction and Neuroinflammation

    Directory of Open Access Journals (Sweden)

    Priyanka eChanana

    2016-03-01

    Full Text Available ABSTRACTRationale- Panax quinquefolius (American Ginseng is known for its therapeutic potential against various neurological disorders, but its plausible mechanism of action still remains undeciphered. GABA (Gamma Amino Butyric Acid plays an important role in sleep wake cycle homeostasis. Thus there exists rationale in exploring the GABA-ergic potential of Panax quinquefolius as neuroprotective strategy in sleep deprivation induced secondary neurological problems.Objective- The present study was designed to explore the possible GABA-ergic mechanism in the neuro-protective effect of Panax quinquefolius against 72-hours sleep deprivation induced anxiety like behaviour, oxidative stress, mitochondrial dysfunction, HPA-axis activation and neuroinflammation.Materials and Methods- Male laca mice were sleep deprived for 72-hours by using Grid suspended over water method. Panax quinquefolius (American Ginseng 50, 100 and 200 mg/kg was administered alone and in combination with GABA modulators (GABA Cl- channel inhibitor, GABA-benzodiazepine receptor inhibitor and GABAA agonist for 8 days, starting five days prior to 72-hours sleep deprivation period. Various behavioural (locomotor activity, mirror chamber test, biochemical (lipid peroxidation, reduced glutathione, catalase, nitrite levels, mitochondrial complexes, neuroinflammation marker (Tumour Necrosis Factor, TNF-alpha, serum corticosterone, and histopathological sections of brains were assessed. Results- 72-hours sleep deprivation significantly impaired locomotor activity, caused anxiety-like behaviour, conditions of oxidative stress, alterations in mitochondrial enzyme complex activities, raised serum corticosterone levels, brain TNFα levels and led to neuroinflammation like signs in discrete brain areas as compared to naive group. Panax quinquefolius (100 and 200 mg/kg treatment restored the behavioural, biochemical, mitochondrial, molecular and histopathological alterations. Pre-treatment of

  10. Effect of chronic (-)-nicotine treatment on rat cerebral benzodiazepine receptors

    International Nuclear Information System (INIS)

    Magata, Yasuhiro; Kitano, Haruhiro; Shiozaki, Toshiki; Iida, Yasuhiko; Nishizawa, Sadahiko; Saji, Hideo; Konishi, Junji

    2000-01-01

    The purpose of this study was to clarify the effect of (-)-nicotine on cerebral benzodiazepine receptors (BzR) with radiotracer methods. The effect of (-)-nicotine on BzR was examined in in vitro studies using chronic (-)-nicotine-treated rats using 3 H-diazepam. The in vitro radioreceptor assay showed a 14% increase in the maximum number of binding sites of BzR in chronic (-)-nicotine-treated rats in comparison with the control rats. Moreover, a convenient in vivo uptake index of 125 I-iomazenil was calculated and a higher uptake of the radioactivity was observed in the chronic (-)-nicotine-treated group than in the control group. Although further studies of the mechanism of (-)-nicotine on such BzR changes are required, an increase in the amount of BzR in the cerebral cortex was found in rats that underwent chronic (-)-nicotine treatment, and this result contributed to the understanding of the effects of (-)-nicotine and smoking on neural functions

  11. Effect of chronic (-)-nicotine treatment on rat cerebral benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Magata, Yasuhiro E-mail: magata@kuhp.kyoto-u.ac.jp; Kitano, Haruhiro; Shiozaki, Toshiki; Iida, Yasuhiko; Nishizawa, Sadahiko; Saji, Hideo; Konishi, Junji

    2000-01-01

    The purpose of this study was to clarify the effect of (-)-nicotine on cerebral benzodiazepine receptors (BzR) with radiotracer methods. The effect of (-)-nicotine on BzR was examined in in vitro studies using chronic (-)-nicotine-treated rats using {sup 3}H-diazepam. The in vitro radioreceptor assay showed a 14% increase in the maximum number of binding sites of BzR in chronic (-)-nicotine-treated rats in comparison with the control rats. Moreover, a convenient in vivo uptake index of {sup 125}I-iomazenil was calculated and a higher uptake of the radioactivity was observed in the chronic (-)-nicotine-treated group than in the control group. Although further studies of the mechanism of (-)-nicotine on such BzR changes are required, an increase in the amount of BzR in the cerebral cortex was found in rats that underwent chronic (-)-nicotine treatment, and this result contributed to the understanding of the effects of (-)-nicotine and smoking on neural functions.

  12. Regulation of renal peripheral benzodiazepine receptors by anion transport inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Basile, A.S.; Lueddens, W.M.; Skolnick, P.

    1988-01-01

    The in vitro and in vivo regulation of (/sup 3/H)Ro 5-4864 binding to peripheral benzodiazepine receptors (PBR) by ion transport/exchange inhibitors was studied in the kidney. The potencies of 9-anthroic acid, furosemide, bumetanide, hydrochlorothiazide and SITS as inhibitors of (/sup 3/H)Ro 5-4864 binding to renal membranes were consistent with their actions as anion transport inhibitors (Ki approx. = 30 - 130 ..mu..M). In contrast, spironolactone, amiloride, acetazolamide, and ouabain were less potent (Ki=100-1000 ..mu..M). Administration of furosemide to rats for five days resulted in a profound diuresis accompanied by a significant increase in PBR density (43%) that was apparent by the fifth day of treatment. Administration of hydrochlorothiazide or Ro 5-4864 for five days also caused diuresis and increased renal PBR density. Both the diuresis and increased density of PBR produced by Ro 5-4864 were blocked by coadministration of PK 11195, which alone had no effect on either PBR density or urine volume. The equilibrium binding constants of (/sup 3/H)Ro 5-4864 to cardiac membranes were unaffected by administration of any of these drugs. These findings suggest that renal PBR may be selectively modulated in vivo and in vitro by administration of ion transport/exchange inhibitors. 36 references, 4 tables.

  13. Immunocytochemical mapping of an RDL-like GABA receptor subunit and of GABA in brain structures related to learning and memory in the cricket Acheta domesticus.

    Science.gov (United States)

    Strambi, C; Cayre, M; Sattelle, D B; Augier, R; Charpin, P; Strambi, A

    1998-01-01

    The distribution of putative RDL-like GABA receptors and of gamma-aminobutyric acid (GABA) in the brain of the adult house cricket Acheta domesticus was studied using specific antisera. Special attention was given to brain structures known to be related to learning and memory. The main immunostaining for the RDL-like GABA receptor was observed in mushroom bodies, in particular the upper part of mushroom body peduncle and the two arms of the posterior calyx. Weaker immunostaining was detected in the distal part of the peduncle and in the alpha and beta lobes. The dorso- and ventrolateral protocerebrum neuropils appeared rich in RDL-like GABA receptors. Staining was also detected in the glomeruli of the antennal lobe, as well as in the ellipsoid body of the central complex. Many neurons clustered in groups exhibit GABA-like immunoreactivity. Tracts that were strongly immunostained innervated both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and ventrolateral protocerebrum were also rich in GABA-like immunoreactivity. The data demonstrated a good correlation between the distribution of the GABA-like and of the RDL-like GABA receptor immunoreactivity. The prominent distribution of RDL-like GABA receptor subunits, in particular areas of mushroom bodies and antennal lobes, underlines the importance of inhibitory signals in information processing in these major integrative centers of the insect brain.

  14. Exploring QSARs of the interaction of flavonoids with GABA (A) receptor using MLR, ANN and SVM techniques.

    Science.gov (United States)

    Deeb, Omar; Shaik, Basheerulla; Agrawal, Vijay K

    2014-10-01

    Quantitative Structure-Activity Relationship (QSAR) models for binding affinity constants (log Ki) of 78 flavonoid ligands towards the benzodiazepine site of GABA (A) receptor complex were calculated using the machine learning methods: artificial neural network (ANN) and support vector machine (SVM) techniques. The models obtained were compared with those obtained using multiple linear regression (MLR) analysis. The descriptor selection and model building were performed with 10-fold cross-validation using the training data set. The SVM and MLR coefficient of determination values are 0.944 and 0.879, respectively, for the training set and are higher than those of ANN models. Though the SVM model shows improvement of training set fitting, the ANN model was superior to SVM and MLR in predicting the test set. Randomization test is employed to check the suitability of the models.

  15. The effect of GABA receptor ligands in experimental spina bifida occulta.

    Science.gov (United States)

    Briner, W

    2001-01-01

    The pathophysiology behind spina bifida and other neural tube defects (NTDs) is unclear. Folic acid is one variable, but other factors remain. Studies suggest that substances active at the GABA receptor may produce NTDs. To test this hypothesis pregnant rats were exposed to either the GABA a agonist muscimol (1, 2 or 4 mg/kg), the GABA a antagonist bicuculline (.5, 1, or 2 mg/kg), the GABA b agonist baclofen (15, 30, 60 mg/kg), or the GABA b antagonist hydroxysaclofen (1, 3, or 5 mg/kg) during neural tube formation. Normal saline was used as a control and valproic acid (600 mg/kg) as a positive control. The embryos were analyzed for the presence of a spina bifida like NTD. After drug administration the pregnancies were allowed to proceed to the 21st day of gestation. Then embryos were removed and skeletons staining and cleared. Vertebral arch closure was measured. Results indicate that the GABAa receptor agonist muscimol, the GABAa receptor antagonist bicuculline, and the GABAb agonist baclofen produced NTDs characterized by widening of the vertebral arch. Oppositely the GABAb antagonist hydroxysaclofen produced narrowing of the vertebral arches. The findings indicate that GABA a or b ligands are capable of altering neural formation. GABA may play a greater than appreciated role in neural tube formation and may be important in NTDs. The narrowing of the vertebral arch produced by the GABA b antagonist hydroxysalcofen suggests that GABA b receptor may play an undefined role in neural tube closure that differs from the GABA a receptor.

  16. GABA(B) receptor phosphorylation regulates KCTD12-induced K+ current desensitization

    Czech Academy of Sciences Publication Activity Database

    Adelfinger, L.; Tureček, Rostislav; Ivankova, K.; Jensen, A. A.; Moss, S. J.; Gassmann, M.; Bettler, B.

    2014-01-01

    Roč. 91, č. 3 (2014), s. 369-379 ISSN 0006-2952 Institutional support: RVO:68378041 Keywords : GABA-B * G-protein coupled receptor * GPCR Subject RIV: FH - Neurology Impact factor: 5.009, year: 2014

  17. Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism

    Science.gov (United States)

    2015-10-01

    AWARD NUMBER: W81XWH-13-1-0144 TITLE: Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism PRINCIPAL INVESTIGATOR...SUBTITLE 5a. CONTRACT NUMBER Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism 5b. GRANT NUMBER W81XWH-13-1-0144 5c...ABSTRACT Autism spectrum disorder (ASD) is a polygenic signaling disorder that may result, in part, from an imbalance in excitatory and inhibitory

  18. GABA type a receptor trafficking and the architecture of synaptic inhibition.

    Science.gov (United States)

    Lorenz-Guertin, Joshua M; Jacob, Tija C

    2018-03-01

    Ubiquitous expression of GABA type A receptors (GABA A R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABA A Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABA A R function. Here we review the current understanding of how GABA A Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABA A R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABA A R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018. © 2017 Wiley Periodicals, Inc.

  19. Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex

    International Nuclear Information System (INIS)

    Malatynska, E.; Knapp, R.J.; Ikeda, M.; Yamamura, H.I.

    1988-01-01

    Convulsive seizures are a potential side effect of antidepressant drug treatment and can be produced by all classes of antidepressants. It is also know that some convulsant and anticonvulsant drug actions are mediated by the GABA-receptor chloride-ionophore complex. Drugs acting at this complex appear to induce convulsions by inhibiting chloride conductance through the associated chloride channel. Using the method of GABA-stimulated 36 Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs can inhibit the GABA-receptor chloride uptake, and that the degree of chloride channel inhibition by these drugs correlates with the frequency of convulsive seizures induced by them

  20. Hypertension alters GABA receptor-mediated inhibition of neurons in the nucleus of the solitary tract.

    Science.gov (United States)

    Mei, Lin; Zhang, Jing; Mifflin, Steve

    2003-12-01

    Previous studies have demonstrated that microinjection of baclofen, a GABA(B) receptor agonist, into the nucleus of the solitary tract (NTS) results in an enhanced pressor response in hypertensive (HT) rats compared with normotensive (NT) rats, suggesting a possible alteration in the responses of neurons in this area to activation of GABA(B) receptors. The following studies were designed to determine whether HT alters the sensitivity of neurons in the NTS to GABA receptor agonists. Sham-operated NT and unilateral nephrectomized, renal-wrap HT Sprague-Dawley rats were anesthetized, and the responses of NTS neurons receiving aortic nerve (AN) afferent inputs to iontophoretic application of GABA, the GABA(A) receptor agonist muscimol, and the GABA(B) agonist baclofen were examined. The AN input was classified as monosynaptic (MSN) if the cell responded to each of two stimuli separated by 5 ms with an action potential. If the cell did not respond, the input was considered polysynaptic (PSN). In MSNs, inhibition of AN-evoked discharge by GABA was not altered in 1 wk of HT but was reduced in 4 wk of HT, whereas in PSNs, sensitivity to GABA was reduced at 1 and 4 wk of HT. In HT rats, inhibition of AN-evoked discharge by baclofen was enhanced in MSNs, but not in PSNs, after 1 and 4 wk of HT, whereas inhibition by muscimol was reduced in MSNs and PSNs at 1 and 4 wk of HT. Changes in sensitivity to muscimol and baclofen within MSNs were the same whether the MSN received a slowly or a rapidly conducted AN afferent input. The results demonstrate that early in HT the sensitivity of NTS neurons to inhibitory amino acids is altered and that these changes are maintained for > or =4 wk. The alterations are dependent on the subtype of GABA receptor being activated and whether the neuron receives a mono- or polysynaptic baroreceptor afferent input.

  1. Characterization of GABA/sub A/ receptor-mediated 36chloride uptake in rat brain synaptoneurosomes

    International Nuclear Information System (INIS)

    Luu, M.D.; Morrow, A.L.; Paul, S.M.; Schwartz, R.D.

    1987-01-01

    γ-Aminobutyric acid (GABA) receptor-mediated 36 chloride ( 36 Cl - ) uptake was measured in synaptoneurosomes from rat brain. GABA and GABA agonists stimulated 36 Cl - uptake in a concentration-dependent manner with the following order of potency: Muscimol>GABA>piperidine-4-sulfonic acid (P4S)>4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridin-3-ol (THIP)=3-aminopropanesulfonic acid (3APS)>>taurine. Both P4S and 3APS behaved as partial agonists, while the GABA/sub B/ agonist, baclofen, was ineffective. The response to muscimol was inhibited by bicuculline and picrotoxin in a mixed competitive/non-competitive manner. Other inhibitors of GABA receptor-opened channels or non-neuronal anion channels such as penicillin, picrate, furosemide and disulfonic acid stilbenes also inhibited the response to muscimol. A regional variation in muscimol-stimulated 36 Cl - uptake was observed; the largest responses were observed in the cerebral cortex, cerebellum and hippocampus, moderate responses were obtained in the striatum and hypothalamus and the smallest response was observed in the pons-medulla. GABA receptor-mediated 36 Cl - uptake was also dependent on the anion present in the media. The muscinol response varied in media containing the following anions: Br - >Cl - ≥NO 3 - >I - ≥SCN - >>C 3 H 5 OO - ≥ClO 4 - >F - , consistent with the relative anion permeability through GABA receptor-gated anion channels and the enhancement of convulsant binding to the GABA receptor-gated Cl - channel. 43 references, 4 figures, 3 tables

  2. Metabotropic GABAB receptors mediate GABA inhibition of acetylcholine release in the rat neuromuscular junction.

    Science.gov (United States)

    Malomouzh, Artem I; Petrov, Konstantin A; Nurullin, Leniz F; Nikolsky, Evgeny E

    2015-12-01

    Gamma-aminobutyric acid (GABA) is an amino acid which acts as a neurotransmitter in the central nervous system. Here, we studied the effects of GABA on non-quantal, spontaneous, and evoked quantal acetylcholine (ACh) release from motor nerve endings. We found that while the application of 10 μM of GABA had no effect on spontaneous quantal ACh release, as detected by the frequency of miniature endplate potentials, GABA reduced the non-quantal ACh release by 57%, as determined by the H-effect value. Finally, the evoked quantal ACh release, estimated by calculating the quantal content of full-sized endplate potentials (EPPs), was reduced by 34%. GABA's inhibitory effect remained unchanged after pre-incubation with picrotoxin, an ionotropic GABAA receptor blocker, but was attenuated following application of the GABAB receptor blocker CGP 55845, which itself had no effect on ACh release. An inhibitor of phospholipase C, U73122, completely prevented the GABA-induced decrease in ACh release. Immunofluorescence demonstrated the presence of both subunits of the GABAB receptor (GABAB R1 and GABAB R2) in the neuromuscular junction. These findings suggest that metabotropic GABAB receptors are expressed in the mammalian neuromuscular synapse and their activation results in a phospholipase C-mediated reduction in the intensity of non-quantal and evoked quantal ACh release. We investigated the effect of gamma-aminobutyric acid (GABA) on neuromuscular transmission. GABA reduced the non-quantal and evoked quantal release of acetylcholine. These effects are mediated by GABAB receptors and are implemented via phospholipase C (PLC) activation. Our findings suggest that in the mammalian neuromuscular synapse, metabotropic GABAB receptors are expressed and their activation results in a reduction in the intensity of acetylcholine release. © 2015 International Society for Neurochemistry.

  3. Modulation of the γ-aminobutyric acid (GABA) system by Passiflora incarnata L.

    Science.gov (United States)

    Appel, Kurt; Rose, Thorsten; Fiebich, Bernd; Kammler, Thomas; Hoffmann, Christine; Weiss, Gabriele

    2011-06-01

    Passiflora incarnata L. (Passifloraceae) is important in herbal medicine for treating anxiety or nervousness, Generalized Anxiety Disorder (GAD), symptoms of opiate withdrawal, insomnia, neuralgia, convulsion, spasmodic asthma, ADHD, palpitations, cardiac rhythm abnormalities, hypertension, sexual dysfunction and menopause. However, the mechanism of action is still under discussion. Despite gaps in our understanding of neurophysiological processes, it is increasingly being recognized that dysfunction of the GABA system is implicated in many neuropsychiatric conditions, including anxiety and depressive disorders. Therefore, the in vitro effects of a dry extract of Passiflora incarnata (sole active ingredient in Pascoflair® 425 mg) on the GABA system were investigated. The extract inhibited [(3) H]-GABA uptake into rat cortical synaptosomes but had no effect on GABA release and GABA transaminase activity. Passiflora incarnata inhibited concentration dependently the binding of [(3) H]- SR95531 to GABA(A) -receptors and of [(3) H]-CGP 54626 to GABA(B) -receptors. Using the [(35) S]-GTPγS binding assay Passiflora could be classified as an antagonist of the GABA(B) receptor. In contrast, the ethanol- and the benzodiazepine-site of the GABA(A) -receptor were not affected by this extract. In conclusion, the first evidence was shown that numerous pharmacological effects of Passiflora incarnata are mediated via modulation of the GABA system including affinity to GABA(A) and GABA(B) receptors, and effects on GABA uptake. Copyright © 2010 John Wiley & Sons, Ltd.

  4. Characterization of central- and peripheral-type benzodiazepine receptors in rat salivary glands.

    Science.gov (United States)

    Yamagishi, H; Kawaguchi, M

    1998-01-15

    Benzodiazepines have been shown to inhibit salivary secretion from the rat salivary gland. This action is mediated by specific benzodiazepine binding sites in the glands. The presence and characteristics of central- and peripheral-type benzodiazepine receptors in rat parotid and submandibular glands were examined employing [3H]Ro15-1788 and [3H]PK11195 as radioligands. [3H]Ro15-1788 and [3H]PK11195 bound with high affinity for both salivary glands ([3H]Ro15-1788: 24.5 and 37.4 mM, [3H]PK11195: 1.37 and 1.88 nM, for parotid and submandibular glands, respectively). [3H]Ro15-1788 binding sites occupied only 0.22 to 0.43% of the total binding for benzodiazepine receptors in the glands. The rank order of the competing potency of [3H]Ro15-1788 binding (Ro15-1788 = clonazepam > diazepam > flunitrazepam > PK11195 > Ro5-4864) and [3H]PK11195 binding (Ro5-4864 = PK11195 > diazepam = flunitrazepam > clonazepam) demonstrated that [3H]Ro15-1788 and [3H]PK11195 binding sites were characteristic of the central and peripheral type, respectively. These studies show that both central- and peripheral-type benzodiazepine receptors exist in rat parotid and submandibular glands.

  5. Spatial distributions of GABA receptors and local inhibition of Ca2+ transients studied with GABA uncaging in the dendrites of CA1 pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yuya Kanemoto

    Full Text Available GABA (γ-amino-butylic acid-mediated inhibition in the dendrites of CA1 pyramidal neurons was characterized by two-photon uncaging of a caged-GABA compound, BCMACM-GABA, and one-photon uncaging of RuBi-GABA in rat hippocampal slice preparations. Although we found that GABA(A-mediated currents were diffusely distributed along the dendrites, currents elicited at the branch points of the apical dendritic trunk were approximately two times larger than those elsewhere in the dendrite. We examined the inhibitory action of the GABA-induced currents on Ca(2+ transients evoked with a single back-propagating action potential (bAP in oblique dendrites. We found that GABA uncaging selectively inhibited the Ca(2+ transients in the region adjacent (20 µm. Our data indicate that GABA inhibition results in spatially confined inhibition of Ca(2+ transients shortly after bAP, and suggest that this effect is particularly potent at the dendritic branch points where GABA receptors cluster.

  6. Activation of GABAA receptors containing the α4 subunit by GABA and pentobarbital

    Science.gov (United States)

    Akk, Gustav; Bracamontes, John; Steinbach, Joe Henry

    2004-01-01

    The activation properties of GABAA receptors containing α4β2γ2 and α4β2δ subunits were examined in the presence of GABA or pentobarbital. The receptors were expressed transiently in HEK 293 cells, and the electrophysiological experiments were carried out using cell-attached single-channel patch clamp or whole-cell macroscopic recordings. The data show that GABA is a stronger activator of α4β2γ2 receptors than α4β2δ receptors. Single-channel clusters were recorded from α4β2γ2 receptors in the presence of 10–5000 μm GABA. The maximal intracluster open probability was 0.35, with a half-maximal response elicited by 32 μm GABA. Simultaneous kinetic analysis of single-channel currents obtained at various GABA concentrations yields a channel opening rate constant of 250 s−1, and a KD of 20 μm. In contrast, only isolated openings were observed in the presence of GABA for the α4β2δ receptor. Pentobarbital was a strong activator of both α4β2γ2 and α4β2δ receptors. The maximal cluster open probability, recorded in the presence of 100 μm pentobarbital, was 0.7. At higher pentobarbital concentrations, the cluster open probability was reduced, probably due to channel block. The results from single-channel experiments were confirmed by macroscopic recordings from HEK cells in the presence of GABA or pentobarbital. PMID:14966300

  7. Positive allosteric modulation of GABA-A receptors reduces capsaicin-induced primary and secondary hypersensitivity in rats

    DEFF Research Database (Denmark)

    Hansen, Rikke Rie; Erichsen, Helle K; Brown, David T

    2012-01-01

    GABA-A receptor positive allosteric modulators (PAMs) mediate robust analgesia in animal models of pathological pain, in part via enhancing injury-induced loss of GABA-A-α2 and -α3 receptor function within the spinal cord. As yet, a lack of clinically suitable tool compounds has prevented...... this concept being tested in humans. Prior to assessing the efficacy of GABA-A receptor PAMs in a human volunteer pain model we have compared compounds capable of variously modulating GABA-A receptor function in comparable rat models of capsaicin-induced acute nocifensive flinching behaviour and secondary...

  8. Peripheral-type benzodiazepine receptors: autoradiographic localization in whole-body sections of neonatal rats.

    Science.gov (United States)

    Anholt, R R; De Souza, E B; Oster-Granite, M L; Snyder, S H

    1985-05-01

    We have developed a procedure that allows the autoradiographic localization of benzodiazepine receptors in whole-body sections of neonatal rats. Central-type benzodiazepine receptors, visualized with [3H]methylclonazepam, are restricted to nervous tissue. In contrast, peripheral-type benzodiazepine receptors, visualized with [3H]Ro5-4864, occur widely, but with discrete localizations throughout the body. Peripheral-type benzodiazepine receptors are most concentrated in the adrenal cortex and the skin. Substantial levels of these receptors are also evident in the heart, the salivary glands, discrete regions of the kidney, the epithelium of the lung, the nasal and lingual epithelia, the lining of the pulmonary arteries, the thymus, the hair follicles of the vibrissae, the tooth buds and the bone marrow. Considerable binding of [3H]Ro5-4864 is observed in the brown fat pads, the liver and the spleen, but high levels of nonspecific binding preclude accurate evaluation of the actual specific binding in these organs. Only low levels of [3H]Ro5-4864 binding sites are found in the brain and they are virtually undetectable in the skeletal muscle, the eye, the inner ear and the gastrointestinal tract. High levels of peripheral-type benzodiazepine receptor appear present in tissues that derive their metabolic energy primarily from oxidative phosphorylation, whereas only low levels are present in tissues that can derive their metabolic energy largely from glycogenolysis. Association of these receptors with mitochondria and a possible role in modulation of energy metabolism is suggested further by the observation that the histochemically visualized distribution of cytochrome oxidase activity overlaps the autoradiographic pattern of [3H]Ro5-4864 binding sites.

  9. Benzodiazepine effect of 125I-iomazenil-benzodiazepine receptor binding and serum corticosterone level in a rat model

    International Nuclear Information System (INIS)

    Fukumitsu, Nobuyoshi; Ogi, Shigeyuki; Uchiyama, Mayuki; Mori, Yutaka

    2005-01-01

    To test the change in free or unoccupied benzodiazepine receptor (BZR) density in response to diazepam, we investigated 125 I-iomazenil ( 125 I-IMZ) binding and serum corticosterone levels in a rat model. Wistar male rats, which received psychological stress using a communication box for 5 days, were divided into two groups according to the amount of administered diazepam: no diazepam [D (0)] group and 10 mg/kg per day [D (10)] group of 12 rats each. The standardized uptake value (SUV) of 125 I-IMZ of the D (10) group were significantly lower (P 125 I-IMZ, it is clear that diazepam competed with endogenous ligand for the free BZR sites, and the frontal, parietal and temporal cortices, globus pallidus, hippocampus, amygdala and hypothalamus are important areas in which 125 I-IMZ binding is strongly affected by administration of diazepam

  10. Brain benzodiazepine receptor-mediated effects on plasma catecholamine and corticosterone concentrations in rats

    NARCIS (Netherlands)

    De Boer, S F; Van der Gugten, J; Slangen, J L; de Boer, Sietse

    The effects of the benzodiazepine (BDZ) receptor agonist chlordiazepoxide (CDP) and antagonist flumazenil (Ro 15-1788), given alone and in combination, on basal and novel environment stress (NES)-elevated plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) contents were investigated.

  11. Differential effects of thiopental and pentobarbital on spinal GABA(A) receptors.

    Science.gov (United States)

    Yang, Chuan-Xiu; Zhang, Xiao-Bing; Gong, Neng; Wang, Meng-Ya; Xu, Tian-Le

    2008-10-01

    General anesthetics thiopental and pentobarbital possess very similar chemical structures whereas their clinical potency is quite different. The underlying molecular mechanism is not fully understood. This study was designed to assess the differential effects of thiopental and pentobarbital on GABA(A) receptors of mechanically dissociated rat spinal dorsal horn neurons by using whole-cell patch-clamp technique. Pentobarbital, at a concentration of 30 microM, which markedly enhanced sub-saturated GABA-induced current (I(GABA)), had no effect on thiopental-induced maximal current. Similarly, the pentobarbital-induced maximal current was also not affected by 30 microM thiopental. Moreover, a linear summation of thiopental-induced maximal current and pentobarbital-induced sub-maximal current was observed. In addition, pentobarbital failed to further enhance I(GABA) in the presence of thiopental at a concentration with maximal modulatory effects on I(GABA), and vice versa. Our results thus suggest that thiopental and pentobarbital might exert the GABA mimetic effects independently, but share a common mechanism to produce the GABA modulatory effects.

  12. Benzodiazepine receptor and neurotransmitter studies in the brain of suicides

    Energy Technology Data Exchange (ETDEWEB)

    Manchon, M.; Kopp, N.; Rouzioux, J.J.; Lecestre, D.; Deluermoz, S.; Miachon, S.

    1987-12-14

    The characteristics of benzodiazepine binding sites were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. /sup 3/H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. The authors observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, and an increase in % of type I binding sites. Among neurotransmitters, only norepinephrine differed significantly between controls and suicides. 36 references, 3 figures, 1 table.

  13. Benzodiazepine receptor and neurotransmitter studies in the brain of suicides

    International Nuclear Information System (INIS)

    Manchon, M.; Kopp, N.; Rouzioux, J.J.; Lecestre, D.; Deluermoz, S.; Miachon, S.

    1987-01-01

    The characteristics of benzodiazepine binding sites were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. 3 H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. The authors observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, and an increase in % of type I binding sites. Among neurotransmitters, only norepinephrine differed significantly between controls and suicides. 36 references, 3 figures, 1 table

  14. Inhibition of Activity of GABA Transporter GAT1 by δ-Opioid Receptor

    Directory of Open Access Journals (Sweden)

    Lu Pu

    2012-01-01

    Full Text Available Analgesia is a well-documented effect of acupuncture. A critical role in pain sensation plays the nervous system, including the GABAergic system and opioid receptor (OR activation. Here we investigated regulation of GABA transporter GAT1 by δOR in rats and in Xenopus oocytes. Synaptosomes of brain from rats chronically exposed to opiates exhibited reduced GABA uptake, indicating that GABA transport might be regulated by opioid receptors. For further investigation we have expressed GAT1 of mouse brain together with mouse δOR and μOR in Xenopus oocytes. The function of GAT1 was analyzed in terms of Na+-dependent [3H]GABA uptake as well as GAT1-mediated currents. Coexpression of δOR led to reduced number of fully functional GAT1 transporters, reduced substrate translocation, and GAT1-mediated current. Activation of δOR further reduced the rate of GABA uptake as well as GAT1-mediated current. Coexpression of μOR, as well as μOR activation, affected neither the number of transporters, nor rate of GABA uptake, nor GAT1-mediated current. Inhibition of GAT1-mediated current by activation of δOR was confirmed in whole-cell patch-clamp experiments on rat brain slices of periaqueductal gray. We conclude that inhibition of GAT1 function will strengthen the inhibitory action of the GABAergic system and hence may contribute to acupuncture-induced analgesia.

  15. Aldosterone-reversible decrease in the density of renal peripheral benzodiazepine receptors in the rat after adrenalectomy

    International Nuclear Information System (INIS)

    Basile, A.S.; Ostrowski, N.L.; Skolnick, P.

    1987-01-01

    A statistically significant decrease in the density of peripheral benzodiazepine receptors was observed in renal membranes of rats beginning 2 weeks after adrenalectomy when compared with sham-operated controls. This decrease in peripheral benzodiazepine receptor density was manifest as a decrease in the maximum binding of two ligands, [ 3 H]Ro 5-4864 and [ 3 H]PK 11195, without accompanying changes in their Kd for this site. Similar changes were not seen in another aldosterone-sensitive organ, the submandibular salivary gland. The decrease in peripheral benzodiazepine receptor density observed in adrenalectomized rat renal membranes was restored to control levels after 1 week of aldosterone administration using a dose (12.5 micrograms/kg/day) that had no effect on peripheral benzodiazepine receptor density in sham-operated animals. In contrast, dexamethasone administration (50 micrograms/kg/day, 1 week) had no effect on renal peripheral benzodiazepine receptor density when administered to either adrenalectomized or sham-operated rats. Further, adrenal demedullation had no effect on renal peripheral benzodiazepine receptor density or affinity. The decrease in peripheral benzodiazepine receptor density was localized to the renal cortex and the outer stripe of the medulla by gross dissection of renal slices and renal tissue section autoradiography. The specific effect of adrenalectomy on renal peripheral benzodiazepine receptor density, the lack of direct effect of aldosterone on [ 3 H] Ro 5-4864 binding and the localization of the change in peripheral benzodiazepine receptor density to the renal cortex and outer stripe suggest that these changes may reflect an adaptation of the renal nephron (possibly the distal convoluted tubule, intermediate tubule and/or the collecting duct) to the loss of mineralocorticoid hormones

  16. Identification of amino acids involved in histamine potentiation of GABA(A receptors

    Directory of Open Access Journals (Sweden)

    Ulrike eThiel

    2015-05-01

    Full Text Available Histamine is a neurotransmitter involved in a number of physiological and neuronal functions. In mammals, such as humans and rodents, the histaminergic neurons found in the tuberomamillary nucleus (TMN project widely throughout the central nervous system (CNS. Histamine acts as positive modulator of GABA(A receptors (GABA(ARs and, in high concentrations (10 mM, as negative modulator of the strychnine-sensitive glycine receptor. However, the exact molecular mechanisms by which histamine acts on GABA(ARs are unknown. In our study, we aimed to identify amino acids potentially involved in the modulatory effect of histamine on GABA(ARs. We expressed GABA(ARs with 12 different point mutations in Xenopus laevis oocytes and characterized the effect of histamine on GABA-induced currents using the two-electrode voltage clamp technique. Our data demonstrate that the amino acid residues ß2(N265 and ß2(M286, which are important for modulation by propofol, are not involved in the action of histamine. However, we found that histamine modulation is dependent on the amino acid residues alpha1(R120, ß2(Y157, ß3(D163, ß3(V175 and ß3(Q185. We showed that the amino acid residues ß2(Y157 and ß3(Q185 mediate the positive modulatory effect of histamine on GABA-induced currents, whereas alpha1(R120 and ß2(D163 form a potential histamine interaction site in GABA(ARs.

  17. Computational prediction of MicroRNAs targeting GABA receptors and experimental verification of miR-181, miR-216 and miR-203 targets in GABA-A receptor

    Directory of Open Access Journals (Sweden)

    Zhao Chunling

    2012-02-01

    Full Text Available Abstract Background GABA receptors are well known as the inhibitory receptors in the central nervous system and are also found in peripheral tissues. We have previously shown that GABA receptors are involved in lung development and fluid homeostasis. However, the microRNAs that regulate GABA receptors have not yet been identified. Results In this study, we used the online software, TargetScan and miRanda, to query the microRNAs that directly target GABA receptors and then selected some of them to verify experimentally using 3'-UTR reporter assays. Computational approaches predict many microRNA binding sites on the 3'-UTR of GABAA receptors, but not on GABAC receptors. 3'-UTR reporter assays only verified miR-181, miR-216, and miR-203 as the microRNAs that target GABA receptor α1-subunit among 10 microRNAs tested. Conclusions Our studies reinforce that microRNA target prediction needs to be verified experimentally. The identification of microRNAs that target GABA receptors provides a basis for further studies of post-transcriptional regulation of GABA receptors.

  18. Unsaturated free fatty acids increase benzodiazepine receptor agonist binding depending on the subunit composition of the GABAA receptor complex.

    Science.gov (United States)

    Witt, M R; Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nielsen, M

    1996-11-01

    It has been shown previously that unsaturated free fatty acids (FFAs) strongly enhance the binding of agonist benzodiazepine receptor ligands and GABAA receptor ligands in the CNS in vitro. To investigate the selectivity of this effect, recombinant human GABAA/benzodiazepine receptor complexes formed by different subunit compositions (alpha x beta y gamma 2, x = 1, 2, 3, and 5; y = 1, 2, and 3) were expressed using the baculovirus-transfected Sf9 insect cell system. At 10(-4) M, unsaturated FFAs, particularly arachidonic (20:4) and docosahexaenoic (22:6) acids, strongly stimulated (> 200% of control values) the binding of [3H]flunitrazepam ([3H]FNM) to the alpha 3 beta 2 gamma 2 receptor combination in whole cell preparations. No effect or small increases in levels of unsaturated FFAs on [3H]FNM binding to alpha 1 beta x gamma 2 and alpha 2 beta x gamma 2 receptor combinations were observed, and weak effects (130% of control values) were detected using the alpha 5 beta 2 gamma 2 receptor combination. The saturated FFAs, stearic and palmitic acids, were without effect on [3H]FNM binding to any combination of receptor complexes. The hydroxylated unsaturated FFAs, ricinoleic and ricinelaidic acids, were shown to decrease the binding of [3H]FNM only if an alpha 1 beta 2 gamma 2 receptor combination was used. Given the heterogeneity of the GABAA/ benzodiazepine receptor subunit distribution in the CNS, the effects of FFAs on the benzodiazepine receptor can be assumed to vary at both cellular and regional levels.

  19. The changes in drug binding activity of GABA receptor and animal neural-behavior after gamma irradiation

    International Nuclear Information System (INIS)

    Zheng Hui; Zhen Rong; Zhao Naikun; Xue Hong; Wang Zihui

    2004-01-01

    Objective: The purpose of this study was to investigate the effect of irradiation on gamma-aminobutyric-acid receptor (GABA-R) as well as behavioral changes after brain 60 Co γ-irradiation. Methods: The mice were irradiated with gamma rays (20 Gy; 10 Gy and 5 Gy) . The drug binding activity of GABA receptor in brain receptor was measured by fluorescence anisotropy (FA) and equilibrium dissociation constants. The behavioral changes were observed by the locomotor activity test, elevated plus-maze test and hole-board test at 1, 10, 24 and 48 hr after irradiation. Results: 1. The drug binding activity of the GABA receptor was decreased and the equilibrium dissociation constant (K d ) was significantly increased compared with the negative control group 2 hr after irradiation, and a spike value appeared at 24 hr. It showed that the irradiation might damage or decrease the binding activity and the bio-activity of GABA receptor. 2. The animal experiment confirmed that the irradiated animal model showed neural-behavioral changes of anxiety or depression. 3. The decreased binding activity of GABA receptor and changes in behavior of irradiated animal were dependent on radiation intensity. 4. The changes of behavior was similar to the blocked GABA receptor group. It suggests the relationship of radiation and GABA receptor. Conclusion: These results suggest that GABA receptor may be involved in radiation injury. The functional changes of GABA receptor may be an induction factor of behavioral disorder. The article also discussed the effect of anxiety and results obtained from the point of view of GABA receptor system involvement in the changes observed after irradiation. (authors)

  20. Differential antagonism of tetramethylenedisulfotetramine-induced seizures by agents acting at NMDA and GABA{sub A} receptors

    Energy Technology Data Exchange (ETDEWEB)

    Shakarjian, Michael P., E-mail: michael_shakarjian@nymc.edu [Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, NY, 10595 (United States); Department of Medicine, Division of Pulmonary and Critical Care Medicine, UMDNJ–Robert Wood Johnson Medical School, Piscataway, NJ 08854 (United States); Velíšková, Jana, E-mail: jana_veliskova@nymc.edu [Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 (United States); Department of Obstetrics and Gynecology, New York Medical College, Valhalla, NY 10595 (United States); Department of Neurology, New York Medical College, Valhalla, NY 10595 (United States); Stanton, Patric K., E-mail: patric_stanton@nymc.edu [Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 (United States); Department of Neurology, New York Medical College, Valhalla, NY 10595 (United States); Velíšek, Libor, E-mail: libor_velisek@nymc.edu [Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595 (United States); Department of Neurology, New York Medical College, Valhalla, NY 10595 (United States); Department of Pediatrics, New York Medical College, Valhalla, NY 10595 (United States)

    2012-11-15

    Tetramethylenedisulfotetramine (TMDT) is a highly lethal neuroactive rodenticide responsible for many accidental and intentional poisonings in mainland China. Ease of synthesis, water solubility, potency, and difficulty to treat make TMDT a potential weapon for terrorist activity. We characterized TMDT-induced convulsions and mortality in male C57BL/6 mice. TMDT (ip) produced a continuum of twitches, clonic, and tonic–clonic seizures decreasing in onset latency and increasing in severity with increasing dose; 0.4 mg/kg was 100% lethal. The NMDA antagonist, ketamine (35 mg/kg) injected ip immediately after the first TMDT-induced seizure, did not change number of tonic–clonic seizures or lethality, but increased the number of clonic seizures. Doubling the ketamine dose decreased tonic–clonic seizures and eliminated lethality through a 60 min observation period. Treating mice with another NMDA antagonist, MK-801, 0.5 or 1 mg/kg ip, showed similar effects as low and high doses of ketamine, respectively, and prevented lethality, converting status epilepticus EEG activity to isolated interictal discharges. Treatment with these agents 15 min prior to TMDT administration did not increase their effectiveness. Post-treatment with the GABA{sub A} receptor allosteric enhancer diazepam (5 mg/kg) greatly reduced seizure manifestations and prevented lethality 60 min post-TMDT, but ictal events were evident in EEG recordings and, hours post-treatment, mice experienced status epilepticus and died. Thus, TMDT is a highly potent and lethal convulsant for which single-dose benzodiazepine treatment is inadequate in managing electrographic seizures or lethality. Repeated benzodiazepine dosing or combined application of benzodiazepines and NMDA receptor antagonists is more likely to be effective in treating TMDT poisoning. -- Highlights: ► TMDT produces convulsions and lethality at low doses in mice. ► Diazepam pre- or post-treatments inhibit TMDT-induced convulsions and death

  1. GABA(B) receptors are heteromultimers with a family of auxiliary subunits

    Czech Academy of Sciences Publication Activity Database

    Schwenk, J.; Metz, M.; Zolles, G.; Tureček, Rostislav; Bildl, W.; Tarusawa, E.; Kulik, A.; Unger, A.; Gassmann, M.; Schulte, U.; Fakler, B.; Bettler, B.

    2010-01-01

    Roč. 277, Suppl. 1 (2010), s. 85-86 ISSN 1742-464X. [Congress of the Federation of European Biochemical Societies /35./. 27.06.2010-01.07.2010, Gotheburg] Institutional research plan: CEZ:AV0Z50390512 Keywords : GABA (B) receptors Subject RIV: FH - Neurology

  2. Proconvulsant Action of Two GABA(B) Receptor Antagonists Is Age-Dependent

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2013-01-01

    Roč. 62, Suppl.1 (2013), S109-S114 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP304/10/1274 Institutional support: RVO:67985823 Keywords : cortical seizures * development * GABA B receptors * rat Subject RIV: FH - Neurology Impact factor: 1.487, year: 2013

  3. Contradictory effects of GABA-B receptor agonists on cortical epileptic afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Tabashidze, Nana

    2008-01-01

    Roč. 75, č. 1 (2008), s. 173-178 ISSN 0361-9230 R&D Projects: GA ČR(CZ) GA305/05/2581 Institutional research plan: CEZ:AV0Z50110509 Keywords : GABA -B receptor agonists * epileptic afterdischarges * cortex Subject RIV: FH - Neurology Impact factor: 2.281, year: 2008

  4. Native GABA(B) receptors are heteromultimers with a family of auxiliary subunits

    Czech Academy of Sciences Publication Activity Database

    Schwenk, J.; Metz, M.; Zolles, G.; Tureček, Rostislav; Fritzius, T.; Bildl, W.; Tarusawa, E.; Kulik, A.; Unger, A.; Ivankova, K.; Seddik, R.; Tiao, J. Y.; Rajalu, M.; Trojanová, Johana; Rohde, V.; Gassmann, M.; Schulte, U.; Fakler, B.; Bettler, B.

    2010-01-01

    Roč. 465, č. 7295 (2010), s. 231-237 ISSN 0028-0836 R&D Projects: GA ČR GA309/06/1304 Institutional research plan: CEZ:AV0Z50390512 Keywords : GABA (B) * nhibitor neurotransmitter * receptors Subject RIV: FH - Neurology Impact factor: 36.101, year: 2010

  5. GABA-A receptors play a minor role in cortical epileptic afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Tabashidze, Nana; Mareš, Pavel

    2011-01-01

    Roč. 1412, - (2011), s. 102-107 ISSN 0006-8993 R&D Projects: GA ČR(CZ) GAP304/10/1274; GA MŠk(CZ) ME08045 Institutional research plan: CEZ:AV0Z50110509 Keywords : Bicuculline * GABA -A receptors * cortical epileptic afterdischarges * immature rats Subject RIV: FH - Neurology Impact factor: 2.728, year: 2011

  6. Benzodiazepine effect of {sup 125}I-iomazenil-benzodiazepine receptor binding and serum corticosterone level in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Fukumitsu, Nobuyoshi [Proton Medical Research Center, University of Tsukuba, Ibaragi, 305-8575 (Japan)]. E-mail: gzl13162@nifty.ne.jp; Ogi, Shigeyuki [Department of Radiology, Jikei University School of Medicine, Tokyo, 105-8461 (Japan); Uchiyama, Mayuki [Department of Radiology, Jikei University School of Medicine, Tokyo, 105-8461 (Japan); Mori, Yutaka [Department of Radiology, Jikei University School of Medicine, Tokyo, 105-8461 (Japan)

    2005-01-01

    To test the change in free or unoccupied benzodiazepine receptor (BZR) density in response to diazepam, we investigated {sup 125}I-iomazenil ({sup 125}I-IMZ) binding and serum corticosterone levels in a rat model. Wistar male rats, which received psychological stress using a communication box for 5 days, were divided into two groups according to the amount of administered diazepam: no diazepam [D (0)] group and 10 mg/kg per day [D (10)] group of 12 rats each. The standardized uptake value (SUV) of {sup 125}I-IMZ of the D (10) group were significantly lower (P<.05) than those of the D (0) group in the frontal, parietal and temporal cortices, globus pallidus, hippocampus, amygdala and hypothalamus. The serum corticosterone level ratio in the D (10) group was significantly lower than that in the D (0) group (P<.05). From the change in serum corticosterone levels, diazepam attenuated the psychological stress produced by the physical stress to animals in adjacent compartments. From the reduced binding of {sup 125}I-IMZ, it is clear that diazepam competed with endogenous ligand for the free BZR sites, and the frontal, parietal and temporal cortices, globus pallidus, hippocampus, amygdala and hypothalamus are important areas in which {sup 125}I-IMZ binding is strongly affected by administration of diazepam.

  7. Activation of alpha6-containing GABAA receptors by pentobarbital occurs through a different mechanism than activation by GABA.

    Science.gov (United States)

    Fisher, Matthew T; Fisher, Janet L

    2010-03-08

    The GABA(A) receptors are ligand-gated chloride channels which are the targets for many clinically used sedatives, including the barbiturates. The barbiturate pentobarbital acts through multiple sites on the GABA(A) receptor. At low concentrations (muM), it acts as a positive allosteric modulator while at higher concentrations it can directly activate the receptor. This agonist action is influenced by the subunit composition of the receptor, and pentobarbital is a more effective agonist than GABA only at receptors containing an alpha6 subunit. The conformational change that translates GABA binding into channel opening is known to involve a lysine residue located in an extracellular domain between the 2nd and 3rd transmembrane domains. Mutations of this residue disrupt activation of the channel by GABA and have been linked to inherited epilepsy. Pentobarbital binds to the receptor at a different agonist site than GABA, but could use a common signal transduction mechanism to gate the channel. To address this question, we compared the effect of a mutating the homologous lysine residue in the alpha1 or alpha6 subunits (K278 or K277, respectively) to methionine on direct activation of recombinant GABA(A) receptors by GABA or pentobarbital. We found that this mutation reduced GABA sensitivity for both alpha1 and alpha6 subunits, but affected pentobarbital sensitivity only for the alpha1 subunit. This suggests that pentobarbital acts through a distinct signal transduction pathway at the alpha6 subunit, which may account for its greater efficacy compared to GABA at receptors containing this subunit.

  8. Study on measurement of free ligand concentration in blood and quantitative analysis of brain benzodiazepine receptor

    International Nuclear Information System (INIS)

    Hashimoto, Kenji; Goromaru, Tsuyoshi; Inoue, Osamu; Itoh, Takashi; Yamasaki, Toshiro.

    1988-01-01

    We developed the method to determine rapidly the free ligand concentration in the blood as an input function for the purpose of quantitative analysis of binding potential (B max /K d ) of brain benzodiazepine receptor in vivo. It was found that the unmetabolized radioligand in the blood after intravenous administration of 3 H-Ro 15 - 1788 could be extracted by chloroform, whereas the radioactive metabolites could not be extracted. And the plasma protein binding of 3 H-Ro 15 - 1788 was determined using an ultrafiltration method. The biodistribution of 3 H-Ro 15 - 1788 in the cerebral cortex, cerebellum and pons-medulla after intravenous administration of the radiotracer in the control and forced-swimmed mice was examined. And the time course of the free ligand concentration in the blood was determined as described above. Further, the binding potential of benzodiazepine receptor in the mouse brain was analyzed using a simple mathematical model. It was suggested that the binding potential of benzodiazepine receptor in the mouse brain was significantly decreased by forced-swimming. In conclusion, it was found that these methods would be useful for quantitative analysis of clinical data in the human brain using 11 C-Ro 15 - 1788 and positron emission tomography (PET). (author)

  9. Methamphetamine-evoked depression of GABAB receptor signaling in GABA neurons of the VTA

    Science.gov (United States)

    Padgett, CL; Lalive, AL; Tan, KR; Terunuma, M; Munoz, MB; Pangalos, MN; Martínez-Hernández, J; Watanabe, M; Moss, SJ; Luján, R; Lüscher, C; Slesinger, PA

    2012-01-01

    Psychostimulants induce neuroadaptations in excitatory and fast inhibitory transmission in the ventral tegmental area (VTA). Mechanisms underlying drug-evoked synaptic plasticity of slow inhibitory transmission mediated by GABAB receptors and G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels, however, are poorly understood. Here, we show that one day after methamphetamine (METH) or cocaine exposure, both synaptically-evoked and baclofen-activated GABABR-GIRK currents were significantly depressed in VTA GABA neurons, and remained depressed for 7 days. Presynaptic inhibition mediated by GABABRs on GABA terminals was also weakened. Quantitative immunoelectron microscopy revealed internalization of GABAB1R and GIRK2, which occurred coincident with dephosphorylation of Ser783 in GABAB2R, a site implicated in regulating GABABR surface expression. Inhibition of protein phosphatases recovered GABABR-GIRK currents in VTA GABA neurons of METH-injected mice. This psychostimulant-evoked impairment in GABABR signaling removes an intrinsic brake on GABA neuron spiking, which may augment GABA transmission in the mesocorticolimbic system. PMID:22405207

  10. Benzodiazepine-induced shaking behavior in the rat: structure-activity and relation to serotonin and benzodiazepine receptors.

    Science.gov (United States)

    Pranzatelli, M R

    1989-06-01

    In studying the role of serotonin (5-HT) in the mechanism of action of benzodiazepine (BDZ)-induced wet-dog shakes (WDS), only certain 1,4-substituted BDZ agonists were found to induce WDS at doses up to 60 mg/kg in the rat with the rank order of potency at peak dose effect clonazepam greater than nitrazepam = flunitrazepam much greater than nimetazepam = lorazepam. BDZs evoking WDS at lowest doses contained an R7 nitro group on the A ring. Non-BDZ agonists (CL 218,872), inverse agonists (beta-CCE), peripheral type receptor agonists (Ro 5-4864), and BDZ antagonists (Ro 15-1788) did not induce shaking behavior. Several 5-HT1 and 5-HT2 agonists and antagonists were tested as blockers, but only putative 5-HT1A agonists reduced WDS, 8-OH-DPAT and ipsapirone but not PAPP and 5-MeO-DMT having a significant effect. The effect of 8-OH-DPAT was dose dependent, with an ID50 of 0.86 mg/kg, but it was not reversed by 5-HT or adrenergic antagonists at the doses studied. Intracisternal 5,7-dihydroxytryptamine lesions did not alter frequency, latency, or time course of BDZ-induced WDS. BDZ-evoked WDS were enhanced by Ro 15-1788 (which inhibited ataxia) but were unaffected by the various types of BDZ agonists. Several BDZ agonists induced both WDS and ataxia, but ataxia was not blocked by serotonergic drugs. No significant correlation with ataxia, BDZ radioligand binding, antipentylenetetrazol activity, or other BDZ property was found. BDZ-evoked WDS may relate to the unique predominance of BDZ II and 5-HT1A receptors in the hippocampus, an important site for WDS, but 5-HT1A agonists appear to modulate WDS by opposing pharmacologic actions rather than by direct receptor antagonism. These data indicate a species difference in the shakes induced by BDZs in rats (5-HT2 independent) and in mice (5-HT2 related).

  11. Synthetic and computer assisted analysis of the pharmacophore for agonists at benzodiazepine receptors.

    Science.gov (United States)

    Diaz-Arauzo, H; Koehler, K F; Hagen, T J; Cook, J M

    1991-01-01

    In order to employ rational drug design in the discovery of selective benzodiazepine receptor agonists and inverse agonists, pharmacophore/receptor models for both these activities must first be established. Recently, a pharmacophore for the inverse agonist site has been formulated employing the most recent receptor mapping techniques (22). The continuation of this approach to the pharmacophore for agonist ligands has permitted a definition of this site independently of the inverse agonist model. The agonist pharmacophore/receptor contains two hydrogen bond donating sites of interaction (H1 and H2) located about 6.5 A from each other, as well as three areas of lipophilic interaction (L1-L3). The areas L1 and L2 are critical for agonist activity; moreover, some ligands also require an interaction in a third lipophilic area termed L3. This is in agreement with previous work (12-23). In addition, an area of negative steric interaction (S1) between the ligand and receptor-binding protein is defined. In regard to the pharmacophore, it was established that the alignment rule for agonist beta-carbolines is different from that which elicits inverse agonist activity. Consideration of the pharmacophore has resulted in the synthesis of a new beta-carboline 16 which elicits agonist activity. This ligand 16 not only satisfied the requirements of the pharmacophore, but more importantly it elicited both anticonvulsant and anxiolytic activity, but was devoid of the myorelaxant/ataxic properties associated with the benzodiazepines.

  12. In vivo study of drug interaction with brain benzodiazepine receptor

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, O.; Shinotoh, H.; Ito, T.; Suzuki, K.; Hashimoto, K.; Yamasaki, T.

    1985-05-01

    The possibility of direct estimation of in vivo Bz receptor occupancy in brain was evaluated using C-11, or H-3-flumazepil (Ro15-1788). In animal experiments, 1 ..mu..Ci of H-3-Ro15-1788 was injected at 0.5 or 20 hr after i.v. injection of various dosage of clonazepam. Then radioactivity in cerebral cortex, cerebellum and blood at 5 min. after injection of the tracer was compared. Competitive inhibition of in vivo binding was clearly observed when clonazepam was pretreated at 0.5 hr before injection of the tracer. On the other hand, brain radioactivity was increased when clonazepam was administered at 20 hr before injection of the tracer. This increase in binding of H-3-Ro15-1788 might be caused by rebound of Bz receptor function by treatment with Bz agonist, and this rebound may have an important role in physiological function. Clinical investigation concerning drug interaction with brain Bz receptor was performed in normal volunteer and patients with neurological disorders. The distribution of C-11-Ro15-1788 in the brain of patients chronically treated with clonazepam were significantly heterogeneous. However, cerebral blood flow estimated with N-13 NH3 of these patients were normal.

  13. Valerian inhibits rat hepatocarcinogenesis by activating GABA(A) receptor-mediated signaling.

    Science.gov (United States)

    Kakehashi, Anna; Kato, Ayumi; Ishii, Naomi; Wei, Min; Morimura, Keiichirou; Fukushima, Shoji; Wanibuchi, Hideki

    2014-01-01

    Valerian is widely used as a traditional medicine to improve the quality of sleep due to interaction of several active components with the γ-aminobutyric acid (GABA) A receptor (GABA(A)R) system. Recently, activation of GABA signaling in stem cells has been reported to suppress cell cycle progression in vivo. Furthermore, possible inhibitory effects of GABA(A)R agonists on hepatocarcinogenesis have been reported. The present study was performed to investigate modulating effects of Valerian on hepatocarcinogenesis using a medium-term rat liver bioassay. Male F344 rats were treated with one of the most powerful Valerian species (Valeriana sitchensis) at doses of 0, 50, 500 and 5000 ppm in their drinking water after initiation of hepatocarcinogenesis with diethylnitrosamine (DEN). Formation of glutathione S-transferase placental form positive (GST-P(+)) foci was significantly inhibited by Valerian at all applied doses compared with DEN initiation control rats. Generation of 8-hydroxy-2'-deoxyguanosine in the rat liver was significantly suppressed by all doses of Valerian, likely due to suppression of Nrf2, CYP7A1 and induction of catalase expression. Cell proliferation was significantly inhibited, while apoptosis was induced in areas of GST-P(+) foci of Valerian groups associated with suppression of c-myc, Mafb, cyclin D1 and induction of p21(Waf1/Cip1), p53 and Bax mRNA expression. Interestingly, expression of the GABA(A)R alpha 1 subunit was observed in GST-P(+) foci of DEN control rats, with significant elevation associated with Valerian treatment. These results indicate that Valerian exhibits inhibitory effects on rat hepatocarcinogenesis by inhibiting oxidative DNA damage, suppressing cell proliferation and inducing apoptosis in GST-P(+) foci by activating GABA(A)R-mediated signaling.

  14. GLUTAMATO REGULA EL DESTINO ENDOCITÍCO DE LOS RECEPTORES METABOTROPICOS DE GABA

    OpenAIRE

    VARGAS BARRIA, KARINA JAZMINA

    2009-01-01

    La disponibilidad de los receptores en membrana está controlada por mecanismos de tráfico intracelular, los cuales han sido ampliamente estudiados para los receptores ele glutamato y relacionados con fenómenos plásticos como L TP y L TD. Estos a su vez han sido relacionados con procesos cognitivos como memoria y aprendizaje. Se conoce poco acerca de la importancia del tráfico de los receptores gabaérgicos sobre la plasticidad. Este conocimiento es virtualmente nulo en el caso d...

  15. Application of gamma-aminobutyric acid type A-benzodiazepine receptor imaging for study of neuropsychiatric disorders

    International Nuclear Information System (INIS)

    Bao Weiqi; Qiu Chun; Guan Yihui

    2012-01-01

    Gamma-aminobutyric acid type A-benzodiazepine receptors are heterogeneous polypeptide pentamers widely spread in the central nervous system on the neuron membrane. Different subunit combinations educe various neuro-inhibitory pharmacological effects such as sedative, hypnosis, anticonvulsion and anxiolysis. PET can be utilized to study the binding of the receptors in vivo. PET radioligands of gamma-aminobutyric acid type A-benzodiazepine receptors can be classified into 3 types: antagonists,agonists and reverse agonists, of which antagonist radiotracer 11 C-flumazenil is the most commonly applied in epilepsy, anxiety disorders, depression, vegetative state,addiction and other neuro-psychiatric disorders. (authors)

  16. SKF97541, GABA-B receptor agonist, exhibits both anti- and procovulsant effets in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Tabashidze, Nana

    2007-01-01

    Roč. 48, s6 (2007), s. 18-18 ISSN 0013-9580. [Annual Meeting of the American Epilepsy Society. 31.112007-3.12.2007, Philadelphia] R&D Projects: GA ČR(CZ) GA304/05/2582 Institutional research plan: CEZ:AV0Z50110509 Keywords : cpo1 * GABA-B receptor * anti- and proconvulsant effects Subject RIV: FH - Neurology

  17. An antagonist of GABA-B receptors potentiates activity of cortical epileptic foci

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Bernášková, Klára; Kubová, Hana

    2012-01-01

    Roč. 61, č. 3 (2012), s. 325-329 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) LC554; GA ČR(CZ) GAP304/10/1274 Institutional research plan: CEZ:AV0Z50110509 Keywords : epileptic focus * GABA-B receptor * cerebral cortex * rat Subject RIV: FH - Neurology Impact factor: 1.531, year: 2012

  18. Anticonvulsant action of GABA(B) receptor positive modulator CGP7930 in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2012-01-01

    Roč. 100, 1-2 (2012), s. 49-54 ISSN 0920-1211 R&D Projects: GA MŠk(CZ) LC554; GA ČR(CZ) GAP304/10/1274 Institutional research plan: CEZ:AV0Z50110509 Keywords : GABA(B) receptors * cerebral cortex * epileptic afterdischarges * immature rats Subject RIV: FH - Neurology Impact factor: 2.241, year: 2012

  19. GABA(B) receptors inhibit backpropagating dendritic spikes in hippocampal CA1 pyramidal cells in vivo.

    Science.gov (United States)

    Leung, L Stan; Peloquin, Pascal

    2006-01-01

    Spike backpropagation has been proposed to enhance dendritic depolarization and synaptic plasticity. However, relatively little is known about the inhibitory control of spike backpropagation in vivo. In this study, the backpropagation of the antidromic spike into the dendrites of CA1 pyramidal cells was studied by extracellular recording in urethane-anesthetized rats. The population antidromic spike (pAS) in CA1 following stimulation of the alveus was recorded simultaneously with a 16-channel silicon probe and analyzed as current source density (CSD). The pAS current sink was shown to sequentially invade the soma and then the apical and basal dendrites. When the pAS was preceded sinks were reduced and delayed. Dendritic spike suppression was large after a high-intensity CA3 conditioning stimulus that evoked a population spike, small after a low-intensity CA3 conditioning stimulus, and weak after conditioning by another pAS. The late (150-400 ms latency) inhibition of the backpropagating pAS at the apical and basal dendrites was partially relieved by a GABA(B) receptor antagonist, CGP35348 or CGP56999A, given intracerebroventricularly (icv). CGP35348 icv also decreased the latency of the antidromic spike sinks at all depths. A compartment cable model of a CA1 pyramidal cell with excitable dendrites, combined with a model of extracellular potential generation, confirms that GABA(B) receptor activation delays a backpropagating spike and blocks distal dendritic spikes. GABA(B) receptor-mediated conductance increase and hyperpolarization, amplified by removing dendritic I(A) inactivation, contribute to conditioned dendritic spike suppression. In addition, the model shows that slow Na(+) channel inactivation also participates in conditioned spike suppression, which may partly explain the small dendritic spike suppression after conditioning with a weak orthodromic stimulus or another antidromic spike. Thus, both theory and experiment confirm an important role of the GABA

  20. GABA(A)-benzodiazepine receptor complex ligands and stress-induced hyperthermia in singly housed mice.

    NARCIS (Netherlands)

    Olivier, B.; Bouwknecht, J.A.; Pattij, T.; Leahy, C.; Oorschot, R. van; Zethof, T.J.

    2002-01-01

    Stress-induced hyperthermia (SIH) in singly housed mice, in which the rectal temperature of a mouse is measured twice with a 10-min interval, enables to study the effects of a drug on the basal (T(1)) and on the stress-enhanced temperature (T(2)), 10 min later, using the rectal procedure as

  1. Alterations of muscarinic and GABA receptor binding in the posterior cingulate cortex in schizophrenia.

    Science.gov (United States)

    Newell, Kelly A; Zavitsanou, Katerina; Jew, Stephen Kum; Huang, Xu-Feng

    2007-01-30

    The posterior cingulate cortex (PCC), a key component of the limbic system, has been implicated in the pathology of schizophrenia because of its sensitivity to NMDA receptor antagonists. Recent studies have shown that the PCC is dysfunctional in schizophrenia, and it is now suspected to be critically involved in the pathogenesis of schizophrenia. Studies also suggest that there are abnormalities in muscarinic and GABAergic neurotransmission in schizophrenia. Therefore, in the present study we used quantitative autoradiography to investigate the binding of [(3)H]pirenzepine, [(3)H]AF-DX 384 and [(3)H]muscimol, which respectively label M1/4 and M2/4 muscarinic and GABA(A) receptors, in the PCC of schizophrenia and control subjects matched for age and post-mortem interval. The present study found that [(3)H]pirenzepine binding was significantly decreased in the superficial (-24%, p=0.002) and deep (-35%, pM4, M2/M4 and GABA(A) receptors in the PCC in schizophrenia. Whilst the exact mechanism causing these alterations is not yet known, a possible increased acetylcholine and down regulated GABA stimulation in the PCC of schizophrenia is suggested.

  2. Gene expression changes in GABA(A receptors and cognition following chronic ketamine administration in mice.

    Directory of Open Access Journals (Sweden)

    Sijie Tan

    Full Text Available Ketamine is a well-known anesthetic agent and a drug of abuse. Despite its widespread use and abuse, little is known about its long-term effects on the central nervous system. The present study was designed to evaluate the effect of long-term (1- and 3-month ketamine administration on learning and memory and associated gene expression levels in the brain. The Morris water maze was used to assess spatial memory and gene expression changes were assayed using Affymetrix Genechips; a focus on the expression of GABA(A receptors that mediate a tonic inhibition in the brain, was confirmed by quantitative real-time PCR and western blot. Compared with saline controls, there was a decline in learning and memory performance in the ketamine-treated mice. Genechip results showed that 110 genes were up-regulated and 136 genes were down-regulated. An ontology analysis revealed the most significant effects of ketamine were on GABA(A receptors. In particular, there was a significant up-regulation of both mRNA and protein levels of the alpha 5 subunit (Gabra5 of the GABA(A receptors in the prefrontal cortex. In conclusion, chronic exposure to ketamine impairs working memory in mice, which may be explained at least partly by up-regulation of Gabra5 subunits in the prefrontal cortex.

  3. Chronic prenatal ethanol exposure alters hippocampal GABA(A) receptors and impairs spatial learning in the guinea pig.

    Science.gov (United States)

    Iqbal, U; Dringenberg, H C; Brien, J F; Reynolds, J N

    2004-04-02

    Chronic prenatal ethanol exposure (CPEE) can injure the developing brain, and may lead to the fetal alcohol syndrome (FAS). Previous studies have demonstrated that CPEE upregulates gamma-aminobutyric acid type A (GABA(A)) receptor expression in the cerebral cortex, and decreases functional synaptic plasticity in the hippocampus, in the adult guinea pig. This study tested the hypothesis that CPEE increases GABA(A) receptor expression in the hippocampus of guinea pig offspring that exhibit cognitive deficits in a hippocampal-dependent spatial learning task. Timed, pregnant guinea pigs were treated with ethanol (4 g/kg maternal body weight per day), isocaloric-sucrose/pair-feeding, or water throughout gestation. GABA(A) receptor subunit protein expression in the hippocampus was measured at two development ages: near-term fetus and young adult. In young adult guinea pig offspring, CPEE increased spontaneous locomotor activity in the open-field and impaired task acquisition in the Morris water maze. CPEE did not change GABA(A) receptor subunit protein expression in the near-term fetal hippocampus, but increased expression of the beta2/3-subunit of the GABA(A) receptor in the hippocampus of young adult offspring. CPEE did not change either [(3)H]flunitrazepam binding or GABA potentiation of [(3)H]flunitrazepam binding, but decreased the efficacy of allopregnanolone potentiation of [(3)H]flunitrazepam binding, to hippocampal GABA(A) receptors in adult offspring. Correlational analysis revealed a relationship between increased spontaneous locomotor activity and growth restriction in the hippocampus induced by CPEE. Similarly, an inverse relationship was found between performance in the water maze and the efficacy of allopregnanolone potentiation of [(3)H]flunitrazepam binding in the hippocampus. These data suggest that alterations in hippocampal GABA(A) receptor expression and pharmacological properties contribute to hippocampal-related behavioral and cognitive deficits

  4. Role of GABA(B) receptors in learning and memory and neurological disorders.

    Science.gov (United States)

    Heaney, Chelcie F; Kinney, Jefferson W

    2016-04-01

    Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Benzodiazepine receptor quantification in vivo in humans using [11C]flumazenil and PET

    DEFF Research Database (Denmark)

    Lassen, N A; Bartenstein, P A; Lammertsma, A A

    1995-01-01

    Carbon-11-labeled flumazenil combined with positron emission tomography (PET) was used to measure the concentration (Bmax) of the benzodiazepine (Bz) receptor in the brain and its equilibrium dissociation constant (KD) for flumazenil in five normal subjects. The steady-state approach was used...... injecting the tracer as a bolus of high specific activity. In each subject two studies were carried out. The first study was performed at essentially zero receptor occupancy, the tracer alone study. The second study was performed at a steady-state receptor occupancy of about 50%, achieved by a prolonged...... constant infusion of nonlabeled ("cold") flumazenil starting 2h before the bolus tracer injection and continuing until the end of scanning period. In this second study the free concentration of unmetabolized flumazenil in plasma water was measured in multiple blood samples. The observed tissue and plasma...

  6. P2Y1 receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes.

    Science.gov (United States)

    Jacob, Pedro F; Vaz, Sandra H; Ribeiro, Joaquim A; Sebastião, Ana M

    2014-08-01

    Astrocytes express a variety of purinergic (P2) receptors, involved in astrocytic communication through fast increases in [Ca(2+) ]i . Of these, the metabotropic ATP receptors (P2Y) regulate cytoplasmic Ca(2+) levels through the PLC-PKC pathway. GABA transporters are a substrate for a number of Ca(2+) -related kinases, raising the possibility that calcium signalling in astrocytes impact the control of extracellular levels of the major inhibitory transmitter in the brain. To access this possibility we tested the influence of P2Y receptors upon GABA transport into astrocytes. Mature primary cortical astroglial-enriched cultures expressed functional P2Y receptors, as evaluated through Ca(2+) imaging, being P2Y1 the predominant P2Y receptor subtype. ATP (100 μM, for 1 min) caused an inhibition of GABA transport through either GAT-1 or GAT-3 transporters, decreasing the Vmax kinetic constant. ATP-induced inhibition of GATs activity was still evident in the presence of adenosine deaminase, precluding an adenosine-mediated effect. This, was mimicked by a specific agonist for the P2Y1,12,13 receptor (2-MeSADP). The effect of 2-MeSADP on GABA transport was blocked by the P2 (PPADS) and P2Y1 selective (MRS2179) receptor antagonists, as well as by the PLC inhibitor (U73122). 2-MeSADP failed to inhibit GABA transport in astrocytes where intracellular calcium had been chelated (BAPTA-AM) or where calcium stores were depleted (α-cyclopiazonic acid, CPA). In conclusion, P2Y1 receptors in astrocytes inhibit GABA transport through a mechanism dependent of P2Y1 -mediated calcium signalling, suggesting that astrocytic calcium signalling, which occurs as a consequence of neuronal firing, may operate a negative feedback loop to enhance extracellular levels of GABA. © 2014 Wiley Periodicals, Inc.

  7. Activation of α6-containing GABAA receptors by pentobarbital occurs through a different mechanism than activation by GABA

    Science.gov (United States)

    Fisher, Matthew T.; Fisher, Janet L.

    2010-01-01

    The GABAA receptors are ligand-gated chloride channels which are the targets for many clinically used sedatives, including the barbiturates. The barbiturate pentobarbital acts through multiple sites on the GABAA receptor. At low concentrations (μM), it acts as a positive allosteric modulator while at higher concentrations it can directly activate the receptor. This agonist action is influenced by the subunit composition of the receptor, and pentobarbital is a more effective agonist than GABA only at receptors containing an α6 subunit. The conformational change that translates GABA binding into channel opening is known to involve a lysine residue located in an extracellular domain between the 2nd and 3rd transmembrane domains. Mutations of this residue disrupt activation of the channel by GABA and have been linked to inherited epilepsy. Pentobarbital binds to the receptor at a different agonist site than GABA, but could use a common signal transduction mechanism to gate the channel. To address this question, we compared the effect of a mutating the homologous lysine residue in the α1 or α6 subunits (K278 or K277, respectively) to methionine on direct activation of recombinant GABAA receptors by GABA or pentobarbital. We found that this mutation reduced GABA sensitivity for both α1 and α6 subunits, but affected pentobarbital sensitivity only for the α1 subunit. This suggests that pentobarbital acts through a distinct signal transduction pathway at the α6 subunit, which may account for its greater efficacy compared to GABA at receptors containing this subunit. PMID:20109529

  8. GABA(B) receptor GTP-binding is decreased in the prefrontal cortex but not the hippocampus of aged rats.

    Science.gov (United States)

    McQuail, Joseph A; Bañuelos, Cristina; LaSarge, Candi L; Nicolle, Michelle M; Bizon, Jennifer L

    2012-06-01

    Gamma aminobutyric acid (GABA)(B) receptors (GABA(B)Rs) have been linked to a wide range of physiological and cognitive processes and are of interest for treating a number of neurodegenerative and psychiatric disorders. As many of these diseases are associated with advanced age, it is important to understand how the normal aging process impacts GABA(B)R expression and signaling. Thus, we investigated GABA(B)R expression and function in the prefrontal cortex (PFC) and hippocampus of young and aged rats characterized in a spatial learning task. Baclofen-stimulated GTP-binding and GABA(B)R1 and GABA(B)R2 proteins were reduced in the prefrontal cortex of aged rats but these reductions were not associated with spatial learning abilities. In contrast, hippocampal GTP-binding was comparable between young and aged rats but reduced hippocampal GABA(B)R1 expression was observed in aged rats with spatial learning impairment. These data demonstrate marked regional differences in GABA(B)R complexes in the adult and aged brain and could have implications for both understanding the role of GABAergic processes in normal brain function and the development of putative interventions that target this system. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. γ1-Containing GABA-A Receptors Cluster at Synapses Where they Mediate Slower Synaptic Currents than γ2-Containing GABA-A Receptors

    Directory of Open Access Journals (Sweden)

    Christine L. Dixon

    2017-06-01

    Full Text Available GABA-A receptors (GABAARs are pentameric ligand-gated ion channels that are assembled mainly from α (α1–6, β (β1–3 and γ (γ1–3 subunits. Although GABAARs containing γ2L subunits mediate most of the inhibitory neurotransmission in the brain, significant expression of γ1 subunits is seen in the amygdala, pallidum and substantia nigra. However, the location and function of γ1-containing GABAARs in these regions remains unclear. In “artificial” synapses, where the subunit composition of postsynaptic receptors is specifically controlled, γ1 incorporation slows the synaptic current decay rate without affecting channel deactivation, suggesting that γ1-containing receptors are not clustered and therefore activated by diffuse neurotransmitter. However, we show that γ1-containing receptors are localized at neuronal synapses and form clusters in both synaptic and extrasynaptic regions. In addition, they exhibit rapid membrane diffusion and a higher frequency of exchange between synaptic and perisynaptic populations compared to γ2L-containing GABAARs. A point mutation in the large intracellular domain and a pharmacological analysis reveal that when a single non-conserved γ2L residue is mutated to its γ1 counterpart (T349L, the synaptic current decay is slowed from γ2L- to γ1-like without changing the clustering or diffusion properties of the receptors. In addition, previous fast perfusion and single channel kinetic experiments revealed no difference in the intrinsic closing rates of γ2L- and γ1-containing receptors when expressed in HEK293 cells. These observations together with Monte Carlo simulations of synaptic function confirm that decreased clustering does not control γ1-containing GABAAR kinetics. Rather, they suggest that γ1- and γ2L-containing receptors exhibit differential synaptic current decay rates due to differential gating dynamics when localized at the synapse.

  10. GABA_A receptor function is regulated by lipid bilayer elasticity

    DEFF Research Database (Denmark)

    Søgaard, Rikke; Werge, Thomas; Berthelsen, Camilla

    2006-01-01

    Docosahexaenoic acid ( DHA) and other polyunsaturated fatty acids ( PUFAs) promote GABA(A) receptor [ (3)H]-muscimol binding, and DHA increases the rate of GABAA receptor desensitization. Triton X-100, a structurally unrelated amphiphile, similarly promotes [ (3)H]-muscimol binding. The mechanism......( s) underlying these effects are poorly understood. DHA and Triton X-100, at concentrations that affect GABAA receptor function, increase the elasticity of lipid bilayers measured as decreased bilayer stiffness using gramicidin channels as molecular force transducers. We have previously shown...... that membrane protein function can be regulated by amphiphile-induced changes in bilayer elasticity and hypothesized that GABAA receptors could be similarly regulated. We therefore studied the effects of four structurally unrelated amphiphiles that decrease bilayer stiffness ( Triton X-100, octyl...

  11. An atypical residue in the pore of Varroa destructor GABA-activated RDL receptors affects picrotoxin block and thymol modulation.

    Science.gov (United States)

    Price, Kerry L; Lummis, Sarah C R

    2014-12-01

    GABA-activated RDL receptors are the insect equivalent of mammalian GABAA receptors, and play a vital role in neurotransmission and insecticide action. Here we clone the pore lining M2 region of the Varroa mite RDL receptor and show that it has 4 atypical residues when compared to M2 regions of most other insects, including bees, which are the major host of Varroa mites. We create mutant Drosophila RDL receptors containing these substitutions and characterise their effects on function. Using two electrode voltage clamp electrophysiology we show that one substitution (T6'M) ablates picrotoxin inhibition and increases the potency of GABA. This mutation also alters the effect of thymol, which enhances both insect and mammalian GABA responses, and is widely used as a miticide. Thymol decreases the GABA EC50 of WT receptors, enhancing responses, but in T6'M-containing receptors it is inhibitory. The other 3 atypical residues have no major effects on either the GABA EC50, the picrotoxin potency or the effect of thymol. In conclusion we show that the RDL 6' residue is important for channel block, activation and modulation, and understanding its function also has the potential to prove useful in the design of Varroa-specific insecticidal agents. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Cloning, purification, crystallization and preliminary X-ray analysis of a bacterial GABA receptor with a Venus flytrap fold

    International Nuclear Information System (INIS)

    Moréra, Solange; Gueguen-Chaignon, Virginie; Raffoux, Aurélie; Faure, Denis

    2008-01-01

    A 1.35 Å resolution data set was collected from a crystal of the periplasmic GABA receptor Atu2422 from A. tumefaciens. Atu2422 adopts a closed Venus flytrap conformation. In response to infection by the pathogen Agrobacterium tumefaciens, plants synthesize several stress amino acids, including γ-aminobutyric acid (GABA), which modulates the expression of bacterial virulence factors. GABA penetrates into the bacterial cytoplasm via an ABC transporter that is associated with the periplasmic receptor Atu2422. Mature receptor Atu2422 (without its signal peptide) was overexpressed in Escherichia coli, purified and crystallized. A complete data set was collected to 1.35 Å resolution at 100 K. The crystals belonged to the monoclinic space group C2 and contained one molecule in the asymmetric unit. Molecular replacement was performed and the initial electron-density maps revealed a closed form of this Venus flytrap (VFT) receptor, suggesting the presence of an endogenous E. coli ligand

  13. Structure and functional interaction of the extracellular domain of human GABA[subscript B] receptor GBR2

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yong; Xiong, Dazhi; Mosyak, Lidia; Malito, David L.; Kniazeff, Julie; Chen, Yan; Burmakina, Svetlana; Quick, Matthias; Bush, Martin; Javitch, Jonathan A.; Pin, Jean-Philippe; Fan, Qing R. (CNRS-UMR); (Columbia)

    2012-10-24

    Inhibitory neurotransmission is mediated primarily by GABA. The metabotropic GABA{sub B} receptor is a G protein-coupled receptor central to mammalian brain function. Malfunction of GABA{sub B} receptor has been implicated in several neurological disorders. GABA{sub B} receptor functions as a heterodimeric assembly of GBR1 and GBR2 subunits, where GBR1 is responsible for ligand-binding and GBR2 is responsible for G protein coupling. Here we demonstrate that the GBR2 ectodomain directly interacts with the GBR1 ectodomain to increase agonist affinity by selectively stabilizing the agonist-bound conformation of GBR1. We present the crystal structure of the GBR2 ectodomain, which reveals a polar heterodimeric interface. We also identify specific heterodimer contacts from both subunits, and GBR1 residues involved in ligand recognition. Lastly, our structural and functional data indicate that the GBR2 ectodomain adopts a constitutively open conformation, suggesting a structural asymmetry in the active state of GABA{sub B} receptor that is unique to the GABAergic system.

  14. Midazolam inhibits chondrogenesis via peripheral benzodiazepine receptor in human mesenchymal stem cells.

    Science.gov (United States)

    Chen, Yung-Ching; Wu, King-Chuen; Huang, Bu-Miin; So, Edmund Cheung; Wang, Yang-Kao

    2018-05-01

    Midazolam, a benzodiazepine derivative, is widely used for sedation and surgery. However, previous studies have demonstrated that Midazolam is associated with increased risks of congenital malformations, such as dwarfism, when used during early pregnancy. Recent studies have also demonstrated that Midazolam suppresses osteogenesis of mesenchymal stem cells (MSCs). Given that hypertrophic chondrocytes can differentiate into osteoblast and osteocytes and contribute to endochondral bone formation, the effect of Midazolam on chondrogenesis remains unclear. In this study, we applied a human MSC line, the KP cell, to serve as an in vitro model to study the effect of Midazolam on chondrogenesis. We first successfully established an in vitro chondrogenic model in a micromass culture or a 2D high-density culture performed with TGF-β-driven chondrogenic induction medium. Treatment of the Midazolam dose-dependently inhibited chondrogenesis, examined using Alcian blue-stained glycosaminoglycans and the expression of chondrogenic markers, such as SOX9 and type II collagen. Inhibition of Midazolam by peripheral benzodiazepine receptor (PBR) antagonist PK11195 or small interfering RNA rescued the inhibitory effects of Midazolam on chondrogenesis. In addition, Midazolam suppressed transforming growth factor-β-induced Smad3 phosphorylation, and this inhibitory effect could be rescued using PBR antagonist PK11195. This study provides a possible explanation for Midazolam-induced congenital malformations of the musculoskeletal system through PBR. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  15. Size-exclusion chromatographic reconstitution of the bovine brain benzodiazepine receptor : Effects of lipid environment on the binding characteristics

    NARCIS (Netherlands)

    Viel, G.T; Yang, Q; Lundahl, P; Ensing, K; de Zeeuw, R.A

    1997-01-01

    The benzodiazepine receptor from calf brain was solubilized with sodium deoxycholate (2 mg/ml) in the presence of 0.5 M KCl and protease inhibitors, and bound flunitrazepam with an equilibrium dissociation constant (K-d) of 2.7+/-1.2 nM and with 0.40+/-0.04 pmol binding sites per mg protein (B-max).

  16. Basolateral amygdala GABA-A receptors mediate stress-induced memory retrieval impairment in rats.

    Science.gov (United States)

    Sardari, Maryam; Rezayof, Ameneh; Khodagholi, Fariba; Zarrindast, Mohammad-Reza

    2014-04-01

    The present study was designed to investigate the involvement of GABA-A receptors of the basolateral amygdala (BLA) in the impairing effect of acute stress on memory retrieval. The BLAs of adult male Wistar rats were bilaterally cannulated and memory retrieval was measured in a step-through type passive avoidance apparatus. Acute stress was evoked by placing the animals on an elevated platform for 10, 20 and 30 min. The results indicated that exposure to 20 and 30 min stress, but not 10 min, before memory retrieval testing (pre-test exposure to stress) decreased the step-through latency, indicating stress-induced memory retrieval impairment. Intra-BLA microinjection of a GABA-A receptor agonist, muscimol (0.005-0.02 μg/rat), 5 min before exposure to an ineffective stress (10 min exposure to stress) induced memory retrieval impairment. It is important to note that pre-test intra-BLA microinjection of the same doses of muscimol had no effect on memory retrieval in the rats unexposed to 10 min stress. The blockade of GABA-A receptors of the BLA by injecting an antagonist, bicuculline (0.4-0.5 μg/rat), 5 min before 20 min exposure to stress, prevented stress-induced memory retrieval. Pre-test intra-BLA microinjection of the same doses of bicuculline (0.4-0.5 μg/rat) in rats unexposed to 20 min stress had no effect on memory retrieval. In addition, pre-treatment with bicuculline (0.1-0.4 μg/rat, intra-BLA) reversed muscimol (0.02 μg/rat, intra-BLA)-induced potentiation on the effect of stress in passive avoidance learning. It can be concluded that pre-test exposure to stress can induce memory retrieval impairment and the BLA GABA-A receptors may be involved in stress-induced memory retrieval impairment.

  17. Ligands for expression cloning and isolation of GABA(B) receptors.

    Science.gov (United States)

    Froestl, Wolfgang; Bettler, Bernhard; Bittiger, Helmut; Heid, Jakob; Kaupmann, Klemens; Mickel, Stuart J; Strub, Dietrich

    2003-03-01

    The scope of the plenary lecture at the occasion of the Xth Meeting on Heterocyclic Structures in Medicinal Chemistry, Palermo 2002, is considerably larger than that of the main lecture at the XVIth International Symposium on Medicinal Chemistry, Bologna 2000, described by Froestl et al. in Farmaco 56 (2001) 101. Additional information is presented, in particular, on the reaction conditions for the 31 step synthesis of the combined affinity chromatography and photoaffinity radioligand [125I]CGP84963 and on the recent developments of the molecular biology of GABA(B) receptors. Copyright 2003 Editions scienctifiques et médicales Elsevier SAS

  18. Platelet peripheral benzodiazepine receptors are decreased in Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Bonuccelli, U.; Nuti, A.; Del Dotto, P.; Piccini, P.; Martini, C.; Giannacccini, G.; Lucacchini, A.; Muratorio, A. (Univ. of Pisa (Italy))

    1991-01-01

    Peripheral benzodiazepine (BDZ) receptors are located in a variety of tissues, including platelets, in the nuclear and/or mitochondrial membranes. The authors studied the density of peripheral BDZ receptors in platelets of 10 de novo Parkinson's disease (PD) patients, 18 PD patients treated with a levodopa/carbidopa combination, and in 15 healthy subjects matched for sex and age. The binding assay was conducted using ({sup 3}H)PK 11195, a specific ligand for peripheral BDZ receptors. A significant decrease in the density of ({sup 3}H)PK 11195 binding sites has been observed in PD patients with respect to controls but not between de novo and treated PD patients. No correlation has been found between the decrease in density of ({sup 3}H)PK 11195 binding sites in platelets and either the duration or severity of PD. Peripheral BDZ receptors are implicated in the regulation of mitochondrial respiratory function. Thus, their decrease in PD might parallel the abnormalities in mitochondrial function recently found in this neurologic disease.

  19. Methodology for benzodiazepine receptor binding assays at physiological temperature. Rapid change in equilibrium with falling temperature

    International Nuclear Information System (INIS)

    Dawson, R.M.

    1986-01-01

    Benzodiazepine receptors of rat cerebellum were assayed with [ 3 H]-labeled flunitrazepam at 37 0 C, and assays were terminated by filtration in a cold room according to one of three protocols: keeping each sample at 37 degrees C until ready for filtration, taking the batch of samples (30) into the cold room and filtering sequentially in the order 1-30, and taking the batch of 30 samples into the cold room and filtering sequentially in the order 30-1. the results for each protocol were substantially different from each other, indicating that rapid disruption of equilibrium occurred as the samples cooled in the cold room while waiting to be filtered. Positive or negative cooperativity of binding was apparent, and misleading effects of gamma-aminobutyric acid on the affinity of diazepam were observed, unless each sample was kept at 37 0 C until just prior to filtration

  20. Benzodiazepine receptor distribution and cerebral blood flow in early blindness. A PET study

    International Nuclear Information System (INIS)

    Mishina, Masahiro; Senda, Michio; Kiyosawa, Motohiro

    2000-01-01

    We studied benzodiazepine receptor (BZR) distribution, which is thought to be affected by neuronal density in the cerebral cortex, and CBF using [ 11 C]flumazenil and [ 15 O]water PET in early blind (EB) and in blindfold sighted control (SC) subjects. PET images were co-registered to the subject's MRI. Using SPM96, MRI images were normalized in the Talairach and Tournoux coordinate system, and accordingly MRI-registered PET images were spatially normalized. Statistical parametric maps were computed on a voxel-by-voxel basis, using the general linear model. CBF for EB was significantly larger in the Brodmann area 17 and 18, especially anterior area, than that for SC, while there was no significant difference in BZR distribution. Our BZR data suggest that the amount of neurons do not change due to early visual deprivation in the visual cortex, in spite of high CBF in visual cortex of EB subjects. (author)

  1. Block of GABA(A) receptor ion channel by penicillin: electrophysiological and modeling insights toward the mechanism.

    Science.gov (United States)

    Rossokhin, Alexey V; Sharonova, Irina N; Bukanova, Julia V; Kolbaev, Sergey N; Skrebitsky, Vladimir G

    2014-11-01

    GABA(A) receptors (GABA(A)R) mainly mediate fast inhibitory neurotransmission in the central nervous system. Different classes of modulators target GABA(A)R properties. Penicillin G (PNG) belongs to the class of noncompetitive antagonists blocking the open GABA(A)R and is a prototype of β-lactam antibiotics. In this study, we combined electrophysiological and modeling approaches to investigate the peculiarities of PNG blockade of GABA-activated currents recorded from isolated rat Purkinje cells and to predict the PNG binding site. Whole-cell patch-сlamp recording and fast application system was used in the electrophysiological experiments. PNG block developed after channel activation and increased with membrane depolarization suggesting that the ligand binds within the open channel pore. PNG blocked stationary component of GABA-activated currents in a concentration-dependent manner with IC50 value of 1.12mM at -70mV. The termination of GABA and PNG co-application was followed by a transient tail current. Protection of the tail current from bicuculline block and dependence of its kinetic parameters on agonist affinity suggest that PNG acts as a sequential open channel blocker that prevents agonist dissociation while the channel remains blocked. We built the GABA(A)R models based on nAChR and GLIC structures and performed an unbiased systematic search of the PNG binding site. Monte-Carlo energy minimization was used to find the lowest energy binding modes. We have shown that PNG binds close to the intracellular vestibule. In both models the maximum contribution to the energy of ligand-receptor interactions revealed residues located on the level of 2', 6' and 9' rings formed by a bundle of M2 transmembrane segments, indicating that these residues most likely participate in PNG binding. The predicted structural models support the described mechanism of PNG block. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Preservation of peripheral benzodiazepine receptors: differential effects of freezing on [3H]Ro 5-4864 and [3H]PK 11195 binding

    International Nuclear Information System (INIS)

    Basile, A.S.; Ostrowski, N.L.; Skolnick, P.

    1987-01-01

    A statistically significant decrease in the density of peripheral benzodiazepine receptors was observed in renal membranes of rats beginning 2 weeks after adrenalectomy when compared with sham-operated controls. This decrease in peripheral benzodiazepine receptor density was manifest as a decrease in the Bmax of two ligands [ 3 H]Ro 5-4864 and [ 3 H]PK 11195, without accompanying changes in their apparent affinity (Kd) for this site. Similar changes were not seen in another aldosterone-sensitive organ, the submandibular salivary gland. The decrease in peripheral benzodiazepine receptor density in observed in adrenalectomized rat renal membranes was restored to control levels after 1 week of aldosterone administration using a dose (12.5 micrograms/kg/day) that had no effect on peripheral benzodiazepine receptor density in sham-operated animals. In contrast, dexamethasone administration (50 micrograms/kg/day, 1 week) had no effect on renal peripheral benzodiazepine receptor density when administered to either adrenalectomized or sham-operated rats. Further, adrenal demedullation had no effect on renal peripheral benzodiazepine receptor density or affinity. The decrease in peripheral benzodiazepine receptor density was localized to the renal cortex and the outer stripe of the medulla by gross dissection of renal slices and renal tissue section autoradiography. The specific effect of adrenalectomy on renal peripheral benzodiazepine receptor density, the lack of direct effect of aldosterone on [ 3 H]Ro 5-4864 binding, and the localization of the change in peripheral benzodiazepine receptor density to the renal cortex and outer stripe suggests that these changes may reflect an adaptation of the renal nephron (possibly the distal convoluted tubule, intermediate tubule and/or the collecting duct) to the loss of mineralocorticoid hormones

  3. Neurotoxins from Snake Venoms and α-Conotoxin ImI Inhibit Functionally Active Ionotropic γ-Aminobutyric Acid (GABA) Receptors*

    Science.gov (United States)

    Kudryavtsev, Denis S.; Shelukhina, Irina V.; Son, Lina V.; Ojomoko, Lucy O.; Kryukova, Elena V.; Lyukmanova, Ekaterina N.; Zhmak, Maxim N.; Dolgikh, Dmitry A.; Ivanov, Igor A.; Kasheverov, Igor E.; Starkov, Vladislav G.; Ramerstorfer, Joachim; Sieghart, Werner; Tsetlin, Victor I.; Utkin, Yuri N.

    2015-01-01

    Ionotropic receptors of γ-aminobutyric acid (GABAAR) regulate neuronal inhibition and are targeted by benzodiazepines and general anesthetics. We show that a fluorescent derivative of α-cobratoxin (α-Ctx), belonging to the family of three-finger toxins from snake venoms, specifically stained the α1β3γ2 receptor; and at 10 μm α-Ctx completely blocked GABA-induced currents in this receptor expressed in Xenopus oocytes (IC50 = 236 nm) and less potently inhibited α1β2γ2 ≈ α2β2γ2 > α5β2γ2 > α2β3γ2 and α1β3δ GABAARs. The α1β3γ2 receptor was also inhibited by some other three-finger toxins, long α-neurotoxin Ls III and nonconventional toxin WTX. α-Conotoxin ImI displayed inhibitory activity as well. Electrophysiology experiments showed mixed competitive and noncompetitive α-Ctx action. Fluorescent α-Ctx, however, could be displaced by muscimol indicating that most of the α-Ctx-binding sites overlap with the orthosteric sites at the β/α subunit interface. Modeling and molecular dynamic studies indicated that α-Ctx or α-bungarotoxin seem to interact with GABAAR in a way similar to their interaction with the acetylcholine-binding protein or the ligand-binding domain of nicotinic receptors. This was supported by mutagenesis studies and experiments with α-conotoxin ImI and a chimeric Naja oxiana α-neurotoxin indicating that the major role in α-Ctx binding to GABAAR is played by the tip of its central loop II accommodating under loop C of the receptors. PMID:26221036

  4. Neurotoxins from snake venoms and α-conotoxin ImI inhibit functionally active ionotropic γ-aminobutyric acid (GABA) receptors.

    Science.gov (United States)

    Kudryavtsev, Denis S; Shelukhina, Irina V; Son, Lina V; Ojomoko, Lucy O; Kryukova, Elena V; Lyukmanova, Ekaterina N; Zhmak, Maxim N; Dolgikh, Dmitry A; Ivanov, Igor A; Kasheverov, Igor E; Starkov, Vladislav G; Ramerstorfer, Joachim; Sieghart, Werner; Tsetlin, Victor I; Utkin, Yuri N

    2015-09-11

    Ionotropic receptors of γ-aminobutyric acid (GABAAR) regulate neuronal inhibition and are targeted by benzodiazepines and general anesthetics. We show that a fluorescent derivative of α-cobratoxin (α-Ctx), belonging to the family of three-finger toxins from snake venoms, specifically stained the α1β3γ2 receptor; and at 10 μm α-Ctx completely blocked GABA-induced currents in this receptor expressed in Xenopus oocytes (IC50 = 236 nm) and less potently inhibited α1β2γ2 ≈ α2β2γ2 > α5β2γ2 > α2β3γ2 and α1β3δ GABAARs. The α1β3γ2 receptor was also inhibited by some other three-finger toxins, long α-neurotoxin Ls III and nonconventional toxin WTX. α-Conotoxin ImI displayed inhibitory activity as well. Electrophysiology experiments showed mixed competitive and noncompetitive α-Ctx action. Fluorescent α-Ctx, however, could be displaced by muscimol indicating that most of the α-Ctx-binding sites overlap with the orthosteric sites at the β/α subunit interface. Modeling and molecular dynamic studies indicated that α-Ctx or α-bungarotoxin seem to interact with GABAAR in a way similar to their interaction with the acetylcholine-binding protein or the ligand-binding domain of nicotinic receptors. This was supported by mutagenesis studies and experiments with α-conotoxin ImI and a chimeric Naja oxiana α-neurotoxin indicating that the major role in α-Ctx binding to GABAAR is played by the tip of its central loop II accommodating under loop C of the receptors. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. GABA and glutamate receptors have different effects on excitability and are differentially regulated by calcium in spider mechanosensory neurons.

    Science.gov (United States)

    Torkkeli, Päivi H; Meisner, Shannon; Pfeiffer, Keram; French, Andrew S

    2012-12-01

    GABA and glutamate receptors belonging to the ligand-gated chloride-channel family are primary targets of insecticides and antiparasitics, so their molecular structure, pharmacology and biophysical properties have attracted significant attention. However, little is known about the physiological roles of these channels or how they regulate neuronal excitability and animal behavior. Mechanosensory neurons of VS-3 slit sensilla in the patella of the tropical wandering spider, Cupiennius salei, react to the GABA(A)-receptor agonists, GABA and muscimol, with depolarization and an increase in intracellular [Ca(2+)] and, during random noise stimulation, with a mixed inhibitory-excitatory response. We established that the GABA(A)-receptors in all VS-3 neurons are identical, but there are at least two types of glutamate receptors and some neurons do not respond to glutamate at all. Immunohistochemistry with antibodies against Drosophila inhibitory glutamate receptor (GluCls) α-subunit suggests that in addition to VS-3 neurons, these receptors may also be present in the efferent neurons surrounding the sensory neurons. Most VS-3 neurons were inhibited but not depolarized by glutamate during random stimulation, but some depolarized and had a similar excitatory-inhibitory response to glutamate as to muscimol. The membrane-permeable Ca(2+)-chelator BAPTA-AM abolished muscimol effects but potentiated glutamate effects, indicating that GABA and glutamate receptors are differentially modulated by Ca(2+), leading to diverse regulation of neuronal excitability. We hypothesize that this could be achieved by different Ca(2+)-triggered phosphorylation processes at each receptor type. These findings are important for understanding the significance of Ca(2+)-mediated regulation of transmitter receptor molecules and its role in controlling excitability. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  6. Decreased GABA receptor in the cerebral cortex of epileptic rats: effect of Bacopa monnieri and Bacoside-A

    Directory of Open Access Journals (Sweden)

    Mathew Jobin

    2012-02-01

    Full Text Available Abstact Background Gamma amino butyric acid (GABA, the principal inhibitory neurotransmitter in the cerebral cortex, maintains the inhibitory tones that counter balances neuronal excitation. When this balance is perturbed, seizures may ensue. Methods In the present study, alterations of the general GABA, GABAA and GABAB receptors in the cerebral cortex of the epileptic rat and the therapeutic application of Bacopa monnieri were investigated. Results Scatchard analysis of [3H]GABA, [3H]bicuculline and [3H]baclofen in the cerebral cortex of the epileptic rat showed significant decrease in Bmax (P Aά1, GABAAγ, GABAAδ, GABAB and GAD where down regulated (P Aά5 subunit and Cyclic AMP responsible element binding protein were up regulated. Confocal imaging study confirmed the decreased GABA receptors in epileptic rats. Epileptic rats have deficit in radial arm and Y maze performance. Conclusions Bacopa monnieri and Bacoside-A treatment reverses epilepsy associated changes to near control suggesting that decreased GABA receptors in the cerebral cortex have an important role in epileptic occurrence; Bacopa monnieri and Bacoside-A have therapeutic application in epilepsy management.

  7. 3D-QSAR model of flavonoids binding at benzodiazepine site in GABAA receptors.

    Science.gov (United States)

    Huang, X; Liu, T; Gu, J; Luo, X; Ji, R; Cao, Y; Xue, H; Wong, J T; Wong, B L; Pei, G; Jiang, H; Chen, K

    2001-06-07

    With flavone as a structural template, three-dimensional quantitative structure-activity relationship (3D-QSAR) studies and ab initio calculations were performed on a series of flavonoids. A reasonable pharmacophore model was built through CoMFA, CoMSIA, and HQSAR analyses and electrostatic potential calculations. A plausible binding mode for flavonoids with GABA(A) receptors was rationalized. On the basis of the commonly recognized binding site, the specific S1 and S2 subsites relating to substituent positions were proposed. The different binding affinities could be explained according to the frontier orbitals and electrostatic potential (ESP) maps. The ESP could be used as a novel starting point for designing more selective BZ-binding-site ligands.

  8. GABA(A receptors containing the α2 subunit are critical for direction-selective inhibition in the retina.

    Directory of Open Access Journals (Sweden)

    Olivia Nicola Auferkorte

    Full Text Available Far from being a simple sensor, the retina actively participates in processing visual signals. One of the best understood aspects of this processing is the detection of motion direction. Direction-selective (DS retinal circuits include several subtypes of ganglion cells (GCs and inhibitory interneurons, such as starburst amacrine cells (SACs. Recent studies demonstrated a surprising complexity in the arrangement of synapses in the DS circuit, i.e. between SACs and DS ganglion cells. Thus, to fully understand retinal DS mechanisms, detailed knowledge of all synaptic elements involved, particularly the nature and localization of neurotransmitter receptors, is needed. Since inhibition from SACs onto DSGCs is crucial for generating retinal direction selectivity, we investigate here the nature of the GABA receptors mediating this interaction. We found that in the inner plexiform layer (IPL of mouse and rabbit retina, GABA(A receptor subunit α2 (GABA(AR α2 aggregated in synaptic clusters along two bands overlapping the dendritic plexuses of both ON and OFF SACs. On distal dendrites of individually labeled SACs in rabbit, GABA(AR α2 was aligned with the majority of varicosities, the cell's output structures, and found postsynaptically on DSGC dendrites, both in the ON and OFF portion of the IPL. In GABA(AR α2 knock-out (KO mice, light responses of retinal GCs recorded with two-photon calcium imaging revealed a significant impairment of DS responses compared to their wild-type littermates. We observed a dramatic drop in the proportion of cells exhibiting DS phenotype in both the ON and ON-OFF populations, which strongly supports our anatomical findings that α2-containing GABA(ARs are critical for mediating retinal DS inhibition. Our study reveals for the first time, to the best of our knowledge, the precise functional localization of a specific receptor subunit in the retinal DS circuit.

  9. Studying cerebellar circuits by remote control of selected neuronal types with GABA-A receptors

    Directory of Open Access Journals (Sweden)

    William Wisden

    2009-12-01

    Full Text Available Although GABA-A receptor-mediated inhibition of cerebellar Purkinje cells by molecular layer interneurons (MLIs has been studied intensely on the cellular level, it has remained unclear how this inhibition regulates cerebellum-dependent behaviour. We have implemented two complementary approaches to investigate the function of the MLI-Purkinje cell synapse on the behavioral level. In the first approach we permanently disrupted inhibitory fast synaptic transmission at the synapse by genetically removing the postsynaptic GABA-A receptors from Purkinje cells (PC-Δγ2 mice. We found that chronic disruption of the MLI-Purkinje cell synapse strongly impaired cerebellar learning of the vestibular occular reflex (VOR, presumably by disrupting the temporal patterns of Purkinje cell activity. However, in PC-Δγ2 mice the baseline VOR reflex was only mildly affected; indeed PC-Δγ2 mice showed no ataxia or gait abnormalities suggesting that MLI control of Purkinje cell activity is either not involved in ongoing motor tasks or that the system has found a way to compensate for its loss. To investigate the latter possibility we have developed an alternative genetic technique; we made the MLI-Purkinje cell synapse selectively sensitive to rapid manipulation with the GABAA receptor modulator zolpidem (PC-γ2-swap mice. Minutes after intraperitoneal zolpidem injection, these PC-γ2-swap mice developed severe motor abnormalities, revealing a substantial contribution of the MLI-Purkinje cell synapse to real time motor control. The cell-type selective permanent knockout of synaptic GABAergic input, and the fast reversible modulation of GABAergic input at the same synapse illustrate how pursuing both strategies gives a fuller view.

  10. Subchronic treatment with antiepileptic drugs modifies pentylenetetrazol-induced seizures in mice: Its correlation with benzodiazepine receptor binding

    Directory of Open Access Journals (Sweden)

    Luisa Rocha

    2008-06-01

    Full Text Available Luisa RochaPharmacobiology Department, Center for Research and Advanced Studies, Calz, Tenorios, MéxicoAbstract: Experiments using male CD1 mice were carried out to investigate the effects of subchronic (daily administration for 8 days pretreatments with drugs enhancing GABAergic transmission (diazepam, 10 mg/kg, ip; gabapentin, 100 mg/kg, po; or vigabatrin, 500 mg/kg, po on pentylenetetrazol (PTZ-induced seizures, 24 h after the last injection. Subchronic administration of diazepam reduced latencies to clonus, tonic extension and death induced by PTZ. Subchronic vigabatrin produced enhanced latency to the first clonus but faster occurrence of tonic extension and death induced by PTZ. Subchronic gabapentin did not modify PTZ-induced seizures. Autoradiography experiments revealed reduced benzodiazepine receptor binding in several brain areas after subchronic treatment with diazepam or gabapentin, whereas subchronic vigabatrin did not induce significant receptor changes. The present results indicate differential effects induced by the subchronic administration of diazepam, vigabatrin, and gabapentin on the susceptibility to PTZ-induced seizures, benzodiazepine receptor binding, or both.Keywords: diazepam, gabapentin, vigabatrin, pentylenetetrazol, benzodiazepine receptors

  11. Peripheral benzodiazepines receptor (PBR stimulates steroidogenesis: A potential neuroprotective pathway following brain damage

    Directory of Open Access Journals (Sweden)

    George E. Barreto

    2015-04-01

    Full Text Available The effects of neuroactive steroids have been highly assessed for their significance on inflammation resolution induced by cytotoxic agents. Steroids are derived from cholesterol, and this regulatory pathway may be a target for possible protective strategies. For example, the increased expression of peripheral benzodiazepine receptor (PBR stimulates steroids production, and the action of specific ligands on PBR favors the reduction of glial activity and act as a protective mechanism. The augmented expression of PBR and steroidogenic acute regulatory protein (StAR after injury is associated with local production of steroids by glial cells. For instance, cholesterol is captured by StAR in the outer mitochondrial membrane that transfers it to PBR, which uses it as substrate for the enzyme P450scc in the inner mitochondrial membrane. Some ligands, such as 4'-Chlorodiazepam (Ro5-4864 and isoquinoline carboxamide (PK 11195, act as agonists of the PBR receptor. Previous studies indicate that Ro5-4864 reduces neuronal loss, thus implying the regulation of mitochondrial transition after a traumatic brain injury. In this work, we assess the effects of PBR ligands directly involved in neuronal cell survival and proliferation after injury, thereby activating potential downstream targets as novel therapeutic approaches.

  12. Functional characterization and expression of thalamic GABA(B) receptors in a rodent model of Parkinson's disease

    NARCIS (Netherlands)

    de Groote, C; Wullner, U; Loschmann, PA; Luiten, PGM; Klockgether, T

    1999-01-01

    Increased GABAergic neurotransmission of the basal ganglia output nuclei projecting to the motor thalamus is thought to contribute to the pathophysiology of Parkinson's disease. We investigated the functional role of thalamic GABA(B) receptors in a rodent model of Parkinson's disease. First, we

  13. Synthesis and biological evaluation of bis-CNB-GABA, a photoactivatable neurotransmitter with low receptor interference and chemical two-photon uncaging properties.

    Science.gov (United States)

    Shi, Diana D; Trigo, Federico F; Semmelhack, Martin F; Wang, Samuel S-H

    2014-02-05

    Photoactivatable "caged" neurotransmitters allow optical control of neural tissue with high spatial and temporal precision. However, the development of caged versions of the chief vertebrate inhibitory neurotransmitter, γ-amino butyric acid (GABA), has been limited by the propensity of caged GABAs to interact with GABA receptors. We describe herein the synthesis and application of a practically useful doubly caged GABA analog, termed bis-α-carboxy-2-nitrobenzyl-GABA (bis-CNB-GABA). Uncaging of bis-CNB-GABA evokes inward GABAergic currents in cerebellar molecular layer interneurons with rise times of 2 ms, comparable to flash duration. Response amplitudes depend on the square of flash intensity, as expected for a chemical two-photon uncaging effect. Importantly, prior to uncaging, bis-CNB-GABA is inactive at the GABAA receptor, evoking no changes in holding current in voltage-clamped neurons and showing an IC50 of at least 2.5 mM as measured using spontaneous GABAergic synaptic currents. Bis-CNB-GABA is stable in solution, with an estimated half-life of 98 days in the light. We expect that bis-CNB-GABA will prove to be an effective tool for high-resolution chemical control of brain circuits.

  14. Cyclohexanol analogues are positive modulators of GABA(A) receptor currents and act as general anaesthetics in vivo.

    Science.gov (United States)

    Hall, Adam C; Griffith, Theanne N; Tsikolia, Maia; Kotey, Francesca O; Gill, Nikhila; Humbert, Danielle J; Watt, Erin E; Yermolina, Yuliya A; Goel, Shikha; El-Ghendy, Bahaa; Hall, C Dennis

    2011-09-30

    GABA(A) receptors meet all the pharmacological criteria required to be considered important general anaesthetic targets. In the following study, the modulatory effects of various commercially available and novel cyclohexanols were investigated on recombinant human γ-aminobutyric acid (GABA(A), α(1)β(2)γ(2s)) receptors expressed in Xenopus oocytes, and compared to the modulatory effects on GABA currents observed with exposures to the intravenous anaesthetic agent, propofol. Submaximal EC(20) GABA currents were typically enhanced by co-applications of 3-300 μM cyclohexanols. For instance, at 30 μM 2,6-diisopropylcyclohexanol (a novel compound) GABA responses were increased ~3-fold (although similar enhancements were achieved at 3 μM propofol). As regards rank order for modulation by the cyclohexanol analogues at 30 μM, the % enhancements for 2,6-dimethylcyclohexanol~2,6-diethylcyclohexanol~2,6-diisopropylcyclohexanol~2,6-di-sec-butylcyclohexanol ≫2,6-di-tert-butylcyclohexanol~4-tert-butylcyclohexanol>cyclohexanol~cyclopentanol~2-methylcyclohexanol. We further tested the potencies of the cyclohexanol analogues as general anaesthetics using a tadpole in vivo assay. Both 2,6-diisopropylcyclohexanol and 2,6-dimethylcyclohexanol were effective as anaesthetics with EC(50)s of 14.0 μM and 13.1 μM respectively, while other cyclohexanols with bulkier side chains were less potent. In conclusion, our data indicate that cyclohexanols are both positive modulators of GABA(A) receptors currents and anaesthetics. The positioning and size of the alkyl groups at the 2 and 6 positions on the cyclohexanol ring were critical determinants of activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. 125I-iomazenil - benzodiazepine receptor binding and serum corticosterone level during psychological stress in a rat model

    International Nuclear Information System (INIS)

    Fukumitsu, Nobuyoshi; Ogi, Shigeyuki; Uchiyama, Mayuki; Mori, Yutaka

    2004-01-01

    To test the hypothesis that benzodiazepine receptor density decreases in response to stress, we correlated 125 I-iomazenil ( 125 I-IMZ) binding with serum corticosterone levels in a rat model. Wistar male rats were divided into four groups; control group (CON, 10 rats), no physical or psychological stress; and one-, three-, and five-day stress groups of 12 rats each (1-DAY, 3-DAY, and 5-DAY, respectively), receiving psychological stress for the given number of days. Psychological stress were given to rats with a communication box. The standardized uptake value (SUV) of 125 I-iomazenil of the 3-DAY and 5-DAY showed that 125 I-iomazenil - benzodiazepine receptor binding was significantly reduced in the cortices, accumbens nuclei, amygdala and caudate putamen (p 125 I-IMZ is a useful radioligand to reflect received stress and its binding in the cortices, accumbens nuclei, amygdala and caudate putamen is strongly affected by psychological stress

  16. Pyrethroid insecticides and radioligand displacement from the GABA receptor chloride ionophore complex

    Energy Technology Data Exchange (ETDEWEB)

    Crofton, K.M.; Reiter, L.W.; Mailman, R.B.

    1987-01-01

    Radioligand binding displacement studies were conducted to determine the effects of Type I and II pyrethroids on /sup 3/H-flunitrazepam (FLU), /sup 3/H-muscimol (MUS), and (/sup 35/S-t-butylbicyclophosphorothionate (TBPS) binding. Competition experiments with /sup 3/H-FLU and /sup 3/H-MUS indicate a lack of competition for binding by the pyrethroids. Type I pyrethroids failed to compete for the binding of (/sup 35/S-TBPS at concentrations as high as 50 pM. Type II pyrethroids inhibited (/sup 35/S-TBPS binding to rat brain synaptosomes with Ki values ranging from 5-10 pM. The data presented suggest that the interaction of Type II pyrethroids with the GABA receptor-ionophore complex is restricted to a site near the TBPS/picrotoxinin binding site.

  17. GABA{sub A} receptor beta 3 subunit gene is possibly paternally imprinted in humans

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-02-15

    As the gene for GABA{sub A} receptor beta 3 subunit (GABRB3) is encompassed by a small molecular deletion in chromosome 15q11-q13, which is the critical region for Angelman syndrome(AS), the GABRB3 gene could be a candidate gene for AS. The abnormal phenotype of AS is manifested only when the deletion is inherited from the mother, not from the father. Therefore, a candidate gene for AS should be paternally imprinted. Although it was reported that the GABRB3 gene was expressed equally from either the maternal or paternal chromosome in mouse brain (i.e., not imprinted), it is well known that imprinting shows tissue specificity, and it remains to be determined if all genes imprinted in the mouse are also imprinted in humans. 4 refs., 1 fig.

  18. Synthesis and in vivo evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Filip; Waterhouse, Rikki N. E-mail: rnw7@columbia.edu; Montoya, Julie A.; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S.; Laruelle, Marc

    2003-05-01

    The synthesis and evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [{sup 11}C] methyl iodide afforded the title compound [{sup 11}C]zolpidem in a yield of 19.19 {+-} 3.23% in 41 {+-} 2 min in specific activities of 0.995-1.19 Ci/{mu}mol (1.115 {+-} 0.105 Ci/{mu}mol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 {+-} 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [{sup 11}C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors.

  19. Peripheral-type benzodiazepine receptors in bronchoalveolar lavage cells of patients with interstitial lung disease

    International Nuclear Information System (INIS)

    Branley, Howard M.; Bois, Roland M. du; Wells, Athol U.; Jones, Hazel A.

    2007-01-01

    Introduction: PK11195 is a ligand with high affinity for peripheral benzodiazepine receptors (PBRs), which are present in large numbers in macrophages. PBRs play a role in antioxidant pathways and apoptosis, key factors in control of lung health. Intrapulmonary PBRs, assessed in vivo by positron emission tomography (PET), are decreased in interstitial lung disease (ILD) despite increased macrophage numbers. We wished to ascertain whether the observed decrease in in vivo expression of PBRs in the PET scans could be accounted for by a reduction in PBRs per cell by saturation-binding assays of R-PK11195 in cells obtained by bronchoalveolar lavage (BAL). Methods: We performed receptor saturation-binding assays with [ 3 H]-R-PK11195 on a mixed population of cells recovered by BAL to quantify the number of R-PK11195 binding sites per macrophage in 10 subjects with ILD and 10 normal subjects. Results: Receptor affinity [dissociation constant (Kd)] was similar in ILD patients and controls. However, R-PK11195 binding sites per cell [(maximal binding sites available (B max )] were decreased in macrophages obtained by BAL from subjects with ILD compared to normal (P<.0005). Microautoradiography confirmed localization of R-PK11195 to macrophages in a mixed inflammatory cell population obtained by BAL. Conclusion: These results demonstrate that in vitro PBR expression per cell on macrophages obtained by BAL is reduced in patients with ILD indicating a potentially functionally different macrophage phenotype. As PBRs are involved in the orchestration of lung inflammatory responses, this finding offers further insight into the role of macrophages in the pathogenesis of ILDs and offers a potential avenue for pharmacological strategy

  20. p-Coumaric acid activates the GABA-A receptor in vitro and is orally anxiolytic in vivo.

    Science.gov (United States)

    Scheepens, Arjan; Bisson, Jean-Francois; Skinner, Margot

    2014-02-01

    The increasing prevalence and social burden of subclinical anxiety in the western world represents a significant psychosocial and financial cost. Consumers are favouring a more natural and nonpharmacological approach for alleviating the effects of everyday stress and anxiety. The gamma-aminobutyric acid (GABA) receptor is the primary mediator of central inhibitory neurotransmission, and GABA-receptor agonists are well known to convey anxiolytic effects. Using an in vitro screening approach to identify naturally occurring phytochemical GABA agonists, we discovered the plant secondary metabolite p-coumaric acid to have significant GABAergic activity, an effect that could be blocked by co-administration of the specific GABA-receptor antagonist, picrotoxin. Oral administration of p-coumaric acid to rodents induced a significant anxiolytic effect in vivo as measured using the elevated plus paradigm, in line with the effects of oral diazepam. Given that p-coumaric acid is reasonably well absorbed following oral consumption in man and is relatively nontoxic, it may be suitable for the formulation of a safe and effective anxiolytic functional food. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Insights into the binding of GABA to the insect RDL receptor from atomistic simulations: a comparison of models

    Science.gov (United States)

    Comitani, Federico; Cohen, Netta; Ashby, Jamie; Botten, Dominic; Lummis, Sarah C. R.; Molteni, Carla

    2014-01-01

    The resistance to dieldrin (RDL) receptor is an insect pentameric ligand-gated ion channel (pLGIC). It is activated by the neurotransmitter γ-aminobutyric acid (GABA) binding to its extracellular domain; hence elucidating the atomistic details of this interaction is important for understanding how the RDL receptor functions. As no high resolution structures are currently available, we built homology models of the extracellular domain of the RDL receptor using different templates, including the widely used acetylcholine binding protein and two pLGICs, the Erwinia Chrysanthemi ligand-gated ion channel (ELIC) and the more recently resolved GluCl. We then docked GABA into the selected three dimensional structures, which we used as starting points for classical molecular dynamics simulations. This allowed us to analyze in detail the behavior of GABA in the binding sites, including the hydrogen bond and cation-π interaction networks it formed, the conformers it visited and the possible role of water molecules in mediating the interactions; we also estimated the binding free energies. The models were all stable and showed common features, including interactions consistent with experimental data and similar to other pLGICs; differences could be attributed to the quality of the models, which increases with increasing sequence identity, and the use of a pLGIC template. We supplemented the molecular dynamics information with metadynamics, a rare event method, by exploring the free energy landscape of GABA binding to the RDL receptor. Overall, we show that the GluCl template provided the best models. GABA forming direct salt-bridges with Arg211 and Glu204, and cation-π interactions with an aromatic cage including Tyr109, Phe206 and Tyr254, represents a favorable binding arrangement, and the interaction with Glu204 can also be mediated by a water molecule.

  2. Benzodiazepine receptor imaging with iomazenil SPECT in aphasic patients with cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Koshi, Yasuhiko; Kitamura, Shin; Ohyama, Masashi [Nippon Medical School, Tokyo (Japan)] (and others)

    1999-08-01

    To investigate the relationship between prognosis of aphasia and neuronal damage in the cerebral cortex, we evaluated the distribution of central-type benzodiazepine receptor (BZR) binding in post-stroke aphasics with [{sup 123}I]iomazenil and SPECT. We performed iomazenil SPECT in six aphasic patients (aged from 45 to 75 years; all right-handed) with unilateral left cerebral infarction. Three patients showed signs of Broca's aphasia and the other three Wernicke's aphasia. Cerebral blood flow (CBF) imaging was performed with [{sup 123}I]iodoamphetamine (IMP). The regions of interest (ROIs) on both images were set in the cerebral cortex, cerebellar cortex and language relevant area in both hemispheres. Three patients were classified in the mild prognosis group and the other three in the moderate prognosis group. The left language-relevant area was more closely concerned with the difference in aphasic symptoms than the right one in both BZR and CBF distribution, but the ipsilateral to the contralateral ratio (I/C ratio) in the language-relevant areas in the BZR distribution was significantly lower in the moderate prognosis group than in the mild prognosis group, although no difference was seen for these values between the two groups in the CBF distribution. These results suggest that BZR imaging, which makes possible an increase in neuronal cell viability in the cerebral cortex, is useful not only for clarifying the aphasic symptoms but also for evaluating the prognosis of aphasia in patients with cerebral infarction. (author)

  3. Benzodiazepine receptor imaging with iomazenil SPECT in aphasic patients with cerebral infarction

    International Nuclear Information System (INIS)

    Koshi, Yasuhiko; Kitamura, Shin; Ohyama, Masashi

    1999-01-01

    To investigate the relationship between prognosis of aphasia and neuronal damage in the cerebral cortex, we evaluated the distribution of central-type benzodiazepine receptor (BZR) binding in post-stroke aphasics with [ 123 I]iomazenil and SPECT. We performed iomazenil SPECT in six aphasic patients (aged from 45 to 75 years; all right-handed) with unilateral left cerebral infarction. Three patients showed signs of Broca's aphasia and the other three Wernicke's aphasia. Cerebral blood flow (CBF) imaging was performed with [ 123 I]iodoamphetamine (IMP). The regions of interest (ROIs) on both images were set in the cerebral cortex, cerebellar cortex and language relevant area in both hemispheres. Three patients were classified in the mild prognosis group and the other three in the moderate prognosis group. The left language-relevant area was more closely concerned with the difference in aphasic symptoms than the right one in both BZR and CBF distribution, but the ipsilateral to the contralateral ratio (I/C ratio) in the language-relevant areas in the BZR distribution was significantly lower in the moderate prognosis group than in the mild prognosis group, although no difference was seen for these values between the two groups in the CBF distribution. These results suggest that BZR imaging, which makes possible an increase in neuronal cell viability in the cerebral cortex, is useful not only for clarifying the aphasic symptoms but also for evaluating the prognosis of aphasia in patients with cerebral infarction. (author)

  4. 125I-iomazenil-benzodiazepine receptor binding during psychological stress in rats

    International Nuclear Information System (INIS)

    Fukumitsu, Nobuyoshi; Tsuchida, Daisuke; Ogi, Shigeyuki; Uchiyama, Mayuki; Mori, Yutaka

    2002-01-01

    We investigated the changes in 125 I-iomazenil ( 125 I-IMZ) benzodiazepine receptor (BZR) binding with psychological stress in a rat model. Six male Wistar rats were placed under psychological stress for 1 hour by using a communication box. No physical stress was not received. 1.85 MBq of 125 I-IMZ was injected into the lateral tail vein and the rat was killed 3 hours later. Twenty-micormeter-thick sections of the brain were collected and % injected dose per body weight (% ID/BW) of eleven regions (frontal, parietal, temporal, occipital cortices, caudate putamen, accumubens nuclei, globus pallidus, amygdala, thalamus, hippocampus and hypothalamus) were calculated by autoradiography. The %ID/BW of rats which were placed under psychological stress was compared with that of 6 control rats. The %ID/BW of rats which were placed under psychological stress diffusely tended to show a reduction in 125 I-IMZ-BZR binding. A significant decrease in BZR binding was observed in the hippocampus of the rats which were placed under psychological stress. 125 I-IMZ-BZR binding tended to decrease throughout the brain. (author)

  5. Maternal Characteristics of Women Exposed to Hypnotic Benzodiazepine Receptor Agonist during Pregnancy

    Directory of Open Access Journals (Sweden)

    Bjarke Askaa

    2014-01-01

    Full Text Available Background. There is little knowledge regarding the characteristics of women treated with hypnotic benzodiazepine receptor agonists (HBRAs during pregnancy. In this large Danish cohort study, we characterize women exposed to HBRA during pregnancy. We determined changes in prevalence of HBRA use from 1997 to 2010 and exposure to HBRAs in relation to pregnancy. Methods. We performed a retrospective cohort study including 911,017 pregnant women in the period from 1997 to 2010. Information was retrieved from The Danish Birth Registry and The Registry of Medicinal Product Statistics to identify pregnant women redeeming a prescription of HBRAs. Results. We identified 2,552 women exposed to HBRAs during pregnancy, increasing from 0.18% in 1997 to 0.23% in 2010. Compared to unexposed women, exposed women were characterized by being older, with higher BMI, in their third or fourth parity, of lower income and education level, more frequently smokers, and more likely to be comedicated with antipsychotic, anxiolytic, or antidepressant drugs (P<0.0001. Conclusion. Women using HBRAs during their pregnancy differ from unexposed women in socioeconomic factors and were more likely to receive comedication. The consumption of HBRAs was reduced during pregnancy compared to before conception.

  6. Photochemical Proteolysis of an Unstructured Linker of the GABAAR Extracellular Domain Prevents GABA but Not Pentobarbital Activation

    Science.gov (United States)

    Hanek, Ariele P.; Lester, Henry A.

    2010-01-01

    The GABA type A receptor (GABAAR) is the major inhibitory receptor in the mammalian central nervous system and the target of numerous pharmaceuticals. The α-subunit of these pentameric Cys-loop neurotransmitter-gated ion channels contributes to the binding of both GABA and allosteric modulators such as the benzodiazepines, suggesting a role for this subunit in the conformational changes associated with activation of the receptor. Herein we use the nonsense suppression methodology to incorporate a photoactivatable unnatural amino acid and photochemically cleave the backbone of the α subunit of the α1β2 GABAAR in a linker region that is believed to span the subunit. Proteolytic cleavage impairs GABA but not pentobarbital activation, strongly suggesting that conformational changes involving this linker region are critical to the GABA activation pathway. PMID:20363860

  7. GABA and its B-receptor are present at the node of Ranvier in a small population of sensory fibers, implicating a role in myelination

    DEFF Research Database (Denmark)

    Corell, Mikael; Wicher, Grzegorz; Radomska, Katarzyna J

    2015-01-01

    to study the function of this receptor during development. The results show that GABA, via its B receptor, is involved in the myelination process but not in Schwann cell proliferation. The data from adult nerves suggest additional roles in axon-glia communication after injury....... throughout development and after injury. A small population of myelinated sensory fibers displayed all of these molecules at the node of Ranvier, indicating a role in axon-glia communication. Functional studies using GABAB receptor agonists and antagonists were performed in fetal DRG primary cultures......The γ-aminobutyric acid (GABA) type B receptor has been implicated in glial cell development in the peripheral nervous system (PNS), although the exact function of GABA signaling is not known. To investigate GABA and its B receptor in PNS development and degeneration, we studied the expression...

  8. Tryptic mapping and membrane topology of the benzodiazepine receptor alpha-subunit

    Energy Technology Data Exchange (ETDEWEB)

    Lentes, K.U.; Venter, J.C.

    1986-05-01

    Rat brain membrane benzodiazepine receptors (BZR) were photoaffinity labelled specifically (in presence or absence of 6 ..mu..M clonazepam) with 10 nM /sup 3/H-flunitrazepam (FNZ). Digestion of the FNZ-labelled, membrane-bound BZR with 200 ..mu..g trypsin/mg membrane protein yielded H/sub 2/O-soluble BZR-fragments of molecular mass (M/sub r/) 34, 31, 28, 24, 21, 18, 16, 12, 10 and 7kDa. Because the 34kDa-peptide is the largest fragment containing a FNZ-binding site they conclude that this represents the extracellular domain of the BZR. In the remaining pellet two labelled peptides with M/sub r/ of 44kDa and 28kDa were found that required the use of detergents for their solubilization; they therefore contain the membrane anchoring domain. Digestion of the 0.5% Na-deoxycholate solubilized, intact BZR (M/sub r/ 51kDa) resulted in the same tryptic pattern as the membrane form of the receptor plus two larger fragments of M/sub r/ 45kDa and 40kDa. Arrangement of all tryptic fragments with reference to the FNZ binding site reveals a membrane topology of the BZR alpha-subunit with 67% (34kDa) for the extracellular domain, 21% (11kDa) for the membrane anchoring domain and 12% (6kDa) for a putative cytoplasmic domain. The overlap between some of the labelled fragments suggest that the BZ binding site must be located near the membrane surface of the extracellular domain.

  9. Apparent target size of rat brain benzodiazepine receptor, acetylcholinesterase, and pyruvate kinase is highly influenced by experimental conditions

    International Nuclear Information System (INIS)

    Nielsen, M.; Braestrup, C.

    1988-01-01

    Radiation inactivation is a method to determine the apparent target size of molecules. In this report we examined whether radiation inactivation of various enzymes and brain receptors is influenced by the preparation of samples preceding irradiation. The apparent target sizes of endogenous acetylcholinesterase and pyruvate kinase from rat brain and from rabbit muscle and benzodiazepine receptor from rat brain were investigated in some detail. In addition the target sizes of alcohol dehydrogenase (from yeast and horse liver), beta-galactosidase (from Escherichia coli), lactate dehydrogenase (endogenous from rat brain), and 5-HT2 receptors, acetylcholine muscarine receptors, and [ 35 S] butyl bicyclophosphorothionate tertiary binding sites from rat brain were determined. The results show that apparent target sizes are highly influenced by the procedure applied for sample preparation before irradiation. The data indicate that irradiation of frozen whole tissue as opposed to lyophilized tissue or frozen tissue homogenates will estimate the smallest and most relevant functional target size of a receptor or an enzyme

  10. Ethanol activation of protein kinase A regulates GABA-A receptor subunit expression in the cerebral cortex and contributes to ethanol-induced hypnosis

    Directory of Open Access Journals (Sweden)

    Sandeep eKumar

    2012-04-01

    Full Text Available Protein kinases are implicated in neuronal cell functions such as modulation of ion channel function, trafficking and synaptic excitability. Both protein kinase C (PKC and A (PKA are involved in regulation of γ-aminobutyric acid type A (GABA-A receptors through phosphorylation. However, the role of PKA in regulating GABA-A receptors following acute ethanol exposure is not known. The present study investigated the role of PKA in ethanol effects on GABA-A receptor α1 subunit expression in the P2 synaptosomal fraction of the rat cerebral cortex. Additionally, GABA-related behaviors were also examined. Rats were administered ethanol (2.0 – 3.5 g/kg or saline and PKC, PKA and GABA-A receptor α1 subunit levels were measured by Western blot analysis. Ethanol (3.5 g/kg transiently increased GABA-A receptor α1 subunit expression and PKA RIIβ subunit expression at similar time points whereas PKA RIIα was increased at later time points. In contrast, PKC isoform expression remained unchanged. Notably, the moderate ethanol dose (2.0g/kg had no effect on GABA-A α1 subunit levels although PKA RIIα and RIIβ were increased at 10 and 60 minutes, when PKC isozymes are also known to be elevated. To determine if PKA activation was responsible for the ethanol-induced elevation of GABA-A α1 subunits, the PKA antagonist H89 was administered to rats prior to ethanol exposure. H89 administration prevented ethanol-induced increases in GABA-A receptor α1 subunit expression. Moreover, increasing PKA activity intracerebroventricularly with Sp-cAMP prior to a hypnotic dose of ethanol increased ethanol-induced loss of righting reflex duration. This effect appears to be mediated in part by GABA-A receptors as increasing PKA activity also increased the duration of muscimol-induced loss of righting reflex. Overall these data suggest that PKA mediates ethanol-induced GABA-A receptor expression and contributes to ethanol behavioral effects involving GABA-A receptors.

  11. 5-HT1A receptor blockade reverses GABA(A) receptor alpha(3) subunit-mediated anxiolytic effects on stress-induced hyperthermia

    NARCIS (Netherlands)

    Vinkers, Christiaan H.; van Oorschot, Ruud; Korte, S. Mechiel; Olivier, Berend; Groenink, Lucianne

    Stress-related disorders are associated with dysfunction of both serotonergic and GABAergic pathways, and clinically effective anxiolytics act via both neurotransmitter systems. As there is evidence that the GABA(A) and the serotonin receptor system interact, a serotonergic component in the

  12. Glutamate AMPA/kainate receptors, not GABA(A) receptors, mediate estradiol-induced sex differences in the hypothalamus.

    Science.gov (United States)

    Todd, Brigitte J; Schwarz, Jaclyn M; Mong, Jessica A; McCarthy, Margaret M

    2007-02-15

    Sex differences in brain morphology underlie physiological and behavioral differences between males and females. During the critical perinatal period for sexual differentiation in the rat, gonadal steroids act in a regionally specific manner to alter neuronal morphology. Using Golgi-Cox impregnation, we examined several parameters of neuronal morphology in postnatal day 2 (PN2) rats. We found that in the ventromedial nucleus of the hypothalamus (VMN) and in areas just dorsal and just lateral to the VMN that there was a sex difference in total dendritic spine number (males greater) that was abolished by treating female neonates with exogenous testosterone. Dendritic branching was similarly sexually differentiated and hormonally modulated in the VMN and dorsal to the VMN. We then used spinophilin, a protein that positively correlates with the amount of dendritic spines, to investigate the mechanisms underlying these sex differences. Estradiol, which mediates most aspects of masculinization and is the aromatized product of testosterone, increased spinophilin levels in female PN2 rats to that of males. Muscimol, an agonist at GABA(A) receptors, did not affect spinophilin protein levels in either male or female neonates. Kainic acid, an agonist at glutamatergic AMPA/kainate receptors, mimicked the effect of estradiol in females. Antagonizing AMPA/kainate receptors with NBQX prevented the estradiol-induced increase in spinophilin in females but did not affect spinophilin level in males. (c) 2007 Wiley Periodicals, Inc.

  13. Expression of specific ionotropic glutamate and GABA-A receptor subunits is decreased in central amygdala of alcoholics

    Directory of Open Access Journals (Sweden)

    Zhe eJin

    2014-09-01

    Full Text Available The central nucleus of amygdala (CeA has a role for mediating fear and anxiety responses. It is also involved in emotional imbalance caused by alcohol abuse and dependence and in regulating relapse to alcohol abuse. Growing evidences suggest that excitatory glutamatergic and inhibitory γ-aminobutyric acid-ergic (GABAergic transmissions in the CeA are affected by chronic alcohol exposure. Human post-mortem CeA samples from male alcoholics (n=9 and matched controls (n=9 were assayed for the expression level of ionotropic glutamate and GABA-A receptors subunit mRNAs using quantitative real-time reverse transcription-PCR (RT-qPCR. Our data revealed that out of the 16 ionotropic glutamate receptor subunits, mRNAs encoding two AMPA [2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-ylpropanoic acid] receptor subunits GluA1 and GluA4; one kainate receptor subunit GluK2; one NMDA (N-methyl-D-aspartate receptor subunit GluN2D and one delta receptor subunit GluD2 were significantly decreased in the CeA of alcoholics. In contrast, of the 19 GABA-A receptor subunits, only the mRNA encoding the α2 subunit was significantly down-regulated in the CeA of the alcoholics as compared with control subjects. Our findings imply that the down-regulation of specific ionotropic glutamate and GABA-A receptor subunits in the CeA of alcoholics may represent one of the molecular substrates underlying the new balance between excitatory and inhibitory neurotransmission in alcohol dependence.

  14. Radiosynthesis and initial evaluation of [18F]-FEPPA for PET imaging of peripheral benzodiazepine receptors

    International Nuclear Information System (INIS)

    Wilson, Alan A.; Garcia, Armando; Parkes, Jun; McCormick, Patrick; Stephenson, Karin A.; Houle, Sylvain; Vasdev, Neil

    2008-01-01

    Introduction: A novel [ 18 F]-radiolabelled phenoxyanilide, [ 18 F]-FEPPA, has been synthesized and evaluated, in vitro and ex vivo, as a potential positron emission tomography imaging agent for the peripheral benzodiazepine receptor (PBR). Methods: [ 18 F]-FEPPA and two other radiotracers for imaging PBR, namely [ 11 C]-PBR28 and [ 11 C]-PBR28-d3, were synthesised and evaluated in vitro and ex vivo as potential PBR imaging agents. Results: [ 18 F]-FEPPA is efficiently prepared in one step from its tosylate precursor and [ 18 F]-fluoride in high radiochemical yields and at high specific activity. FEPPA displayed a K i of 0.07 nM for PBR in rat mitochondrial membrane preparations and a suitable lipophilicity for brain penetration (log P of 2.99 at pH 7.4). Upon intravenous injection into rats, [ 18 F]-FEPPA showed moderate brain uptake [standard uptake value (SUV) of 0.6 at 5 min] and a slow washout (SUV of 0.35 after 60 min). Highest uptake of radioactivity was seen in the hypothalamus and olfactory bulb, regions previously reported to be enriched in PBR in rat brain. Analysis of plasma and brain extracts demonstrated that [ 18 F]-FEPPA was rapidly metabolized, but no lipophilic metabolites were observed in either preparation and only 5% radioactive metabolites were present in brain tissue extracts. Blocking studies to determine the extent of specific binding of [ 18 F]-FEPPA in rat brain were problematic due to large perturbations in circulating radiotracer and the lack of a reference region. Conclusions: Further evaluation of the potential of [ 18 F]-FEPPA will require the employment of rigorous kinetic models and/or appropriate animal models

  15. Embryonic GABA(B) receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice.

    Science.gov (United States)

    Stratton, Matthew S; Staros, Michelle; Budefeld, Tomaz; Searcy, Brian T; Nash, Connor; Eitel, Chad; Carbone, David; Handa, Robert J; Majdic, Gregor; Tobet, Stuart A

    2014-01-01

    Neurons of the paraventricular nucleus of the hypothalamus (PVN) regulate the hypothalamic- pituitary-adrenal (HPA) axis and the autonomic nervous system. Females lacking functional GABA(B) receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABA(B) receptor to a 7-day critical period (E11-E17) during embryonic development. Experiments tested the role of GABA(B) receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABA(B) receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABA(B) receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABA(B) receptor antagonist. Embryonic exposure to GABA(B) receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABA(B) receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity.

  16. Embryonic GABA(B receptor blockade alters cell migration, adult hypothalamic structure, and anxiety- and depression-like behaviors sex specifically in mice.

    Directory of Open Access Journals (Sweden)

    Matthew S Stratton

    Full Text Available Neurons of the paraventricular nucleus of the hypothalamus (PVN regulate the hypothalamic- pituitary-adrenal (HPA axis and the autonomic nervous system. Females lacking functional GABA(B receptors because of a genetic disruption of the R1 subunit have altered cellular characteristics in and around the PVN at birth. The genetic disruption precluded appropriate assessments of physiology or behavior in adulthood. The current study was conducted to test the long term impact of a temporally restricting pharmacological blockade of the GABA(B receptor to a 7-day critical period (E11-E17 during embryonic development. Experiments tested the role of GABA(B receptor signaling in fetal development of the PVN and later adult capacities for adult stress related behaviors and physiology. In organotypic slices containing fetal PVN, there was a female specific, 52% increase in cell movement speeds with GABA(B receptor antagonist treatment that was consistent with a sex-dependent lateral displacement of cells in vivo following 7 days of fetal exposure to GABA(B receptor antagonist. Anxiety-like and depression-like behaviors, open-field activity, and HPA mediated responses to restraint stress were measured in adult offspring of mothers treated with GABA(B receptor antagonist. Embryonic exposure to GABA(B receptor antagonist resulted in reduced HPA axis activation following restraint stress and reduced depression-like behaviors. There was also increased anxiety-like behavior selectively in females and hyperactivity in males. A sex dependent response to disruptions of GABA(B receptor signaling was identified for PVN formation and key aspects of physiology and behavior. These changes correspond to sex specific prevalence in similar human disorders, namely anxiety disorders and hyperactivity.

  17. Comparison of benzodiazepine receptor and regional cerebral blood flow imagings of epileptiform foci in hippocampal kindled rabbits

    International Nuclear Information System (INIS)

    Kurokawa, Kenzo

    1993-01-01

    To compare the benzodiazepine (Bz) receptor imaging and regional cerebral blood flow (rCBF) imaging in the detection of epileptic foci, the distribution pattern of the Bz receptor and rCBF in hippocampal kindled rabbits was examined by a double tracer autoradiography using ethyl 7-[ 125 I]-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1, 5-a][1,4] benzodiazepine-3-carboxylate ( 125 I-Ro 16-0154) and 99m Tc-hexamethyl-propyleneamine oxime ( 99m Tc-HMPAO). In visual and quantitative analyses, 125 I-Ro 16-0154 accumulation in brain slices extracted after the completion of the kindling was markedly and extensively decreased in the kindled CA1 region mimicking a primary epileptic focus. 125 I-Ro 16-0154 accumulation was moderately decreased in the ipsilateral temporal lobe, dentate gyrus, CA2, CA4, and bilateral CA3 regions, regarded as the propagated sites of seizure discharges. 99m Tc-HMPAO accumulation was found to be decreased in the ipsilateral CA1, frontal, temporal and dentate gyri. However, the decrease was much more slight and less extensive than that in 125 I-Ro 16-0154 accumulation. These results suggest that Bz receptor imaging is much more sensitive in the detection of epileptic foci than rCBF imaging, and therefore that Bz receptor imaging is useful in clinical epilepsy. (author)

  18. The GABA(A) receptor is an FMRP target with therapeutic potential in fragile X syndrome

    NARCIS (Netherlands)

    Braat, Sien; D'Hulst, Charlotte; Heulens, Inge; De Rubeis, Silvia; Mientjes, Edwin; Nelson, David L.; Willemsen, Rob; Bagni, Claudia; Van Dam, Debby; De Deyn, Peter P.; Kooy, R. Frank

    2015-01-01

    Previous research indicates that the GABA(A)ergic system is involved in the pathophysiology of the fragile X syndrome, a frequent form of inherited intellectual disability and associated with autism spectrum disorder. However, the molecular mechanism underlying GABA(A)ergic deficits has remained

  19. KCTD Hetero-oligomers Confer Unique Kinetic Properties on Hippocampal GABA(B) Receptor-Induced K+ Currents

    Czech Academy of Sciences Publication Activity Database

    Fritzius, T.; Tureček, Rostislav; Seddik, R.; Kobayashi, H.; Tiao, J.; Rem, P.D.; Metz, M.; Králíková, Michaela; Bouvier, M.; Gassmann, M.; Bettler, B.

    2017-01-01

    Roč. 37, č. 5 (2017), s. 1162-1175 ISSN 0270-6474 R&D Projects: GA ČR(CZ) GA14-28334S Institutional support: RVO:68378041 Keywords : G-protein coupled receptor * GABA-B * GPCR Subject RIV: FH - Neurology OBOR OECD: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology Impact factor: 5.988, year: 2016

  20. Identification and distribution of a GABA receptor mutation conferring dieldrin resistance in the malaria vector Anopheles funestus in Africa

    OpenAIRE

    Wondji, Charles S.; Dabire, Roch K.; Tukur, Zainab; Irving, Helen; Djouaka, Rousseau; Morgan, John C.

    2011-01-01

    Growing problems of pyrethroid resistance in Anopheles funestus have intensified efforts to identify alternative insecticides. Many agrochemicals target the GABA receptors, but cross-resistance from dieldrin resistance may preclude their introduction. Dieldrin resistance was detected in An. funestus populations from West (Burkina Faso) and central (Cameroon) Africa, but populations from East (Uganda) and Southern Africa (Mozambique and Malawi) were fully susceptible to this insecticide. Parti...

  1. The shivering threshold in rabbits with JM-1232(-), a new benzodiazepine receptor agonist.

    Science.gov (United States)

    Masamune, Taishi; Sato, Hiroaki; Okuyama, Katsumi; Imai, Yusuke; Iwashita, Hironobu; Ishiyama, Tadahiko; Oguchi, Takeshi; Sessler, Daniel I; Matsukawa, Takashi

    2009-07-01

    JM-1232(-) is a novel isoindoline derivative which shows sedative and hypnotic activities through the benzodiazepine site of gamma-aminobutyric acid type A (GABAA) receptors. Typical doses of midazolam, another GABAA receptor agonist, slightly reduce the shivering threshold in humans. We thus determined the extent to which JM-1232(-) decreases the shivering threshold. Eighteen rabbits, lightly anesthetized with isoflurane 0.2 minimum alveolar anesthetic concentration (MAC), were randomly assigned to infusions of 1) saline (control), 2) 0.01 mg x kg(-1) x min(-1) JM-1232(-), or 3) 0.1 mg x kg(-1) x min(-1) JM-1232(-). Body temperature was reduced at a rate of 2-3 degrees C/h by perfusing water at 10 degrees C though a U-shaped plastic tube positioned in the colon. Cooling continued until shivering was observed by an investigator blinded to treatment, or until core temperature reached 34 degrees C. Core temperatures were recorded from the distal esophagus, and core temperature at the onset of shivering defined the threshold. Data were analyzed by one-way analysis of variance with Student-Newman-Keuls tests. Results are presented as means +/- SD; P shivered at 36.5 +/- 0.3 degrees C. Five of the six rabbits given JM-1232(-) at a rate of 0.01 mg x kg(-1) x min(-1) shivered at 35.7 +/- 0.8 degrees C, and one of these rabbits failed to shiver at 34.0 degrees C. None of the rabbits given JM-1232(-) at a rate of 0.1 mg x kg(-1) x min(-1) shivered before reaching the 34.0 degrees C cutoff temperature. A low dose of JM-1232(-) reduced the shivering threshold in rabbits approximately 0.8 degrees C which is similar to the effects in humans given premedication doses of midazolam. In contrast, a 10-fold larger dose reduced the threshold more than 2.5 degrees C. This is a substantial decrement and might facilitate induction of therapeutic hypothermia.

  2. The effect of heart-and kidney-Benefiting Chinese Herbal Medicine on the function of cholinergic M-and Gamma amino-butyric acid (GABA) receptor in brain tissues of analogue dementia rats

    International Nuclear Information System (INIS)

    Mo Qizhong; Gong Bin; Fang Jun

    1993-01-01

    3 H-QNB and 3 H-GABA were used as radioactive ligand for M-and GABA receptors respectively. M-and GABA receptors were assayed by radioligand binding assay (RBA) in cerebral cortex, hippocampus and cerebellum of analogue dementia rats. It was found that R t of M receptor was decreased in cerebral cortex and hippocampus and R t of GABA receptor was decreased in cerebellum of analogue dementia rats. The dissociation constant (K D ) of M-receptor was decreased significantly in cerebral cortex and K D value of (GABA) receptor was decreased in cerebellum of analogue dementia rats. The decreased R t of M-and GABA receptor in brain tissue of analogue dementia rats was raised by Heart- and Kidney-Benefiting Chinese Herbs as well as hydergin

  3. Acute sleep deprivation preconditions the heart against ischemia/ reperfusion injury: the role of central GABA-A receptors

    Directory of Open Access Journals (Sweden)

    Hoda Parsa

    2017-11-01

    Full Text Available Objective(s: Central γ-aminobutyric acid (GABA neurotransmission modulates cardiovascular functions and sleep. Acute sleep deprivation (ASD affects functions of various body organs via different mechanisms. Here, we evaluated the effect of ASD on cardiac ischemia/reperfusion injury (IRI, and studied the role of GABA-A receptor inhibition in central nucleus of amygdala (CeA by assessing nitric oxide (NO and oxidative stress. Materials and Methods: The CeA in sixty male Wistar rats was cannulated for saline or bicuculline (GABA-A receptor antagonist administration. All animals underwent 30 min of coronary occlusion (ischemia, followed by 2 hr reperfusion (IR. The five experimental groups (n=12 included are as follows: IR: received saline; BIC+IR: received Bicuculline; MLP+IR: received saline, followed by the placement of animals in an aquarium with multiple large platforms; ASD+IR: underwent ASD in an aquarium with multiple small platforms; and BIC+ASD+IR: received bicuculline prior to ASD. Results: Bicuculline administration increased the malondialdehyde levels and infarct size, and decreased the NO metabolites levels and endothelial nitric oxide synthase (eNOS gene expression in infarcted and non-infarcted areas in comparison to IR group. ASD reduced malondialdehyde levels and infarct size and increased NO metabolites, corticosterone levels and eNOS expression in infarcted and non-infarcted areas as compared to the IR group. Levels of malondialdehyde were increased while levels of NO metabolites, corticosterone and eNOS expression in infarcted and non-infarcted areas were reduced in the BIC+ASD+IR as compared to the ASD+IR group. Conclusion: Blockade of GABA-A receptors in the CeA abolishes ASD-induced cardioprotection by suppressing oxidative stress and NO production.

  4. Acetylcholine induces GABA release onto rod bipolar cells through heteromeric nicotinic receptors expressed in A17 amacrine cells.

    Directory of Open Access Journals (Sweden)

    Claudio eElgueta

    2015-02-01

    Full Text Available Abstract Acetylcholine (ACh is a major retinal neurotransmitter that modulates visual processing through a large repertoire of cholinergic receptors expressed on different retinal cell types. ACh is released from starburst amacrine cells under scotopic conditions, but its effects on cells of the rod pathway have not been investigated. Using whole-cell patch clamp recordings in slices of rat retina, we found that ACh application triggers GABA release onto rod bipolar (RB cells. GABA was released from A17 amacrine cells and activated postsynaptic GABAA and GABAC receptors in RB cells. The sensitivity of ACh-induced currents to nicotinic ACh receptor (nAChR antagonists (TMPH ~ mecamylamine > erysodine > DhβE > MLA together with the differential potency of specific agonists to mimic ACh responses (cytisine >> RJR2403 ~ choline, suggest that A17 cells express heteromeric nAChRs containing the β4 subunit. Activation of nAChRs induced GABA release after Ca2+ accumulation in A17 cell dendrites and varicosities mediated by L-type voltage-gated calcium channels (VGCCs and intracellular Ca2+ stores. Inhibition of acetyl-cholinesterase depolarized A17 cells and increased spontaneous inhibitory postsynaptic currents in RB cells, indicating that endogenous ACh enhances GABAergic inhibition of RB cells. Moreover, injection of neostigmine or cytisine reduced the b-wave of the scotopic flash electroretinogram, suggesting that cholinergic modulation of GABA release controls RB cell activity in vivo. These results describe a novel regulatory mechanism of RB cell inhibition and complement our understanding of the neuromodulatory control of retinal signal processing.

  5. Increased GABA(A receptor ε-subunit expression on ventral respiratory column neurons protects breathing during pregnancy.

    Directory of Open Access Journals (Sweden)

    Keith B Hengen

    Full Text Available GABAergic signaling is essential for proper respiratory function. Potentiation of this signaling with allosteric modulators such as anesthetics, barbiturates, and neurosteroids can lead to respiratory arrest. Paradoxically, pregnant animals continue to breathe normally despite nearly 100-fold increases in circulating neurosteroids. ε subunit-containing GABA(ARs are insensitive to positive allosteric modulation, thus we hypothesized that pregnant rats increase ε subunit-containing GABA(AR expression on brainstem neurons of the ventral respiratory column (VRC. In vivo, pregnancy rendered respiratory motor output insensitive to otherwise lethal doses of pentobarbital, a barbiturate previously used to categorize the ε subunit. Using electrode array recordings in vitro, we demonstrated that putative respiratory neurons of the preBötzinger Complex (preBötC were also rendered insensitive to the effects of pentobarbital during pregnancy, but unit activity in the VRC was rapidly inhibited by the GABA(AR agonist, muscimol. VRC unit activity from virgin and post-partum females was potently inhibited by both pentobarbital and muscimol. Brainstem ε subunit mRNA and protein levels were increased in pregnant rats, and GABA(AR ε subunit expression co-localized with a marker of rhythm generating neurons (neurokinin 1 receptors in the preBötC. These data support the hypothesis that pregnancy renders respiratory motor output and respiratory neuron activity insensitive to barbiturates, most likely via increased ε subunit-containing GABA(AR expression on respiratory rhythm-generating neurons. Increased ε subunit expression may be critical to preserve respiratory function (and life despite increased neurosteroid levels during pregnancy.

  6. Functional characterization of the 1,5-benzodiazepine clobazam and its major active metabolite N-desmethylclobazam at human GABAA receptors expressed in Xenopus laevis oocytes

    DEFF Research Database (Denmark)

    Hammer, Harriet; Ebert, Bjarke; Jensen, Henrik S.

    2015-01-01

    by the 1,4-benzodiazepine clonazepam. All three compounds potentiated GABA EC20-evoked responses through the α1,2,3,5β2γ2S GABAARs in a reversible and concentration-dependent manner, with each displaying similar EC50 values at the four subtypes. Furthermore, the degrees of potentiation of the GABA EC20...... for novel modulators targeting this low-affinity binding site in GABAARs. In conclusion, the non-selective modulation exerted by clobazam, N-desmethylclobazam and clonazepam at the α1β2γ2S, α2β2γ2S, α3β2γ2S and α5β2γ2S GABAARs indicate that the observed clinical differences between clobazam and 1...

  7. 3β-Methyl-Neurosteroid Analogs are Preferential Positive Allosteric Modulators and Direct Activators of Extrasynaptic δGABA-A Receptors in the Hippocampus Dentate Gyrus Subfield.

    Science.gov (United States)

    Chuang, Shu-Hui; Reddy, Doodipala Samba

    2018-03-30

    Neurosteroids are powerful modulators of GABA-A receptors. Ganaxolone (3α-hydroxy-3β-methyl-5α-pregnan-20-one, GX) and synthetic analogs of the neurosteroid allopregnanolone (AP) are designed to treat epilepsy and related conditions. However, their precise mechanism of action in native neurons remains unclear. Here, we sought to determine the mode of action of GX and its analogs at GABA-A receptors in native hippocampal neurons by analyzing extrasynaptic receptor-mediated tonic currents and synaptic receptor-mediated phasic currents. Concentration-response profiles of GX were determined in two cell types: δ-containing dentate gyrus granule cells (DGGCs) and γ2-containing CA1 pyramidal cells (CA1PCs). GX produced significantly greater potentiation of the GABA-A receptor-activated chloride currents in DGGCs (500%) than CA1PCs (200%). In the absence of GABA, GX evoked 2-fold greater inward currents in DGGCs than CA1PCs, which were 2-fold greater than AP within DGGCs. In hippocampus slices, GX potentiated and directly activated tonic currents in DGGCs. These responses were significantly diminished in DGGCs from δ-subunit knockout (δKO) mice, confirming GX's selectivity for δGABA-A receptors. Like AP, GX potentiation of tonic currents was prevented by protein kinase C inhibition. Furthermore, GX's protection against hippocampus kindled seizures was significantly diminished in δKO mice. GX analogs exhibited greater potency and efficacy than GX on δGABA-A receptor-mediated tonic inhibition. In summary, these results provide strong evidence that GX and its analogs are preferential allosteric modulators and direct activators of extrasynaptic δGABA-A receptors regulating network inhibition and seizures in the dentate gyrus. Therefore, these findings provide a mechanistic rationale for the clinical use of synthetic neurosteroids in epilepsy and seizure disorders. The American Society for Pharmacology and Experimental Therapeutics.

  8. The GABA A-Receptor γ2 (GABRG2 Gene in obsessive-compulsive disorder O gene do receptor GABA A- γ2 (GABRG2 no transtorno obsessivo-compulsivo

    Directory of Open Access Journals (Sweden)

    Margaret A. Richter

    2009-12-01

    Full Text Available OBJECTIVE: The γ-aminobutyric acid type A (GABA A system may be implicated in obsessive-compulsive disorder, based on its major role in modulation of anxiety and its function as the principal inhibitory neurotransmitter system in the cortex. In addition, glutamatergic/GABAergic mechanisms appear to play a role in the pathophysiology of obsessive-compulsive disorder, making the GABA A receptor-γ2 (GABργ2 gene a good candidate for susceptibility in this disorder. METHOD: 118 probands meeting DSM-IV criteria for primary obsessive-compulsive disorder and their available parents were recruited for participation in this study and informed consent was obtained. An NciI restriction site polymorphism in the second intron was genotyped and data was analyzed using the Transmission Disequilibrium Test. RESULTS: In total, 61 of the participating families were informative (i.e., with at least one heterozygous parent. No biases were observed in the transmission of either of the two alleles (χ2 = 0.016, 1 d.f., p = 0.898 to the affected probands in the total sample. CONCLUSION/DISCUSSION: While these results do not provide support for a major role for the GABA A receptor-γ2 in obsessive-compulsive disorder, further investigations of this gene in larger samples are warranted.OBJETIVO: O sistema gabaérgico tipo A (GABA A pode estar implicado no transtorno obsessivo-compulsivo devido ao seu grande papel na modulação da ansiedade e da sua função como o principal neurotransmissor inibidor no córtex. Além disso, mecanismos glutamatérgicos/gabaérgicos parecem desempenhar um papel na fisiopatologia do transtorno obsessivo-compulsivo, tornando o gene do receptor GABA A-γ2 (GABRG2 um bom gene candidato para a suscetibilidade genética a este transtorno. MÉTODO: 118 probandos que preencheram os critérios do DSM-IV para transtorno obsessivo-compulsivo primário e seus pais (quando disponíveis foram recrutados para a participação neste estudo

  9. {sup 125}I-iomazenil - benzodiazepine receptor binding and serum corticosterone level during psychological stress in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Fukumitsu, Nobuyoshi E-mail: GZL13162@nifty.ne.jp; Ogi, Shigeyuki; Uchiyama, Mayuki; Mori, Yutaka

    2004-02-01

    To test the hypothesis that benzodiazepine receptor density decreases in response to stress, we correlated {sup 125}I-iomazenil ({sup 125}I-IMZ) binding with serum corticosterone levels in a rat model. Wistar male rats were divided into four groups; control group (CON, 10 rats), no physical or psychological stress; and one-, three-, and five-day stress groups of 12 rats each (1-DAY, 3-DAY, and 5-DAY, respectively), receiving psychological stress for the given number of days. Psychological stress were given to rats with a communication box. The standardized uptake value (SUV) of {sup 125}I-iomazenil of the 3-DAY and 5-DAY showed that {sup 125}I-iomazenil - benzodiazepine receptor binding was significantly reduced in the cortices, accumbens nuclei, amygdala and caudate putamen (p<0.05). Serum corticosterone level ratio appeared to be slightly elevated in 3-DAY and 5-DAY, although this elevation was not significant. These data suggest that {sup 125}I-IMZ is a useful radioligand to reflect received stress and its binding in the cortices, accumbens nuclei, amygdala and caudate putamen is strongly affected by psychological stress.

  10. Molecular determinants of desensitization and assembly of the chimeric GABA(A) receptor subunits (alpha1/gamma2) and (gamma2/alpha1) in combinations with beta2 and gamma2

    DEFF Research Database (Denmark)

    Elster, L; Kristiansen, U; Pickering, D S

    2001-01-01

    Two gamma-aminobutyric acid(A) (GABA(A)) receptor chimeras were designed in order to elucidate the structural requirements for GABA(A) receptor desensitization and assembly. The (alpha1/gamma2) and (gamma2/alpha1) chimeric subunits representing the extracellular N-terminal domain of alpha1 or gam...... receptor with respect to the direct activation by pentobarbital. This suggests differences in the mechanism of channel activation for pentobarbital and GABA....

  11. Temperature dependence and GABA modulation of [3H]triazolam binding in the rat brain

    International Nuclear Information System (INIS)

    Earle, M.E.; Concas, A.; Wamsley, J.K.; Yamamura, H.I.

    1987-01-01

    The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of [ 3 H]TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0 0 C; K/sub d/ = 1.96 +/- 0.85 nM at 37 0 C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0 0 C and 1160 +/- 383 fmoles/mg protein at 37 0 C). Saturation studies of [ 3 H]TZ binding in the presence or absence of GABA (100μM) showed a GABA-shift. At 0 0 C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37 0 C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables

  12. Role of the amygdala GABA-A receptors in ACPA-induced deficits during conditioned fear learning.

    Science.gov (United States)

    Nasehi, Mohammad; Roghani, Farnaz; Ebrahimi-Ghiri, Mohaddeseh; Zarrindast, Mohammad-Reza

    2017-05-01

    The basolateral amygdala (BLA) is a key structure for the emotional processing and storage of memories associated with emotional events, especially fear. On the other hand, endocannabinoids and CB1 receptors play a key role in learning and memory partly through long-term synaptic depression of GABAergic synapses in the BLA. The aim of this study was to explore the effects of GABA-A receptor agonist and antagonist in the fear-related memory acquisition deficits induced by ACPA (a selective CB1 cannabinoid receptor agonist). This study used context and tone fear conditioning paradigms to assess fear-related memory in male NMRI mice. Our results showed that the pre-training intraperitoneal administration of ACPA (0.5mg/kg) or (0.1 and 0.5mg/kg) decreased the percentage of freezing time in the contextual and tone fear conditioning, respectively. This indicated an impaired context- or tone-dependent fear memory acquisition. Moreover, the pre-training intra-BLA microinjection of GABA-A receptor agonist, muscimol, at 0.05 and 0.5μg/mouse impaired context-dependent fear memory, while the same doses of GABA-A antagonist, bicuculline, impaired tone-dependent fear memory. However, a subthreshold dose of muscimol or bicuculline increased the effect of ACPA at 0.1 and 0.5 or 0.05mg/kg on context- or tone-dependent fear memory, respectively. In addition, bicuculline at the lower dose increased the ACPA response on locomotor activity compared to its respective group. Such findings highlighted an interaction between BLA GABAergic and cannabinoidergic systems during the acquisition phase of conditioned fear memories. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. GABAA receptor γ2 subunit knockdown mice have enhanced anxiety-like behavior but unaltered hypnotic response to benzodiazepines

    Directory of Open Access Journals (Sweden)

    De Blas Angel L

    2005-04-01

    Full Text Available Abstract Background Gamma-aminobutyric acid type A receptors (GABAA-Rs are the major inhibitory receptors in the mammalian brain and are modulated by a number of sedative/hypnotic drugs including benzodiazepines and anesthetics. The significance of specific GABAA-Rs subunits with respect to behavior and in vivo drug responses is incompletely understood. The γ2 subunit is highly expressed throughout the brain. Global γ2 knockout mice are insensitive to the hypnotic effects of diazepam and die perinatally. Heterozygous γ2 global knockout mice are viable and have increased anxiety-like behaviors. To further investigate the role of the γ2 subunit in behavior and whole animal drug action, we used gene targeting to create a novel mouse line with attenuated γ2 expression, i.e., γ2 knockdown mice. Results Knockdown mice were created by inserting a neomycin resistance cassette into intron 8 of the γ2 gene. Knockdown mice, on average, showed a 65% reduction of γ2 subunit mRNA compared to controls; however γ2 gene expression was highly variable in these mice, ranging from 10–95% of normal. Immunohistochemical studies demonstrated that γ2 protein levels were also variably reduced. Pharmacological studies using autoradiography on frozen brain sections demonstrated that binding of the benzodiazepine site ligand Ro15-4513 was decreased in mutant mice compared to controls. Behaviorally, knockdown mice displayed enhanced anxiety-like behaviors on the elevated plus maze and forced novelty exploration tests. Surprisingly, mutant mice had an unaltered response to hypnotic doses of the benzodiazepine site ligands diazepam, midazolam and zolpidem as well as ethanol and pentobarbital. Lastly, we demonstrated that the γ2 knockdown mouse line can be used to create γ2 global knockout mice by crossing to a general deleter cre-expressing mouse line. Conclusion We conclude that: 1 insertion of a neomycin resistance gene into intron 8 of the γ2 gene variably

  14. GABA(B) receptor modulation of serotonin neurons in the dorsal raphé nucleus and escalation of aggression in mice.

    Science.gov (United States)

    Takahashi, Aki; Shimamoto, Akiko; Boyson, Christopher O; DeBold, Joseph F; Miczek, Klaus A

    2010-09-01

    The serotonin (5-HT) system in the brain has been studied more than any other neurotransmitter for its role in the neurobiological basis of aggression. However, which mechanisms modulate the 5-HT system to promote escalated aggression is not clear. We here explore the role of GABAergic modulation in the raphé nuclei, from which most 5-HT in the forebrain originates, on escalated aggression in male mice. Pharmacological activation of GABA(B), but not GABA(A), receptors in the dorsal raphé nucleus (DRN) escalated aggressive behaviors. In contrast, GABA agonists did not escalate aggressive behaviors after microinjection into the median raphé nucleus. The aggression-heightening effect of the GABA(B) agonist baclofen depended on the activation of 5-HT neurons in the DRN because it was blocked by coadministration of the 5-HT(1A) agonist 8-OH-DPAT [((+/-)-8-hydroxy-2-(di-n-propylamino)tetralin) hydrobromide] (DPAT), which acts on autoreceptors and inhibits 5-HT neural activity. In vivo microdialysis showed that GABA(B) activation in the DRN increased extracellular 5-HT level in the medial prefrontal cortex. This may be attributable to an indirect action via presynaptic GABA(B) receptors. The presynaptic GABA(B) receptors suppress Ca(2+) channel activity and inhibit neurotransmission, and the coadministration of N-type Ca(2+) channel blocker facilitated the effect of baclofen. These findings suggest that the indirect disinhibition of 5-HT neuron activity by presynaptic GABA(B) receptors on non-5-HT neurons in the DRN is one of the neurobiological mechanisms of escalated aggression.

  15. Positive modulation of GABA(B) receptors decreased nicotine self-administration and counteracted nicotine-induced enhancement of brain reward function in rats.

    Science.gov (United States)

    Paterson, Neil E; Vlachou, Styliani; Guery, Sebastien; Kaupmann, Klemens; Froestl, Wolfgang; Markou, Athina

    2008-07-01

    Acute administration of gamma-aminobutyric acid (GABA)-B receptor agonists decreases nicotine, cocaine, ethanol, and heroin self-administration and also decreases food-maintained responding and suppresses locomotor activity at high doses. GABA(B) receptor-positive modulators may represent potentially improved therapeutic compounds because of their fewer side effects than receptor agonists. The present study investigated the effects of administration of the GABA(B) receptor-positive modulators 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) and N-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl]-2-methyl-5-[4-(trifluoromethyl)phenyl]-4-pyrimidinamine (BHF177) and coadministration of the GABA(B) receptor-positive modulator N,N'-dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine (GS39783) with the GABA(B) receptor agonist (3-amino-2[S]-hydroxypropyl)-methylphosphinic acid (CGP44532) on nicotine- and food-maintained responding under fixed ratio (FR) 5 and progressive ratio schedules of reinforcement. Furthermore, the effects of BHF177 and CGP44532 on nicotine-induced enhancement of brain reward function were evaluated. The results indicated that administration of CGP7930 decreased nicotine self-administration under an FR5 schedule. Administration of either GS39783 or CGP44532 selectively decreased nicotine self-administration, whereas coadministration of these compounds had additive effects. BHF177 administration selectively decreased nicotine- but not food-maintained responding under FR5 and progressive ratio schedules. The nicotine-induced enhancement of brain reward function was blocked by BHF177 or CGP44532, although the highest doses of both compounds, particularly CGP44532, decreased brain reward function when administered alone, suggesting an additive, rather than interactive, effect. Overall, the present results indicate that GABA(B) receptor-positive modulators, similarly to GABA(B) receptor agonists, attenuated the reinforcing and reward

  16. Lipid raft localization of GABA A receptor and Na+, K+-ATPase in discrete microdomain clusters in rat cerebellar granule cells

    DEFF Research Database (Denmark)

    Dalskov, Stine-Mathilde; Immerdal, Lissi; Niels-Christiansen, Lise-Lotte W

    2005-01-01

    and Na(+), K(+)-ATPase were largely soluble in ice cold Triton X-100. This indicates that Brij 98 extraction defines an unusual type of cholesterol-independent lipid rafts that harbour membrane proteins also associated with underlying scaffolding/cytoskeletal proteins such as gephyrin (GABA(A) receptor......The microdomain localization of the GABA(A) receptor in rat cerebellar granule cells was studied by subcellular fractionation and fluorescence- and immunogold electron microscopy. The receptor resided in lipid rafts, prepared at 37 degrees C by extraction with the nonionic detergent Brij 98......, reflecting clustering of the two proteins in separate membrane microdomains. Both proteins were observed in patchy "hot spots" at the cell surface as well as in isolated lipid rafts. Their insolubility in Brij 98 was only marginally affected by methyl-beta-cyclodextrin. In contrast, both the GABA(A) receptor...

  17. Identification and distribution of a GABA receptor mutation conferring dieldrin resistance in the malaria vector Anopheles funestus in Africa.

    Science.gov (United States)

    Wondji, Charles S; Dabire, Roch K; Tukur, Zainab; Irving, Helen; Djouaka, Rousseau; Morgan, John C

    2011-07-01

    Growing problems of pyrethroid resistance in Anopheles funestus have intensified efforts to identify alternative insecticides. Many agrochemicals target the GABA receptors, but cross-resistance from dieldrin resistance may preclude their introduction. Dieldrin resistance was detected in An. funestus populations from West (Burkina Faso) and central (Cameroon) Africa, but populations from East (Uganda) and Southern Africa (Mozambique and Malawi) were fully susceptible to this insecticide. Partial sequencing of the dieldrin target site, the γ-aminobutyric acid (GABA) receptor, identified two amino acid substitutions, A296S and V327I. The A296S mutation has been associated with dieldrin resistance in other species. The V327I mutations was detected in the resistant sample from Burkina Faso and Cameroon and consistently associated with the A296S substitution. The full-length of the An. funestus GABA-receptor gene, amplified by RT-PCR, generated a sequence of 1674 bp encoding 557 amino acid of the protein in An. funestus with 98% similarity to that of Anopheles gambiae. Two diagnostic assays were developed to genotype the A296S mutation (pyrosequencing and PCR-RFLP), and use of these assays revealed high frequency of the resistant allele in Burkina Faso (60%) and Cameroon (82%), moderate level in Benin (16%) while low frequency or absence of the mutation was observed respectively in Uganda (7.5%) or 0% in Malawi and Mozambique. The distribution of the Rdl(R) mutation in An. funestus populations in Africa suggests extensive barriers to gene flow between populations from different regions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Postsynaptic GABA(B Receptors Contribute to the Termination of Giant Depolarizing Potentials in CA3 Neonatal Rat Hippocampus

    Directory of Open Access Journals (Sweden)

    Ilgam Khalilov

    2017-06-01

    Full Text Available During development, hippocampal CA3 network generates recurrent population bursts, so-called Giant Depolarizing Potentials (GDPs. GDPs are characterized by synchronous depolarization and firing of CA3 pyramidal cells followed by afterhyperpolarization (GDP-AHP. Here, we explored the properties of GDP-AHP in CA3 pyramidal cells using gramicidin perforated patch clamp recordings from neonatal rat hippocampal slices. We found that GDP-AHP occurs independently of whether CA3 pyramidal cells fire action potentials (APs or remain silent during GDPs. However, the amplitude of GDP-AHP increased with the number of APs the cells fired during GDPs. The reversal potential of the GDP-AHP was close to the potassium equilibrium potential. During voltage-clamp recordings, current-voltage relationships of the postsynaptic currents activated during GDP-AHP were characterized by reversal near the potassium equilibrium potential and inward rectification, similar to the responses evoked by the GABA(B receptor agonists. Finally, the GABA(B receptor antagonist CGP55845 strongly reduced GDP-AHP and prolonged GDPs, eventually transforming them to the interictal and ictal-like discharges. Together, our findings suggest that the GDP-AHP involves two mechanisms: (i postsynaptic GABA(B receptor activated potassium currents, which are activated independently on whether the cell fires or not during GDPs; and (ii activity-dependent, likely calcium activated potassium currents, whose contribution to the GDP-AHP is dependent on the amount of firing during GDPs. We propose that these two complementary inhibitory postsynaptic mechanisms cooperate in the termination of GDP.

  19. Demonstration of the dynamic mass redistribution label-free technology as a useful cell-based pharmacological assay for endogenously expressed GABAA receptors

    DEFF Research Database (Denmark)

    Klein, Anders Bue; Nittegaard-Nielsen, Mia; Christensen, Julie T.

    2015-01-01

    the immortalized IMR-32 neuroblastoma cell line, which expresses relatively high levels of several endogenous GABAA receptor subunits, we show that GABA produces concentration-dependent cellular responses that can be measured and quantified in real-time. With the aid of the GABAA receptor-specific agonist muscimol...

  20. Involvement of medial septal glutamate and GABA(A) receptors in behaviour-induced acetylcholine release in the hippocampus : A dual probe microdialysis study

    NARCIS (Netherlands)

    Moor, E; Schirm, E; Jacso, J; Westerink, BHC

    1998-01-01

    In the present study, the role of medial septal receptors in behaviour-induced increase in acetylcholine (ACh) release in hippocampus was investigated using dual-probe microdialysis in combination with a simple behavioural procedure, gamma-Aminobutyric acid (GABA) and glutamate receptor agonists and

  1. Identification and cloning of a gamma 3 subunit splice variant of the human GABA(A) receptor.

    Science.gov (United States)

    Poulsen, C F; Christjansen, K N; Hastrup, S; Hartvig, L

    2000-05-31

    cDNA sequences encoding two forms of the GABA(A) gamma 3 receptor subunit were cloned from human hippocampus. The nucleotide sequences differ by the absence (gamma 3S) or presence (gamma 3L) of 18 bp located in the presumed intracellular loop between transmembrane region (TM) III and IV. The extra 18 bp in the gamma 3L subunit generates a consensus site for phosphorylation by protein kinase C (PKC). Analysis of human genomic DNA encoding the gamma 3 subunit reveals that the 18 bp insert is contiguous with the upstream proximal exon.

  2. Stress-restress evokes sustained iNOS activity and altered GABA levels and NMDA receptors in rat hippocampus

    DEFF Research Database (Denmark)

    Harvey, Brian H; Oosthuizen, Frasia; Brand, Linda

    2004-01-01

    . The NOS isoform involved, and the role of stress-mediated corticosterone release in NOS activation, was verified with the administration of selective iNOS and nNOS inhibitors, aminoguanidine (50 mg/kg/day i.p.) and 7-nitroindazole (12.5 mg/kg/day i.p.), and the steroid synthesis inhibitor, ketoconazole...... (24 mg/kg/day i.p.), administered for 21 days prior to and during the stress procedure. RESULTS: Stress evoked a sustained increase in NOS activity, but reduced NMDA receptor density and total GABA levels. Aminoguanidine or ketoconazole, but not 7-nitroindazole or saline, blocked stress-induced NOS...

  3. Learning and memory deficits in male adult mice treated with a benzodiazepine sleep-inducing drug during the juvenile period

    Directory of Open Access Journals (Sweden)

    Yusuke Furukawa

    2016-07-01

    Full Text Available Gamma-aminobutyric acid (GABA, the major inhibitory neurotransmitter in the mammalian central nervous system, is also known to be important for brain development. Therefore, disturbances of GABA receptor (GABA-R mediated signaling (GABA-R signal during brain development may influence normal brain maturation and cause late-onset brain malfunctions. In this study, we examined whether the temporal stimulation of the GABA-R signal during brain development induces late-onset adverse effects on the brain in adult male mice. To stimulate the GABA-R signal, we used either the benzodiazepine sleep-inducing drug triazolam (TZ or the non-benzodiazepine drug zolpidem (ZP. We detected deficits in learning and memory in mice treated with TZ during the juvenile period, as seen in the fear conditioning test. On the other hand, ZP administration during the juvenile period had little effect. In addition, decreased protein expression of GluR1 and GluR4, which are excitatory neurotransmitter receptors, was detected in the hippocampi of mice treated with TZ during the juvenile period. We measured mRNA expression of the immediate early genes (IEGs, which are neuronal activity markers, in the hippocampus shortly after the administration of TZ or ZP to juvenile mice. Decreased IEG expression was detected in mice with juvenile TZ administration, but not in mice with juvenile ZP administration. Our findings demonstrate that TZ administration during the juvenile period can induce irreversible brain dysfunction in adult mice. It may need to take an extra care for the prescription of benzodiazepine sleep-inducing drugs to juveniles because it might cause late onset learning and memory defects.

  4. Improvement of chronic hepatic encephalopathy in dogs by the benzodiazepine-receptor partial inverse agonist sarmazenil, but not by the antagonist flumazenil

    NARCIS (Netherlands)

    Meyer, H. P.; Legemate, D. A.; van den Brom, W.; Rothuizen, J.

    1998-01-01

    Therapeutic modulation of the increased GABAergic tone in chronic hepatic encephalopathy (HE) by the benzodiazepine receptor (BR) antagonist flumazenil (F) has led to conflicting results in humans and animal models for HE. The BR inverse agonist sarmazenil (S) has only been used in animal models of

  5. [Benzodiazepines and forensic aspects].

    Science.gov (United States)

    Michel, L; Lang, J-P

    2003-01-01

    Adverse effects of benzodiazepines are well known since the first one was used in 1958 (chlordiazepoxide). The literature collects study-cases or rarely controlled studies concerning side effects or paradoxical reactions to benzodiazepines. They mostly described drowsiness and behavioral disinhibition, including increased well-being feeling but also hostility, rage access with feeling of invulnerability, serious crimes and sometimes homicides. Delusional, manic, confusional or depressive states are also pointed out. Rate for aggressive behaviour is 0.3 to 0.7% but distinction should be done between accidental or "idiosyncratic" reaction and voluntary sought disinhibition, clearly more frequent. No benzodiazepine has any specificity for these adverse effects but pharmacology, doses, associated drugs (or alcohol) and psychopathology interact to produce hazardous psychic states. Pharmacology: GABA induces a decrease in serotonin compound and vigilance. Pharmacokinetic: first dose effect or over-dose effect, short half-life, lipophily, affinity, digestive absorption, active metabolites interact. Psychopathology: age, alcohol association, psychological status (high initial level of hostility, impulsivity, frustration, personality disorder and depressive status). External conditions: chronic illness, affective and professional frustrations, physical or psychic exhaustion contribute also. Some benzodiazepines (flunitrazepam, diazepam, clorazepate, triazolam, alprazolam, lorazepam, for example) are more often concerned for pharmacokinetics characteristics but also prescription habits. Forensic aspects should be considered in case of homicide. Especially, reality of benzodiazepines consumption and awareness of the potential paradoxical reaction should be precisely evaluated. Special focus on voluntary induced disinhibition has to be done for forensic considerations. Relationship but also crime facilitations are sometimes consciously sought. Some benzodiazepines have already

  6. Repeated Administration of the GABA\\(_B\\) Receptor Positive Modulator BHF177 Decreased Nicotine Self-Administration, and Acute Administration Decreased Cue-Induced Reinstatement of Nicotine Seeking in Rats

    OpenAIRE

    Vlachou, Styliani; Guery, Sebastien; Froestl, Wolfgang; Benedict, Jessica; Finn, M. G.; Markou, Athina; Banerjee, Deboshri

    2011-01-01

    Abstract: Rationale \\(\\gamma\\)-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain and is implicated in the modulation of central reward processes. Acute or chronic administration of GABA\\(_B\\) receptor agonists or positive modulators decreased self-administration of various drugs of abuse. Furthermore, GABA\\(_B\\) receptor agonists inhibited cue-induced reinstatement of nicotine- and cocaine-seeking behavior. Because of their fewer adverse side effects compared with...

  7. Anticonvulsant action of GABA-B receptor agonist SKF97541 Differs from that of Baclofen

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2008-01-01

    Roč. 57, č. 5 (2008), s. 789-792 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA305/05/2581 Institutional research plan: CEZ:AV0Z50110509 Keywords : PTZ seizures * GABA -B * ontogeny Subject RIV: FH - Neurology Impact factor: 1.653, year: 2008

  8. Differential Compartmentalization and Distinct Functions of GABA(B) Receptor Variants

    Czech Academy of Sciences Publication Activity Database

    Vigot, B.; Barbieri, S.; Bräuner-Osborne, H.; Tureček, Rostislav; Shigemoto, R.; Zhang, Y.P.; Luján, R.; Jacobson, L.H.; Biermann, B.; Fritschy, J.M.; Vacher, C.M.; Müller, M.; Sansing, G.; Guetg, N.; Cryan, J.F.; Kaupmann, K.; Gassmann, M.; Oertner, T.G.; Bettler, B.

    2006-01-01

    Roč. 50, - (2006), s. 589-601 ISSN 0896-6273 R&D Projects: GA ČR GA309/03/1158 Institutional research plan: CEZ:AV0Z50390512 Keywords : GABA(B) Subject RIV: FH - Neurology Impact factor: 13.894, year: 2006

  9. (/sup 3/H)Clonazepam, like (/sup 3/H)flunitrazepam, is a photoaffinity label for the central type of benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Sieghart, W. (Vienna Univ. (Austria)); Moehler, H. (Hoffmann-La Roche (F.) and Co., Basel (Switzerland))

    1982-06-16

    (/sup 3/H)Clonazepam, like (/sup 3/H)flunitrazepam, is irreversibly bound to membrane proteins of brain tissue when exposed to UV light. In polyacrylamide gel electrophoresis followed by fluorography, the same pattern of photolabelled proteins was obtained in cerebellum and in hippocampus when either (/sup 3/H)clonazepam or (/sup 3/H)flunitrazepam was used as photoaffinity label. Since (/sup 3/H)clonazepam does not interact with the peripheral type of benzodiazepine binding site present in the brain, these results confirm previous evidence that the proteins photolabelled with (/sup 3/H)flunitrazepam are associated with the central type of benzodiazepine receptor.

  10. Effects of LiCl/pilocarpine-induced status epilepticus on rat brain mu and benzodiazepine receptor binding: Regional and ontogenetic studies

    Czech Academy of Sciences Publication Activity Database

    Rocha, L.; Suchomelová, Lucie; Mareš, Pavel; Kubová, Hana

    2007-01-01

    Roč. 1181, - (2007), s. 104-117 ISSN 0006-8993 R&D Projects: GA MŠk(CZ) LC554; GA ČR GA304/05/2582 Grant - others: CONACyT (MX) 45943-M Institutional research plan: CEZ:AV0Z50110509 Keywords : benzodiazepine receptor * µ receptor binding * status epilepticus Subject RIV: ED - Physiology Impact factor: 2.218, year: 2007

  11. GLP-1 and Exendin-4 Transiently Enhance GABA(A) Receptor-Mediated Synaptic and Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons

    OpenAIRE

    Korol, Sergiy V.; Jin, Zhe; Babateen, Omar; Birnir, Bryndis

    2015-01-01

    GLP-1 is a hormone that stimulates insulin secretion. Receptors for GLP-1 are also found in the brain, including the hippocampus, the centre for memory and learning. Diabetes mellitus is a risk factor for decreased memory functions. We studied effects of GLP-1 and exendin-4, a GLP-1 receptor agonist, on γ-aminobutyric acid (GABA) signaling in hippocampal CA3 pyramidal neurons. GABA is the main inhibitory neurotransmitter and decreases neuronal excitability. GLP-1 (0.01 – 1 nmol/L) transiently...

  12. Effect of THIP and SL 76002, two clinically experimented GABA-mimetic compounds, on anterior pituitary GABA receptors and prolactin secretion in the rat

    International Nuclear Information System (INIS)

    Apud, J.A.; Masotto, C.; Racagni, G.

    1987-01-01

    In the present study, the ability of three direct GABA agonists, muscimol, THIP and SL 76002 to displace 3 H-GABA binding from anterior pituitary and medio-basal hypothalamus membranes was evaluated. Further, the effect of both THIP and SL 76002 on baseline prolactin levels or after stimulation of hormone release with haloperidol has been also studied. Either muscimol, THIP or SL 76002 have shown to posses 7-, 7- and 3-fold higher affinity, respectively, for the central nervous system than for the anterior pituitary 3 H-GABA binding sites. Moreover, THIP and SL 76002 have demonstrated to be respectively, 25- and 1000- fold less potent than muscimol in inhibiting 3 H- GABA binding at the level of the anterior pituitary and about 25- and 2700-fold less potent at the level of the medio-basal hypothalamus. Under basal conditions, either THIP or SL 76002 were ineffective to reduce prolactin release. However, after stimulation of prolactin secretion through blockade of the dopaminergic neurotransmission with haloperidol (0.1 mg/kg), both THIP (10 mg/kg) and SL 76002 (200 mg/kg) significantly counteracted the neuroleptic-induced prolactin rise with a potency which is in line with their ability to inhibit 3 H-GABA binding in the anterior pituitary. The present results indicate that both compounds inhibit prolactin release under specific experimental situations probably through a GABAergic mechanism. In view of the endocrine effects of these GABA-mimetic compounds, the possibility arises for an application of these type of drugs in clinical neuroendocrinology. 35 references, 3 figures, 2 tables

  13. Attenuating GABA(A) receptor signaling in dopamine neurons selectively enhances reward learning and alters risk preference in mice.

    Science.gov (United States)

    Parker, Jones G; Wanat, Matthew J; Soden, Marta E; Ahmad, Kinza; Zweifel, Larry S; Bamford, Nigel S; Palmiter, Richard D

    2011-11-23

    Phasic dopamine (DA) transmission encodes the value of reward-predictive stimuli and influences both learning and decision-making. Altered DA signaling is associated with psychiatric conditions characterized by risky choices such as pathological gambling. These observations highlight the importance of understanding how DA neuron activity is modulated. While excitatory drive onto DA neurons is critical for generating phasic DA responses, emerging evidence suggests that inhibitory signaling also modulates these responses. To address the functional importance of inhibitory signaling in DA neurons, we generated mice lacking the β3 subunit of the GABA(A) receptor specifically in DA neurons (β3-KO mice) and examined their behavior in tasks that assessed appetitive learning, aversive learning, and risk preference. DA neurons in midbrain slices from β3-KO mice exhibited attenuated GABA-evoked IPSCs. Furthermore, electrical stimulation of excitatory afferents to DA neurons elicited more DA release in the nucleus accumbens of β3-KO mice as measured by fast-scan cyclic voltammetry. β3-KO mice were more active than controls when given morphine, which correlated with potential compensatory upregulation of GABAergic tone onto DA neurons. β3-KO mice learned faster in two food-reinforced learning paradigms, but extinguished their learned behavior normally. Enhanced learning was specific for appetitive tasks, as aversive learning was unaffected in β3-KO mice. Finally, we found that β3-KO mice had enhanced risk preference in a probabilistic selection task that required mice to choose between a small certain reward and a larger uncertain reward. Collectively, these findings identify a selective role for GABA(A) signaling in DA neurons in appetitive learning and decision-making.

  14. Increased GABA-A receptor binding and reduced connectivity at the motor cortex in children with hemiplegic cerebral palsy: a multimodal investigation using 18F-fluoroflumazenil PET, immunohistochemistry, and MR imaging.

    Science.gov (United States)

    Park, Hae-Jeong; Kim, Chul Hoon; Park, Eun Sook; Park, Bumhee; Oh, So Ra; Oh, Maeng-Keun; Park, Chang Il; Lee, Jong Doo

    2013-08-01

    γ-aminobutyric acid (GABA)-A receptor-mediated neural transmission is important to promote practice-dependent plasticity after brain injury. This study investigated alterations in GABA-A receptor binding and functional and anatomic connectivity within the motor cortex in children with cerebral palsy (CP). We conducted (18)F-fluoroflumazenil PET on children with hemiplegic CP to investigate whether in vivo GABA-A receptor binding is altered in the ipsilateral or contralateral hemisphere of the lesion site. To evaluate changes in the GABA-A receptor subunit after prenatal brain injury, we performed GABA-A receptor immunohistochemistry using rat pups with a diffuse hypoxic ischemic insult. We also performed diffusion tensor MR imaging and resting-state functional MR imaging on the same children with hemiplegic CP to investigate alterations in anatomic and functional connectivity at the motor cortex with increased GABA-A receptor binding. In children with hemiplegic CP, the (18)F-fluoroflumazenil binding potential was increased within the ipsilateral motor cortex. GABA-A receptors with the α1 subunit were highly expressed exclusively within cortical layers III, IV, and VI of the motor cortex in rat pups. The motor cortex with increased GABA-A receptor binding in children with hemiplegic CP had reduced thalamocortical and corticocortical connectivity, which might be linked to increased GABA-A receptor distribution in cortical layers in rats. Increased expression of the GABA-A receptor α1 subunit within the ipsilateral motor cortex may be an important adaptive mechanism after prenatal brain injury in children with CP but may be associated with improper functional connectivity after birth and have adverse effects on the development of motor plasticity.

  15. Modulation of cholinephosphotransferase activity in breast cancer cell lines by Ro5-4864, a peripheral benzodiazepine receptor agonist

    International Nuclear Information System (INIS)

    Akech, Jacqueline; Roy, Somdutta Sinha; Das, Salil K.

    2005-01-01

    Changes in phospholipid and fatty acid profile are hallmarks of cancer progression. Increase in peripheral benzodiazepine receptor expression has been implicated in breast cancer. The benzodiazepine, Ro5-4864, increases cell proliferation in some breast cancer cell lines. Biosynthesis of phosphatidylcholine (PC) has been identified as a marker for cells proliferating at high rates. Cholinephosphotransferase (CPT) is the terminal enzyme for the de novo biosynthesis of PC. We have addressed here whether Ro5-4864 facilitates some cancer causing mechanisms in breast cancer. We report that cell proliferation increases exponentially in aggressive breast cancer cell lines 11-9-1-4 and BT-549 when treated with nanomolar concentrations of Ro5-4864. This increase is seen within 24 h of treatment, consistent with the cell doubling time in these cells. Ro5-4864 also upregulates c-fos expression in breast cancer cell lines 11-9-1-4 and BT-549, while expression in non-tumorigenic cell line MCF-12A was either basal or slightly downregulated. We further examined the expression of the CPT gene in breast cancer (11-9-1-4, BT-549) and non-tumorigenic cell lines (MCF-12A, MCF-12F). We found that the CPT gene is overexpressed in breast cancer cell lines compared to the non-tumorigenic cell lines. Furthermore, the activity of CPT in forming PC is increased in the breast cancer cell lines cultured for 24 h. Additionally, we examined the CPT activity in the presence of nanomolar concentrations of Ro5-4864. Biosynthesis of PC was increased in breast cancer cell lines upon treatment. We therefore propose that Ro5-4864 facilitates PC formation, a process important in membrane biogenesis for proliferating cells

  16. The Direct Actions of GABA, 2'-Methoxy-6-Methylflavone and General Anaesthetics at β3γ2L GABAA Receptors: Evidence for Receptors with Different Subunit Stoichiometries.

    Science.gov (United States)

    Chua, Han Chow; Absalom, Nathan L; Hanrahan, Jane R; Viswas, Raja; Chebib, Mary

    2015-01-01

    2'-Methoxy-6-methylflavone (2'MeO6MF) is an anxiolytic flavonoid which has been shown to display GABAA receptor (GABAAR) β2/3-subunit selectivity, a pharmacological profile similar to that of the general anaesthetic etomidate. Electrophysiological studies suggest that the full agonist action of 2'MeO6MF at α2β3γ2L GABAARs may mediate the flavonoid's in vivo effects. However, we found variations in the relative efficacy of 2'MeO6MF (2'MeO6MF-elicited current responses normalised to the maximal GABA response) at α2β3γ2L GABAARs due to the presence of mixed receptor populations. To understand which receptor subpopulation(s) underlie the variations observed, we conducted a systematic investigation of 2'MeO6MF activity at all receptor combinations that could theoretically form (α2, β3, γ2L, α2β3, α2γ2L, β3γ2L and α2β3γ2L) in Xenopus oocytes using the two-electrode voltage clamp technique. We found that 2'MeO6MF activated non-α-containing β3γ2L receptors. In an attempt to establish the optimal conditions to express a uniform population of these receptors, we found that varying the relative amounts of β3:γ2L subunit mRNAs resulted in differences in the level of constitutive activity, the GABA concentration-response relationships, and the relative efficacy of 2'MeO6MF activation. Like 2'MeO6MF, general anaesthetics such as etomidate and propofol also showed distinct levels of relative efficacy across different injection ratios. Based on these results, we infer that β3γ2L receptors may form with different subunit stoichiometries, resulting in the complex pharmacology observed across different injection ratios. Moreover, the discovery that GABA and etomidate have direct actions at the α-lacking β3γ2L receptors raises questions about the structural requirements for their respective binding sites at GABAARs.

  17. GABA-A and NMDA receptor expression is altered in the caudate but not the putamen of the postmortem brains of alcoholics.

    Directory of Open Access Journals (Sweden)

    Amol K Bhandage

    2014-12-01

    Full Text Available Chronic consumption of alcohol by humans has been shown to lead to impairment of executive and cognitive functions. Here we have studied the changes that take place in the dorsal striatum in post-mortem brains of alcoholics and normal controls. The results show a significant change in the expression of both the excitatory ionotropic glutamate receptor and the inhibitory GABA-A receptor subunit genes in the caudate but not the putamen of the striatum. The mRNA levels in the caudate encoding the glutamate receptor subunit GluN2A and the GABA-A receptor subunits δ, ε and ρ2 were significantly decreased whereas the GluD1, GluD2 and the GABA-A γ1 mRNA levels were significantly increased in the alcoholics as compared to controls. Interestingly in controls, 11 glutamate and 5 GABA-A receptor genes were more prominently (fold-increase varied from 1.24 to 2.91 expressed in the caudate than the putamen. We have previously shown in post-mortem samples from alcoholics that the expression level of glutamate and GABA-A receptor genes in the dorsal-lateral prefrontal cortex is similar to that of normal controls (Jin et al., 2011a;Jin et al., 2014b. This is in contrast to the present study. As the caudate is vital for automatic thinking, the results indicate that the balance between voluntary and automatic control of behaviours is altered in alcoholics. Our results suggest that there may be diminished executive control on goal-directed alcohol-seeking behaviour and, rather, a shift to greater striatal control over behaviours that may be critical in the progress of becoming an alcoholic.

  18. The GABA[subscript A] Receptor Agonist Muscimol Induces an Age- and Region-Dependent Form of Long-Term Depression in the Mouse Striatum

    Science.gov (United States)

    Zhang, Xiaoqun; Yao, Ning; Chergui, Karima

    2016-01-01

    Several forms of long-term depression (LTD) of glutamatergic synaptic transmission have been identified in the dorsal striatum and in the nucleus accumbens (NAc). Such experience-dependent synaptic plasticity might play important roles in reward-related learning. The GABA[subscript A] receptor agonist muscimol was recently found to trigger a…

  19. A case of relapsing encephalitis positive for gamma aminobutyric acid (GABA)A receptor antibody associated with Type B3 thymoma.

    Science.gov (United States)

    Kitano, Takaya; Kinoshita, Makoto; Shimazu, Kohki; Fushimi, Hiroaki; Omori, Kenichi; Hazama, Takanori

    2016-11-29

    A 87-year-old female presented with subacute progression of cognitive decline. Fluid-attenuated inversion recovery images of brain MRI showed multifocal high-intensity lesions. Thoracic CT image revealed the presence of thymoma, and serum autoantibody screening showed positivity for anti-gamma aminobutyric acid (GABA) A receptor antibody. Histopathological analysis confirmed type B3 thymoma after thymectomy. The patient received both plasmapheresis and intravenous methylprednisolone therapy, and showed remarkable amelioration of clinical symptoms and MRI abnormal high intensity. However, after 2 month from the clinical recovery, the patient showed recurrence of brain lesions and intravenous methylprednisolone monotherapy was performed. Continuation of oral steroid therapy was required to maintain the quienscent state of inflammation within the central nervous system. Anti-GABA A receptor antibody is a recently discovered novel autoantibody associated with autoimmue encephalitis. Due to the limited number of literature reported, clinical course and therapeutic response of GABA A receptor antibody encephalitis remains elusive. Here we reported a rare case of GABA A receptor antibody encephalitis with type B3 thymoma. Clinical, radiological and therapeutic courses described in our report highlight the importance of immunotherapy for treatment of the disease.

  20. GABA(A receptor-mediated acceleration of aging-associated memory decline in APP/PS1 mice and its pharmacological treatment by picrotoxin.

    Directory of Open Access Journals (Sweden)

    Yuji Yoshiike

    Full Text Available Advanced age and mutations in the genes encoding amyloid precursor protein (APP and presenilin (PS1 are two serious risk factors for Alzheimer's disease (AD. Finding common pathogenic changes originating from these risks may lead to a new therapeutic strategy. We observed a decline in memory performance and reduction in hippocampal long-term potentiation (LTP in both mature adult (9-15 months transgenic APP/PS1 mice and old (19-25 months non-transgenic (nonTg mice. By contrast, in the presence of bicuculline, a GABA(A receptor antagonist, LTP in adult APP/PS1 mice and old nonTg mice was larger than that in adult nonTg mice. The increased LTP levels in bicuculline-treated slices suggested that GABA(A receptor-mediated inhibition in adult APP/PS1 and old nonTg mice was upregulated. Assuming that enhanced inhibition of LTP mediates memory decline in APP/PS1 mice, we rescued memory deficits in adult APP/PS1 mice by treating them with another GABA(A receptor antagonist, picrotoxin (PTX, at a non-epileptic dose for 10 days. Among the saline vehicle-treated groups, substantially higher levels of synaptic proteins such as GABA(A receptor alpha1 subunit, PSD95, and NR2B were observed in APP/PS1 mice than in nonTg control mice. This difference was insignificant among PTX-treated groups, suggesting that memory decline in APP/PS1 mice may result from changes in synaptic protein levels through homeostatic mechanisms. Several independent studies reported previously in aged rodents both an increased level of GABA(A receptor alpha1 subunit and improvement of cognitive functions by long term GABA(A receptor antagonist treatment. Therefore, reduced LTP linked to enhanced GABA(A receptor-mediated inhibition may be triggered by aging and may be accelerated by familial AD-linked gene products like Abeta and mutant PS1, leading to cognitive decline that is pharmacologically treatable at least at this stage of disease progression in mice.

  1. Synthesis of iodine-123 labelled analogues of the partial agonist (S)-and (R)-bretazenil for the study of CNS benzodiazepine receptors using SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, Andrew; Mattner, Filomena; McPhee, Meredith; Kassiou, Michael; Najdovski, Ljubco; Dikic, Branko [Australian Nuclear Science and Technology Organisation, Radiopharmaceutical Div., Menai, Sydney, NSW (Australia)

    1996-09-01

    The (S) and (R)-[{sup 123}I]iodinated analogues of the benzodiazepine receptor partial agonist bretazenil have been synthesized for study of the central benzodiazepine receptor using SPECT, (S)- and (R)-[{sup 123}I]iodobretazenil were prepared from the appropriate tin precursors by electrophilic iododestannylation with Na[{sup 123}I] in the presence of Chloramine-T. The products were purified by semi-preparative reverse-phase HPLC with radiochemical yields of 80% in a total synthesis time of 50 minutes. The specific activity was determined to be greater than 2500 Ci/mmol. The radiochemical and chemical purity assessed by radio-TLC and HPLC were found to be 98%. The enantiomeric purity of the (S) and (R) isomers were greater than 97% as assessed by analytical chiral HPLC analysis. (author).

  2. γ-aminobutyric acid (GABA) mediated transmembrane chloride flux with membrane vesicles from rat brain measured by quench flow technique: kinetic homogeneity of ion flux and receptor desensitization

    International Nuclear Information System (INIS)

    Cash, D.J.; Subbarao, K.

    1987-01-01

    Transmembrane chloride flux mediated by the GABA/sub A/ receptor and the desensitization of the receptor were followed using quench flow technique with 36 Cl - and a membrane preparation from rat cerebral cortex. Measurements in short times allowed these two processes to be resolved. In general the ion-flux activity was desensitized in two phases. A fast phase took place in circa 200 ms (100 μM GABA) followed by a slower phase in several seconds. A minority of the membrane preparations did not display the fast phase. It is desirable to be able to separate these two phases of desensitization to facilitate analysis of the responses of the receptor. A short preincubation with GABA removed the fast phase from a subsequent measurement. In the absence of the fast phase the whole ion-flux equilibrium was seen as a single phase. The measurements presented covering a time range of 0.01 seconds to 10 seconds show a single phase of ion flux which can be described by a first order ion influx process and a single first order desensitization process with a halt time of circa 1 s (100 μM GABA). The results imply a single population of vesicles containing a single population of GABA receptor (remaining active) with a single phase of desensitization. An understanding of this homogeneity, and how to ensure it, gives a basis for quantitatively testing the effects of drugs on these responses. Ion flux measurements with quench flow technique are a suitable tool for investigation of the mechanism of action of neurotransmitter receptors from brain. 37 references, 3 figures

  3. Presynaptic nicotinic α7 and non-α7 receptors stimulate endogenous GABA release from rat hippocampal synaptosomes through two mechanisms of action.

    Directory of Open Access Journals (Sweden)

    Stefania Zappettini

    Full Text Available BACKGROUND: Although converging evidence has suggested that nicotinic acetylcholine receptors (nAChR play a role in the modulation of GABA release in rat hippocampus, the specific involvement of different nAChR subtypes at presynaptic level is still a matter of debate. In the present work we investigated, using selective α7 and α4β2 nAChR agonists, the presence of different nAChR subtypes on hippocampal GABA nerve endings to assess to what extent and through which mechanisms they stimulate endogenous GABA release. METHODOLOGY/FINDINGS: All agonists elicited GABA overflow. Choline (Ch-evoked GABA overflow was dependent to external Ca(2+, but unaltered in the presence of Cd(2+, tetrodotoxin (TTX, dihydro-β-erythroidine (DHβE and 1-(4,4-Diphenyl-3-butenyl-3-piperidinecarboxylic acid hydrochloride SKF 89976A. The effect of Ch was blocked by methyllycaconitine (MLA, α-bungarotoxin (α-BTX, dantrolene, thapsigargin and xestospongin C, suggesting that GABA release might be triggered by Ca(2+ entry into synaptosomes through the α7 nAChR channel with the involvement of calcium from intracellular stores. Additionally, 5-Iodo-A-85380 dihydrochloride (5IA85380 elicited GABA overflow, which was Ca(2+ dependent, blocked by Cd(2+, and significantly inhibited by TTX and DHβE, but unaffected by MLA, SKF 89976A, thapsigargin and xestospongin C and dantrolene. These findings confirm the involvement of α4β2 nAChR in 5IA85380-induced GABA release that seems to occur following membrane depolarization and opening calcium channels. CONCLUSIONS/SIGNIFICANCE: Rat hippocampal synaptosomes possess both α7 and α4β2 nAChR subtypes, which can modulate GABA release via two distinct mechanisms of action. The finding that GABA release evoked by the mixture of sub-maximal concentration of 5IA85380 plus sub-threshold concentrations of Ch was significantly larger than that elicited by the sum of the effects of the two agonists is compatible with the possibility that

  4. Rat intra-hippocampal NMDA infusion induces cell-specific damage and changes in expression of NMDA and GABA(A) receptor subunits

    Czech Academy of Sciences Publication Activity Database

    Rambousek, Lukáš; Kletečková, Lenka; Kubesová, A.; Jirák, D.; Valeš, Karel; Fritschy, J.M.

    2016-01-01

    Roč. 105, Jun (2016), s. 594-606 ISSN 0028-3908 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GA14-20613S; GA ČR(CZ) GAP303/12/1464 Institutional support: RVO:67985823 Keywords : excitotoxicity * NMDA receptor * GABA A receptor * hippocampus * neuroinflammation * neurodegeneration * interneurons * spatial learning * carousel maze Subject RIV: FH - Neurology Impact factor: 5.012, year: 2016

  5. Reduced parahippocampal and lateral temporal GABA{sub A}-[{sup 11}C]flumazenil binding in major depression: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Klumpers, Ursula M.H. [VU University Medical Center, Department of Psychiatry, Amsterdam (Netherlands); GGZ inGeest, partner of VUmc, Department of Psychiatry, Amsterdam (Netherlands); VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam (Netherlands); Veltman, Dick J. [VU University Medical Center, Department of Psychiatry, Amsterdam (Netherlands); VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam (Netherlands); Drent, Madeleine L. [VU University Medical Center, Department of Endocrinology, Amsterdam (Netherlands); Boellaard, Ronald; Lammertsma, Adriaan A. [VU University Medical Center, Department of Nuclear Medicine and PET Research, Amsterdam (Netherlands); VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam (Netherlands); Comans, Emile F.I. [VU University Medical Center, Department of Nuclear Medicine and PET Research, Amsterdam (Netherlands); Meynen, Gerben [VU University Medical Center, Department of Psychiatry, Amsterdam (Netherlands); Hoogendijk, Witte J.G. [VU University Medical Center, Department of Psychiatry, Amsterdam (Netherlands); VU University Medical Center, Center for Neurogenomics and Cognitive Research, Amsterdam (Netherlands); VU University Medical Center, Neuroscience Campus Amsterdam, Amsterdam (Netherlands)

    2010-03-15

    Major depressive disorder (MDD) has been related to both a dysfunctional {gamma}-amino butyric acid (GABA) system and to hyperactivity of the hypothalamic-pituitary-adrenal axis (HPA). Although GABA has been suggested to inhibit HPA axis activity, their relationship has never been studied at the level of the central GABA{sub A}-benzodiazepine receptor in depressed patients or in relation to antidepressant treatment. Eleven depressed outpatients were compared, before and after treatment with citalopram, with nine age-matched healthy controls. The subjects were scanned using the positron emission tomography (PET) tracer [{sup 11}C]flumazenil ([{sup 11}C]FMZ). Parametric voxel-by-voxel Logan plots were compared with methods based on regions of interest (ROI), to provide volume of distribution (V{sub T}) and binding potential (BP{sub ND}) values. Plasma GABA levels were determined and a dexamethasone-corticotropin releasing hormone (DEX-CRH) test was performed. In MDD, parametric voxel-by-voxel Logan plots showed bilateral reduced [{sup 11}C]FMZ binding in the parahippocampal gyrus and right lateral superior temporal gyrus (p uncorrected {<=}0.001). In the temporal area, [{sup 11}C]FMZ binding showed a strong inverse correlation with HPA axis activity. Plasma GABA did not discriminate MDD from controls, but correlated inversely with [{sup 11}C]FMZ binding in the right insula. Following treatment with citalopram, voxel-based analysis revealed reduced binding in the right lateral temporal gyrus and dorsolateral prefrontal cortex. The bilateral reduction in limbic parahippocampal and right temporal [{sup 11}C]FMZ binding found in MDD indicates decreased GABA{sub A}-benzodiazepine receptor complex affinity and/or number. The inverse relationship between GABA{sub A} binding in the temporal lobe and HPA axis activity, suggests that HPA axis hyperactivity is partly due to reduced GABA-ergic inhibition. (orig.)

  6. Loss of ethanol conditioned taste aversion and motor stimulation in knockin mice with ethanol-insensitive α2-containing GABA(A) receptors.

    Science.gov (United States)

    Blednov, Y A; Borghese, C M; McCracken, M L; Benavidez, J M; Geil, C R; Osterndorff-Kahanek, E; Werner, D F; Iyer, S; Swihart, A; Harrison, N L; Homanics, G E; Harris, R A

    2011-01-01

    GABA type A receptors (GABA(A)-Rs) are potential targets of ethanol. However, there are multiple subtypes of this receptor, and, thus far, individual subunits have not been definitively linked with specific ethanol behavioral actions. Interestingly, though, a chromosomal cluster of four GABA(A)-R subunit genes, including α2 (Gabra2), was associated with human alcoholism (Am J Hum Genet 74:705-714, 2004; Pharmacol Biochem Behav 90:95-104, 2008; J Psychiatr Res 42:184-191, 2008). The goal of our study was to determine the role of receptors containing this subunit in alcohol action. We designed an α2 subunit with serine 270 to histidine and leucine 277 to alanine mutations that was insensitive to potentiation by ethanol yet retained normal GABA sensitivity in a recombinant expression system. Knockin mice containing this mutant subunit were tested in a range of ethanol behavioral tests. These mutant mice did not develop the typical conditioned taste aversion in response to ethanol and showed complete loss of the motor stimulant effects of ethanol. Conversely, they also demonstrated changes in ethanol intake and preference in multiple tests. The knockin mice showed increased ethanol-induced hypnosis but no difference in anxiolytic effects or recovery from acute ethanol-induced motor incoordination. Overall, these studies demonstrate that the effects of ethanol at GABAergic synapses containing the α2 subunit are important for specific behavioral effects of ethanol that may be relevant to the genetic linkage of this subunit with human alcoholism.

  7. Synthesis and evaluation of [{sup 123}I]labelled analogues of the partial inverse agonist Ro 15-4513 for the study of diazepam-insensitive benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, Andrew E-mail: akx@ansto.gov.au; Mardon, Karine; McPhee, Meredith; Mattner, Filomena; Dikic, Branko; Ridley, Damon

    1999-08-01

    The imidazobenzodiazepines ethyl 8-iodo-5,6 dihydro-5-methyl-6-oxo-4H-imidazo[1,5a][1,4] benzodiazepine-3-carboxylate 1 and tert-butyl 8-iodo-5,6 dihydro-5-methyl-6-oxo-4H-imidazo [1,5a][1,4] benzodiazepine-3-carboxylate 2 were prepared to study the diazepam-insensitive (DI) benzodiazepine receptor (BZR) subtype. The [{sup 123}I] analogues were prepared via iododestannylation reactions in radiochemical yields of 70-80% and a specific activity >2,500 Ci/mmol. The tert-butyl analogue [{sup 123}I]-2 exhibited nanomolar affinity for BZRs in homogenate membranes of rat cerebellum with K{sub d} values for the diazepam-sensitive (DS) and DI receptors of 3.18{+-}0.58 and 13.55{+-}2.72 nM, respectively. The B{sub max} for cerebellar DS and DI receptors were 1,276{+-}195 and 518{+-}26 fmol/mg protein, respectively.

  8. Expression of the GABA(A) receptor alpha6 subunit in cultured cerebellar granule cells is developmentally regulated by activation of GABA(A) receptors

    DEFF Research Database (Denmark)

    Carlson, B X; Belhage, B; Hansen, Gert Helge

    1997-01-01

    Da (alpha6 subunit) radioactive peaks in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In contrast, THIP-treated granule cells at 8 DIV demonstrated a small but significant decrease from control cultures in the photoincorporation of [3H]Ro15-4513 in the 51-kDa peak; however...... that the major effect of THIP was to increase alpha6 subunit clustering on granule cell bodies as well as neurites, 15-fold and sixfold, respectively. Using in situ hybridization, a small THIP-induced increase in alpha6 mRNA was detected at 4 DIV; however, no effect was apparent at 8 DIV. These data suggest......(A) receptor subunit. Membranes prepared from these cultures were photolabeled with the imidazobenzodiazepine [3H]Ro15-4513. In THIP-treated cultures at 4 days in vitro (DIV), photolabeled [3H]Ro15-4513 binding in membranes was significantly increased for both the 51 kilodalton, kDa, (alpha1 subunit) and 56-k...

  9. A versatile optical tool for studying synaptic GABAA receptor trafficking.

    Science.gov (United States)

    Lorenz-Guertin, Joshua M; Wilcox, Madeleine R; Zhang, Ming; Larsen, Mads B; Pilli, Jyotsna; Schmidt, Brigitte F; Bruchez, Marcel P; Johnson, Jon W; Waggoner, Alan S; Watkins, Simon C; Jacob, Tija C

    2017-11-15

    Live-cell imaging methods can provide critical real-time receptor trafficking measurements. Here, we describe an optical tool to study synaptic γ-aminobutyric acid (GABA) type A receptor (GABA A R) dynamics through adaptable fluorescent-tracking capabilities. A fluorogen-activating peptide (FAP) was genetically inserted into a GABA A R γ2 subunit tagged with pH-sensitive green fluorescent protein (γ2 pH FAP). The FAP selectively binds and activates Malachite Green (MG) dyes that are otherwise non-fluorescent in solution. γ2 pH FAP GABA A Rs are expressed at the cell surface in transfected cortical neurons, form synaptic clusters and do not perturb neuronal development. Electrophysiological studies show γ2 pH FAP GABA A Rs respond to GABA and exhibit positive modulation upon stimulation with the benzodiazepine diazepam. Imaging studies using γ2 pH FAP-transfected neurons and MG dyes show time-dependent receptor accumulation into intracellular vesicles, revealing constitutive endosomal and lysosomal trafficking. Simultaneous analysis of synaptic, surface and lysosomal receptors using the γ2 pH FAP-MG dye approach reveals enhanced GABA A R turnover following a bicucculine-induced seizure paradigm, a finding not detected by standard surface receptor measurements. To our knowledge, this is the first application of the FAP-MG dye system in neurons, demonstrating the versatility to study nearly all phases of GABA A R trafficking. © 2017. Published by The Company of Biologists Ltd.

  10. New effects of GABAB receptor allosteric modulator rac-BHFF on ambient GABA, uptake/release, Em and synaptic vesicle acidification in nerve terminals.

    Science.gov (United States)

    Pozdnyakova, N; Dudarenko, M; Borisova, T

    2015-09-24

    Positive allosteric modulators of GABAB receptors have great therapeutic potential for medications of anxiety, depression, etc. The effects of recently discovered modulator rac-BHFF on the key characteristics of GABAergic neurotransmission were investigated in cortical and hippocampal presynaptic nerve terminals of rats (synaptosomes). The ambient level of [(3)H]GABA that is a balance between release and uptake of the neurotransmitter increased significantly in the presence of rac-BHFF (at concentrations 10-30μM). The initial velocity of synaptosomal [(3)H]GABA uptake was suppressed by the modulator. In the presence of GABA transporter blocker NO-711, it was shown that rac-BHFF increased tonic release of [(3)H]GABA from synaptosomes (at concentrations 3-30μM). Rac-BHFF within the concentration range of 0.3-30μM did not enhance inhibiting effect of (±)-baclofen on depolarization-induced exocytotic release of [(3)H]GABA. Rac-BHFF (0.3-30μM) caused dose-dependent depolarization of the plasma membrane and dissipation of the proton gradient of synaptic vesicles in synaptosomes that was shown in the absence/presence of GABAB receptor antagonist saclofen using fluorescent dyes rhodamine 6G and acridine orange, respectively, and so, the above effects of rac-BHFF were not associated with the modulation of presynaptic GABAB receptors. Therefore, drug development strategy of positive allosteric modulation of GABAB receptors is to eliminate the above side effects of rac-BHFF in presynapse, and vice versa, these new properties of rac-BHFF may be exploited appropriately. Copyright © 2015. Published by Elsevier Ltd.

  11. Activation of GABA-A receptors during postnatal brain development increases anxiety- and depression-related behaviors in a time- and dose-dependent manner in adult mice.

    Science.gov (United States)

    Salari, Ali-Akbar; Bakhtiari, Amir; Homberg, Judith R

    2015-08-01

    Disturbances of the gamma-amino butyric acid-ergic (GABAergic) system during postnatal development can have long-lasting consequences for later life behavior, like the individual's response to stress. However, it is unclear which postnatal windows of sensitivity to GABA-ergic modulations are associated with what later-life behavioral outcomes. Therefore, we sought to determine whether neonatal activation of the GABA-A receptor during two postnatal periods, an early window (postnatal day 3-5) and a late window (postnatal day 14-16), can affect anxiety- and depression-related behaviors in male mice in later life. To this end, mice were treated with either saline or muscimol (50, 100, 200, 300 and 500μg/kg) during the early and late postnatal periods. An additional group of mice was treated with the GABA-A receptor antagonist bicuculline+muscimol. When grown to adulthood male mice were exposed to behavioral tests to measure anxiety- and depression-related behaviors. Baseline and stress-induced corticosterone (CORT) levels were also measured. The results indicate that early postnatal and to a lesser extent later postnatal exposure to the GABA-A receptor agonist muscimol increased anxiety-like behavior and stress-induced CORT levels in adults. Moreover, the early postnatal treatment with muscimol increased depression-like behavior with increasing baseline CORT levels. The anxiogenic and depression-like later-life consequences could be antagonized by bicuculline. Our findings suggest that GABA-A receptor signaling during early-life can influence anxiety- and depression-related behaviors in a time- and dose-dependent manner in later life. Our findings help to increase insight in the developmental mechanisms contributing to stress-related disorders. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  12. Music therapy inhibits morphine-seeking behavior via GABA receptor and attenuates anxiety-like behavior induced by extinction from chronic morphine use.

    Science.gov (United States)

    Kim, Ki Jin; Lee, Sang Nam; Lee, Bong Hyo

    2018-05-01

    Morphine is a representative pain killer. However, repeated use tends to induce addiction. Music therapy has been gaining interest as a useful type of therapy for neuropsychiatric diseases. The present study examined whether Korean traditional music (KT) could suppress morphine-seeking behavior and anxiety-like behavior induced by extinction from chronic morphine use and additionally investigated a possible neuronal mechanism. Male Sprague-Dawley rats were trained to intravenously self-administer morphine hydrochloride (1.0 mg/kg) using a fixed ratio 1 schedule in daily 2 h session during 3 weeks. After training, rats who established baseline (variation less than 20% of the mean of infusion for 3 consecutive days) underwent extinction. Music was played twice a day during extinction. In the second experiment, the selective antagonists of GABA A and GABA B receptors were treated before the last playing to investigate the neuronal mechanism focusing on the GABA receptor pathway. Another experiment of elevated plus maze was performed to investigate whether music therapy has an anxiolytic effect at the extinction phase. KT but not other music (Indian road or rock music) reduced morphine-seeking behavior induced by a priming challenge with morphine. And, this effect was blocked by the GABA receptor antagonists. In addition, KT showed anxiolytic effects against withdrawal from morphine. Results of this study suggest that KT suppresses morphine-seeking behavior via GABA receptor pathway. In addition, KT showed to have anxiolytic effects, suggesting it has bi-directional effects on morphine. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    Science.gov (United States)

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo." The pattern evok...

  14. Alterations of benzodiazepine receptor binding potential in anxiety and somatoform disorders measured by 123I-iomazenil SPECT

    International Nuclear Information System (INIS)

    Tokunaga, Mari; Ida, Ituro; Mikuni, Masahiko; Higuchi, Teruhiko.

    1997-01-01

    123 I-iomazenil (IMZ), a newly developed radioligand which acts on benzodiazepine receptors (BZR) as a partial inverse agonist, made it possible to evaluate the function of central BZR by single photon emission tomography (SPECT). To examine the alterations of the binding potential (BP) in the anxiety state, 123 I-IMZ SPECT was performed in five patients with anxiety and somatoform disorders, and five epileptic patients without anxiety symptoms served as a reference. The BP of BZR was determined by using a table look-up procedure based on a three-compartment, two-parameter model in the bilateral superior frontal, inferior frontal, temporal, parietal, occipital, and cerebellar cortex. The mean BP of patients with anxiety and somatoform disorders was significantly decreased in the superior frontal, temporal, and parietal cortex, in comparison with that of epileptic patients. A significant correlation was observed between the anxiety levels scored on the Hamilton anxiety scale and BP in the right temporal cortex and left superior frontal cortex. These changes in BZR revealed by SPECT suggest the usefulness of 123 I-IMZ SPECT to objectively evaluate anxiety levels in patients with anxiety symptoms. (author)

  15. Radiosynthesis and in vivo evaluation of N-[11C]methylated imidazopyridineacetamides as PET tracers for peripheral benzodiazepine receptors

    International Nuclear Information System (INIS)

    Sekimata, Katsuhiko; Hatano, Kentaro; Ogawa, Mikako; Abe, Junichiro; Magata, Yasuhiro; Biggio, Giovanni; Serra, Mariangela; Laquintana, Valentino; Denora, Nunzio; Latrofa, Andrea; Trapani, Giuseppe; Liso, Gaetano; Ito, Kengo

    2008-01-01

    Imidazopyridineacetoamide 5-8, a series of novel and potentially selective peripheral benzodiazepine receptor (PBR) ligands with affinities comparable to those of known PBR ligands, was investigated. Radiosyntheses of [ 11 C]5, 6, 7 or 8 was accomplished by N-methylation of the corresponding desmethyl precursors with [ 11 C]methyl iodide in the presence of NaH in dimethylformamide (DMF), resulting in 25% to 77% radiochemical yield and specific activitiy of 20 to 150 MBq/nmol. Each of the labeled compounds was injected in ddY mice, and the radioactivity and weight of dissected peripheral organs and brain regions were measured. Organ distribution of [ 11 C]7 was consistent with the known PBR distribution. Moreover, [ 11 C]7 showed the best combination of brain uptake and PBR binding, leading to its high retention in the olfactory bulb and cerebellum, areas where PBR density is high in mouse brain. Coinjection of PK11195 or unlabeled 7 significantly reduced the brain uptake of [ 11 C]7. These results suggest that [ 11 C]7 could be a useful radioligand for positron emission tomography imaging of PBRs

  16. Tratamento da doença de Meige com droga agonista de receptores GABA

    Directory of Open Access Journals (Sweden)

    Luiz Augusto Franco de Andrade

    1985-09-01

    Full Text Available A doença de Meige é distúrbio de movimento que consiste no aparecimento espontâneo de blefarospasmo associado a movimentos distônicos de musculatura orofacial. Associadamene podem ser encontrados torcicolo espasmódico, disfonia espástica e distonia de extremidades. Várias hipóteses foram formuladas para explicar esse distúrbio, tendo em vista a resposta a drogas com ação conhecida nos sistemas de neurotransmissores do cérebro. Algumas evidências apontam para um estado de preponderância dopaminérgica e, nesse sentido, justifica-se a estimulação da atividade GABA, sabendo-se que esse neurotrans-missor age sobre uma das alças de controle da produção de dopamina na substância negra. Por essa razão investigamos a ação de um agonista GABA, o baclofen, sobre a doença de Meige. Foram incluídos no protocolo 5 pacientes, 4 mulheres e um homem, com idade variando entre 50 e 63 anos e duração da doença variando entre 4 meses e 18 anos. Todos apresentavam blefaros-pasmo-distonia orofacial e, além disso três apresentavam disfonia espástica e um distonia de extremidades. A droga era iniciada em dose de 20mg/dia, aumentada em lOmg a cada três dias até ser obtida resposta ou surgirem efeitos colaterais. Um dos pacientes apresentou melhora marcada do blefaros-pasmo-distonia orofacial e outro melhora moderada dos mesmos sintomas, em avaliação 30 dias após estabilização da dose. Não houve melhora da disfonia espástica e ocorreu melhora moderada da distonia de extremidades. Não podemos afirmar que a melhora observada ao fim de um mês se mantenha, ou mesmo que melhora mais significativa fosse observada em avaliação feita mais tardiamente. Concluimos que o baclofen pode ser útil, pelo menos por algum tempo, na doença de Meige.

  17. Histamine H3 receptor activation selectively inhibits dopamine D1 receptor-dependent [3H]GABA release from depolarization-stimulated slices of rat substantia nigra pars reticulata

    International Nuclear Information System (INIS)

    Aceves, J.; Young, J.M.; Arias-Montano, J.A.; Floran, B.; Garcia, M.

    1997-01-01

    The release of [ 3 H]GABA from slices of rat substantia nigra pars reticulata induced by increasing extracellular K + from 6 to 15 mM in the presence of 10 μM sulpiride was inhibited by 73±3% by 1 μM SCH 23390, consistent with a large component of release dependent upon D 1 receptor activation. The histamine H 3 receptor-selective agonist immepip (1 μM) and the non-selective agonist histamine (100 μM) inhibited [ 3 H]GABA release by 78±2 and 80±2%, respectively. The inhibition by both agonists was reversed by the H 3 receptor antagonist thioperamide (1 μM). However, in the presence of 1 μM SCH 23390 depolarization-induced release of [ 3 H]GABA was not significantly decreased by 1 μM immepip. In rats depleted of dopamine by pretreatment with reserpine, immepip no longer inhibited control release of [ 3 H]GABA, but in the presence of 1 μM SKF 38393, which produced a 7±1-fold stimulation of release, immepip reduced the release to a level not statistically different from that in the presence of immepip alone. Immepip (1 μM) also inhibited the depolarization-induced release of [ 3 H]dopamine from substantia nigra pars reticulata slices, by 38±3%.The evidence is consistent with the proposition that activation of histamine H 3 receptors leads to the selective inhibition of the component of depolarization-induced [ 3 H]GABA release in substantia nigra pars reticulata slices which is dependent upon D 1 receptor activation. This appears to be largely an action at the terminals of the striatonigral GABA projection neurons, which may be enhanced by a partial inhibition of dendritic [ 3 H]dopamine release. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  18. [Treatment of nausea and vomiting with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatinantagonists, benzodiazepines and cannabinoids in palliative care patients : a systematic review].

    Science.gov (United States)

    Benze, G; Geyer, A; Alt-Epping, B; Nauck, F

    2012-09-01

    Various recommendations exist for the treatment of nausea and vomiting in palliative care but only few studies and even less systematic reviews look into antiemetic therapy for patients receiving palliative care. This systematic review aims to analyze the current evidence for antiemetic treatment with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines and cannabinoids in palliative care patients with far advanced cancer not receiving chemotherapy or radiotherapy, acquired immune deficiency syndrome (AIDS), chronic obstructive pulmonary disease (COPD), progressive heart failure, amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). Results regarding evidence of treatment with prokinetic and neuroleptic agents will be published separately. The electronic databases PubMed and EmBase were systematically searched for studies (published 1966-2011) dealing with antiemetic therapy in palliative care and electronic retrieval was completed by manual searching. Studies with patients undergoing chemotherapy or radiotherapy, pediatric studies and studies published in languages other than English or German were excluded. Studies addressing therapy with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines or cannabinoids were identified and selected for this systematic review. In the general search 75 relevant studies were found. Of those 36 addressed 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines and cannabinoids, 13 considered 5HT3 receptor antagonists, 10 somatostatin antagonists, 9 steroids, 5 cannabinoids, 4 anticholinergics, 1 antihistamines and none benzodiazepines. Furthermore six systematic reviews exist. Evidence for any drug used as an antiemetic is low. Concerning 5HT3 receptor antagonists data are insufficient for recommendations on the treatment of patients with AIDS and MS due to

  19. Positive modulation of delta-subunit containing GABAA receptors in mouse neurons

    DEFF Research Database (Denmark)

    Vardya, Irina; Hoestgaard-Jensen, Kirsten; Nieto-Gonzalez, Jose Luis

    2012-01-01

    (A) receptors in mouse neurons in vitro and in vivo. Whole-cell patch-clamp recordings were carried out in the dentate gyrus in mouse brain slices. In granule cells, AA29504 (1 μM) caused a 4.2-fold potentiation of a tonic current induced by THIP (1 μM), while interneurons showed a potentiation of 2.6-fold......, and possibly recruits perisynaptic δ-containing receptors to participate in synaptic phasic inhibition in dentate gyrus....

  20. Radiosynthesis and initial evaluation of [{sup 18}F]-FEPPA for PET imaging of peripheral benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Alan A. [PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada); Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)], E-mail: alan.wilson@camhpet.ca; Garcia, Armando; Parkes, Jun [PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada); McCormick, Patrick [PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada); Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8 (Canada); Stephenson, Karin A. [PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada); Houle, Sylvain; Vasdev, Neil [PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8 (Canada); Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8 (Canada)

    2008-04-15

    Introduction: A novel [{sup 18}F]-radiolabelled phenoxyanilide, [{sup 18}F]-FEPPA, has been synthesized and evaluated, in vitro and ex vivo, as a potential positron emission tomography imaging agent for the peripheral benzodiazepine receptor (PBR). Methods: [{sup 18}F]-FEPPA and two other radiotracers for imaging PBR, namely [{sup 11}C]-PBR28 and [{sup 11}C]-PBR28-d3, were synthesised and evaluated in vitro and ex vivo as potential PBR imaging agents. Results: [{sup 18}F]-FEPPA is efficiently prepared in one step from its tosylate precursor and [{sup 18}F]-fluoride in high radiochemical yields and at high specific activity. FEPPA displayed a K{sub i} of 0.07 nM for PBR in rat mitochondrial membrane preparations and a suitable lipophilicity for brain penetration (log P of 2.99 at pH 7.4). Upon intravenous injection into rats, [{sup 18}F]-FEPPA showed moderate brain uptake [standard uptake value (SUV) of 0.6 at 5 min] and a slow washout (SUV of 0.35 after 60 min). Highest uptake of radioactivity was seen in the hypothalamus and olfactory bulb, regions previously reported to be enriched in PBR in rat brain. Analysis of plasma and brain extracts demonstrated that [{sup 18}F]-FEPPA was rapidly metabolized, but no lipophilic metabolites were observed in either preparation and only 5% radioactive metabolites were present in brain tissue extracts. Blocking studies to determine the extent of specific binding of [{sup 18}F]-FEPPA in rat brain were problematic due to large perturbations in circulating radiotracer and the lack of a reference region. Conclusions: Further evaluation of the potential of [{sup 18}F]-FEPPA will require the employment of rigorous kinetic models and/or appropriate animal models.

  1. Alterations in in-vivo benzodiazepine-receptor binding of C-11-Ro15-1788 (flumazepil)

    International Nuclear Information System (INIS)

    Yamasaki, T.; Inoue, O.; Shinoto, H.; Ito, T.; Hashimoto, K.; Suzuki, K.; Tateno, Y.

    1985-01-01

    Alterations of the central benzodiazepine - receptor function caused by the change of physiological or psychological conditions, were recognized in both animal and human studies. Before the human study, animal experiments using tritiated Ro15-1788 were carried out. The stress was produced by forcing the mice to swim in a water-basin at 16 0 C for 5 min. Within 3 min after the forced swimming, the tracer was injected. Brain radioactivities in stress-loaded mice increased over a period of 15 min after the intra-venous injection of tracers, while brain activities of carrier-added tracer decreased. In human study, approximately 5 mCi of C-11-Ro15-1788, which specific activity is 0.3-1.0 Ci/μmol, were intravenously injected to each case. Measurements of the brain activity were performed using positron-CT, with blood sample collection. 31 human studies were performed on. Cerebral cortex time activity curves in several volunteers in nervous and stressful state, showed the same pattern to that in the stress-loaded animal experiment. It is important that the significant different time course of cerebral activity after the injection of labelled Ro15-1788, was observed in stressful state, compared with control, in both human and animal study. From these results, it will be concluded the positron CT study using /sup 11/C-Ro15-1788 will become a new technic to detect the change of psychological conditions in human brain and to diagnose some kind of neuropsychiatric disease

  2. Functional Characterization of Native, High-Affinity GABAA Receptors in Human Pancreatic β Cells

    Directory of Open Access Journals (Sweden)

    Sergiy V. Korol

    2018-04-01

    Full Text Available In human pancreatic islets, the neurotransmitter γ-aminobutyric acid (GABA is an extracellular signaling molecule synthesized by and released from the insulin-secreting β cells. The effective, physiological GABA concentration range within human islets is unknown. Here we use native GABAA receptors in human islet β cells as biological sensors and reveal that 100–1000 nM GABA elicit the maximal opening frequency of the single-channels. In saturating GABA, the channels desensitized and stopped working. GABA modulated insulin exocytosis and glucose-stimulated insulin secretion. GABAA receptor currents were enhanced by the benzodiazepine diazepam, the anesthetic propofol and the incretin glucagon-like peptide-1 (GLP-1 but not affected by the hypnotic zolpidem. In type 2 diabetes (T2D islets, single-channel analysis revealed higher GABA affinity of the receptors. The findings reveal unique GABAA receptors signaling in human islets β cells that is GABA concentration-dependent, differentially regulated by drugs, modulates insulin secretion and is altered in T2D. Keywords: GABA, GABAA receptor, Pancreatic islet, Type 2 diabetes

  3. VTA GABA neurons modulate specific learning behaviours through the control of dopamine and cholinergic systems

    Directory of Open Access Journals (Sweden)

    Meaghan C Creed

    2014-01-01

    Full Text Available The mesolimbic reward system is primarily comprised of the ventral tegmental area (VTA and the nucleus accumbens (NAc as well as their afferent and efferent connections. This circuitry is essential for learning about stimuli associated with motivationally-relevant outcomes. Moreover, addictive drugs affect and remodel this system, which may underlie their addictive properties. In addition to DA neurons, the VTA also contains approximately 30% ɣ-aminobutyric acid (GABA neurons. The task of signalling both rewarding and aversive events from the VTA to the NAc has mostly been ascribed to DA neurons and the role of GABA neurons has been largely neglected until recently. GABA neurons provide local inhibition of DA neurons and also long-range inhibition of projection regions, including the NAc. Here we review studies using a combination of in vivo and ex vivo electrophysiology, pharmacogenetic and optogenetic manipulations that have characterized the functional neuroanatomy of inhibitory circuits in the mesolimbic system, and describe how GABA neurons of the VTA regulate reward and aversion-related learning. We also discuss pharmacogenetic manipulation of this system with benzodiazepines (BDZs, a class of addictive drugs, which act directly on GABAA receptors located on GABA neurons of the VTA. The results gathered with each of these approaches suggest that VTA GABA neurons bi-directionally modulate activity of local DA neurons, underlying reward or aversion at the behavioural level. Conversely, long-range GABA projections from the VTA to the NAc selectively target cholinergic interneurons (CINs to pause their firing and temporarily reduce cholinergic tone in the NAc, which modulates associative learning. Further characterization of inhibitory circuit function within and beyond the VTA is needed in order to fully understand the function of the mesolimbic system under normal and pathological conditions.

  4. Functional pharmacology of cloned heterodimeric GABA-B receptors expressed in mammalian cells

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Krogsgaard-Larsen, P

    1999-01-01

    1. In this study we report a new assay of heterodimeric gamma-amino-butanoic acid subtype B (GABAB) receptors where either GABABR1a or GABABR1b are co-expressed with GABABR2 and the chimeric G-protein Galphaq-z5 in tsA cells. In this manner we obtained a robust response to GABAB agonists measured...

  5. Probing the orthosteric binding site of GABAA receptors with heterocyclic GABA carboxylic acid bioisosteres

    DEFF Research Database (Denmark)

    Petersen, Jette G; Bergmann, Rikke; Krogsgaard-Larsen, Povl

    2013-01-01

    The ionotropic GABAA receptors (GABAARs) are widely distributed in the central nervous system where they play essential roles in numerous physiological and pathological processes. A high degree of structural heterogeneity of the GABAAR has been revealed and extensive effort has been made to devel...

  6. Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice.

    Science.gov (United States)

    Liu, Xinhuai; Porteous, Robert; Herbison, Allan E

    2017-01-01

    Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABA A and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABA A -mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.

  7. Glycine transporter 1 modulates GABA release from amacrine cells by controlling occupancy of coagonist binding site of NMDA receptors.

    Science.gov (United States)

    Rozsa, Eva; Vigh, Jozsef

    2013-09-01

    The occupancy of coagonist binding sites of NMDA receptors (NMDARs) by glycine or d-serine has been thought to mediate NMDAR-dependent excitatory signaling, as simultaneous binding of glutamate and a coagonist is obligatory for NMDAR activation. Amacrine cells (ACs) mediating GABAergic feedback inhibition of mixed bipolar cells (Mbs) in the goldfish retina have been shown to express NMDARs. Here we studied whether NMDAR-mediated GABAergic inhibitory currents (IGABA) recorded from the axon terminals of Mbs are influenced by experimental manipulations altering retinal glycine and d-serine levels. Feedback IGABA in Mb axon terminals was triggered by focal NMDA application or by synaptically released glutamate from depolarized Mb terminals. In both cases, blocking the coagonist binding sites of NMDARs eliminated the NMDAR-dependent IGABA, demonstrating that coagonist binding is critical in mediating NMDAR activity-triggered GABA release. Glycine transporter 1 (GLYT1) inhibition increased IGABA, indicating that coagonist binding sites of NMDARs on ACs providing GABAergic feedback inhibition to Mbs were not saturated. Focal glycine application, in the presence of the ionotropic glycine receptor blocker strychnine, triggered a GLYT1-dependent current in ACs, suggesting that GLYT1 expressed by putative glycinergic ACs controls the saturation level of NMDARs' coagonist sites. External d-serine also increased NMDAR activation-triggered IGABA in Mbs, further substantiating that the coagonist sites were unsaturated. Together, our findings demonstrate that coagonist modulation of glutamatergic input to GABAergic ACs via NMDARs is strongly reflected in the AC neuronal output (i.e., transmitter release) and thus is critical in GABAergic signal transfer function in the inner retina.

  8. Regional specific binding of [11C]RO 15 1788 to central type benzodiazepine receptors in human brain: quantitative evaluation by PET

    International Nuclear Information System (INIS)

    Pappata, S.; Samson, Y.; Chavoix, C.; Prenant, C.; Maziere, M.; Baron, J.C.

    1988-01-01

    The central type benzodiazepine receptors were studied in 17 healthy human subjects with 11 C-RO 15 1788 and positron emission tomography (PET). The brain regional distribution of the tracer in eight control studies performed after injection of trace doses of 11 C-RO 15 1788 was consistent with that of benzodiazepine receptors. Saturation studies with co-injected cold RO 15 1788 in the remaining subjects showed a dose-dependent decrease of brain radiotracer until full inhibition of specific binding was achieved with doses above 0.1 mg/kg (four studies). Based on the results, a simple method to estimate the specifically bound 11 C-RO 15 1788 regionally in a single PET study is proposed, using the data from the full-saturation studies as a stable estimate of the nondisplaceable radioligand concentration. Using this method, it was found that quasiequilibrium between the estimated specifically bound and nondisplaceable components was achieved at times equal to or longer than 20 min after tracer administration. The validity of this method was partly supported by further results, showing a good agreement between the regional specific binding so calculated and postmortem data of receptor density

  9. Participation of GABA(B) receptors in cortical postictal excitability in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2018-01-01

    Roč. 818, Jan 5 (2018), s. 26-29 ISSN 0014-2999 R&D Projects: GA MŠk(CZ) LH15032; GA MŠk(CZ) LH11015; GA ČR(CZ) GA15-16605S Institutional support: RVO:67985823 Keywords : cerebral cortex * epileptic afterdischarges * GABAB receptors * ontogeny * rat Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology Impact factor: 2.896, year: 2016

  10. Anticonvulsant and behavioral effects of GABA(B) receptor positive modulator CGP7930 in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel; Tichá, Kateřina; Mikulecká, Anna

    2013-01-01

    Roč. 28, č. 1 (2013), s. 113-120 ISSN 1525-5050 R&D Projects: GA MŠk(CZ) LC554; GA ČR(CZ) GAP304/10/1274 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : GABAB receptor * pharmacology * ontogeny * rat Subject RIV: FH - Neurology Impact factor: 2.061, year: 2013

  11. Generation of functional inhibitory synapses incorporating defined combinations of GABA(A or glycine receptor subunits

    Directory of Open Access Journals (Sweden)

    Christine Laura Dixon

    2015-12-01

    Full Text Available Fast inhibitory neurotransmission in the brain is mediated by wide range of GABAA receptor (GABAAR and glycine receptor (GlyR isoforms, each with different physiological and pharmacological properties. Because multiple isoforms are expressed simultaneously in most neurons, it is difficult to define the properties of inhibitory postsynaptic currents mediated by individual isoforms in vivo. Although recombinant expression systems permit the expression of individual isoforms in isolation, they require exogenous agonist application which cannot mimic the dynamic neurotransmitter profile characteristic of native synapses. We describe a neuron-HEK293 cell co-culture technique for generating inhibitory synapses incorporating defined combinations of GABAAR or GlyR subunits. Primary neuronal cultures, prepared from embryonic rat cerebral cortex or spinal cord, are used to provide presynaptic GABAergic and glycinergic terminals, respectively. When the cultures are mature, HEK293 cells expressing the subunits of interest plus neuroligin 2A are plated onto the neurons, which rapidly form synapses onto HEK293 cells. Patch clamp electrophysiology is then used to analyze the physiological and pharmacological properties of the inhibitory postsynaptic currents mediated by the recombinant receptors. The method is suitable for investigating the kinetic properties or the effects of drugs on inhibitory postsynaptic currents mediated by defined GABAAR or GlyR isoforms of interest, the effects of hereditary disease mutations on the formation and function of both types of synapses, and synaptogenesis and synaptic clustering mechanisms. The entire cell preparation procedure takes 2 – 5 weeks.

  12. Up-regulation of P2X7 receptor-mediated inhibition of GABA uptake by nerve terminals of the human epileptic neocortex.

    Science.gov (United States)

    Barros-Barbosa, Aurora R; Fonseca, Ana L; Guerra-Gomes, Sónia; Ferreirinha, Fátima; Santos, Agostinho; Rangel, Rui; Lobo, M Graça; Correia-de-Sá, Paulo; Cordeiro, J Miguel

    2016-01-01

    Thirty percent of patients with epilepsy are refractory to medication. The majority of these patients have mesial temporal lobe epilepsy (MTLE). This prompts for new pharmacologic targets, like ATP-mediated signaling pathways, since the extracellular levels of the nucleotide dramatically increase during in vitro epileptic seizures. In this study, we investigated whether sodium-dependent high-affinity γ-aminobutyric acid (GABA) and glutamate uptake by isolated nerve terminals of the human neocortex could be modulated by ATP acting via slow-desensitizing P2X7 receptor (P2X7R). Modulation of [(3) H]GABA and [(14) C]glutamate uptake by ATP, through activation of P2X7R, was investigated in isolated nerve terminals of the neocortex of cadaveric controls and patients with drug-resistant epilepsy (non-MTLE or MTLE) submitted to surgery. Tissue density and distribution of P2X7R in the human neocortex was assessed by Western blot analysis and immunofluorescence confocal microscopy. The P2X7R agonist, 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP, 3-100 μm) decreased [(3) H]GABA and [(14) C]glutamate uptake by nerve terminals of the neocortex of controls and patients with epilepsy. The inhibitory effect of BzATP (100 μm) was prevented by the selective P2X7R antagonist, A-438079 (3 μm). Down-modulation of [(14) C]glutamate uptake by BzATP (100 μm) was roughly similar in controls and patients with epilepsy, but the P2X7R agonist inhibited more effectively [(3) H]GABA uptake in the epileptic tissue. Neocortical nerve terminals of patients with epilepsy express higher amounts of the P2X7R protein than control samples. High-frequency cortical activity during epileptic seizures releases huge amounts of ATP, which by acting on low-affinity slowly desensitizing ionotropic P2X7R, leads to down-modulation of neuronal GABA and glutamate uptake. Increased P2X7R expression in neocortical nerve terminals of patients with epilepsy may, under high-frequency firing, endure GABA signaling and

  13. Simultaneous optical recording in multiple cells by digital holographic microscopy of chloride current associated to activation of the ligand-gated chloride channel GABA(A) receptor.

    Science.gov (United States)

    Jourdain, Pascal; Boss, Daniel; Rappaz, Benjamin; Moratal, Corinne; Hernandez, Maria-Clemencia; Depeursinge, Christian; Magistretti, Pierre Julius; Marquet, Pierre

    2012-01-01

    Chloride channels represent a group of targets for major clinical indications. However, molecular screening for chloride channel modulators has proven to be difficult and time-consuming as approaches essentially rely on the use of fluorescent dyes or invasive patch-clamp techniques which do not lend themselves to the screening of large sets of compounds. To address this problem, we have developed a non-invasive optical method, based on digital holographic microcopy (DHM), allowing monitoring of ion channel activity without using any electrode or fluorescent dye. To illustrate this approach, GABA(A) mediated chloride currents have been monitored with DHM. Practically, we show that DHM can non-invasively provide the quantitative determination of transmembrane chloride fluxes mediated by the activation of chloride channels associated with GABA(A) receptors. Indeed through an original algorithm, chloride currents elicited by application of appropriate agonists of the GABA(A) receptor can be derived from the quantitative phase signal recorded with DHM. Finally, chloride currents can be determined and pharmacologically characterized non-invasively simultaneously on a large cellular sampling by DHM.

  14. Simultaneous optical recording in multiple cells by digital holographic microscopy of chloride current associated to activation of the ligand-gated chloride channel GABA(A receptor.

    Directory of Open Access Journals (Sweden)

    Pascal Jourdain

    Full Text Available Chloride channels represent a group of targets for major clinical indications. However, molecular screening for chloride channel modulators has proven to be difficult and time-consuming as approaches essentially rely on the use of fluorescent dyes or invasive patch-clamp techniques which do not lend themselves to the screening of large sets of compounds. To address this problem, we have developed a non-invasive optical method, based on digital holographic microcopy (DHM, allowing monitoring of ion channel activity without using any electrode or fluorescent dye. To illustrate this approach, GABA(A mediated chloride currents have been monitored with DHM. Practically, we show that DHM can non-invasively provide the quantitative determination of transmembrane chloride fluxes mediated by the activation of chloride channels associated with GABA(A receptors. Indeed through an original algorithm, chloride currents elicited by application of appropriate agonists of the GABA(A receptor can be derived from the quantitative phase signal recorded with DHM. Finally, chloride currents can be determined and pharmacologically characterized non-invasively simultaneously on a large cellular sampling by DHM.

  15. Synthesis, Modelling, and Anticonvulsant Studies of New Quinazolines Showing Three Highly Active Compounds with Low Toxicity and High Affinity to the GABA-A Receptor

    Directory of Open Access Journals (Sweden)

    Mohamed F. Zayed

    2017-01-01

    Full Text Available Some novel fluorinated quinazolines (5a–j were designed and synthesized to be evaluated for their anticonvulsant activity and their neurotoxicity. Structures of all newly synthesized compounds were confirmed by their infrared (IR, mass spectrometry (MS spectra, 1H nuclear magnetic resonance (NMR, 13C-NMR, and elemental analysis (CHN. The anticonvulsant activity was evaluated by a subcutaneous pentylenetetrazole (scPTZ test and maximal electroshock (MES-induced seizure test, while neurotoxicity was evaluated by a rotorod test. The molecular docking was performed for all newly-synthesized compounds to assess their binding affinities to the GABA-A receptor in order to rationalize their anticonvulsant activities in a qualitative way. The data obtained from the molecular modeling was correlated with that obtained from the biological screening. These data showed considerable anticonvulsant activity for all newly-synthesized compounds. Compounds 5b, 5c, and 5d showed the highest binding affinities toward the GABA-A receptor, along with the highest anticonvulsant activities in experimental mice. These compounds also showed low neurotoxicity and low toxicity in the median lethal dose test compared to the reference drugs. A GABA enzymatic assay was performed for these highly active compounds to confirm the obtained results and explain the possible mechanism for anticonvulsant action. The most active compounds might be used as leads for future modification and optimization.

  16. Region-selective effects of neuroinflammation and antioxidant treatment on peripheral benzodiazepine receptors and NMDA receptors in the rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Biegon, A.; Alvarado, M.; Budinger, T.F.; Grossman, R.; Hensley, K.; West, M.S.; Kotake, Y.; Ono, M.; Floyd, R.A.

    2001-12-10

    Following induction of acute neuroinflammation by intracisternal injection of endotoxin (lipopolysaccharide) in rats, quantitative autoradiography was used to assess the regional level of microglial activation and glutamate (NMDA) receptor binding. The possible protective action of the antioxidant phenyl-tert-butyl nitrone in this model was tested by administering the drug in the drinking water for 6 days starting 24 hours after endotoxin injection. Animals were killed 7 days post-injection and consecutive cryostat brain sections labeled with [3H]PK11195 as a marker of activated microglia and [125I]iodoMK801 as a marker of the open-channel, activated state of NMDA receptors. Lipopolysaccharide increased [3H]PK11195 binding in the brain, with the largest increases (2-3 fold) in temporal and entorhinal cortex, hippocampus, and substantia innominata. A significant (>50 percent) decrease in [125I]iodoMK801 binding was found in the same brain regions. Phenyl-tert-butyl nitrone treatment resulted in a partial inhibition ({approx}25 percent decrease) of the lipopolysaccharide-induced increase in [3H]PK11195 binding but completely reversed the lipopolysaccharide-induced decrease in [125I]iodoMK80 binding in the entorhinal cortex, hippocampus, and substantia innominata. Loss of NMDA receptor function in cortical and hippocampal regions may contribute to the cognitive deficits observed in diseases with a neuroinflammatory component, such as meningitis or Alzheimer's disease.

  17. Benzodiazepines inhibit the acetylcholine receptor-operated potassium current (IK.ACh) by different mechanisms in guinea-pig atrial myocytes.

    Science.gov (United States)

    Okada, Muneyoshi; Mizuno, Wataru; Nakarai, Ryu; Matada, Takashi; Yamawaki, Hideyuki; Hara, Yukio

    2012-07-01

    The anticholinergic effects of 7 benzodiazepines, bromazepam, camazepam, chlordiazepoxide, diazepam, lorazepam, medazepam and triazolam, were compared by examining their inhibitory effects on the acetylcholine receptor-operated potassium current (I(K).(ACh)) in guinea-pig atrial myocytes. All of these benzodiazepines (0.3-300 µM) inhibited carbachol (1 µM)-induced I(K).(ACh) in a concentration-dependent manner. The ascending order of IC(50) values for carbachol-induced I(K).(ACh) was as follows; medazepam, diazepam, camazepam, triazolam, bromazepam, lorazepam and chlordiazepoxide (>300 µM). The compounds, except for bromazepam, also inhibited I(K).(ACh) activated by an intracellular loading of 100 µM guanosine 5'-[γ-thio]triphosphate (GTPγS) in a concentration-dependent manner. The ascending order of IC(50) values for GTPγS-activated I(K).(ACh) was as follows; medazepam, diazepam, camazepam, lorazepam, triazolam chlordiazepoxide (>300 µM) and bromazepam (>300 µM). To clarify the molecular mechanism of the inhibition, IC(50) ratio, the ratio of IC(50) for GTPγS-activated I(K).(ACh) to carbachol-induced I(K).(ACh), was calculated. The IC(50) ratio for camazepam, diazepam, lorazepam, medazepam and triazolam was close to unity, while it for chlordiazepoxide could not be calculated. These compounds would act on the GTP binding protein and/or potassium channel to achieve the anticholinergic effects in atrial myocytes. In contrast, since the IC(50) ratio for bromazepam is presumably much higher than unity judging from the IC(50) values (104.0 ± 30.0 µM for carbachol-induced I(K).(ACh) and >300 µM for GTPγS-activated I(K).(ACh), it would act on the muscarinic receptor. In summary, benzodiazepines had the anticholinergic effects on atrial myocytes through inhibiting I(K).(ACh) by different molecular mechanisms.

  18. PET and SPECT in medically non-refractory complex partial seizures. Temporal asymmetries of glucose consumption, Benzodiazepine receptor density

    International Nuclear Information System (INIS)

    Matheja, P.; Kuwert, T.; Wolf, K.; Schober, O.; Stodieck, S.R.G.; Diehl, B.; Ringelstein, E.B.; Schuierer, G.

    1998-01-01

    Aim: In contrast to medically refractory complex partial seizures (CPS), only limited knowledge exists on cerebral perfusion and metabolism in medically non-refractory CPS. The aim of this study was to investigate the frequency of temporal asymmetries in regional cerebral glucose consumption (rCMRGlc), regional cerebral blood flow (rCBF), and regional cerebral benzodiazepine receptor density (BRD) in this group of patients. Methods: The study included 49 patients with medically non-refractory cryptogenic CPS (age: 36.0±16.1 years). rCMRGlc was studied with F-18-FDG-PET (FDG), rCBF with Tc-99m-ECD-SPECT (ECD), and BRD with I-123-iomazenil-SPECT (IMZ). All studies were performed interictally and within four weeks in each patient. Duration of epilepsy ranged from 0.1 to 42 years (median 4.0 years). SPECT was performed with the triple-headed SPECT camera Multispect 3, PET with the PET camera ECAT EXACT 47. Using linear profiles, glucose consumption, as well as uptake of ECD and IMZ, were measured in four temporal regions of interest (ROIs), and asymmetry indices were calculated (ASY). The results were compared to 95% confidence intervals determined in control subjects. Results: Thirty-five of the 49 (71%) patients had at least one significantly elevated ASY; temporal rCMRGlc was asymmetrical in 41% of the patients, temporal BRD in 29%, and temporal rCBF in 24%. One patient had an asymmetry of all three variables, two of temporal rCMRGlc and BRD, three of temporal rCMRGlc and rCBF, and another four of rCBF and BRD. Fourteen patients had an isolated temporal asymmetry in rCMRGlc, seven in BRD, and four in rCBF. A discrepancy in lateralization between the three modalities was not observed. Conclusion: The majority of patients with medically non-refractory CPS have focal abnormalities of blood flow and metabolism in their temporal lobe. In this group of patients, FDG-PET demonstrates abnormalities with the highest frequency of the three modalities studied, followed by IMZ

  19. [11C]Flumazenil metabolite measurement in plasma is not necessary for accurate brain benzodiazepine receptor quantification

    International Nuclear Information System (INIS)

    Sanabria-Bohorquez, S.M.; Veraart, C.; Labar, D.; Bol, A.; Volder, A.G. de; Michel, C.; Leveque, P.

    2000-01-01

    In this work, a mathematical correction for metabolites has been validated which estimates the relative amount of [ 11 C]flumazenil ([ 11 C]FMZ) in the total plasma curve from the tissue kinetic data without the need for direct metabolite measurement in blood plasma samples. Kinetic data were obtained using a 90-min three-injection protocol on five normal volunteers. First, the relative amount of [ 11 C]FMZ in plasma was modelled by a two-parameter exponential function. The parameters were estimated either directly by fitting this model to the blood plasma metabolite measurements, or indirectly from the simultaneous fitting of tissue time activity curves from several brain regions with a non-linear FMZ kinetic model. Second, the direct and indirect metabolite corrections were fixed and the FMZ compartmental parameters were determined on a regional basis in the brain. The validation was performed by comparing the regional values of benzodiazepine receptor density B max and equilibrium dissociation constant K d obtained with the direct metabolite correction with those values obtained with the indirect correction. For B max , the correlation coefficient r 2 was above 0.97 for all subjects and the slope values of the linear regression were within the interval [0.97, 1.2]. For K d , r 2 was above 0.96, and the slope values of the linear regression were within the interval [0.99, 1.1]. Simulation studies were performed in order to evaluate whether this metabolite correction method could be used in a clinical protocol where only a single [ 11 C]FMZ injection and a linear compartmental model are used. The resulting [ 11 C]FMZ distribution volume estimates were found to be linearly correlated with the true values, with r 2 =1.0 and a slope value of 1.1. The mathematical metabolite correction proved to be a feasible and reliable method to estimate the relative amount of [ 11 C]FMZ in plasma and the compartmental model parameters for three-injection protocols. Although

  20. Inhibition of GABA A receptor improved special memory impairment in the local model of demyelination in rat hippocampus.

    Science.gov (United States)

    Mousavi Majd, Alireza; Ebrahim Tabar, Forough; Afghani, Arghavan; Ashrafpour, Sahand; Dehghan, Samaneh; Gol, Mohammad; Ashrafpour, Manouchehr; Pourabdolhossein, Fereshteh

    2018-01-15

    Cognitive impairment and memory deficit are common features in multiple Sclerosis patients. The mechanism of memory impairment in MS is unknown, but neuroimaging studies suggest that hippocampal demyelination is involved. Here, we investigate the role of GABA A receptor on spatial memory in the local model of hippocampal demyelination. Demyelination was induced in male Wistar rats by bilaterally injection of lysophosphatidylcholine (LPC) 1% into the CA1 region of the hippocampus. The treatment groups were received daily intraventricular injection of bicuculline (0.025, 0.05μg/2μl/animal) or muscimol (0.1, 0.2μg/2μl/animal) 5days after LPC injection. Morris Water Maze was used to evaluate learning and memory in rats. We used Luxol fast blue staining and qPCR to assess demyelination extention and MBP expression level respectively. Immunohistochemistry (IHC) for CD45 and H&E staining were performed to assess inflammatory cells infiltration. Behavioral study revealed that LPC injection in the hippocampus impaired learning and memory function. Animals treated with both doses of bicuculline improved spatial learning and memory function; however, muscimol treatment had no effect. Histological and MBP expression studies confirmed that demylination in LPC group was maximal. Bicuculline treatment significantly reduced demyelination extension and increased the level of MBP expression. H&E and IHC results showed that bicuculline reduced inflammatory cell infiltration in the lesion site. Bicuculline improved learning and memory and decreased demyelination extention in the LPC-induced hippocampal demyelination model. We conclude that disruption of GABAergic homeostasis in hippocampal demyelination context may be involved in memory impairment with the implications for both pathophysiology and therapy. Copyright © 2017. Published by Elsevier B.V.

  1. Neonatal treatment with monoamine uptake inhibitors alters later response in behavioural 'despair' test to beta and GABA-B receptor agonists.

    Science.gov (United States)

    Hilakivi, L A; Taira, T; Hilakivi, I; Loikas, P

    1988-07-01

    The administration of monoamine uptake-inhibiting antidepressant drugs to rats during the early postnatal period was previously shown to lengthen the duration of subsequent immobility in Porsolt's swim test, hence suggesting increased behavioural 'despair' in these animals. Because the mechanism of the antidepressant action may be related to changes in the cerebral monoamine or gamma-aminobutyric acid (GABA) function, the present study was carried out to examine the response in the swim test to a beta-receptor agonist salbutamol, or to the GABA-B receptor agonists progabide and baclofen in rats treated with antidepressant drugs during the second and third postnatal week: either desipramine 5 mg/kg, nomifensine 10 mg/kg or zimeldine 25 mg/kg. When tested a month later i.e. at the age of two months these rats were immobile in water for a longer period than the controls. Salbutamol 10 mg/kg and progabide 100 mg/kg increased the immobility time in the control rats but neither drug affected the rats treated with desipramine, nomifensine or zimeldine. When the animals were 5 months of age, salbutamol 10 mg/kg and baclofen 10 mg/kg shortened the immobility time in the desipramine-treated rats. The control rats and those treated with zimeldine were not affected by the drugs. The results indicate that in the rats which were neonatally treated with antidepressants, the immobility time in water is lengthened in adulthood. Moreover, the response to beta-receptor and GABA-B receptor agonists is increased from the response observed in the control rats.

  2. Viral vector-mediated overexpression of estrogen receptor-alpha in striatum enhances the estradiol-induced motor activity in female rats and estradiol-modulated GABA release.

    Science.gov (United States)

    Schultz, Kristin N; von Esenwein, Silke A; Hu, Ming; Bennett, Amy L; Kennedy, Robert T; Musatov, Sergei; Toran-Allerand, C Dominique; Kaplitt, Michael G; Young, Larry J; Becker, Jill B

    2009-02-11

    Classical estrogen receptor-signaling mechanisms involve estradiol binding to intracellular nuclear receptors [estrogen receptor-alpha (ERalpha) and estrogen receptor-beta (ERbeta)] to promote changes in protein expression. Estradiol can also exert effects within seconds to minutes, however, a timescale incongruent with genomic signaling. In the brain, estradiol rapidly potentiates stimulated dopamine release in the striatum of female rats and enhances spontaneous rotational behavior. Furthermore, estradiol rapidly attenuates the K(+)-evoked increase of GABA in dialysate. We hypothesize that these rapid effects of estradiol in the striatum are mediated by ERalpha located on the membrane of medium spiny GABAergic neurons. This experiment examined whether overexpression of ERalpha in the striatum would enhance the effect of estradiol on rotational behavior and the K(+)-evoked increase in GABA in dialysate. Ovariectomized female rats were tested for rotational behavior or underwent microdialysis experiments after unilateral intrastriatal injections of a recombinant adeno-associated virus (AAV) containing the human ERalpha cDNA (AAV.ERalpha) into the striatum; controls received either the same vector into areas outside the striatum or an AAV containing the human alkaline phosphatase gene into the striatum (AAV.ALP). Animals that received AAV.ERalpha in the striatum exhibited significantly greater estradiol-induced contralateral rotations compared with controls and exhibited behavioral sensitization of contralateral rotations induced by a low-dose of amphetamine. ERalpha overexpression also enhanced the inhibitory effect of estradiol on K(+)-evoked GABA release suggesting that disinhibition of dopamine release from terminals in the striatum resulted in the enhanced rotational behavior.

  3. Molecular cloning, spatiotemporal and functional expression of GABA receptor subunits RDL1 and RDL2 of the rice stem borer Chilo suppressalis.

    Science.gov (United States)

    Sheng, Cheng-Wang; Jia, Zhong-Qiang; Ozoe, Yoshihisa; Huang, Qiu-Tang; Han, Zhao-Jun; Zhao, Chun-Qing

    2018-03-01

    Insect γ-aminobutyric acid (GABA) receptor (GABAR) is one of the major targets of insecticides. In the present study, cDNAs (CsRDL1A and CsRDL2S) encoding the two isoforms of RDL subunits were cloned from the rice stem borer Chilo suppressalis. Transcripts of both genes demonstrated similar expression patterns in different tissues and developmental stages, although CsRDL2S was ∼2-fold more abundant than CsRDL1A throughout all development stages. To investigate the function of channels formed by CsRDL subunits, both genes were expressed in Xenopus laevis oocytes singly or in combination in different ratios. Electrophysiological results using a two-electrode voltage clamp demonstrated that GABA activated currents in oocytes injected with both cRNAs. The EC 50 value of GABA in activating currents was smaller in oocytes co-injected with CsRDL1A and CsRDL2S than in oocytes injected singly. The IC 50 value of the insecticide fluralaner in inhibiting GABA responses was smaller in oocytes co-injected with different cRNAs than in oocytes injected singly. Co-injection also changed the potency of the insecticide dieldrin in oocytes injected singly. These findings suggested that heteromeric GABARs were formed by the co-injections of CsRDL1A and CsRDL2S in oocytes. Although the presence of Ser at the 2'-position in the second transmembrane segment was responsible for the insensitivity of GABARs to dieldrin, this amino acid did not affect the potencies of the insecticides fipronil and fluralaner. These results lead us to hypothesize that C. suppressalis may adapt to insecticide pressure by regulating the expression levels of CsRDL1A and CsRDL2S and the composition of both subunits in GABARs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Neuroregulation of the Hypothalamus-Pituitary-Adrenal (HPA Axis in Humans: Effects of GABA-, Mineralocorticoid-, and GH-Secretagogue-Receptor Modulation

    Directory of Open Access Journals (Sweden)

    Roberta Giordano

    2006-01-01

    Full Text Available The hypothalamus-pituitary-adrenal (HPA axis exerts a variety of effects at both the central and peripheral level. Its activity is mainly regulated by CRH, AVP, and the glucocorticoid-mediated feedback action. Moreover, many neurotransmitters and neuropeptides influence HPA axis activity by acting at the hypothalamic and/or suprahypothalamic level. Among them, GABA and Growth Hormone Secretagogues (GHS/GHS-receptor systems have been shown to exert a clear inhibitory and stimulatory effect, respectively, on corticotroph secretion. Alprazolam (ALP, a GABA-A receptor agonist, shows the most marked inhibitory effect on both spontaneous and stimulated HPA axis activity, in agreement with its peculiar efficacy in panic disorders and depression where an HPA axis hyperactivation is generally present. Ghrelin and synthetic GHS possess a marked ACTH/cortisol-releasing effect in humans and the ghrelin/GHS-R system is probably involved in the modulation of the HPA response to stress and nutritional/metabolic variations. The glucocorticoid-mediated negative feedback action is mediated by both glucocorticoid (GR and mineralocorticoid (MR receptors activation at the central level, mainly in the hippocampus. In agreement with animal studies, MRs seem to play a crucial role in the maintenance of the circadian ACTH and cortisol rhythm, through the modulation of CRH and AVP release. GABA agonists (mainly ALP, ghrelin, as well as MR agonists/antagonists, may represent good tools to explore the activity of the HPA axis in both physiological conditions and pathological states characterized by an impaired control of the corticotroph function.

  5. GABA type B receptor signaling in proopiomelanocortin neurons protects against obesity, insulin resistance, and hypothalamic inflammation in male mice on a high-fat diet.

    OpenAIRE

    Ito Yoshihiro; Banno Ryoichi; Shibata Miyuki; Adachi Koichi; Hagimoto Shigeru; Hagiwara Daisuke; Ozawa Yoshiharu; Goto Motomitsu; Suga Hidetaka; Sugimura Yoshihisa; Bettler Bernhard; Oiso Yutaka; Arima Hiroshi

    2013-01-01

    There is evidence suggesting that the GABA system in the arcuate nucleus, where orexigenic neuropeptide Y and agouti-related peptide as well as anorexigenic proopiomelanocortin (POMC) are expressed, plays an important role in energy balance. In this study, we generated POMC-specific GABAB receptor-deficient [knock-out (KO)] mice. Male KO mice on a high-fat diet (HFD) showed mild increases in body weight (BW) at the age of 9 weeks compared to wild-type (WT) mice, and the differences remained s...

  6. Facilitation of glutamate and GABA release by P2X receptor activation in supraoptic neurons from freshly isolated rat brain slices

    Czech Academy of Sciences Publication Activity Database

    Vávra, Vojtěch; Bhattacharya, Anirban; Zemková, Hana

    2011-01-01

    Roč. 188, - (2011), s. 1-12 ISSN 0306-4522 R&D Projects: GA AV ČR(CZ) IAA500110910; GA ČR(CZ) GA305/07/0681; GA ČR(CZ) GD305/08/H037; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : ATP * purinergic P2X receptors * GABA * glutamate * supraoptic nucleus * patch clamp Subject RIV: ED - Physiology Impact factor: 3.380, year: 2011

  7. Modulation of postsynaptic potentials in rat cortical neurons by valerian extracts macerated with different alcohols: involvement of adenosine A(1)- and GABA(A)-receptors.

    Science.gov (United States)

    Sichardt, K; Vissiennon, Z; Koetter, U; Brattström, A; Nieber, K

    2007-10-01

    Valeriana officinalis (valerian) is used traditionally as a mild sedative. Research into valerian is sparse, and studies differ greatly with respect to design, measures and preparations used. This study compares the action of a methanol (M-E), ethanol (E-E) and an extract macerated with ethylacetate (EA-E) from roots of valerian (Valeriana officinalis L., Valerianaceae) on postsynaptic potentials (PSPs) in cortical neurons. Intracellular recordings were performed in rat brain slice preparations containing pyramidal cells of the cingulate cortex. PSPs were induced by electrical field stimulation. The M-E induced strong inhibition in the concentration range 0.1-15 mg/mL, whereas the E-E (1-10 mg/mL) did not influence significantly the PSPs. The maximum inhibition induced by the M-E was completely antagonized by 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 0.1 microm), an antagonist on the adenosine A(1) receptor. Contrary to the M-E, the EA-E (10 mg/mL) induced an increase of the PSPs, which was completely blocked by the GABA(A) receptor antagonist picrotoxin (100 microm). The data suggest that activation of adenosine A(1) and GABA(A) receptors is mediated by different components within the valerian extract. The two mechanisms may contribute independently to the sleep-inducing effect of valerian.

  8. Long-range regulatory polymorphisms affecting a GABA receptor constitute a quantitative trait locus (QTL for social behavior in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Andres Bendesky

    Full Text Available Aggregation is a social behavior that varies between and within species, providing a model to study the genetic basis of behavioral diversity. In the nematode Caenorhabditis elegans, aggregation is regulated by environmental context and by two neuromodulatory pathways, one dependent on the neuropeptide receptor NPR-1 and one dependent on the TGF-β family protein DAF-7. To gain further insight into the genetic regulation of aggregation, we characterize natural variation underlying behavioral differences between two wild-type C. elegans strains, N2 and CB4856. Using quantitative genetic techniques, including a survey of chromosome substitution strains and QTL analysis of recombinant inbred lines, we identify three new QTLs affecting aggregation in addition to the two known N2 mutations in npr-1 and glb-5. Fine-mapping with near-isogenic lines localized one QTL, accounting for 5%-8% of the behavioral variance between N2 and CB4856, 3' to the transcript of the GABA neurotransmitter receptor gene exp-1. Quantitative complementation tests demonstrated that this QTL affects exp-1, identifying exp-1 and GABA signaling as new regulators of aggregation. exp-1 interacts genetically with the daf-7 TGF-β pathway, which integrates food availability and population density, and exp-1 mutations affect the level of daf-7 expression. Our results add to growing evidence that genetic variation affecting neurotransmitter receptor genes is a source of natural behavioral variation.

  9. Positive allosteric modulation of the GHB high-affinity binding site by the GABAA receptor modulator monastrol and the flavonoid catechin

    DEFF Research Database (Denmark)

    Eghorn, Laura Friis; Høstgaard-Jensen, Kirsten; Kongstad, Kenneth Thermann

    2014-01-01

    whether GHB high-affinity binding sites are also sensitive to allosteric modulation, we screened both known GABAA receptor ligands and a library of natural compounds in the rat cortical membrane GHB specific high-affinity [3H]NCS-382 binding assay. Two hits were identified: Monastrol, a positive...... allosteric modulator of GABA function at δ-containing GABAA receptors, and the naturally occurring flavonoid catechin. These compounds increased [3H]NCS-382 binding to 185-272% in high micromolar concentrations. Monastrol and (+)-catechin significantly reduced [3H]NCS-382 dissociation rates and induced...... modulation was critically probe-dependent. Both monastrol and (+)-catechin were agonists at recombinant α4β3δ receptors expressed in Xenopus laevis oocytes. When monastrol and GHB were co-applied no changes were seen compared to the individual responses. In summary, we have identified the compounds monastrol...

  10. Kampo medicine: Evaluation of the pharmacological activity of 121 herbal drugs on GABA(A and 5 HT3A receptors

    Directory of Open Access Journals (Sweden)

    Katrin M Hoffmann

    2016-07-01

    Full Text Available Kampo medicine is a form of Japanese phytotherapy originating from traditional Chinese medicine (TCM. During the last several decades, much attention has been paid to the pharmacological effects of these medical plants and its constituents. However, in many cases, a systematic screening of Kampo remedies to determine pharmacologically relevant targets is still lacking. In this study, we performed a broad screening of Kampo remedies to look for pharmacologically relevant 5 HT3A and GABA(A receptor ligands. Several of the Kampo remedies are currently used for symptoms such as nausea, emesis, gastrointestinal motility disorders, anxiety, restlessness or insomnia. Therefore, we analyzed the pharmacological effects of 121 herbal drugs from Kampo medicine as ethanol tinctures on heterologously expressed 5 HT3A and GABA(A receptors, due to the involvement of these receptors in such pathophysiological processes. The tinctures of Lindera aggregata (radix and Leonurus japonicus (herba were the most effective inhibitory compounds on the 5 HT3A receptor. Further investigation of known ingredients in these compounds led to the identification of leonurine from Leonurus as a new natural 5 HT3A receptor antagonist. We also identified several potentiating herbs (e.g., Magnolia officinalis (cortex, Syzygium aromaticum (flos and Panax ginseng (radix for the GABAA receptor, which are all traditionally used for their sedative or anxiolytic effects. A variety of tinctures with antagonistic effects, for instance Salvia miltiorrhiza (radix were also detected. Therefore, this study reveals new insights into the pharmacological action of a broad spectrum of herbal drugs from Kampo, allowing a better understanding of their physiological effects and clinical applications.

  11. Synthesis of [{sup 123}I]iodine labelled imidazo[1,2-b] pyridazines as potential probes for the study of peripheral benzodiazepine receptors using SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, A.; Mattner, F.; Dikic, B. [Radiopharmaceuticals Div. ANSTO, Menai, NSW (Australia); Barlin, G. [Div. of Neurosciences, John Curtin School of Medical Research, Australian National Univ., Canberra (Australia)

    2004-07-01

    The pyridazines 3-acetamidomethyl-6-chloro-2-(4'-iodophenyl)imidazo[1,2-b]pyridazine 1 (IC{sub 50} = 1.6 nM) and 3-benzamidomethyl-6-iodo-2-(4'-t-butylphenyl)imidazo[1,2-b] pyridazine 2 (IC{sub 50} = 4.2 nM), are high affinity and selective ligands for the peripheral benzodiazepine receptors (PBR) compared to the central benzodiazepine counterparts. The [{sup 123}I]1 and [{sup 123}I]2 labelled analogues of these compounds were subsequently synthesised for the potential study of the PBR in vivo using SPECT. Radioiodination of [{sup 123}I]1 was achieved by iododestannylation of the corresponding tributyl tin precursor with Na[{sup 123}I] in the presence of peracetic acid or chloramine-T and the product isolated by C-18 RP HPLC. Radioiodination of [{sup 123}I]2 was achieved by copper assisted bromine [{sup 123}I]iodine exchange of the corresponding bromo precursor in the presence of acetic acid and sodium bisulfate as reducing agent at 200 C. Purification of the crude products were achieved by semi-preparative C-18 RP HPLC to give the products in radiochemical yields > 90%. The products were obtained in > 97% chemical and radiochemical purity and with specific activities > 180 GBq/{mu}mol. (orig.)

  12. Benzodiazepine receptor and cerebral blood flow in early Alzheimer's disease. SPECT study using 123I-Iomazenil and 123I-IMP

    International Nuclear Information System (INIS)

    Kitamura, Shin; Koshi, Yasuhiko; Komiyama, Tasuku; Sakayori, Osamu; Komaba, Yuichi; Ohyama, Masashi; Mishina, Masahiro; Tsuganesawa, Toshikazu; Terashi, Akiro

    1996-01-01

    This study was designed to investigate benzodiazepine receptors (BZR) and cerebral blood flow (CBF) in patients with early Alzheimer's disease. Imaging of BZR and measurement of CBF were performed by SPECT using 123 I-Iomazenil (IMZ) and 123 I-IMP respectively, in seven patients with early Alzheimer's disease and five patients with unilateral left cerebral infarction as controls. The values for the normal cerebral hemisphere (ratio to the contralateral cerebellum) in patients with cerebral infarction were adopted as control values. In patients with Alzheimer's disease, the CBF (ratio to cerebellum) decreased significantly in the frontal cortex and the parietal cortex compared with the control values. There was no significant difference in late IMZ SPECT counts (ratio to cerebellum) and washout (the ratio of late-to-early IMZ SPECT counts) between patients with Alzheimer's disease and the controls. However, the late IMZ SPECT counts and washout decreased in one patient with moderate dementia. There was a significant correlation between the severity of dementia and the late IMZ SPECT counts in the temporal cortex and the parietal cortex. These results suggest that benzodiazepine binding sites are relatively well preserved in patients with early Alzheimer's disease, and reduction of the CBF is caused by neuronal dysfunction rather than by neuronal loss. IMZ SPECT study is useful and necessary for clarifying the pathophysiological state in Alzheimer's disease. (author)

  13. Effects of cocaine history on postsynaptic GABA receptors on dorsal raphe serotonin neurons in a stress-induced relapse model in rats.

    Science.gov (United States)

    Li, Chen; Kirby, Lynn G

    2016-01-01

    The serotonin (5-hydroxytryptamine, 5-HT) system plays an important role in stress-related psychiatric disorders and substance abuse. Stressors and stress hormones can inhibit the dorsal raphe nucleus (DRN)-5-HT system, which composes the majority of forebrain-projecting 5-HT. This inhibition is mediated via stimulation of GABA synaptic activity at DRN-5-HT neurons. Using swim stress-induced reinstatement of morphine conditioned place-preference, recent data from our laboratory indicate that morphine history sensitizes DRN-5-HT neurons to GABAergic inhibitory effects of stress. Moreover, GABAA receptor-mediated inhibition of the serotonergic DRN is required for this reinstatement. In our current experiment, we tested the hypothesis that GABAergic sensitization of DRN-5-HT neurons is a neuroadaptation elicited by multiple classes of abused drugs across multiple models of stress-induced relapse by applying a chemical stressor (yohimbine) to induce reinstatement of previously extinguished cocaine self-administration in Sprague-Dawley rats. Whole-cell patch-clamp recordings of GABA synaptic activity in DRN-5-HT neurons were conducted after the reinstatement. Behavioral data indicate that yohimbine triggered reinstatement of cocaine self-administration. Electrophysiology data indicate that 5-HT neurons in the cocaine group exposed to yohimbine had increased amplitude of inhibitory postsynaptic currents compared to yoked-saline controls exposed to yohimbine or unstressed animals in both drug groups. These data, together with previous findings, indicate that interaction between psychostimulant or opioid history and chemical or physical stressors may increase postsynaptic GABA receptor density and/or sensitivity in DRN-5-HT neurons. Such mechanisms may result in serotonergic hypofunction and consequent dysphoric mood states which confer vulnerability to stress-induced drug reinstatement. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  14. Dual effect of beta-amyloid on α7 and α4β2 nicotinic receptors controlling the release of glutamate, aspartate and GABA in rat hippocampus.

    Directory of Open Access Journals (Sweden)

    Elisa Mura

    Full Text Available BACKGROUND: We previously showed that beta-amyloid (Aβ, a peptide considered as relevant to Alzheimer's Disease, is able to act as a neuromodulator affecting neurotransmitter release in absence of evident sign of neurotoxicity in two different rat brain areas. In this paper we focused on the hippocampus, a brain area which is sensitive to Alzheimer's Disease pathology, evaluating the effect of Aβ (at different concentrations on the neurotransmitter release stimulated by the activation of pre-synaptic cholinergic nicotinic receptors (nAChRs, α4β2 and α7 subtypes. Particularly, we focused on some neurotransmitters that are usually involved in learning and memory: glutamate, aspartate and GABA. METHODOLOGY/FINDINGS: WE USED A DUAL APPROACH: in vivo experiments (microdialysis technique on freely moving rats in parallel to in vitro experiments (isolated nerve endings derived from rat hippocampus. Both in vivo and in vitro the administration of nicotine stimulated an overflow of aspartate, glutamate and GABA. This effect was greatly inhibited by the highest concentrations of Aβ considered (10 µM in vivo and 100 nM in vitro. In vivo administration of 100 nM Aβ (the lowest concentration considered potentiated the GABA overflow evoked by nicotine. All these effects were specific for Aβ and for nicotinic secretory stimuli. The in vitro administration of either choline or 5-Iodo-A-85380 dihydrochloride (α7 and α4β2 nAChRs selective agonists, respectively elicited the hippocampal release of aspartate, glutamate, and GABA. High Aβ concentrations (100 nM inhibited the overflow of all three neurotransmitters evoked by both choline and 5-Iodo-A-85380 dihydrochloride. On the contrary, low Aβ concentrations (1 nM and 100 pM selectively acted on α7 subtypes potentiating the choline-induced release of both aspartate and glutamate, but not the one of GABA. CONCLUSIONS/SIGNIFICANCE: The results reinforce the concept that Aβ has relevant

  15. Roles of hippocampal GABA(A) and muscarinic receptors in consolidation of context memory and context-shock association in contextual fear conditioning: a double dissociation study.

    Science.gov (United States)

    Chang, Shih-Dar; Liang, K C

    2012-07-01

    Contextual fear conditioning involves forming a context representation and associating it to a shock, both of which involved the dorsal hippocampus (DH) according to our recent findings. This study tested further whether the two processes may rely on different neurotransmitter systems in the DH. Male Wistar rats with cannula implanted into the DH were subjected to a two-phase training paradigm of contextual fear conditioning to separate context learning from context-shock association in two consecutive days. Immediately after each training phase, different groups of rats received bilateral intra-DH infusion of the GABA(A) agonist muscimol, 5HT(1A) agonist 8-OH-DPAT, NMDA antagonist APV or muscarinic antagonist scopolamine at various doses. On the third day, freezing behavior was tested in the conditioning context. Results showed that intra-DH infusion of muscimol impaired conditioned freezing only if it was given after context learning. In contrast, scopolamine impaired conditioned freezing only if it was given after context-shock training. Posttraining infusion of 8-OH-DPAT or APV had no effect on conditioned freezing when the drug was given at either phase. These results showed double dissociation for the hippocampal GABAergic and cholinergic systems in memory consolidation of contextual fear conditioning: forming context memory required deactivation of the GABA(A) receptors, while forming context-shock memory involved activation of the muscarinic receptors. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Benzodiazepine receptors mediated anxiolytic-like effects of some 1,3,5-triaryl-4,5-dihydro-1h-pyrazole derivatives

    Directory of Open Access Journals (Sweden)

    Ozgur Devrim Can

    2016-06-01

    Results: In the hole-board tests, compounds 2g, 2h, 2k and 2s significantly increased total number of the head-dipping behavior and number of the explored holes. In the plus-maze tests, the same compounds increased the time spent in the open arms and the number of entries into the open arms. These findings indicated that these four compounds have anxiolytic-like effects. Reference drug diazepam (1 mg/kg, i.p also showed its anxiolytic activity in both of the tests, as expected. Conclusion: Benzodiazepine receptors mediated the anxiolytic-like effects of 2g, 2h, 2k and 2s coded 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivative compounds. [Cukurova Med J 2016; 41(2.000: 304-315

  17. Detection of viable cortical neurons using benzodiazepine receptor imaging after reversible focal ischaemia in rats: comparison with regional cerebral blood flow

    International Nuclear Information System (INIS)

    Watanabe, Yoshiyuki; Nakano, Takayuki; Yutani, Kenji; Nishimura, Hiroshi; Nishimura, Tsunehiko; Kusuoka, Hideo; Nakamura, Hironobu

    2000-01-01

    To elucidate the utility of benzodiazepine receptor imaging for the detection of viable cortical neurons, dual-tracer autoradiography using iodine-125 iomazenil (IMZ) and iodine-123 N-isopropyl-4-iodoamphetamine (IMP) was performed in a model of reversible focal ischaemia during the acute and subacute phases. The right middle cerebral artery of anaesthetized rats was occluded for 60 min using an intraluminal filament and reperfused. In the acute phase study, 125 I-IMZ (370 kBq) was injected via the femoral vein at 2 h after reperfusion, and 123 I-IMP (37 MBq) was injected at 50 min post-injection. Rats were sacrificed 10 min after the injection of 123 I-IMP. In the subacute phase study, the same procedure was performed at 5 days after reperfusion. In the acute phase, the IMP uptake was significantly decreased in almost all areas of the lesioned hemisphere, an exception being the cerebellum; however, the IMZ uptake was significantly decreased only in ischaemic cores. The discrepancy between IMZ and IMP uptake was observed in the lateral neocortex and the lateral caudate putamen (CPu), which were most frequently damaged in this ischaemic model. In the subacute phase, the IMZ uptake in lesioned rats was significantly decreased only in the parietal lobe and hippocampus, though the IMP uptake was decreased in many regions of lesioned hemispheres (the frontal, parietal cortex, CPu, hippocampus and thalamus). Histopathological findings indicated that both the IMP and the IMZ uptake was markedly decreased in necrotic areas. Although the IMP uptake was significantly decreased in the ischaemic areas, the IMZ uptake was maintained in these areas. These results suggest that benzodiazepine receptor imaging is superior to regional cerebral blood flow imaging for the detection of viable cortical neurons in both the acute and subacute phases of ischaemia. (orig.)

  18. Increased expression of mitochondrial benzodiazepine receptors following low-level light treatment facilitates enhanced protoporphyrin IX production in glioma-derived cells in vitro

    Science.gov (United States)

    Bisland, S. K.; Hassanali, N. S.; Johnson, C.; Wilson, B. C.

    2007-02-01

    This study investigates whether low level light treatment (LLLT) can enhance the expression of Peripheral-type mitochondrial benzodiazepine receptors (PBRs) on the glioma-derived tumour cell line, CNS-1, and by doing so promote the synthesis of protoporphyrin IX (PpIX) and increase the photodynamic therapy (PDT)-induced cell kill using 5-aminolevulinic acid (ALA). The endogenous photosensitizer, (PpIX) and related metabolites including coproporphyrin III are known to traffic via the PBRs on the outer mitochondrial membrane on their passage into or out of the mitochondria. Astrocyte-derived cells within the brain express PBRs, while neurons express the central-type of benzodiazepine receptor. CNS-1 cells were exposed to a range of differing low-level light protocols immediately prior to PDT. LLLT involved using broad-spectrum light or monochromatic laser light specific to 635 or 905 nm wavelength. Cells (5μ10 5) were exposed to a range of LLLT doses (0, 1 or 5 J/cm2) using a fixed intensity of 10 mW/cm2 and subsequently harvested for cell viability, immunofluorescence or western blot analysis of PBR expression. The amount of PpIX within the cells was determined using chemical extraction techniques. Results confirm the induction of PBR following LLLT is dependent on the dose and wavelength of light used. Broadspectrum light provided the greatest cell kill following PDT, although LLLT with 635 nm or 905 nm also increased cell kill as compared to PDT alone. All LLLT regimens increased PBR expression compared to controls with corresponding increases in PpIX production. These data suggest that by selectively increasing PBR expression in tumour cells, LLLT may facilitate enhanced cell kill using ALA-PDT without damaging surrounding normal brain.

  19. Selective GABA transporter inhibitors tiagabine and EF1502 exhibit mechanistic differences in their ability to modulate the ataxia and anticonvulsant action of the extrasynaptic GABA(A) receptor agonist gaboxadol

    DEFF Research Database (Denmark)

    Madsen, Karsten Kirkegaard; Ebert, Bjarke; Clausen, Rasmus Prætorius

    2011-01-01

    Modulation of the extracellular levels of GABA via inhibition of the synaptic GABA transporter GAT1 by the clinically effective and selective GAT1 inhibitor tiagabine [(R)-N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]nipecotic acid; Gabitril] has proven to be an effective treatment strategy for focal...

  20. Zolpidem, A Clinical Hypnotic that Affects Electronic Transfer, Alters Synaptic Activity Through Potential Gaba Receptors in the Nervous System Without Significant Free Radical Generation

    Directory of Open Access Journals (Sweden)

    Peter Kovacic

    2009-01-01

    Full Text Available Zolpidem (trade name Ambien has attracted much interest as a sleep-inducing agent and also in research. Attention has been centered mainly on receptor binding and electrochemistry in the central nervous system which are briefly addressed herein. A novel integrated approach to mode of action is presented. The pathways to be discussed involve basicity, reduction potential, electrostatics, cell signaling, GABA receptor binding, electron transfer (ET, pharmacodynamics, structure activity relationships (SAR and side effects. The highly conjugated pyridinium salt formed by protonation of the amidine moiety is proposed to be the active form acting as an ET agent. Extrapolation of reduction potentials for related compounds supports the premise that zolpidem may act as an ET species in vivo. From recent literature reports, electrostatics is believed to play a significant role in drug action.

  1. Evaluation of anti-hyperalgesic and analgesic effects of two benzodiazepines in human experimental pain: a randomized placebo-controlled study.

    Directory of Open Access Journals (Sweden)

    Pascal H Vuilleumier

    Full Text Available Compounds that act on GABA-receptors produce anti-hyperalgesia in animal models, but little is known on their effects in humans. The aim of this study was to explore the potential usefulness of GABA-agonism for the control of pain in humans. Two agonists at the benzodiazepine-binding site of GABAA-receptors (clobazam and clonazepam were studied using multiple experimental pain tests. Positive results would support further investigation of GABA agonism for the control of clinical pain.In a randomized double-blind crossover design, 16 healthy male volunteers received clobazam 20 mg, clonazepam 1 mg and tolterodine 1 mg (active placebo. The area of static hyperalgesia after intradermal capsaicin injection was the primary endpoint. Secondary endpoints were: area of dynamic hyperalgesia, response to von Frey hair stimulation, pressure pain thresholds, conditioned pain modulation, cutaneous and intramuscular electrical pain thresholds (1, 5 and 20 repeated stimulation, and pain during cuff algometry.For the primary endpoint, an increase in the area of static hyperalgesia was observed after administration of placebo (p<0.001, but not after clobazam and clonazepam. Results suggestive for an anti-hyperalgesic effect of the benzodiazepines were obtained with all three intramuscular pain models and with cuff algometry. No effect could be detected with the other pain models employed.Collectively, the results are suggestive for a possible anti-hyperalgesic effect of drugs acting at the GABAA-receptors in humans, particularly in models of secondary hyperalgesia and deep pain. The findings are not conclusive, but support further clinical research on pain modulation by GABAergic drugs. Because of the partial results, future research should focus on compounds acting selectively on subunits of the GABA complex, which may allow the achievement of higher receptor occupancy than unselective drugs. Our data also provide information on the most suitable experimental

  2. Co-application of the GABAB receptor agonist, baclofen, and the mGlu receptor agonist, L-CCG-I, facilitates [(3)H]GABA release from rat cortical nerve endings.

    Science.gov (United States)

    Samengo, Irene A; Scotti, Valerio; Martire, Maria

    2013-12-01

    Interaction between different transmitter receptor systems is an emerging feature of neurotransmission at central synapses. G protein-coupled receptors' ability to form dimers or larger hetero-oligomers probably serves to facilitate the integration of diverse signals within the cell. We found that, in nerve terminals isolated from the cerebral cortices of rats, co-application of the GABAB agonist, baclofen, and of the non-selective mGlu agonist, L-CCG-I, potentiates the basal and depolarization-evoked release of [(3)H]GABA via a mechanism that involves mobilization of intracellular Ca(2+) ions. The effect of L-CCG-I + baclofen was abolished by the phospholipase C inhibitor U73122, reduced by Xestospongin C (an IP3 receptor blocker), and blocked by 2-APB, an IP3 receptor antagonist. Pretreatment of the synaptosomes with the lipid-soluble Ca(2+) chelator BAPTA-AM also inhibited the effects of L-CCG-I + baclofen. Subtype-selective non-competitive group I mGlu receptor antagonists, MPEP and CPCCOEt, had no effect on the release enhancement produced by baclofen + L-CCG-I. The enhancement was reversed by the GABAB receptor antagonist, CGP54626, and by the group I/group II mGlu receptor antagonist (R,S)-MCPG. The GABA release-enhancing effects of L-CCG-I + baclofen in our model might reflect the presence on cortical nerve endings of GABAB/group I mGlu receptor heteromers with pharmacological properties distinct from those of the component receptors. Activation of these heteromeric receptors might modify the function of the GABAB receptor in such a way that it facilitates GABAergic transmission, an effect that might be useful under conditions of excessive glutamatergic activity.

  3. Day-night variations in zinc sensitivity of GABA(A) receptor-channels in rat suprachiasmatic nucleus

    Czech Academy of Sciences Publication Activity Database

    Kretschmannová, Karla; Svobodová, Irena; Zemková, Hana

    2003-01-01

    Roč. 120, č. 1 (2003), s. 46-51 ISSN 0169-328X R&D Projects: GA ČR GA309/02/1519; GA AV ČR IAA5011103; GA AV ČR IAA5011105 Institutional research plan: CEZ:AV0Z5011922 Keywords : GABA * circadian rhythm * suprachiasmatic nuclei Subject RIV: ED - Physiology Impact factor: 2.107, year: 2003

  4. Clobazam and its active metabolite N-desmethylclobazam display significantly greater affinities for α₂- versus α₁-GABA(A-receptor complexes.

    Directory of Open Access Journals (Sweden)

    Henrik Sindal Jensen

    Full Text Available Clobazam (CLB, a 1,5-benzodiazepine (BZD, was FDA-approved in October 2011 for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome (LGS in patients 2 years and older. BZDs exert various CNS effects through allosteric modulation of GABAA receptors. The structurally distinct, 1,4-BZD clonazepam (CLN is also approved to treat LGS. The precise mechanisms of action and clinical efficacy of both are unknown. Data show that the GABAA α₁-subunit-selective compound zolpidem [ZOL] exhibits hypnotic/sedative effects. Conversely, data from knock-in mice carrying BZD binding site mutations suggest that the α₂ subunit mediates anticonvulsant effects, without sedative actions. Hence, the specific pattern of interactions across the GABAA receptor complexes of BZDs might be reflected in their clinical efficacies and adverse effect profiles. In this study, GABAA-receptor binding affinities of CLB, N-desmethylclobazam (N-CLB, the major metabolite of CLB, CLN, and ZOL were characterized with native receptors from rat-brain homogenates and on cloned receptors from HEK293 cells transfected with combinations of α (α₁, α₂, α₃, or α₅, β₂, and γ₂ subtypes. Our results demonstrate that CLB and N-CLB have significantly greater binding affinities for α₂- vs. α₁-receptor complexes, a difference not observed for CLN, for which no distinction between α₂ and α₁ receptors was observed. Our experiments with ZOL confirmed the high preference for α₁ receptors. These results provide potential clues to a new understanding of the pharmacologic modes of action of CLB and N-CLB.

  5. Flumazenil, a Benzodiazepine Receptor Anatagonist, in the Reversal of Conscious Sedation following Gastroscopy. A Placebo Controlled, Dose Finding Study

    Directory of Open Access Journals (Sweden)

    Lloyd Sutherland

    1991-01-01

    Full Text Available Tim double-blind, placebo controlled, study assessed the efficacy and safety of flumazenil, a benzodiazepine antagonist, in reversing diazepam-induced sedation in 60 patients undergoing endoscopy. Patients were randomly assigned to one of six treatment groups (placebo, 5, 10, 15, 20 or 25 μg/kg flumazenil. Patient psychomotor function was determined using four standard assessments – Trieger, digit substitution, track tracing and cancellation tests. Flumazenil was well tolerated by all patients. All doses of Flumazenil were superior to placebo in reversing sedation. No significant differences were detected between the various treatment groups. Forty-five minutes after the flumazenil infusion, there were no differences between flumazenil- and placebo-treated patients in psychomotor function. Flumazenil is a safe, effective medication which reverses diazepam-induced conscious sedation. For most patients 0.5 mg given intravenously will reverse sedation.

  6. Differential effects of diazepam treatment and withdrawal on recombinant GABAA receptor expression and functional coupling.

    Science.gov (United States)

    Svob Strac, Dubravka; Vlainić, Josipa; Jazvinsćak Jembrek, Maja; Pericić, Danka

    2008-12-30

    Prolonged exposure to benzodiazepines, drugs known to produce tolerance and dependence and also to be abused, leads to adaptive changes in GABA(A) receptors. To further explore the mechanisms responsible for these phenomena, we studied the effects of prolonged diazepam treatment on the recombinant alpha(1)beta(2)gamma(2S) GABA(A) receptors, stably expressed in human embryonic kidney (HEK) 293 cells. The results demonstrating that long-term (48 and 72 h) exposure of cells to a high concentration of diazepam (50 microM) enhanced the maximum number (B(max)) of [(3)H]flunitrazepam, [(3)H]muscimol and [(3)H]t-butylbicycloorthobenzoate ([(3)H]TBOB) binding sites, without changing their affinity (K(d)), suggested the up-regulation of GABA(A) receptors. As demonstrated by cell counting and WST-1 proliferation assay, the observed increase in receptor expression was not a consequence of stimulated growth of cells exposed to diazepam. Semi-quantitative RT-PCR and Western blot analysis, showing elevated levels of alpha(1) subunit mRNA as well as beta(2) and gamma(2) subunit proteins, respectively, suggested that prolonged high dose diazepam treatment induced de novo receptor synthesis by acting at both transcriptional and translational levels. The finding that the number of GABA(A) receptor binding sites returned to control value 24 h following diazepam withdrawal, makes this process less likely to account for the development of benzodiazepine tolerance and dependence. On the other hand, the results demonstrating that observed functional uncoupling between GABA and benzodiazepine binding sites persisted after the termination of diazepam treatment supported the hypothesis of its possible role in these phenomena.

  7. GABA uptake inhibitors. Design, molecular pharmacology and therapeutic aspects

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, P; Frølund, B; Frydenvang, Karla Andrea

    2000-01-01

    GABAA receptor agonists. The availability of these compounds made it possible to study the pharmacology of the GABA uptake systems and the GABAA receptors separately. Based on extensive cellular and molecular pharmacological studies using 23, 24, and a number of mono- and bicyclic analogues, it has been...... as well as glial GABA uptake in order to enhance the inhibitory effects of synaptically released GABA, or (2) selective blockade of glial GABA uptake in order to increase the amount of GABA taken up into, and subsequently released from, nerve terminals. The bicyclic compound (R)-N-Me-exo-THPO (17) has...

  8. Hypocretin/orexin antagonism enhances sleep-related adenosine and GABA neurotransmission in rat basal forebrain.

    Science.gov (United States)

    Vazquez-DeRose, Jacqueline; Schwartz, Michael D; Nguyen, Alexander T; Warrier, Deepti R; Gulati, Srishti; Mathew, Thomas K; Neylan, Thomas C; Kilduff, Thomas S

    2016-03-01

    Hypocretin/orexin (HCRT) neurons provide excitatory input to wake-promoting brain regions including the basal forebrain (BF). The dual HCRT receptor antagonist almorexant (ALM) decreases waking and increases sleep. We hypothesized that HCRT antagonists induce sleep, in part, through disfacilitation of BF neurons; consequently, ALM should have reduced efficacy in BF-lesioned (BFx) animals. To test this hypothesis, rats were given bilateral IgG-192-saporin injections, which predominantly targets cholinergic BF neurons. BFx and intact rats were then given oral ALM, the benzodiazepine agonist zolpidem (ZOL) or vehicle (VEH) at lights-out. ALM was less effective than ZOL at inducing sleep in BFx rats compared to controls. BF adenosine (ADO), γ-amino-butyric acid (GABA), and glutamate levels were then determined via microdialysis from intact, freely behaving rats following oral ALM, ZOL or VEH. ALM increased BF ADO and GABA levels during waking and mixed vigilance states, and preserved sleep-associated increases in GABA under low and high sleep pressure conditions. ALM infusion into the BF also enhanced cortical ADO release, demonstrating that HCRT input is critical for ADO signaling in the BF. In contrast, oral ZOL and BF-infused ZOL had no effect on ADO levels in either BF or cortex. ALM increased BF ADO (an endogenous sleep-promoting substance) and GABA (which is increased during normal sleep), and required an intact BF for maximal efficacy, whereas ZOL blocked sleep-associated BF GABA release, and required no functional contribution from the BF to induce sleep. ALM thus induces sleep by facilitating the neural mechanisms underlying the normal transition to sleep.

  9. Hippocampal extracellular signal-regulated kinase signaling has a role in passive avoidance memory retrieval induced by GABAA Receptor modulation in mice.

    Science.gov (United States)

    Kim, Dong Hyun; Kim, Jong Min; Park, Se Jin; Lee, Seungheon; Shin, Chan Young; Cheong, Jae Hoon; Ryu, Jong Hoon

    2012-04-01

    Available evidence strongly suggests that the γ-aminobutyric acid type A (GABA(A)) receptor has a crucial role in memory retrieval. However, the signaling mechanisms underlying the role of GABA(A) receptor modulation in memory retrieval are unclear. We conducted one-trial passive avoidance task with pre-retention trial drug administration in the hippocampus to test the effects of GABA(A) receptor modulation on memory retrieval. We further tested the co-involvement of signaling molecules: extracellular signal-regulated kinase (ERK), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), and cAMP responsive element-binding protein (CREB). First, we observed that the phosphorylation of hippocampal ERK was required for memory retrieval during the task. Accordingly, to investigate whether GABA(A) receptor activation or inhibition induces ERK phosphorylation during memory retrieval, drugs that target the GABA(A) receptor were administered into the hippocampus before the retention trial. Muscimol, a GABA(A) receptor agonist, and diazepam, an agonist to benzodiazepine-binding site of GABA(A) receptor, blocked retention trial-induced ERK phosphorylation and impaired memory retrieval. Furthermore, co-treatment with sub-effective dose of U0126, a mitogen-activated protein kinase inhibitor, blocked the upregulation of ERK phosphorylation and impaired memory retrieval, and bicuculline methiodide (BMI), a GABA(A) receptor antagonist, increased ERK phosphorylation induced by the retention trial and facilitated memory retrieval. Finally, the effects of BMI were blocked by the co-application of a sub-effective dose of U0126. These results suggest that GABA(A) receptor-mediated memory retrieval is closely related to ERK activity.

  10. GABA interaction with lipids in organic medium

    International Nuclear Information System (INIS)

    Beltramo, D.; Kivatinitz, S.; Lassaga, E.; Arce, A.

    1987-01-01

    The interaction of 3 H-GABA and 14 C-glutamate with lipids in an aqueous organic partition system was studied. With this partition system 3 H-GABA and 14 C-glutamate were able to interact with sphingomyelin, sulfatide, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidic acid but not with cholesterol or ceramide. In an homogeneous aqueous medium the authors could not demonstrate any interaction between 3 H-GABA-lipids. The apparent dissociation constants (K/sub d/) for 3 H-GABA-lipids or 14 C-glutamate-lipids interactions inorganic medium were in the millimolar range and maximal charge between 3 and 7 moles of GABA or glutamate by mole of lipid. Amino acids such as glutamic acid, β-alanine and glycine displaced 3 H-GABA with the same potency as GABA itself; thus these results show that the interaction lacks pharmacological specificity. To detect this interaction lipid concentrations higher than 2 μM were required and in the partition system 3 H-GABA and lipid phosphorus were both concentrated at the interface. Therefore, lipids tested with a biphasic partition system do not fulfill the classical criteria for a neurotransmitter receptor at least not for GABA and glutamate. 15 references, 1 figure, 3 tables

  11. Reduced GABA{sub A} receptor density contralateral to a potentially epileptogenic MRI abnormality in a patient with complex partial seizures

    Energy Technology Data Exchange (ETDEWEB)

    Kuwert, T. [Dept. of Nuclear Medicine, Muenster Univ. (Germany); Stodieck, S.R.G. [Dept. of Neurology, Muenster Univ. (Germany); Puskas, C. [Dept. of Nuclear Medicine, Muenster Univ. (Germany); Diehl, B. [Dept. of Neurology, Muenster Univ. (Germany); Puskas, Z. [Inst. of Clinical Radiology, Muenster Univ. (Germany); Schuierer, G. [Inst. of Clinical Radiology, Muenster Univ. (Germany); Vollet, B. [Dept. of Nuclear Medicine, Muenster Univ. (Germany); Schober, O. [Dept. of Nuclear Medicine, Muenster Univ. (Germany)

    1996-01-01

    Imaging cerebral GABA{sub A} receptor density (GRD) with single-photon emission tomography (SPET) and iodine-123 iomazenil is highly accurate in lateralizing epileptogenic foci in patients with complex partial seizures of temporal origin. Limited knowledge exists on how iomazenil SPET compares with magnetic resonance imaging (MRI) in this regard. We present a patient with complex partial seizures in whom MRI had identified an arachnoid cyst anterior to the tip of the left temporal lobe. Contralaterally to this structural abnormality, interictal electroencephalography (EEG) performed after sleep deprivation disclosed an intermittent frontotemporal dysrhythmic focus with slow and sharp waves. On iomazenil SPET images GRD was significantly reduced in the right temporal lobe and thus contralaterally to the MRI abnormality, but ipsilaterally to the pathological EEG findings. These data suggest that iomazenil SPET may significantly contribute to the presurgical evaluation of epileptic patients even when MRI identifies potentialy epileptogenic structural lesions. (orig.)

  12. [Suicidal poisoning with benzodiazepines].

    Science.gov (United States)

    Chodorowski, Z; Sein Anand, J

    1997-01-01

    In the period from 1987 to 1996, 103 patients with suicidal benzodiazepines poisoning were treated, including 62 women and 41 men from 16 to 79 (mean 34) years old. 23 persons were poisoned only by benzodiazepines, in 80 remaining cases intoxications were mixed eg. including benzodiazepines and alcohol, tricyclic antidepressants, barbiturates, opioids, phenothiazines. The main causes of suicides were mainly depression, drug addiction and alcoholism. Nobody died in the benzodiazepines group, while mortality rate in the group of mixed poisoning was 4%. Prescribing benzodiazepines by physicians was quite often not justified and facilitated, among others, accumulation of the dose sufficient for suicide attempt. Flumazenil was efficient for leading out from coma in 86% of cases with poisoning only by benzodiazepines and 13% of cases with mixed intoxications mainly containing benzodiazepines and alcohol or carbamazepine.

  13. Gaba /SUB a/ vs gaba /SUB b/ modulation of septal-hippocampal interconnections

    International Nuclear Information System (INIS)

    Blaker, W.D.; Cheney, D.L.; Costa, E.

    1986-01-01

    The authors perform studies to correlate pharmacologically induced decreases in the hippocampal TR /SUB ACh/ with changes in extinction of a foodreinforced lever press response. The authors differentiate the behavioral effects elicited by GABAergic vs. non-GABAergic inhibition of hippocampal cholinergic activity as well as show that GABA /SUB A/ receptor activation in the septum produces a behavioral-biochemical profile different from that elicited by GABA /SUB B/ receptor activation. To characterize GABA receptors tritium-GABA binding was performed in rats injected bilaterally with 1 ug kainic acid into the ventral and dorsal hippocampi. Representative cumulative recorder tracings showing the effect of varius intraseptal doses of the GABA /SUB A/ agonist muscimol on extinction after CRF training are show for one experiment. The most marked differences between muscimol and saline treated rats were seen in the extinction response patterns

  14. Discriminative stimulus properties of the benzodiazepine receptor inverse agonist methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM).

    Science.gov (United States)

    Kirby, L G; Rowan, G A; Smith, R L; Lucki, I

    1994-01-01

    The purpose of this study was to determine whether rats could be trained to discriminate the stimulus properties of the benzodiazepine (BZ) receptor inverse agonist DMCM from saline in a conditioned taste aversion paradigm. On a drug trial, water-deprived rats were injected with DMCM (0.55-0.6 mg/kg IP), allowed access to a 0.25% saccharin solution for 30 min, and then injected with LiCl. On non-drug trials, saline injections bracketed the drinking period. Conditioned controls were treated similarly with DMCM and saline on drug and non-drug trials, but received injections of saline instead of LiCl. At the completion of training, CMCM produced a 69% reduction of saccharin consumption on drug trials, compared with 23% for conditioned controls. The stimulus properties of DMCM were then measured by its ability to reduce the preference for saccharin over water in a two-bottle choice test. DMCM reduced saccharin preference in rats that received discrimination training from 68% to 19%, but did not alter saccharin preference in conditioned controls. Other compounds with varying activity at BZ receptors were evaluated for their ability to substitute for the discriminative stimulus effects of DMCM. Two BZ receptor inverse agonists, beta-CCE (10-18 mg/kg) and FG 7142 (3.2-18 mg/kg), substituted completely for DMCM. Partial substitution for DMCM was shown by the BZ receptor antagonist CGS 8216 (3.2-10 mg/kg) and the non-BZ convulsant pentylenetetrazol (10-20 mg/kg). The BZ receptor agonists chlordiazepoxide (0.32-5.0 mg/kg), diazepam (0.32-10 mg/kg), and alprazolam (0.1-3.2 mg/kg) and the BZ receptor antagonist flumazenil (1.0-32 mg/kg) failed to substitute for the DMCM stimulus. Pretreatment with flumazenil (1.0 mg/kg) blocked the stimulus effects of the training dose of DMCM and produced a shift to the right of the DMCM generalization curve. The pattern of compounds that substituted for the DMCM stimulus and the blockade of that stimulus by flumazenil indicate that the

  15. The effects of neuroleptics on the GABA-induced Cl- current in rat dorsal root ganglion neurons: differences between some neuroleptics.

    Science.gov (United States)

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada

    2002-03-01

    1. Several neuroleptics inhibited the 3 microM gamma-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. 2. The IC(50) for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 microM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 microM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. 3. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. 4. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 microM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. 5. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 microM)-current. However, haloperidol and quetiapine at 100 microM inhibited the desensitization at the beginning of application. 6. Blonanserin (AD-5423) at 30 and 50 microM potentiated the GABA (3 microM)-current to 170.1+/-6.9 and 192.0+/-10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. 7. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold.

  16. The effects of neuroleptics on the GABA-induced Cl− current in rat dorsal root ganglion neurons: differences between some neuroleptics

    Science.gov (United States)

    Yokota, Kenjiro; Tatebayashi, Hideharu; Matsuo, Tadashi; Shoge, Takashi; Motomura, Haruhiko; Matsuno, Toshiyuki; Fukuda, Akira; Tashiro, Nobutada

    2002-01-01

    Several neuroleptics inhibited the 3 μM γ-aminobutyric acid induced-chloride current (GABA-current) on dissociated rat dorsal root ganglion neurons in whole-cell patch-clamp investigations. The IC50 for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 μM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 μM)-current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics. Clozapine reduced the picrotoxin-inhibiton, and may compete with a ligand of the t-butylbicyclophosphorothionate (TBPS) binding site. Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 μM)-current. However, haloperidol reduced the clozapine-inhibition, and may antagonize ligand binding to TBPS binding site. Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 μM)-current. However, haloperidol and quetiapine at 100 μM inhibited the desensitization at the beginning of application. Blonanserin (AD-5423) at 30 and 50 μM potentiated the GABA (3 μM)-current to 170.1±6.9 and 192.0±10.6% of the control current, respectively. Blonanserin shifted GABA concentration-response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin-potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist. The various effects of neuroleptics on the GABA-current may be related to the clinical effects including modifying the seizure threshold. PMID:11906969

  17. Dopaminergic receptor agents and the basal ganglia : pharmacological properties and interactions with the GABA-ergic system

    NARCIS (Netherlands)

    Timmerman, Wigerline

    1992-01-01

    In the present series of studies, attention was focussed particularly on dopaminergic D2 receptor compounds, with emphasis on the enantiomers of the potent and selective dopamine D2 receptor agonist N-0437. Drugs that display activity at D2 receptors are of great interest as potentially new

  18. Radiosynthesis and in vivo evaluation of N-[{sup 11}C]methylated imidazopyridineacetamides as PET tracers for peripheral benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Sekimata, Katsuhiko [Department of Brain Sciences and Molecular Imaging, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522 (Japan); Hatano, Kentaro [Department of Brain Sciences and Molecular Imaging, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522 (Japan)], E-mail: hatanok@nils.go.jp; Ogawa, Mikako [Photon Medical Research Center, Hamamatsu University School of Medicine, Shizuoka 431-3192 Japan (Japan); Abe, Junichiro [Department of Brain Sciences and Molecular Imaging, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522 (Japan); Magata, Yasuhiro [Photon Medical Research Center, Hamamatsu University School of Medicine, Shizuoka 431-3192 Japan (Japan); Biggio, Giovanni; Serra, Mariangela [Department of Experimental Biology, University of Cagliari, Cagliari 09100 (Italy); Laquintana, Valentino; Denora, Nunzio; Latrofa, Andrea; Trapani, Giuseppe; Liso, Gaetano [Pharmaco-Chemistry Department, University of Bari, Bari 70125 (Italy); Ito, Kengo [Department of Brain Sciences and Molecular Imaging, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522 (Japan)

    2008-04-15

    Imidazopyridineacetoamide 5-8, a series of novel and potentially selective peripheral benzodiazepine receptor (PBR) ligands with affinities comparable to those of known PBR ligands, was investigated. Radiosyntheses of [{sup 11}C]5, 6, 7 or 8 was accomplished by N-methylation of the corresponding desmethyl precursors with [{sup 11}C]methyl iodide in the presence of NaH in dimethylformamide (DMF), resulting in 25% to 77% radiochemical yield and specific activitiy of 20 to 150 MBq/nmol. Each of the labeled compounds was injected in ddY mice, and the radioactivity and weight of dissected peripheral organs and brain regions were measured. Organ distribution of [{sup 11}C]7 was consistent with the known PBR distribution. Moreover, [{sup 11}C]7 showed the best combination of brain uptake and PBR binding, leading to its high retention in the olfactory bulb and cerebellum, areas where PBR density is high in mouse brain. Coinjection of PK11195 or unlabeled 7 significantly reduced the brain uptake of [{sup 11}C]7. These results suggest that [{sup 11}C]7 could be a useful radioligand for positron emission tomography imaging of PBRs.

  19. Different sensitivities to competitive inhibition of benzodiazepine receptor binding of {sup 11}C-iomazenil and {sup 11}C-flumazenil in rhesus monkey brain

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Osamu; Hosoi, Rie; Kobayashi, Kaoru [Osaka Univ., Suita (Japan). Medical School; Itoh, Takashi; Gee, A.; Suzuki, Kazutoshi

    2001-04-01

    The in vivo binding kinetics of {sup 11}C-iomazenil were compared with those of {sup 11}C-flumazenil binding in rhesus monkey brain. The monkey was anesthetized with ketamine and intravenously injected with either {sup 11}C-iomazenil or {sup 11}C-flumazenil in combination with the coadministration of different doses of non-radioactive flumazenil (0, 5 and 20 {mu}g/kg). The regional distribution of {sup 11}C-iomazenil in the brain was similar to that of {sup 11}C-flumazenil, but the sensitivity of {sup 11}C-iomazenil binding to competitive inhibition by non-radioactive flumazenil was much less than that of {sup 11}C-flumazenil binding. A significant reduction in {sup 11}C-flumazenil binding in the cerebral cortex was observed with 20 {mu}g/kg of flumazenil, whereas a relatively smaller inhibition of {sup 11}C-iomazenil binding in the same region was observed with the same dose of flumazenil. These results suggest that {sup 11}C-flumazenil may be a superior radiotracer for estimating benzodiazepine receptor occupancy in the intact brain. (author)

  20. Assessment of cerebral benzodiazepine receptor distribution in anxiety disorders by 123I-iomazenil-SPECT. Comparison to cerebral perfusion scintigraphy by 123I-IMP

    International Nuclear Information System (INIS)

    Uchiyama, Mayuki; Sue, Hironari; Fukumitsu, Nobuyoshi; Mori, Yutaka; Kawakami, Kenji

    1997-01-01

    123 I-Iomazenil ( 123 I-IMZ) and 123 I-IMP imaging were performed in 5 patients with anxiety disorder (PAD) and 6 normal volunteers (NV). On 123 I-IMZ delayed imaging, the 2 PAD showed abnormally decreased findings. In anxiety disorder, decreased accumulation on 123 I-IMZ delayed images was seen in left hippocampus and parahippocampal gyrus in one patient, in right frontal and temporal lobe and left occipital pole in the other. Compared with NV, PAD had lower 123 I-IMZ uptake on delayed image in right upper and left lower frontal cortices, indicating the involvement of the benzodiazepine receptor complex in anxiety disorder. Compared with grading for anxiety disorder with Hamilton anxiety scale (HAS) and delayed to early count ratios of 123 I-IMZ, negative correlation (R 123 I-IMP image, positive correlation (R>0.7) was recognized in the hippocampus, the parahippocampal gyrus, the lower outer temporal cortex and the lower frontal cortex. (author)

  1. Rapid and efficient radiosynthesis of [{sup 123}I]I-PK11195, a single photon emission computed tomography tracer for peripheral benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Pimlott, Sally L. [Department of Clinical Physics, West of Scotland Radionuclide Dispensary, Western Infirmary, G11 6NT Glasgow (United Kingdom)], E-mail: s.pimlott@clinmed.gla.ac.uk; Stevenson, Louise [Department of Chemistry, WestCHEM, University of Glasgow, G12 8QQ Glasgow (United Kingdom); Wyper, David J. [Institute of Neurological Sciences, Southern General Hospital, G51 4TF Glasgow (United Kingdom); Sutherland, Andrew [Department of Chemistry, WestCHEM, University of Glasgow, G12 8QQ Glasgow (United Kingdom)

    2008-07-15

    Introduction: [{sup 123}I]I-PK11195 is a high-affinity single photon emission computed tomography radiotracer for peripheral benzodiazepine receptors that has previously been used to measure activated microglia and to assess neuroinflammation in the living human brain. This study investigates the radiosynthesis of [{sup 123}I]I-PK11195 in order to develop a rapid and efficient method that obtains [{sup 123}I]I-PK11195 with a high specific activity for in vivo animal and human imaging studies. Methods: The synthesis of [{sup 123}I]I-PK11195 was evaluated using a solid-state interhalogen exchange method and an electrophilic iododestannylation method, where bromine and trimethylstannyl derivatives were used as precursors, respectively. In the electrophilic iododestannylation method, the oxidants peracetic acid and chloramine-T were both investigated. Results: Electrophilic iododestannylation produced [{sup 123}I]I-PK11195 with a higher isolated radiochemical yield and a higher specific activity than achievable using the halogen exchange method investigated. Using chloramine-T as oxidant provided a rapid and efficient method of choice for the synthesis of [{sup 123}I]I-PK11195. Conclusions: [{sup 123}I]I-PK11195 has been successfully synthesized via a rapid and efficient electrophilic iododestannylation method, producing [{sup 123}I]I-PK11195 with a higher isolated radiochemical yield and a higher specific activity than previously achieved.

  2. Pharmacology of morphine and morphine-3-glucuronide at opioid, excitatory amino acid, GABA and glycine binding sites

    International Nuclear Information System (INIS)

    Bartlett, S.E.; Smith, M.T.; Dood, P.R.

    1994-01-01

    Morphine in high doses and its major metabolite, morphine-3-glucuronide, cause CNS excitation following intrathecal and intracerebroventricular administration by an unknown mechanism. This study investigated whether morphine and morphine-3-glucuronide interact at major excitatory (glutamate), major inhibitory (GABA or glycine), or opioid binding sites. Homogenate binding assays were performed using specific radioligands. At opioid receptors, morphine-3-glucuronide and morphine caused an equipotent sodium shift, consistent with morphine-3-glucuronide behaving as an agonist. This suggests that morphine-3-glucuronide-mediated excitation is not caused by an interaction at opioid receptors. Morphine-3-glucuronide and morphine caused a weak inhibition of the binding of 3 H-MK801 (non-competitive antagonist) and 125 I-ifenprodil (polyamine site antagonist), but at unphysiologically high concentrations. This suggests that CNS excitation would not result from an interaction of morphine-3-glucuronide and high-dose morphine with these sites on the NMDA receptor. Morphine-3-glucuronide and morphine inhibited the binding of 3 H-muscimol (GABA receptor agonist), 3 H-diazepam and 3 H-flunitraxepam (benzodiazepine agonists) binding very weakly, suggesting the excitatory effects of morphine-3-glucuronide and high-dose morphine are not elicited through GABA A receptors. Morphine-3-glucuronide and high-dose morphine did not prevent re-uptake of glutamate into presynaptic nerve terminals. In addition, morphine-3-glucuronide and morphine did not inhibit the binding of 3 H-strychnine (glycine receptor antagonist) to synaptic membranes prepared from bovine spinal cord. It is concluded that excitation caused by high-dose morphine and morphine-3-glucuronide is not mediated by an interaction with postsynaptic amino acid receptors. (au) (30 refs.)

  3. Pharmacology of morphine and morphine-3-glucuronide at opioid, excitatory amino acid, GABA and glycine binding sites

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, S.E.; Smith, M.T. (Department of Pharmacy, The University of Queensland (Australia)); Dood, P.R. (Clinical Research Centre, Royal Brisbane Hospital Foundation, Brisbane (Australia))

    1994-07-01

    Morphine in high doses and its major metabolite, morphine-3-glucuronide, cause CNS excitation following intrathecal and intracerebroventricular administration by an unknown mechanism. This study investigated whether morphine and morphine-3-glucuronide interact at major excitatory (glutamate), major inhibitory (GABA or glycine), or opioid binding sites. Homogenate binding assays were performed using specific radioligands. At opioid receptors, morphine-3-glucuronide and morphine caused an equipotent sodium shift, consistent with morphine-3-glucuronide behaving as an agonist. This suggests that morphine-3-glucuronide-mediated excitation is not caused by an interaction at opioid receptors. Morphine-3-glucuronide and morphine caused a weak inhibition of the binding of [sup 3]H-MK801 (non-competitive antagonist) and [sup 125]I-ifenprodil (polyamine site antagonist), but at unphysiologically high concentrations. This suggests that CNS excitation would not result from an interaction of morphine-3-glucuronide and high-dose morphine with these sites on the NMDA receptor. Morphine-3-glucuronide and morphine inhibited the binding of [sup 3]H-muscimol (GABA receptor agonist), [sup 3]H-diazepam and [sup 3]H-flunitraxepam (benzodiazepine agonists) binding very weakly, suggesting the excitatory effects of morphine-3-glucuronide and high-dose morphine are not elicited through GABA[sub A] receptors. Morphine-3-glucuronide and high-dose morphine did not prevent re-uptake of glutamate into presynaptic nerve terminals. In addition, morphine-3-glucuronide and morphine did not inhibit the binding of [sup 3]H-strychnine (glycine receptor antagonist) to synaptic membranes prepared from bovine spinal cord. It is concluded that excitation caused by high-dose morphine and morphine-3-glucuronide is not mediated by an interaction with postsynaptic amino acid receptors. (au) (30 refs.).

  4. Benzodiazepines: are we overprescribing?

    Science.gov (United States)

    Schiralli, V; McIntosh, M

    1987-04-01

    The authors made a survey of benzodiazepine use in the Family Practice Units at Toronto General Hospital and report the findings. They have examined, among other factors, drugs used, reasons for use, and perceived withdrawal symptoms. The results indicated that 24.3% of respondents had taken benzodiazepines in the previous year, and 12.2% in the previous two weeks. There was no difference in the percentage of use of benzodiazepines by males and females. This study confirms that diazepam was the most common drug used in all age ranges. Finally, 6.1% of benzodiazepine users stated that they had attempted an overdose.

  5. The 18 kDa translocator protein (peripheral benzodiazepine receptor expression in the bone of normal, osteoprotegerin or low calcium diet treated mice.

    Directory of Open Access Journals (Sweden)

    Winnie Wai-Ying Kam

    Full Text Available The presence of the translocator protein (TSPO, previously named as the mitochondrial or peripheral benzodiazepine receptor, in bone cells was studied in vitro and in situ using RT-qPCR, and receptor autoradiography using the selective TSPO ligand PK11195.In vitro, the TSPO is highly expressed in osteoblastic and osteoclastic cells.In situ, constitutive expression of TSPO is found in bone marrow and trabecular bone, e.g., spongiosa. Mice with a reduction of bone turnover induced by a 4-day treatment of osteoprotegerin reduces [(3H]PK11195 binding in the spongiosa (320±128 Bq x mg(-1, 499±106 Bq x mg(-1 in saline-treated controls. In contrast, mice with an increase in bone turnover caused by a 4-day low calcium diet increases [(3H]PK11195 binding in the spongiosa (615±90 Bq x mg(-1. Further, our study includes technical feasibility data on [(18F]fluoride microPET imaging of rodent bone with altered turnover. Despite [(18F]fluoride having high uptake, the in vivo signal differences were small. Using a phantom model, we describe the spillover effect and partial volume loss that affect the quantitative microPET imaging of the small bone structures in experimental mouse models. In summary, we demonstrate the expression of TSPO in small rodent bone tissues, including osteoblasts and osteoclasts. A trend increase in TSPO expression was observed in the spongiosa from low to high bone turnover conditions. However, despite the potential utility of TSPO expression as an in vivo biomarker of bone turnover in experimental rodent models, our small animal PET imaging data using [(18F]fluoride show that even under the condition of a good biological signal-to-noise ratio and high tracer uptake, the currently achievable instrument sensitivity and spatial resolution is unlikely to be sufficient to detect subtle differences in small structures, such as mouse bone.

  6. Glial GABA Transporters as Modulators of Inhibitory Signalling in Epilepsy and Stroke

    DEFF Research Database (Denmark)

    Lie, Maria E K; Al-Khawaja, Anas; Damgaard, Maria

    2017-01-01

    Imbalances in GABA-mediated tonic inhibition are involved in several pathophysiological conditions. A classical way of controlling tonic inhibition is through pharmacological intervention with extrasynaptic GABAA receptors that sense ambient GABA and mediate a persistent GABAergic conductance....... An increase in tonic inhibition may, however, also be obtained indirectly by inhibiting glial GABA transporters (GATs). These are sodium-coupled membrane transport proteins that normally act to terminate GABA neurotransmitter action by taking up GABA into surrounding astrocytes. The aim of the review...

  7. GABA-ergic neurons in the leach central nervous system

    International Nuclear Information System (INIS)

    Cline, H.T.

    1985-01-01

    GABA is a candidate for an inhibitory neurotransmitter in the leech central nervous system because of the well-documented inhibitory action of GABA in other invertebrates. To demonstrate that GABA meets the criteria used to identify a substance as a neurotransmitter, the author examined GABA metabolism and synaptic interactions of inhibitory motor neurons in two leech species, Hirudo medicinalis and Haementeria ghilianii. Segmental ganglia of the leech ventral nerve cord and identified inhibitors have the capacity to synthesize GABA when incubated in the presence of the precursor glutamate. Application of GABA to cell bodies of excitatory motor neurons or muscle fibers innervated by the inhibitors hyperpolarizes the membrane potential of the target cell and activates a chloride ion conductance channel, similar to the inhibitory membrane response following intracellular stimulation of the inhibitor. Bicuculline methiodide (5 x 10 -5 M), GABA receptor antagonist, blocks reversibly the response to applied GABA and the inhibitory synaptic inputs onto the postsynaptic neurons or muscle fibers without interfering with their excitatory inputs. Furthermore, the inhibitors are included among approximately 25 neurons per segmental ganglion that take up GABA by a high affinity uptake system, as revealed by 3 H-GABA-autoradiography. The development of the capacities to synthesize and to take up GABA were examined in leech embryos. The embryos are able to synthesize GABA at early stages of the development of the nervous system, before any neurons have extended neutrites

  8. GABA modulates baroreflex in the ventral tegmental area in rat.

    Science.gov (United States)

    Hatam, Masoumeh; Rasoulpanah, Minoo; Nasimi, Ali

    2015-12-01

    There are some reports demonstrating the cardiovascular functions of the ventral tegmental area (VTA). About 20-30% of the VTA neurons are GABAergic, which might play a role in baroreflex modulation. This study was performed to find the effects of GABA(A), GABA(B) receptors and reversible synaptic blockade of the VTA on baroreflex. Drugs were microinjected into the VTA of urethane anesthetized rats, and the maximum change of blood pressure and the gain of the reflex bradycardia in response to intravenous phenylephrine (Phe) injection were compared with the preinjection and the control values. Microinjection of bicuculline methiodide (BMI, 100 pmol/100 nl), a GABA(A) antagonist, into the VTA strongly decreased the Phe-induced hypertension, indicating that GABA itself attenuated the baroreflex. Muscimol, a GABA(A) agonist (30 mM, 100 nl), produced no significant changes. Baclofen, a GABA(B) receptor agonist (1000 pmole/100 nl), moderately attenuated the baroreflex, however phaclofen, a GABA(B) receptor antagonist (1000 pmole/100 nl), had no significant effect. In conclusion, for the first time, we demonstrated that GABA(A) receptors of the VTA strongly attenuate and GABA(B) receptors of the VTA moderately attenuate baroreflex in rat. © 2015 Wiley Periodicals, Inc.

  9. Benzodiazepine absetzen im Alter

    DEFF Research Database (Denmark)

    Wolter, Dirk

    2017-01-01

    Although viewed critically in geriatrics, benzodiazepine use is still common among old people. Before reducing the dosage the following questions must be considered: 1. Are there indications for benzodiazepine treatment and will discontinuation cause relevant rebound symptoms of the initial disor...

  10. Synthesis of [[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaze pine 3-carboxylate, a potential SPECT imaging agent for diazepam-intensive (DI) benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoshu He; Matecka, Dorota; Ziqiang Gu; Rice, K.C.; Costa, B.R. de (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States)); Lee, K.S. (National Inst. of Mental Health, Washington, DC (United States)); Wong, Garry; Skolnick, Phil (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States). Lab. of Neuroscience)

    1994-01-01

    [[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5-a] [1,4]benzodiazepine 3-carboxylate ([[sup 123]I]3), a high affinity and selective radioligand for the diazepam insensitive (DI) benzodiazepine receptor was synthesized in 2 steps from tert-butyl 8-bromo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaz epine 3-carboxylate. (Author).

  11. Different effects of 5-HT1A receptor agonists and benzodiazepine anxiolytics on the emotional state of naive and stressed mice: a study using the hole-board test.

    Science.gov (United States)

    Tsuji, M; Takeda, H; Matsumiya, T

    2000-10-01

    The effects of 5-HT(1A) receptor agonists on the emotional behavior of naive or stressed mice were examined and compared with those of benzodiazepine anxiolytics. Changes in the emotional state of mice were evaluated in terms of changes in exploratory activity, i.e. total locomotor activity, numbers and duration of rearing and head-dipping and latency to the first head-dipping, using an automatic holeboard apparatus. The 5-HT(1A) receptor full agonists flesinoxan (0.03-1 mg/kg, IP) and 8-OH-DPAT (0.03-1 mg/kg, IP), and the partial agonist buspirone (0.3-10 mg/kg, IP) dose-dependently decreased all of the exploratory behaviors. Significant decreases in both the number and duration of head-dips, and an increase in the latency to head-dipping were observed at 30 min after exposure to acute restraint stress (60 min). These emotional changes were scarcely improved by post-stress treatment with 5-HT(1A) receptor agonists, at doses that alone did not produce a significant behavioral effect. In contrast, pretreatment with flesinoxan (0.1-1 mg/kg, IP) or 8-OH-DPAT (0.1-1 mg/kg, IP) 24 h prior to exposure to stress dose-dependently suppressed the decrease in various exploratory behaviors that was observed immediately after the exposure to acute restraint stress. Moreover, pretreatment with buspirone (1-10 mg/kg, IP) 24 h prior to exposure to stress also significantly suppressed the decrease in rearing behavior and the increase in head-dip latency. However, changes in the emotional response to stress stimuli were not observed in mice that had been pretreated with the benzodiazepine anxiolytics diazepam (0.1-1 mg/kg, IP) and chlordiazepoxide (2-8 mg/kg, IP). The present study clearly demonstrates that the behavioral effects of 5-HT(1A) receptor agonists in both naive and stressed mice were quite different from those of benzodiazepine anxiolytics, as previously reported by us. Notably, 5-HT(1A) receptor agonists but not benzodiazepine anxiolytics protect against various

  12. Effects of gamma-aminobutyric acid (GABA) on synaptogenesis and synaptic function

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, G H; Elster, L

    1998-01-01

    ; that is, GABA acts as a trophic signal. Accordingly, activating preexisting GABA receptors, a trophic GABA signal enhances the growth rate of neuronal processes, facilitates synapse formation, and promotes synthesis of specific proteins. Transcription and de novo synthesis are initiated by the GABA signal......, this ability to target the induced GABAA receptors is probably coupled to the maturation of neurons and not to the action of GABA per se. The induced GABAA receptors apparently mediate a pronounced inhibition of neurotransmitter release, whereas other subtypes of GABAA receptors may be modulatory rather than...

  13. The 18-kDa translocator protein, formerly known as the peripheral-type benzodiazepine receptor, confers proapoptotic and antineoplastic effects in a human colorectal cancer cell line.

    Science.gov (United States)

    Shoukrun, Rami; Veenman, Leo; Shandalov, Yulia; Leschiner, Svetlana; Spanier, Ilana; Karry, Rachel; Katz, Yeshayahu; Weisinger, Gary; Weizman, Abraham; Gavish, Moshe

    2008-11-01

    The involvement of the 18-kDa translocator protein (TSPO), formerly known as the peripheral-type benzodiazepine receptor, in apoptosis regulation of HT29 colorectal cancer cells was studied in-vitro. In-vivo TSPO involvement in tumor growth of HT29 cells xenografted into SCID mice was studied. Knockdown of TSPO expression in the human HT29 cell line was established by stable transfection with vectors containing the TSPO gene in the antisense direction. Successful TSPO knockdown was characterized by reduction of 20% in TSPO RNA levels, 50% in protein expression of the TSPO, and 50% in binding with the TSPO ligand, [3H]PK 11195. Subsequently, in-vitro cell viability and proliferation assays were applied. In addition, transient transfecton with short interfering RNA (siRNA) directed against human TSPO was studied in this way. Furthermore, we also grafted HT29 cells subcutaneously into the right thighs of SCID mice to examine the effects of the putative TSPO agonist, FGIN-1-27, on tumor growth in-vivo. In-vitro TSPO knockdown established by stable transfection of TSPO antisense gene resulted in HT29 clones displaying significantly lower levels of cell death as determined with trypan blue (50% less), lower apoptotic rates (28% less), and higher proliferation rates (48% more one week after seeding and 27% more two weeks after seeding). Transient transfection with anti-human TSPO siRNA resulted in similar viability and antiapoptotic effects. In-vivo, the proapoptotic TSPO ligand, FGIN-1-27 significantly reduced the growth rate of grafted tumors (40% less), in comparison with vehicle-treated mice. TSPO knockdown by genetic manipulation transforms the human HT29 cancer line to a more malignant type in-vitro. In-vivo pharmacological treatment with the putative TSPO agonist FGIN-1-27 reduces tumor growth of the HT29 cell line. These data suggest that TSPO involvement in apoptosis provides a target for anticancer treatment.

  14. Ontogenetic Development of GABA(B)-Receptor Signaling Cascade in Plasma Membranes Isolated From Rat Brain Cortex; the Number of GABA(B)-Receptors Is High Already Shortly After the Birth

    Czech Academy of Sciences Publication Activity Database

    Kagan, Dmytro; Dlouhá, Kateřina; Roubalová, Lenka; Svoboda, Petr

    2012-01-01

    Roč. 61, č. 6 (2012), s. 629-635 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA ČR(CZ) GAP207/12/0919 Institutional research plan: CEZ:AV0Z50110509 Institutional support: RVO:67985823 Keywords : postnatal development * GABAB-receptors * G-protein coupling/activation * baclofen * SKF97541 Subject RIV: CE - Biochemistry Impact factor: 1.531, year: 2012

  15. GABA uptake inhibitors. Design, molecular pharmacology and therapeutic aspects

    DEFF Research Database (Denmark)

    Krogsgaard-Larsen, P; Frølund, B; Frydenvang, Karla Andrea

    2000-01-01

    GABAA receptor agonists. The availability of these compounds made it possible to study the pharmacology of the GABA uptake systems and the GABAA receptors separately. Based on extensive cellular and molecular pharmacological studies using 23, 24, and a number of mono- and bicyclic analogues, it has been...... demonstrated that neuronal and glial GABA transport mechanisms have dissimilar substrate specificities. With GABA transport mechanisms as pharmacological targets, strategies for pharmacological interventions with the purpose of stimulating GABA neurotransmission seem to be (1) effective blockade of neuronal...... recently been reported as the most selective glial GABA uptake inhibitor so far known and may be a useful tool for further elucidation of the pharmacology of GABA transporters. In recent years, a variety of lipophilic analogues of the amino acids 23 and 24 have been developed, and one of these compounds...

  16. Takotsubo Cardiomyopathy and Catatonia in the Setting of Benzodiazepine Withdrawal

    Directory of Open Access Journals (Sweden)

    Teng J. Peng

    2016-01-01

    Full Text Available We report two serious and unusual complications of benzodiazepine withdrawal in a single patient: takotsubo cardiomyopathy and catatonia. This 61-year-old female patient was brought to the emergency department with lethargy and within hours had declined into a state of catatonia. Although there was never a complaint of chest pain, ECG showed deep anterior T-wave inversions and cardiac enzymes were elevated. An echocardiogram was consistent with takotsubo cardiomyopathy. She later received 1 mg of midazolam and within minutes had resolution of catatonic symptoms. Careful history revealed that she had omitted her daily dose of lorazepam for 3 days prior to admission. To our knowledge, the case presented herein is the first report of simultaneous catatonia and takotsubo cardiomyopathy in the setting of benzodiazepine withdrawal. The pathogenesis of both conditions is poorly understood but may be indirectly related to the sudden decrease in γ-aminobutyric acid (GABA signaling during benzodiazepine withdrawal.

  17. Effects of 3alpha-amino-5alpha-pregnan-20-one on GABA A receptor: Synthesis, activity and cytotoxicity

    Czech Academy of Sciences Publication Activity Database

    Matyáš, Libor; Kasal, Alexander; Riera, Z. B.; Sunol, C. E.

    2004-01-01

    Roč. 69, č. 7 (2004), s. 1506-1516 ISSN 0010-0765 R&D Projects: GA AV ČR IBS5011007 Grant - others:CIRIT(ES) 2001SGR00356 Institutional research plan: CEZ:AV0Z4055905 Keywords : receptor * steroids * neurosteroids Subject RIV: CC - Organic Chemistry Impact factor: 1.062, year: 2004

  18. Acute desensitization of presynaptic GABA(B)-mediated inhibition and induction of epileptiform discharges in the neonatal rat hippocampus

    NARCIS (Netherlands)

    Tosetti, P; Bakels, R; Colin-Le Brun, [No Value; Ferrand, N; Gaiarsa, JL; Caillard, O

    The consequences of sustained activation of GABA(B) receptors on GABA(B)-mediated inhibition and network activity were investigated in the neonatal rat hippocampus using whole-cell and extracellular field recordings. GABA(B)-mediated presynaptic control of gamma-aminobutyric acid (GABA) release

  19. Strategy for improved [11C]DAA1106 radiosynthesis and in vivo peripheral benzodiazepine receptor imaging using microPET, evaluation of [11C]DAA1106

    International Nuclear Information System (INIS)

    Probst, Katrin C.; Izquierdo, David; Bird, Joseph L.E.; Brichard, Laurent; Franck, Dominic; Davies, John R.; Fryer, Tim D.; Richards, Hugh K.; Clark, John C.; Davenport, Anthony P.; Weissberg, Peter L.; Warburton, Elizabeth A.

    2007-01-01

    Introduction: The peripheral benzodiazepine receptor (PBR) has shown considerable potential as a clinical marker of neuroinflammation and tumour progression. [ 11 C]DAA1106 ([ 11 C]N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)-acetamide) is a promising positron emission tomography (PET) radioligand for imaging PBRs. Methods: A four-step synthetic route was devised to prepare DAA1123, the precursor for [ 11 C]DAA1106. Two robust, high yielding methods for radiosynthesis based on [ 11 C]-O-methylation of DAA1123 were developed and implemented on a nuclear interface methylation module, producing [ 11 C]DAA1106 with up to 25% radiochemical yields at end-of-synthesis based on [ 11 C]CH 3 I trapped. Evaluation of [ 11 C]DAA1106 for in vivo imaging was performed in a rabbit model with microPET, and the presence of PBR receptor in the target organ was further corroborated by immunohistochemistry. Results: The standard solution method produced 2.6-5.2 GBq (n=19) of [ 11 C]DAA1106, whilst the captive solvent method produced 1.6-6.3 GBq (n=10) of [ 11 C]DAA1106. Radiochemical purities obtained were 99% and specific radioactivity at end-of-synthesis was up to 200 GBq/μmol for both methods. Based on radiochemical product, shorter preparation times and simplicity of synthesis, the captive solvent method was chosen for routine productions of [ 11 C]DAA1106. In vivo microPET [ 11 C]DAA1106 scans of rabbit kidney demonstrated high levels of binding in the cortex. The subsequent introduction of nonradioactive DAA1106 (0.2 μmol) produced considerable displacement of the radioactive signal in this region. The presence of PBR in kidney cortex was further corroborated by immunohistochemistry. Conclusions: A robust, high yielding captive solvent method of [ 11 C]DAA1106 production was developed which enabled efficacious in vivo imaging of PBR expressing tissues in an animal model

  20. Rapid regulation of tonic GABA currents in cultured rat hippocampal neurons.

    Science.gov (United States)

    Ransom, Christopher B; Tao, Wucheng; Wu, Yuanming; Spain, William J; Richerson, George B

    2013-02-01

    Subacute and chronic changes in tonic GABAergic inhibition occur in human and experimental epilepsy. Less is known about how tonic inhibition is modulated over shorter time frames (seconds). We measured endogenous tonic GABA currents from cultured rat hippocampal neurons to evaluate how they are affected by 1) transient increases in extracellular GABA concentration ([GABA]), 2) transient postsynaptic depolarization, and 3) depolarization of presynaptic cells. Transient increases in [GABA] (1 μM) reduced tonic currents; this reduction resulted from GABA-induced shifts in the reversal potential for GABA currents (E(GABA)). Transient depolarization of postsynaptic neurons reversed the effects of exogenous GABA and potentiated tonic currents. The voltage-dependent potentiation of tonic GABA currents was independent of E(GABA) shifts and represented postdepolarization potentiation (PDP), an intrinsic GABA(A) receptor property (Ransom CB, Wu Y, Richerson GB. J Neurosci 30: 7672-7684, 2010). Inhibition of vesicular GABA release with concanamycin A (ConA) did not affect tonic currents. In ConA-treated cells, transient application of 12 mM K(+) to depolarize presynaptic neurons and glia produced a persistent increase in tonic current amplitude. The K(+)-induced increase in tonic current was reversibly inhibited by SKF89976a (40 μM), indicating that this was caused by nonvesicular GABA release from GABA transporter type 1 (GAT1). Nonvesicular GABA release due to GAT1 reversal also occurred in acute hippocampal brain slices. Our results indicate that tonic GABA currents are rapidly regulated by GABA-induced changes in intracellular Cl(-) concentration, PDP of extrasynaptic GABA(A) receptors, and nonvesicular GABA release. These mechanisms may influence tonic inhibition during seizures when neurons are robustly depolarized and extracellular GABA and K(+) concentrations are elevated.

  1. Anion transport and GABA signaling

    Directory of Open Access Journals (Sweden)

    Christian Andreas Huebner

    2013-10-01

    Full Text Available Whereas activation of GABAA receptors by GABA usually results in a hyperpolarizing influx of chloride into the neuron, the reversed chloride driving force in the immature nervous system results in a depolarizing efflux of chloride. This GABAergic depolarization is deemed to be important for the maturation of the neuronal network. The concept of a developmental GABA switch has mainly been derived from in vitro experiments and reliable in vivo evidence is still missing. As GABAA receptors are permeable for both chloride and bicarbonate, the net effect of GABA also critically depends on the distribution of bicarbonate. Whereas chloride can either mediate depolarizing or hyperpolarizing currents, bicarbonate invariably mediates a depolarizing current under physiological conditions. Intracellular bicarbonate is quickly replenished by cytosolic carbonic anhydrases. Intracellular bicarbonate levels also depend on different bicarbonate transporters expressed by neurons. The expression of these proteins is not only developmentally regulated but also differs between cell types and even subcellular regions. In this review we will summarize current knowledge about the role of some of these transporters for brain development and brain function.

  2. Benzodiazepine poisoning in elderly

    Directory of Open Access Journals (Sweden)

    Perković-Vukčević Nataša

    2016-01-01

    Full Text Available Background/Aim. Benzodiazepines are among the most frequently ingested drugs in self-poisonings. Elderly may be at greater risk compared with younger individuals due to impaired metabolism and increased sensitivity to benzodiazepines. The aim of this study was to assess toxicity of benzodiazepines in elderly attempted suicide. Methods. A retrospective study of consecutive presentations to hospital after self-poisoning with benzodiazepines was done. Collected data consisted of patient's characteristics (age, gender, benzodiazepine ingested with its blood concentrations at admission, clinical findings including vital signs and Glasgow coma score, routine blood chemistry, complications of poisoning, details of management, length of hospital stay and outcome. According the age, patients are classified as young (15-40-year old, middle aged (41-65-year old and elderly (older than 65. Results. During a 2-year observational period 387 patients were admitted because of pure benzodiazepine poisoning. The most frequently ingested drug was bromazepam, the second was diazepam. The incidence of coma was significantly higher, and the length of hospital stay significantly longer in elderly. Respiratory failure and aspiration pneumonia occurred more frequently in old age. Also, flumazenil was more frequently required in the group of elderly patients. Conclusion. Massive benzodiazepines overdose in elderly may be associated with a significant morbidity, including deep coma with aspiration pneumonia, respiratory failure, and even death. Flumazenil is indicated more often to reduce CNS depression and prevent complications of prolonged unconsciousness, but supportive treatment and proper airway management of comatose patients is the mainstay of the treatment of acute benzodiazepine poisoning.

  3. Evaluation of C.L.I.N.D.E. as potent peripheral-type benzodiazepine receptor tracer in a rat model of micro-glial activation

    Energy Technology Data Exchange (ETDEWEB)

    Arlicot, N.; Guilloteau, D.; Chalon, S. [Institut National de la Sante et de la Recherche Medicale (INSERM), U619, 37 - Tours (France); Universite Francois Rabelais de Tours, 37 (France); Katsifis, A.; Mattner, F. [ANSTO, Sydney (Australia)

    2008-02-15

    The peripheral-type benzodiazepine receptors (P.B.R.) are localized in mitochondria of glial cells and are very low expressed in normal brain. Their expression rises after micro-glial activation consecutive to brain injury. Accordingly, P.B.R. are potential targets to evaluate neuro inflammatory changes in a variety of C.N.S. disorders. To date no effective tool is available to explore P.B.R. by SPECT. We characterized here 6-chloro-2-(4 iodophenyl)-3-(N,N-diethyl)-imidazo[1,2-a]pyridine- 3-acetamide, C.L.I.N.D.E., in a rat model of excitotoxic lesion. Excitotoxicity was induced in male Wistar rats by unilateral intra striatal injection of different amounts of quinolinic acid (Q.A.: 75, 150 or 300 nmol). One week later, 2 groups of rats (n = 5-6/group) were i.v. injected with [{sup 125}I]-C.L.I.N.D.E. (0.4 MBq), one group being pre-injected with P.K.11195 (5 mg/kg). Brains were removed 30 min after tracer injection and the radioactivity of cerebral areas measured. Complementary ex vivo autoradiography and immunohistochemical studies using O.X.-42 were performed on brain sections In the control group, [{sup 125}I]-C.L.I.N.D.E. binding was significantly higher ( p < 0.001) in lesioned than that in intact side (striatum: 0.552 {+-} 0.109 vs. 0.123 {+-} 0.012% I.D./g tissue; cortex: 0.385 {+-} 0.126 vs. 0.131 {+-} 0.007% with 300 nmol Q.A.). This binding disappeared in rats pretreated with P.K.11195 ( p < 0.001), showing specific binding of C.L.I.N.D.E. to P.B.R.. Ex vivo autoradiography and immunohistochemistry were consistent with this, revealing a spatial correspondence between radioactivity signal and activated micro-glia. Regression analysis yielded a significant correlation ( p < 0.001) between the ligand binding and the dose of Q.A.. These results demonstrate that C.L.I.N.D.E. is suitable for P.B.R. in vivo SPECT imaging to explore their involvement in neuro degenerative disorders associated with micro-glial activation. (authors)

  4. Evaluation of C.L.I.N.D.E. as potent peripheral-type benzodiazepine receptor tracer in a rat model of micro-glial activation

    International Nuclear Information System (INIS)

    Arlicot, N.; Guilloteau, D.; Chalon, S.; Katsifis, A.; Mattner, F.

    2008-01-01

    The peripheral-type benzodiazepine receptors (P.B.R.) are localized in mitochondria of glial cells and are very low expressed in normal brain. Their expression rises after micro-glial activation consecutive to brain injury. Accordingly, P.B.R. are potential targets to evaluate neuro inflammatory changes in a variety of C.N.S. disorders. To date no effective tool is available to explore P.B.R. by SPECT. We characterized here 6-chloro-2-(4 iodophenyl)-3-(N,N-diethyl)-imidazo[1,2-a]pyridine- 3-acetamide, C.L.I.N.D.E., in a rat model of excitotoxic lesion. Excitotoxicity was induced in male Wistar rats by unilateral intra striatal injection of different amounts of quinolinic acid (Q.A.: 75, 150 or 300 nmol). One week later, 2 groups of rats (n = 5-6/group) were i.v. injected with [ 125 I]-C.L.I.N.D.E. (0.4 MBq), one group being pre-injected with P.K.11195 (5 mg/kg). Brains were removed 30 min after tracer injection and the radioactivity of cerebral areas measured. Complementary ex vivo autoradiography and immunohistochemical studies using O.X.-42 were performed on brain sections In the control group, [ 125 I]-C.L.I.N.D.E. binding was significantly higher ( p < 0.001) in lesioned than that in intact side (striatum: 0.552 ± 0.109 vs. 0.123 ± 0.012% I.D./g tissue; cortex: 0.385 ± 0.126 vs. 0.131 ± 0.007% with 300 nmol Q.A.). This binding disappeared in rats pretreated with P.K.11195 ( p < 0.001), showing specific binding of C.L.I.N.D.E. to P.B.R.. Ex vivo autoradiography and immunohistochemistry were consistent with this, revealing a spatial correspondence between radioactivity signal and activated micro-glia. Regression analysis yielded a significant correlation ( p < 0.001) between the ligand binding and the dose of Q.A.. These results demonstrate that C.L.I.N.D.E. is suitable for P.B.R. in vivo SPECT imaging to explore their involvement in neuro degenerative disorders associated with micro-glial activation. (authors)

  5. Evaluation of a radiolabelled peripheral benzodiazepine receptor ligand in the central nervous system inflammation of experimental autoimmune encephalomyelitis: a possible probe for imaging multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Mattner, F.; Katsifis, A.; Ballantyne, P. [ANSTO, Radiopharmaceuticals Division, Lucas Heights (Australia); Staykova, M.; Willenborg, D.O. [Australian National University Medical School, The Canberra Hospital, Neurosciences Research Unit, Woden, Canberra (Australia)

    2005-04-01

    Peripheral benzodiazepine receptors (PBRs) are upregulated on macrophages and activated microglia, and radioligands for the PBRs can be used to detect in vivo neuroinflammatory changes in a variety of neurological insults, including multiple sclerosis. Substituted 2-phenyl imidazopyridine-3-acetamides with high affinity and selectivity for PBRs have been prepared that are suitable for radiolabelling with a number of positron emission tomography and single-photon emission computed tomography (SPECT) isotopes. In this investigation, the newly developed high-affinity PBR ligand 6-chloro-2-(4'-iodophenyl)-3-(N,N-diethyl)imidazo[1,2-a]pyridine-3-acetamide, or CLINDE, was radiolabelled with{sup 123}I and its biodistribution in the central nervous system (CNS) of rats with experimental autoimmune encephalomyelitis (EAE) evaluated. EAE was induced in male Lewis rats by injection of an emulsion of myelin basic protein and incomplete Freund's adjuvant containing Mycobacterium butyricum. Biodistribution studies with{sup 123}I-CLINDE were undertaken on EAE rats exhibiting different clinical disease severity and compared with results in controls. Disease severity was confirmed by histopathology in the spinal cord of rats. The relationship between inflammatory lesions and PBR ligand binding was investigated using ex vivo autoradiography and immunohistochemistry on rats with various clinical scores. {sup 123}I-CLINDE uptake was enhanced in the CNS of all rats exhibiting EAE when compared to controls. Binding reflected the ascending nature of EAE inflammation, with lumbar/sacral cord > thoracic cord > cervical cord > medulla. The amount of ligand binding also reflected the clinical severity of disease. Ex vivo autoradiography and immunohistochemistry revealed a good spatial correspondence between radioligand signal and foci of inflammation and in particular ED-1{sup +} cells representing macrophages and microglia. These results demonstrate the ability of {sup 123}I

  6. Comparison of benzodiazepine receptor SPECT and 18F-FDG PET using a coincidence detection camera in patients with temporal lobe epilepsy: preliminary results

    International Nuclear Information System (INIS)

    Wissmeyer, M.; Geiger, L.; Luescher, D.; Krause, T.; Loevblad, K.; Donati, F.; Wielepp, J.P.

    2002-01-01

    Full text: The aim of this preliminary study was to compare the results of benzodiazepine receptor (BDR) SPECT using 123 I-Iomazenil with those of 18 F-FDG (FDG) PET obtained on a double-headed gamma camera with a coincidence detection system in patients with temporal lobe epilepsy (TLE). We evaluated 6 patients (4 female, 2 male; age range 26-54 years, average 43.5 years) with therapy-refractory TLE due to mesiotemporal sclerosis or other focal brain anomalies. To delineate the epileptogenic zone, clinical evaluation, ictal and interictal surface EEG using the international 10-20 system, brain MRI, interictal CBF SPECT using 99m Tc-ECD, BDR SPECT and FDG coincidence PET were performed. The CBF SPECT, BDR SPECT and coincidence PET scans were viewed independently by 2 observers considering the regional cerebral blood flow, BDR density and FDG uptake asymmetry in the temporal lobe visually as none (0), low (1), moderate (2) and high (3). Ictal and interictal EEG recordings located the epileptogenic focus in all patients in the temporal region. Both the BDR SPECT and the FDG coincidence PET located the epileptogenic focus correctly in circumscribed areas of the temporal lobe in all patients, whereas brain MRI revealed focal anomalies only in 5 of 6 cases . The lateralization to the right (n=4) and left hemisphere (n=2) by interictal CBF SPECT, BDR SPECT and FDG coincidence PET corresponded to the EEG findings in all patients. The visual consideration of the asymmetry revealed a slightly but not statistically significant higher value for the FDG coincidence PET (observer 1: mean 2.333, SD 0.516; observer 2: mean 2.000, SD 0.632) than for the BDR SPECT (observer 1: mean 1.667, SD 1.033; observer 2: mean 1.833, SD 0.753). Visual consideration of the interictal CBF SPECT revealed mean values of 2.000 for both observers. The inter-observer variability was higher in the BDR SPECT than in the FDG coincidence PET and the interictal CBF SPECT, but the difference was not

  7. Effect of Songyu Anshen Fang on expression of hypothalamic GABA ...

    African Journals Online (AJOL)

    hypothalamic GABA and GABA(B) receptor proteins in insomniac rats induced by para-chlorophenylalanine. Xueai Zeng, Junshan Huang, Chunquan Zhou, Xiufeng Wang, Yu Zhang, Yifan. Zhang. Fujian Academy of Traditional Chinese Medicine, Fujian Key Laboratory of Sleep Medicine of Traditional Chinese Medicine,.

  8. Effect of Songyu Anshen Fang on expression of hypothalamic GABA ...

    African Journals Online (AJOL)

    Purpose: To investigate the effects of the Chinese compound, Songyu Anshen Fang (SYF) on levels of GABA and GABA(B) receptor proteins in insomniac rats induced by para-chlorophenylalanine (PCPA). Methods: All rats were randomly separated into either a control group, insomnia group, or a SYF group (at a dose of ...

  9. Flumazenil in treatment benzodiazepine withdrawal syndrome: Case report

    Directory of Open Access Journals (Sweden)

    Ramah Aleksandar J.

    2015-01-01

    Full Text Available Background: Today in the world and in Serbia is growing number of people who are addicted to benzodiazepine. A particular problem is the process of detoxification and treatment of benzodiazepine withdrawal syndrome due to a recurrence of symptoms of anxiety disorder, availability of benzodiazepines, falling motivation. Standard procedures have often proved unsuccessful and the last decade, and the search for new protocols, including the flumazenil, benzodiazepine receptor antagonist, is actualized. Case report: The patient aged 48 years was admitted to the specialist psychiatric clinic, for treatment of benzodiazepine addiction. Anxiety disorder was diagnosed since adolescence perennial addiction on benzodiazepines and the initial withdrawal syndrome. Former motivated topical treatments for detoxification were unsuccessful. The presence of dual diagnosis, persistence of both disorders in perennial cycle, treatment resistance and actual motivation contributed to the decision to opt rapid detoxification from benzodiazepines by flumazenil application protocol, for hospital treatment by adjuvant therapy with lamotrigine. After discharge from hospital in stable condition it was with no signs of withdrawal syndrome and a rebound of anxiety symptoms. Lamotrigine medication continued including CBT, held during the one-year abstinence monitoring, with sufficient social functionality. Discussion: The efficacy and safety of flumazenil in the treatment of benzodiazepine withdrawal syndrome was investigated in numerous clinical trials, and the mechanism of action is complex, from the benzodiazepine antagonist to inverse agonist in certain circumstances, as well as 'up-regulation' receptors, which together leads to a reduction in symptoms of abstinence syndrome and anxiety in the longer term after treatment, thereby acting favorably to the adherence and remission. Conclusions: Flumazenil protocol is an efficient method in the treatment of the benzodiazepine

  10. The endogenous GABA bioactivity of camel, bovine, goat and human milks.

    Science.gov (United States)

    Limon, Agenor; Gallegos-Perez, Jose-Luis; Reyes-Ruiz, Jorge M; Aljohi, Mohammad A; Alshanqeeti, Ali S; Miledi, Ricardo

    2014-02-15

    GABA orally administered has several beneficial effects on health, including the regulation of hyperglycaemic states in humans. Those effects are similar to the effects reported for camel milk (CMk); however, it is not known whether compounds with GABAergic activity are present in milk from camels or other species. We determined CMk free-GABA concentration by LS/MS and its bioactivity on human GABA receptors. We found that camel and goat milks have significantly more bioavailable GABA than cow and human milks and are able to activate GABAρ receptors. The relationship between GABA and taurine concentrations suggests that whole camel milk may be more efficient to activate GABAρ1 receptors than goat milk. Because GABAρ receptors are normally found in enteroendocrine cells in the lumen of the digestive tract, these results suggest that GABA in camel and goat milk may participate in GABA-modulated functions of enteroendocrine cells in the GI lumen. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Anti-absence activity of mGlu1 and mGlu5 receptor enhancers and their interaction with a GABA reuptake inhibitor: Effect of local infusions in the somatosensory cortex and thalamus.

    Science.gov (United States)

    D'Amore, Valerio; von Randow, Constanze; Nicoletti, Ferdinando; Ngomba, Richard Teke; van Luijtelaar, Gilles

    2015-07-01

    Glutamate and γ-aminobutyric acid (GABA) are the key neurotransmitter systems in the cortical-thalamocortical network, involved in normal and pathologic oscillations such as spike-wave discharges (SWDs), which characterize different forms of absence epilepsy. Metabotropic glutamate (mGlu) and GABA receptors are widely expressed within this network. Herein, we examined the effects of two selective positive allosteric modulators (PAMs) of mGlu1 and mGlu5 receptors, the GABA reuptake inhibitor, tiagabine, and their interaction in the somatosensory cortex and thalamus on SWDs in WAG/Rij rats. Male WAG/Rij rats were equipped with bilateral cannulas in the somatosensory cortex (S1po) or the ventrobasal (VB) thalamic nuclei, and with cortical electroencephalography (EEG) electrodes. Rats received a single dose of the mGlu1 receptor PAM, RO0711401, or the mGlu5 receptor PAM, VU0360172, various doses of tiagabine, or VU0360172 combined with tiagabine. Both PAMs suppressed SWDs regardless of the site of injection. Tiagabine enhanced SWDs when injected into the thalamus, but, unexpectedly, suppressed SWDs in a dose-dependent manner when injected into the cortex. Intracortical co-injection of VU0360172 and tiagabine produced slightly larger effects as compared to either VU0360172 or tiagabine alone. Intrathalamic co-injections of VU0360172 and subthreshold doses of tiagabine caused an antiabsence effect similar to that exhibited by VU0360172 alone in the first 10 min. At 30 min, however, the antiabsence effect of VU0360172 was prevented by subthreshold doses of tiagabine, and the combination produced a paradoxical proabsence effect at 40 and 50 min. These data (1) show that mGlu1 and mGlu5 receptor PAMs reduce absence seizures acting at both thalamic and cortical levels; (2) demonstrate for the first time that tiagabine, despite its established absence-enhancing effect, reduces SWDs when injected into the somatosensory cortex; and (3) indicate that the efficacy of VU0360172

  12. Early life stress is a risk factor for excessive alcohol drinking and impulsivity in adults and is mediated via a CRF/GABA(A) mechanism.

    Science.gov (United States)

    Gondré-Lewis, Marjorie C; Warnock, Kaitlin T; Wang, Hong; June, Harry L; Bell, Kimberly A; Rabe, Holger; Tiruveedhula, Veera Venkata Naga Phani Babu; Cook, James; Lüddens, Hartmut; Aurelian, Laure; June, Harry L

    2016-01-01

    Childhood stress and trauma are associated with substance use disorders in adulthood, but the neurological changes that confer increased vulnerability are largely unknown. In this study, maternal separation (MS) stress, restricted to the pre-weaning period, was used as a model to study mechanisms of protracted effects of childhood stress/traumatic experiences on binge drinking and impulsivity. Using an operant self-administration model of binge drinking and a delay discounting assay to measure impulsive-like behavior, we report that early life stress due to MS facilitated acquisition of binge drinking and impulsivity during adulthood in rats. Previous studies have shown heightened levels of corticotropin releasing factor (CRF) after MS, and here, we add that MS increased expression levels of GABA(A) α2 subunit in central stress circuits. To investigate the precise role of these circuits in regulating impulsivity and binge drinking, the CRF1 receptor antagonist antalarmin and the novel GABA(A) α2 subunit ligand 3-PBC were infused into the central amygdala (CeA) and medial prefrontal cortex (mPFC). Antalarmin and 3-PBC at each site markedly reduced impulsivity and produced profound reductions on binge-motivated alcohol drinking, without altering responding for sucrose. Furthermore, whole-cell patch-clamp studies showed that low concentrations of 3-PBC directly reversed the effect of relatively high concentrations of ethanol on α2β3γ2 GABA(A) receptors, by a benzodiazepine site-independent mechanism. Together, our data provide strong evidence that maternal separation, i.e. early life stress, is a risk factor for binge drinking, and is linked to impulsivity, another key risk factor for excessive alcohol drinking. We further show that pharmacological manipulation of CRF and GABA receptor signaling is effective to reverse binge drinking and impulsive-like behavior in MS rats. These results provide novel insights into the role of the brain stress systems in the

  13. GABA predicts visual intelligence.

    Science.gov (United States)

    Cook, Emily; Hammett, Stephen T; Larsson, Jonas

    2016-10-06

    Early psychological researchers proposed a link between intelligence and low-level perceptual performance. It was recently suggested that this link is driven by individual variations in the ability to suppress irrelevant information, evidenced by the observation of strong correlations between perceptual surround suppression and cognitive performance. However, the neural mechanisms underlying such a link remain unclear. A candidate mechanism is neural inhibition by gamma-aminobutyric acid (GABA), but direct experimental support for GABA-mediated inhibition underlying suppression is inconsistent. Here we report evidence consistent with a global suppressive mechanism involving GABA underlying the link between sensory performance and intelligence. We measured visual cortical GABA concentration, visuo-spatial intelligence and visual surround suppression in a group of healthy adults. Levels of GABA were strongly predictive of both intelligence and surround suppression, with higher levels of intelligence associated with higher levels of GABA and stronger surround suppression. These results indicate that GABA-mediated neural inhibition may be a key factor determining cognitive performance and suggests a physiological mechanism linking surround suppression and intelligence. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  14. Canadian boreal pulp and paper feedstocks contain neuroactive substances that interact in vitro with GABA and dopaminergic systems in the brain.

    Science.gov (United States)

    Waye, Andrew; Annal, Malar; Tang, Andrew; Picard, Gabriel; Harnois, Frédéric; Guerrero-Analco, José A; Saleem, Ammar; Hewitt, L Mark; Milestone, Craig B; MacLatchy, Deborah L; Trudeau, Vance L; Arnason, John T

    2014-01-15

    Pulp and paper wood feedstocks have been previously implicated as a source of chemicals with the ability to interact with or disrupt key neuroendocrine endpoints important in the control of reproduction. We tested nine Canadian conifers commonly used in pulp and paper production as well as 16 phytochemicals that have been observed in various pulp and paper mill effluent streams for their ability to interact in vitro with the enzymes monoamine oxidase (MAO), glutamic acid decarboxylase (GAD), and GABA-transaminase (GABA-T), and bind to the benzodiazepine-binding site of the GABA(A) receptor (GABA(A)-BZD). These neuroendocrine endpoints are also important targets for treatment of neurological disorders such as anxiety, epilepsy, or depression. MAO and GAD were inhibited by various conifer extracts of different polarities, including major feedstocks such as balsam fir, black spruce, and white spruce. MAO was selectively stimulated or inhibited by many of the tested phytochemicals, with inhibition observed by a group of phenylpropenes (e.g. isoeugenol and vanillin). Selective GAD inhibition was also observed, with all of the resin acids tested being inhibitory. GABA(A)-BZD ligand displacement was also observed. We compiled a table identifying which of these phytochemicals have been described in each of the species tested here. Given the diversity of conifer species and plant chemicals with these specific neuroactivities, it is reasonable to propose that MAO and GAD inhibition reported in effluents is phytochemical in origin. We propose disruption of these neuroendocrine endpoints as a possible mechanism of reproductive inhibition, and also identify an avenue for potential research and sourcing of conifer-derived neuroactive natural products. © 2013.

  15. Lipid raft integrity affects GABAA receptor, but not NMDA receptor modulation by psychopharmacological compounds.

    Science.gov (United States)

    Nothdurfter, Caroline; Tanasic, Sascha; Di Benedetto, Barbara; Uhr, Manfred; Wagner, Eva-Maria; Gilling, Kate E; Parsons, Chris G; Rein, Theo; Holsboer, Florian; Rupprecht, Rainer; Rammes, Gerhard

    2013-07-01

    Lipid rafts have been shown to play an important role for G-protein mediated signal transduction and the function of ligand-gated ion channels including their modulation by psychopharmacological compounds. In this study, we investigated the functional significance of the membrane distribution of NMDA and GABAA receptor subunits in relation to the accumulation of the tricyclic antidepressant desipramine (DMI) and the benzodiazepine diazepam (Diaz). In the presence of Triton X-100, which allowed proper separation of the lipid raft marker proteins caveolin-1 and flotillin-1 from the transferrin receptor, all receptor subunits were shifted to the non-raft fractions. In contrast, under detergent-free conditions, NMDA and GABAA receptor subunits were detected both in raft and non-raft fractions. Diaz was enriched in non-raft fractions without Triton X-100 in contrast to DMI, which preferentially accumulated in lipid rafts. Impairment of lipid raft integrity by methyl-β-cyclodextrine (MβCD)-induced cholesterol depletion did not change the inhibitory effect of DMI at the NMDA receptor, whereas it enhanced the potentiating effect of Diaz at the GABAA receptor at non-saturating concentrations of GABA. These results support the hypothesis that the interaction of benzodiazepines with the GABAA receptor likely occurs outside of lipid rafts while the antidepressant DMI acts on ionotropic receptors both within and outside these membrane microdomains.

  16. BENZODIAZEPINES IN PSYCHOTIC STATES

    OpenAIRE

    Ananth, Jambur; Solano, Olusegun

    1993-01-01

    SUMMARY Benzodiazepines are primarily used for the treatment of generalized anxiety disorder, insomnia and status epilepticus. These drugs can also be useful in hyperaroused states, catatonic stupor, manic episodes, and akathisia. This paper will review indications for their use in various psychotic conditions.

  17. Functional expression of the GABAA receptor alpha2 and alpha3 subunits at synapses between intercalated medial paracapsular neurons of mouse amygdala

    Directory of Open Access Journals (Sweden)

    Raffaella eGeracitano

    2012-05-01

    Full Text Available In the amygdala, GABAergic neurons in the intercalated medial paracapsular cluster (Imp have been suggested to play a key role in fear learning and extinction. These neurons project to the central amygdaloid nucleus and to other areas within and outside the amygdala. In addition, they give rise to local collaterals that innervate other neurons in the Imp. Several drugs, including benzodiazepines, are allosteric modulators of GABA-A receptors. Benzodiazepines have both anxiolytic and sedative actions, which are mediated through GABA-A receptors containing alpha2/3 and alpha1 subunits, respectively. To establish whether alpha1 or alpha2/3 subunits are expressed at Imp cell synapses, we used paired recordings of anatomically-identified Imp neurons and high resolution immunocytochemistry in the mouse. We observed that a selective alpha3 subunit agonist, TP003 (100 nM, significantly increased the decay time constant of the unitary IPSCs. A similar effect was also induced by zolpidem (10 microM or by diazepam (1 microM. In contrast, lower doses of zolpidem (0.1-1 microM did not significantly alter the kinetics of the unitary IPSCs. Accordingly, immunocytochemical experiments established that the alpha2 and alpha3, but not the alpha1 subunits of the GABA-A receptors, were present at Imp cell synapses of the mouse amygdala. These results define, for the first time, some of the functional GABA-A receptor subunits expressed at synapses of Imp cells. The data also provide an additional rationale to prompt the search of GABA-A receptor alpha3 selective ligands as improved anxiolytic drugs.

  18. Synthesis of [[sup 3]H]tert-butyl 8-chloro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodia zepine 3-carboxylate, a selective, high affinity ligand for the diazepam insensitive (DI) subtype of the benzodiazepine receptor

    Energy Technology Data Exchange (ETDEWEB)

    Ziqiang Gu; Costa, B.R. de; Wong, Garry; Rice, K.C.; Skolnick, Phil (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States))

    1992-12-01

    The preparation of [[sup 3]H]-labelled tert-butyl 8-chloro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a]benzodiazepine 3-carboxylate (TCIB, 6), a high affinity ligand for the diazepam insensitive (DI) subtype of the benzodiazepine receptor (BZR) is described. Synthesis of [[sup 3]H]TCIB was accomplished in 4 steps starting from 5-chloroisatoic anhydride. Tritium-label introduction was achieved in the final step by selective catalytic tritiolysis in 62% radiochemical yield with quantitative isotopic incorporation. (Author).

  19. Receptor studies in biological psychiatry

    International Nuclear Information System (INIS)

    Fujiwara, Yutaka

    1992-01-01

    Recent advances in the pharmacological treatment of endogenous psychosis have led to the development of biological studies in psychiatry. Studies on neurotransmitter receptors were reviewed in order to apply positron-emission tomograph (PET) for biological psychiatry. The dopamine (DA) hypothesis for schizophrenia was advanced on the basis of the observed effects of neuroleptics and methamphetamine, and DA(D 2 ) receptor supersensitivity measured by PET and receptor binding in the schizophrenic brain. The clinical potencies of neuroleptics for schizophrenia were correlated with their abilities to inhibit the D 2 receptor, and not other receptors. The σ receptor was expected to be a site of antipsychotic action. However, the potency of drugs action on it was not correlated with clinical efficacy. Haloperidol binds with high affinity to the σ receptor, which may mediate acute dystonia, an extrapyramidal side effect of neuroleptics. Behavioral and neurochemical changes induced by methamphetamine treatment were studied as an animal model of schizophrenia, and both a decrease of D 2 receptor density and an increase of DA release were detected. The monoamine hypothesis for manic-depressive psychosis was advanced on the basis of the effect of reserpine, monoamine oxidase inhibitor and antidepressants. 3 H-clonidine binding sites were increased in platelet membranes of depressive patients, 3 H-imipramine binding sites were decreased. The GABA A receptor is the target site for the action of anxiolytics and antiepileptics such as benzodiazepines and barbiturates. Recent developments in molecular biology techniques have revealed the structure of receptor proteins, which are classified into two receptor families, the G-protein coupled type (D 2 ) and the ion-channel type (GABA A ). (J.P.N.)

  20. Insulin reduces neuronal excitability by turning on GABA(A channels that generate tonic current.

    Directory of Open Access Journals (Sweden)

    Zhe Jin

    Full Text Available Insulin signaling to the brain is important not only for metabolic homeostasis but also for higher brain functions such as cognition. GABA (γ-aminobutyric acid decreases neuronal excitability by activating GABA(A channels that generate phasic and tonic currents. The level of tonic inhibition in neurons varies. In the hippocampus, interneurons and dentate gyrus granule cells normally have significant tonic currents under basal conditions in contrast to the CA1 pyramidal neurons where it is minimal. Here we show in acute rat hippocampal slices that insulin (1 nM "turns on" new extrasynaptic GABA(A channels in CA1 pyramidal neurons resulting in decreased frequency of action potential firing. The channels are activated by more than million times lower GABA concentrations than synaptic channels, generate tonic currents and show outward rectification. The single-channel current amplitude is related to the GABA concentration resulting in a single-channel GABA affinity (EC(50 in intact CA1 neurons of 17 pM with the maximal current amplitude reached with 1 nM GABA. They are inhibited by GABA(A antagonists but have novel pharmacology as the benzodiazepine flumazenil and zolpidem are inverse agonists. The results show that tonic rather than synaptic conductances regulate basal neuronal excitability when significant tonic conductance is expressed and demonstrate an unexpected hormonal control of the inhibitory channel subtypes and excitability of hippocampal neurons. The insulin-induced new channels provide a specific target for rescuing cognition in health and disease.

  1. Reversal of diastereoselectivity in the synthesis of peptidomimetic 3-carboxamide-1,4-benzodiazepin-5-ones.

    Science.gov (United States)

    Pertejo, Pablo; Corres, Nazaret; Torroba, Tomás; García-Valverde, María

    2015-02-06

    Enantiopure 3-carboxamide-1,4-benzodiazepin-5-ones were synthesized via the Ugi reaction followed by the Staudinger/aza-Wittig or reduction reactions in only two steps. A complete reversal of diastereoselectivity was achieved depending on the cyclization methodology employed. The different orientation of the C3 substituent in our 3-substituted 1,4-benzodiazepin-5-ones with respect to the most studied 1,4-benzodiazepin-2-ones makes them complementary in the development of new drugs because the primary source of binding selectivity of 1,4-benzodiazepines is the selective recognition of ligand conformations by the receptor.

  2. Triazolam-induced modulation of muscarinic acetylcholine receptor in living brain slices as revealed by a new positron-based imaging technique

    International Nuclear Information System (INIS)

    Murata, T.; Matsumura, K.; Onoe, H.; Watanabe, Y.; Sihver, S.; Sihver, W.; Langstroem, B.; Bergstroem, M.; Yonekura, Y.

    1997-01-01

    The effect of triazolam, a potent benzodiazepine (BZ) agonist, on muscarinic acetylcholinergic receptor (mAChR) binding was investigated in living brain slices by use of a novel positron-based imaging technique. Fresh rat brain slices were incubated with [ 11 C]N-methyl-4-piperidylbenzilate ([ 11 C]NMPB), a mAChR antagonist, in oxygenated Krebs-Ringer solution at 37 degree C. During incubation, time-resolved imaging of [ 11 C]NMPB binding in the slices was constructed on the storage phosphor screens. Addition of triazolam (1 μM) plus muscimol (30 μM), a GABA A receptor agonist, to the incubation mixture decreased the specific binding of [ 11 C]NMPB. Ro15-1788, a BZ receptor antagonist, prevented this effect, indicating that the effect was exerted through the GABA A /BZ receptor complex. These results demonstrated that stimulation of the GABA A /BZ receptor lowers the affinity of the mAChR for its ligand, which may underlie the BZ-induced amnesia, a serious clinical side effect of BZ. No such effect in the P2-fraction instead implies that the integrity of the neuronal cells and/or their environment is prerequisite for the modulation of mAChR by GABA A /BZ stimulation. (author)

  3. Fast detection of extrasynaptic GABA with a whole-cell sniffer

    DEFF Research Database (Denmark)

    Christensen, Rasmus K; Petersen, Anders V; Schmitt, Nicole

    2014-01-01

    Gamma-amino-butyric acid (GABA) is the main inhibitory transmitter of the brain. It operates by binding to specific receptors located both inside and outside synapses. The extrasynaptic receptors are activated by spillover from GABAergic synapses and by ambient GABA in the extracellular space....... Ambient GABA is essential for adjusting the excitability of neurons. However, due to the lack of suitable methods, little is known about its dynamics. Here we describe a new technique that allows detection of GABA transients and measurement of the steady state GABA concentration with high spatial...... and temporal resolution. We used a human embryonic kidney (HEK) cell line that stably expresses GABAA receptors composed of α1, β2, and γ2 subunits. We recorded from such a HEK cell with the whole-cell patch-clamp technique. The presence of GABA near the HEK cell generated a measurable electric current whose...

  4. High density of benzodiazepine binding sites in the substantia innominata of the rat

    Energy Technology Data Exchange (ETDEWEB)

    Sarter, M.; Schneider, H.H.

    1988-07-01

    In order to study the neuronal basis of the pharmacological interactions between benzodiazepine receptor ligands and cortical cholinergic turnover, we examined the regional distribution of specific benzodiazepine binding sites using in vitro autoradiography. In the basal forebrain, the substantia innominata contained a high density of (/sup 3/H)lormetazepam (LMZ) binding sites (Bmax = 277 fmol/mg tissue; Kd = 0.55 nM). The label could be displaced by diazepam (IC50 = 100 nM), the benzodiazepine receptor antagonist beta-carboline ZK 93426 (45 nM) and the partial inverse agonist beta-carboline FG 7142 (540 nM). It is hypothesized that the amnesic effects of benzodiazepine receptor agonists are exerted through benzodiazepine receptors which are situated on cholinergic neurons in the substantia innominata and are involved in a tonic inhibition of cortical acetylcholine release. The benzodiazepine receptor antagonist ZK 93426 may exert its nootropic effects via benzodiazepine receptors in the substantia innominata and, consequently, by disinhibiting cortical acetylcholine release.

  5. A novel α5GABA(A)R-positive allosteric modulator reverses hyperactivation of the dopamine system in the MAM model of schizophrenia.

    Science.gov (United States)

    Gill, Kathryn M; Lodge, Daniel J; Cook, James M; Aras, Shamim; Grace, Anthony A

    2011-08-01

    We have shown previously that aberrant hippocampal (HPC) output underlies the dopamine (DA) dysfunction observed in the methylazoxymethanol acetate (MAM) developmental model of schizophrenia in the rodent. This alteration of HPC activity was proposed to result from a reduction in parvalbumin (PV)-expressing GABAergic interneurons and consequent destabilization of the output of pyramidal neurons, as well as disrupted activation across a broad neural network. In vivo extracellular recordings were performed in the ventral tegmental area (VTA) and ventral HPC of saline- (SAL) and MAM-treated animals. A novel benzodiazepine-positive allosteric modulator (PAM), selective for the α5 subunit of the GABA(A) receptor, SH-053-2'F-R-CH3, was tested for its effects on the output of the HPC, leading to dopamine system hyperactivity in MAM-treated animals. In addition, the effect of SH-053-2'F-R-CH3 on the hyperactive locomotor response to amphetamine in MAM animals was examined. We demonstrate that treatment with the α5GABA(A)R PAM reduced the number of spontaneously active DA neurons in the VTA of MAM animals to levels observed in SAL rats, both when administered systemically and when directly infused into the ventral HPC. Moreover, HPC neurons in both SAL and MAM animals showed diminished cortical-evoked responses following α5GABA(A)R PAM treatment. In addition, the increased locomotor response to amphetamine observed in MAM rats was reduced following α5GABA(A)R treatment. This study supports a novel treatment of schizophrenia that targets abnormal HPC output, which in turn normalizes dopaminergic neuronal activity.

  6. Astrocytic GABA transporter activity modulates excitatory neurotransmission

    DEFF Research Database (Denmark)

    Boddum, Kim; Jensen, Thomas P.; Magloire, Vincent

    2016-01-01

    Astrocytes are ideally placed to detect and respond to network activity. They express ionotropic and metabotropic receptors, and can release gliotransmitters. Astrocytes also express transporters that regulate the extracellular concentration of neurotransmitters. Here we report a previously...... unrecognized role for the astrocytic GABA transporter, GAT-3. GAT-3 activity results in a rise in astrocytic Na(+) concentrations and a consequent increase in astrocytic Ca(2+) through Na(+)/Ca(2+) exchange. This leads to the release of ATP/adenosine by astrocytes, which then diffusely inhibits neuronal...... glutamate release via activation of presynaptic adenosine receptors. Through this mechanism, increases in astrocytic GAT-3 activity due to GABA released from interneurons contribute to 'diffuse' heterosynaptic depression. This provides a mechanism for homeostatic regulation of excitatory transmission...

  7. Astrocytic GABA Transporters

    DEFF Research Database (Denmark)

    Schousboe, Arne; Wellendorph, Petrine; Frølund, Bente

    2017-01-01

    , and several of these compounds have been shown to exhibit pronounced anticonvulsant activity in a variety of animal seizure models. As proof of concept of the validity of this drug development approach, one GABA-transport inhibitor, tiagabine, has been developed as a clinically active antiepileptic drug...

  8. Genetic and psychosocial factors for benzodiazepine addiction. An analysis based on the results of the authors’ own research conducted in a group of benzodiazepine addicted and non-addicted individuals

    Directory of Open Access Journals (Sweden)

    Anna Konopka

    2017-03-01

    Full Text Available Purpose: In spite of the fact that the addictive potential of benzodiazepine (BDZ drugs has been known for a long time, benzodiazepine addiction remains a common problem for psychiatry to deal with. The etiology of benzodiazepine addiction is very complex. Among the risk factors, the course of the treatment, demographic status and psychological features of a patient seem to play an important role. The aim of this study was to investigate both psychological and genetic factors differentiating benzodiazepine addicts from non-addicted users.Methods: We analysed a cohort of 120 individuals treated with benzodiazepines divided into two groups: benzodiazepine addicts and non-addicted benzodiazepine users (the control group. In both groups we measured genetic polymorphisms of GABA A2 and MAOA. In both groups some psychometric measurements were performed – we investigated the level of depression, anxiety as a state and as a trait, personality features and the dominant coping style using the Beck Depression Scale, Hamilton Anxiety Scale, Five-Factor Personality Inventory NEO-FFI and the Coping Inventory for Stressful Situations [4,10,17,36,41,44].Results: There are some psychological and situational risk factors for benzodiazepine addiction such as high neuroticism, introversion and lack of the ability to release tension through interpersonal contacts, dominance of emotional coping style and high accumulation of critical life events during both childhood and adulthood. The genetic background still remains a field for further exploration.

  9. Zolpidem, a selective GABA(A) receptor alpha1 subunit agonist, induces comparable Fos expression in oxytocinergic neurons of the hypothalamic paraventricular and accessory but not supraoptic nuclei in the rat

    DEFF Research Database (Denmark)

    Kiss, Alexander; Søderman, Andreas; Bundzikova, Jana

    2006-01-01

    Functional activation of oxytocinergic (OXY) cells in the hypothalamic paraventricular (PVN), supraoptic (SON), and accessory (ACC) nuclei was investigated in response to acute treatment with Zolpidem (a GABA(A) receptor agonist with selectivity for alpha(1) subunits) utilizing dual Fos...... contemporaneousness within the cells of the principal and accessory magnocellular nuclei in response to Zolpidem treatment. The present study provides a comparative background that may help in the further understanding of a possible extend of Zolpidem effect on the brain...... significant activations were also seen in certain groups of accessory structures including the circular nucleus (13.99+/-3.43%), small clusters of accessory neurons (10.55+/-1.94%), and the lateral hypothalamic perivascular nucleus (9.42+/-2.74%). Between the naive and vehicle controls, the dual Fos...

  10. Plasticity of GABA transporters: an unconventional route to shape inhibitory synaptic transmission

    Directory of Open Access Journals (Sweden)

    Annalisa eScimemi

    2014-05-01

    Full Text Available The brain relies on GABAergic neurons to control the ongoing activity of neuronal networks. GABAergic neurons control the firing pattern of excitatory cells, the temporal structure of membrane potential oscillations and the time window for integration of synaptic inputs. These actions require a fine control of the timing of GABA receptor activation which, in turn, depends on the precise timing of GABA release from pre-synaptic terminals and GABA clearance from the extracellular space. Extracellular GABA is not subject to enzymatic breakdown, and its clearance relies entirely on diffusion and uptake by specific transporters. In contrast to glutamate transporters, GABA transporters are abundantly expressed in neuronal pre-synaptic terminals. GABA transporters move laterally within the plasma membrane and are continuously trafficked to/from intracellular compartments. It is hypothesized that due to their proximity to GABA release sites, changes in the concentration and lateral mobility of GABA transporters may have a significant effect on the time course of the GABA concentration profile in and out of the synaptic cleft. To date, this hypothesis remains to be tested. Here we use 3D Monte Carlo reaction-diffusion simulations to analyze how changes in the density of expression and lateral mobility of GABA transporters in the cell membrane affect the extracellular GABA concentration profile and the activation of GABA receptors. Our results indicate that these manipulations mainly alter the GABA concentration profile away from the synaptic cleft. These findings provide novel insights into how the ability of GABA transporters to undergo plastic changes may alter the strength of GABAergic signals and the activity of neuronal networks in the brain.

  11. Desensitization of GABAergic receptors as a mechanism of zolpidem-induced somnambulism.

    Science.gov (United States)

    Juszczak, Grzegorz R

    2011-08-01

    Sleepwalking is a frequently reported side effect of zolpidem which is a short-acting hypnotic drug potentiating activity of GABA(A) receptors. Paradoxically, the most commonly used medications for somnambulism are benzodiazepines, especially clonazepam, which also potentiate activity of GABA(A) receptors. It is proposed that zolpidem-induced sleepwalking can be explained by the desensitization of GABAergic receptors located on serotonergic neurons. According to the proposed model, the delay between desensitization of GABA receptors and a compensatory decrease in serotonin release constitutes the time window for parasomnias. The occurrence of sleepwalking depends on individual differences in receptor desensitization, autoregulation of serotonin release and drug pharmacokinetics. The proposed mechanism of interaction between GABAergic and serotonergic systems can be also relevant for zolpidem abuse and zolpidem-induced hallucinations. It is therefore suggested that special care should be taken when zolpidem is used in patients taking at the same time selective serotonin reuptake inhibitors. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Segregation of acetylcholine and GABA in the rat superior cervical ganglia: functional correlation.

    Directory of Open Access Journals (Sweden)

    Diana eElinos

    2016-04-01

    Full Text Available Sympathetic neurons have the capability to segregate their neurotransmitters (NTs and co-transmitters to separate varicosities of single axons; furthermore, in culture, these neurons can even segregate classical transmitters. In vivo sympathetic neurons employ acetylcholine (ACh and other classical NTs such as gamma aminobutyric acid (GABA. Herein, we explore whether these neurons in vivo segregate these classical NTs in the superior cervical ganglia of the rat. We determined the topographical distribution of GABAergic varicosities, somatic GABAA receptor, as well as the regional distribution of the segregation of ACh and GABA. We evaluated possible regional differences in efficacy of ganglionic synaptic transmission, in the sensitivity of GABAA receptor to GABA and to the competitive antagonist picrotoxin (PTX. We found that sympathetic preganglionic neurons in vivo do segregate ACh and GABA. GABAergic varicosities and GABAA receptor expression showed a rostro-caudal gradient along ganglia; in contrast, segregation exhibited a caudo-rostral gradient. These uneven regional distributions in expression of GABA, GABAA receptors, and level segregation correlate with stronger synaptic transmission found in the caudal region. Accordingly, GABAA receptors of rostral region show larger sensitivity to GABA and PTX. These results suggest the presence of different types of GABAA receptors in each region that result in a different regional levels of endogenous GABA inhibition. Finally, we discuss a possible correlation of these different levels of GABA modulation and the function of the target organs innervated by rostral and caudal ganglionic neurons.

  13. Glutamate modulation of GABA transport in retinal horizontal cells of the skate

    Science.gov (United States)

    Kreitzer, Matthew A; Andersen, Kristen A; Malchow, Robert Paul

    2003-01-01

    Transport of the amino acid GABA into neurons and glia plays a key role in regulating the effects of GABA in the vertebrate retina. We have examined the modulation of GABA-elicited transport currents of retinal horizontal cells by glutamate, the likely neurotransmitter of vertebrate photoreceptors. Enzymatically isolated external horizontal cells of skate were examined using whole-cell voltage-clamp techniques. GABA (1 mm) elicited an inward current that was completely suppressed by the GABA transport inhibitors tiagabine (10 μm) and SKF89976-A (100 μm), but was unaffected by 100 μm picrotoxin. Prior application of 100 μm glutamate significantly reduced the GABA-elicited current. Glutamate depressed the GABA dose-response curve without shifting the curve laterally or altering the voltage dependence of the current. The ionotropic glutamate receptor agonists kainate and AMPA also reduced the GABA-elicited current, and the effects of glutamate and kainate were abolished by the ionotropic glutamate receptor antagonist 6-cyano-7-nitroquinoxaline. NMDA neither elicited a current nor modified the GABA-induced current, and metabotropic glutamate analogues were also without effect. Inhibition of the GABA-elicited current by glutamate and kainate was reduced when extracellular calcium was removed and when recording pipettes contained high concentrations of the calcium chelator BAPTA. Caffeine (5 mm) and thapsigargin (2 nm), agents known to alter intracellular calcium levels, also reduced the GABA-elicited current, but increases in calcium induced by depolarization alone did not. Our data suggest that glutamate regulates GABA transport in retinal horizontal cells through a calcium-dependent process, and imply a close physical relationship between calcium-permeable glutamate receptors and GABA transporters in these cells. PMID:12562999

  14. Glutamate and GABA in appetite regulation

    Directory of Open Access Journals (Sweden)

    Teresa Cardoso Delgado

    2013-08-01

    Full Text Available Appetite is regulated by a coordinated interplay between gut, adipose tissue and brain. A primary site for the regulation of appetite is the hypothalamus where interaction between orexigenic neurons, expressing Neuropeptide Y/Agouti-related protein, and anorexigenic neurons, expressing Pro-opiomelanocortin cocaine/Amphetamine-related transcript, controls energy homeostasis. Within the hypothalamus, several peripheral signals have been shown to modulate the activity of these neurons, including the orexigenic peptide ghrelin and the anorexigenic hormones insulin and leptin. In addition to the accumulated knowledge on neuropeptide signaling, presence and function of amino acid neurotransmitters in key hypothalamic neurons brought a new light into appetite regulation. Therefore, the principal aim of this review will be to describe the current knowledge of the role of amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation and the associated neuronal-astrocytic metabolic coupling mechanisms.Glutamate and GABA dominate synaptic transmission in the hypothalamus and administration of their receptors agonists into hypothalamic nuclei stimulates feeding. By using 13C High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance spectroscopy based analysis, the Cerdán group has shown that increased neuronal firing in mice hypothalamus, as triggered by appetite during the feeding-fasting paradigm, may stimulate the use of lactate as neuronal fuel leading to increased astrocytic glucose consumption and glycolysis. Moreover, fasted mice showed increased hypothalamic [2-13C]GABA content, which may be explained by the existence of GABAergic neurons in key appetite regulation hypothalamic nuclei. Interestingly, increased [2-13C]GABA concentration in the hypothalamus of fasted animals appears to result mainly from reduction in GABA metabolizing pathways, rather than increased GABA synthesis by augmented activity of the

  15. A radioreceptor assay for benzodiazepines

    International Nuclear Information System (INIS)

    Hunt, P.; Husson, J.-M.; Raynaud, J.-P.

    1979-01-01

    A simple, rapid and sensitive radioreceptor assay for determining benzodiazepines in serum is based on the displacement by the drug specific [ 3 H] diazepam binding to a membrane fraction from rat brain. The limit of detection of the more active benzodiazepines is about 0.5 ng. Diazepam, nitrazepam, clobazam and HR 458 have been assayed in human serum after a single oral clinical dose. The results can be used for determining pharmacokinetic parameters. The technique measures not only the parent benzodiazepine but also clinically active metabolites. (author)

  16. An Electrostatic Funnel in the GABA-Binding Pathway.

    Directory of Open Access Journals (Sweden)

    Timothy S Carpenter

    2016-04-01

    Full Text Available The γ-aminobutyric acid type A receptor (GABAA-R is a major inhibitory neuroreceptor that is activated by the binding of GABA. The structure of the GABAA-R is well characterized, and many of the binding site residues have been identified. However, most of these residues are obscured behind the C-loop that acts as a cover to the binding site. Thus, the mechanism by which the GABA molecule recognizes the binding site, and the pathway it takes to enter the binding site are both unclear. Through the completion and detailed analysis of 100 short, unbiased, independent molecular dynamics simulations, we have investigated this phenomenon of GABA entering the binding site. In each system, GABA was placed quasi-randomly near the binding site of a GABAA-R homology model, and atomistic simulations were carried out to observe the behavior of the GABA molecules. GABA fully entered the binding site in 19 of the 100 simulations. The pathway taken by these molecules was consistent and non-random; the GABA molecules approach the binding site from below, before passing up behind the C-loop and into the binding site. This binding pathway is driven by long-range electrostatic interactions, whereby the electrostatic field acts as a 'funnel' that sweeps the GABA molecules towards the binding site, at which point more specific atomic interactions take over. These findings define a nuanced mechanism whereby the GABAA-R uses the general zwitterionic features of the GABA molecule to identify a potential ligand some 2 nm away from the binding site.

  17. GABA, a natural immunomodulator of T lymphocytes

    DEFF Research Database (Denmark)

    Bjurstöm, Helen; Wang, Junyang; Ericsson, Ida

    2008-01-01

    gamma-aminobutyric acid (GABA) is the main neuroinhibitory transmitter in the brain. Here we show that GABA in the extracellular space may affect the fate of pathogenic T lymphocytes entering the brain. We examined in encephalitogenic T cells if they expressed functional GABA channels that could ......M and higher GABA concentrations decreased T cell proliferation. The results are consistent with GABA being immunomodulatory....

  18. Presynaptic Dopamine D2 Receptors Modulate [3H]GABA Release at StriatoPallidal Terminals via Activation of PLC → IP3 → Calcineurin and Inhibition of AC → cAMP → PKA Signaling Cascades.

    Science.gov (United States)

    Jijón-Lorenzo, Rafael; Caballero-Florán, Isaac Hiram; Recillas-Morales, Sergio; Cortés, Hernán; Avalos-Fuentes, José Arturo; Paz-Bermúdez, Francisco Javier; Erlij, David; Florán, Benjamín

    2018-02-21

    Striatal dopamine D2 receptors activate the PLC → IP3 → Calcineurin-signaling pathway to modulate the neural excitability of En+ Medium-sized Spiny GABAergic neurons (MSN) through the regulation of L-type Ca 2+ channels. Presynaptic dopaminergic D2 receptors modulate GABA release at striatopallidal terminals through L-type Ca 2+ channels as well, but their signaling pathway is still undetermined. Since D2 receptors are Gi/o-coupled and negatively modulate adenylyl cyclase (AC), we investigated whether presynaptic D2 receptors modulate GABA release through the same signaling cascade that controls excitability in the striatum or by the inhibition of AC and decreased PKA activity. Activation of D2 receptors stimulated formation of [ 3 H]IP 1 and decreased Forskolin-stimulated [ 3 H]cAMP accumulation in synaptosomes from rat Globus Pallidus. D2 receptor activation with Quinpirole in the presence of L 745,870 decreased, in a dose-dependent manner, K + -induced [ 3 H]GABA release in pallidal slices. The effect was prevented by the pharmacological blockade of Gi/o βγ subunit effects with Gallein, PLC with U 73122, IP3 receptor activation with 4-APB, Calcineurin with FK506. In addition, when release was stimulated with Forskolin to activate AC, D2 receptors also decreased K + -induced [ 3 H]GABA release, an effect occluded with the effect of the blockade of PKA with H89 or stimulation of release with the cAMP analog 8-Br-cAMP. These data indicate that D2 receptors modulate [ 3 H]GABA release at striatopallidal terminals by activating the PLC → IP3 → Calcineurin-signaling cascade, the same one that modulates excitability in soma. Additionally, D2 receptors inhibit release when AC is active. Both mechanisms appear to converge to regulate the activity of presynaptic L-type Ca 2+ channels. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Sodium-independent, bicuculline-sensitive [3H]GABA binding to isolated rat hepatocytes

    International Nuclear Information System (INIS)

    Minuk, G.Y.; Bear, C.E.; Sarjeant, E.J.

    1987-01-01

    To determine whether hepatocytes possess specific receptor sites for gamma-aminobutyric acid (GABA), a potent amino acid neurotransmitter, [ 3 H]GABA, was added to sodium-free suspensions of Percoll-purified hepatocytes derived from collagenase-perfused rat livers under various experimental conditions and in the presence or absence of specific GABA receptor agonists (muscimol) and antagonists (bicuculline). The effects of GABA, muscimol, and bicuculline on hepatocyte resting membrane potentials were also determined. Specific binding of [ 3 H]GABA to hepatocytes was a consistent finding. GABA-hepatocyte interactions were reversible and temperature dependent. Muscimol and bicuculline inhibited binding in a dose-dependent manner (IC50, 30 nM and 50 microM, respectively), whereas strychnine (1.0-100 microM), a nonspecific central nervous system stimulant, had no appreciable effect. Both GABA and muscimol (100 microM) caused significant hyperpolarization of hepatocyte resting membrane potential (delta PD 5.4 +/- 3.1 and 22.2 +/- 16.2 mV, respectively, means +/- SD, P less than 0.0005). Bicuculline (100 microM) inhibited the effect of muscimol (P less than 0.05). The results of this study suggest that specific GABA receptor sites exist on the surface of isolated rat hepatocytes. The presence of such sites raises the possibility that, in addition to adrenergic and cholinergic innervation, hepatic function may be influenced by GABA-ergic neurotransmitter mechanisms

  20. The peripheral benzodiazepine receptor ligand PK11195 binds with high affinity to the acute phase reactant α1-acid glycoprotein: implications for the use of the ligand as a CNS inflammatory marker

    International Nuclear Information System (INIS)

    Lockhart, Andrew; Davis, Bill; Matthews, Julian C.; Rahmoune, Hassan; Hong, Guizhu; Gee, Antony; Earnshaw, David; Brown, John

    2003-01-01

    The peripheral benzodiazepine receptor ligand PK11195 has been used as an in vivo marker of neuroinflammation in positron emission tomography studies in man. One of the methodological issues surrounding the use of the ligand in these studies is the highly variable kinetic behavior of [ 11 C]PK11195 in plasma. We therefore undertook a study to measure the binding of [ 3 H]PK11195 to whole human blood and found a low level of binding to blood cells but extensive binding to plasma proteins. Binding assays using [ 3 H]PK11195 and purified human plasma proteins demonstrated a strong binding to α1-acid glycoprotein (AGP) and a much weaker interaction with albumin. Immunodepletion of AGP from plasma resulted in the loss of plasma [ 3 H]PK11195 binding demonstrating: (i) the specificity of the interaction and (ii) that AGP is the major plasma protein to which PK11195 binds with high affinity. PK11195 was able to displace fluorescein-dexamethasone from AGP with IC 50 of 11 C]PK11195 to the brain parenchyma in diseases with blood brain barrier breakdown. Finally, local synthesis of AGP at the site of brain injury may contribute the pattern of [ 11 C]PK11195 binding observed in neuroinflammatory diseases

  1. Cell-attached recordings of responses evoked by photorelease of GABA in the immature cortical neurons

    Directory of Open Access Journals (Sweden)

    Marat eMinlebaev

    2013-05-01

    Full Text Available We present a novel non-invasive technique to measure the polarity of GABAergic responses based on cell-attached recordings of currents activated by laser-uncaging of GABA. For these recordings, a patch pipette was filled with a solution containing RuBi-GABA, and GABA was released from this complex by a laser beam conducted to the tip of the patch pipette via an optic fiber. In cell-attached recordings from neocortical and hippocampal neurons in postnatal days P2-5 rat brain slices in vitro, we found that laser-uncaging of GABA activates integral cell-attached currents mediated by tens of GABA(A channels. The initial response was inwardly directed, indicating a depolarizing response to GABA. The direction of the initial response was dependent on the pipette potential and analysis of its slope-voltage relationships revealed a depolarizing driving force of +11 mV for the currents through GABA channels. Initial depolarizing responses to GABA uncaging were inverted to hyperpolarizing in the presence of the NKCC1 blocker bumetanide. Current-voltage relationships of the currents evoked by Rubi-GABA uncaging using voltage-ramps at the peak of responses not only revealed a bumetanide-sensitive depolarizing reversal potential of the GABA(A receptor mediated responses, but also showed a strong voltage-dependent hysteresis. Upon desensitization of the uncaged-GABA response, current-voltage relationships of the currents through single GABA(A channels revealed depolarizing responses with the driving force values similar to those obtained for the initial response. Thus, cell-attached recordings of the responses evoked by local intrapipette GABA uncaging are suitable to assess the polarity of the GABA(A-Rs mediated signals in small cell compartments.

  2. PET-derived biodistribution and dosimetry of the benzodiazepine receptor-binding radioligand (11)C-(R)-PK11195 in children and adults.

    Science.gov (United States)

    Kumar, Ajay; Muzik, Otto; Chugani, Diane; Chakraborty, Pulak; Chugani, Harry T

    2010-01-01

    The PET tracer (11)C-(R)-PK11195 (PK) is an antagonist of the peripheral-type benzodiazepine binding site and allows the noninvasive imaging of microglial activation seen in several neurologic disorders affecting the mature and developing brain. The objective of this study was to derive the biodistribution and in vivo radiation dose estimates of PK in children studied for brain inflammatory conditions and in healthy adults. Twenty-two children (mean age +/- SD, 9.5 +/- 4 y; range, 4-17 y; 10 girls) who underwent dynamic PK PET for conditions involving brain inflammation were studied. Seven healthy adults (age, 27.4 +/- 7.5 y; range, 22-41 y; 3 women) were evaluated using the same protocol. Normal-organ time-activity curves and residence times were derived and absorbed doses then calculated using the OLINDA software. Two other healthy young adults (1 man, 1 woman) also underwent sequential whole-body PET using a PET/CT scanner to obtain corresponding CT images and PK pharmacokinetics. PK uptake was highest in the gallbladder and urinary bladder, followed by the liver, kidney, bone marrow, salivary gland, and heart wall, with minimal localization in all other organs including normal brain and lungs. PK was excreted through the hepatobiliary and renal systems. The average effective dose equivalent was 11.6 +/- 0.6 microSv/MBq (mean +/- SD) for young children (age, 4-7 y), 7.7 +/- 1.0 microSv/MBq for older children (age, 8-12 y), 5.3 +/- 0.5 muSv/MBq for adolescents (age, 13-17 y), and 4.6 +/- 2.7 microSv/MBq for adults. The gallbladder wall received the highest radiation dose in children younger than 12 y, whereas the urinary bladder wall received the highest dose in older children and adults. For an administered activity of 17 MBq/kg (0.45 mCi/kg), the effective dose equivalent was about 5 mSv or below for all age groups. At clinically practical administered activities, the radiation dose from (11)C-PK11195 in both children and adults is comparable to that from other

  3. γ-aminobutyric acid (GABA) oral rinse reduces capsaicin-induced burning mouth pain sensation

    DEFF Research Database (Denmark)

    Zhang, Yang; Wang, Kelun; Arendt-Nielsen, Lars

    2018-01-01

    BACKGROUND: In burning mouth patients, analgesia after oral administration of clonazepam may result from modulation of peripheral γ-aminobutyric acid (GABA) receptors. METHODS: The effect of oral administration of test solutions (water, 0.5 mol/L or 0.05 mol/L GABA, 1% lidocaine) was investigated...

  4. Circadian modulation of GABA function in the rat suprachiasmatic nucleus: excitatory effects during the night phase.

    NARCIS (Netherlands)

    De Jeu, M.T.G.; Pennartz, C.M.A.

    2002-01-01

    Gramicidin-perforated patch-clamp recordings were made from slices of the suprachiasmatic nucleus (SCN) of adult rats to characterize the role of gamma-amino butyric acid (GABA) in the circadian timing system. During the day, activation of GABA(A) receptors hyperpolarized the membrane of SCN

  5. GABA shapes the dynamics of bistable perception.

    Science.gov (United States)

    van Loon, Anouk M; Knapen, Tomas; Scholte, H Steven; St John-Saaltink, Elexa; Donner, Tobias H; Lamme, Victor A F

    2013-05-06

    Sometimes, perception fluctuates spontaneously between two distinct interpretations of a constant sensory input. These bistable perceptual phenomena provide a unique window into the neural mechanisms that create the contents of conscious perception. Models of bistable perception posit that mutual inhibition between stimulus-selective neural populations in visual cortex plays a key role in these spontaneous perceptual fluctuations. However, a direct link between neural inhibition and bistable perception has not yet been established experimentally. Here, we link perceptual dynamics in three distinct bistable visual illusions (binocular rivalry, motion-induced blindness, and structure from motion) to measurements of gamma-aminobutyric acid (GABA) concentrations in human visual cortex (as measured with magnetic resonance spectroscopy) and to pharmacological stimulation of the GABAA receptor by means of lorazepam. As predicted by a model of neural interactions underlying bistability, both higher GABA concentrations in visual cortex and lorazepam administration induced slower perceptual dynamics, as reflected in a reduced number of perceptual switches and a lengthening of percept durations. Thus, we show that GABA, the main inhibitory neurotransmitter, shapes the dynamics of bistable perception. These results pave the way for future studies into the competitive neural interactions across the visual cortical hierarchy that elicit conscious perception. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Differential regulation of synaptic and extrasynaptic α4 GABA(A) receptor populations by protein kinase A and protein kinase C in cultured cortical neurons.

    Science.gov (United States)

    Bohnsack, John Peyton; Carlson, Stephen L; Morrow, A Leslie

    2016-06-01

    The GABAA α4 subunit exists in two distinct populations of GABAA receptors. Synaptic GABAA α4 receptors are localized at the synapse and mediate phasic inhibitory neurotransmission, while extrasynaptic GABAA receptors are located outside of the synapse and mediate tonic inhibitory transmission. These receptors have distinct pharmacological and biophysical properties that contribute to interest in how these different subtypes are regulated under physiological and pathological states. We utilized subcellular fractionation procedures to separate these populations of receptors in order to investigate their regulation by protein kinases in cortical cultured neurons. Protein kinase A (PKA) activation decreases synaptic α4 expression while protein kinase C (PKC) activation increases α4 subunit expression, and these effects are associated with increased β3 S408/409 or γ2 S327 phosphorylation respectively. In contrast, PKA activation increases extrasynaptic α4 and δ subunit expression, while PKC activation has no effect. Our findings suggest synaptic and extrasynaptic GABAA α4 subunit expression can be modulated by PKA to inform the development of more specific therapeutics for neurological diseases that involve deficits in GABAergic transmission. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Benzodiazepine receptor equilibrium constants for flumazenil and midazolam determined in humans with the single photon emission computer tomography tracer [123I]iomazenil

    DEFF Research Database (Denmark)

    Videbaek, C; Friberg, L; Holm, S

    1993-01-01

    bolus injection of [123I]iomazenil. The tracer in plasma was determined by high-pressure liquid chromatography and also by a simple octanol extraction procedure. The free concentration of flumazenil and midazolam in plasma water averaged 52% and 3.5% of that in whole plasma. The Kd values for the entire...... cortical rim for flumazenil were 7.4, 10.0, 10.3 and 17.7 nmol/l plasma water and, for midazolam, 73, 76, 58 and 30 nmol/l plasma water. The variation exceeds random methodological error and is probably due to interindividual differences in receptor affinity. The Kd level of midazolam is considerably...

  8. A multilevel prediction of physiological response to challenge: Interactions among child maltreatment, neighborhood crime, endothelial nitric oxide synthase gene (eNOS), and GABA(A) receptor subunit alpha-6 gene (GABRA6).

    Science.gov (United States)

    Lynch, Michael; Manly, Jody Todd; Cicchetti, Dante

    2015-11-01

    Physiological response to stress has been linked to a variety of healthy and pathological conditions. The current study conducted a multilevel examination of interactions among environmental toxins (i.e., neighborhood crime and child maltreatment) and specific genetic polymorphisms of the endothelial nitric oxide synthase gene (eNOS) and GABA(A) receptor subunit alpha-6 gene (GABRA6). One hundred eighty-six children were recruited at age 4. The presence or absence of child maltreatment as well as the amount of crime that occurred in their neighborhood during the previous year were determined at that time. At age 9, the children were brought to the lab, where their physiological response to a cognitive challenge (i.e., change in the amplitude of the respiratory sinus arrhythmia) was assessed and DNA samples were collected for subsequent genotyping. The results confirmed that complex Gene × Gene, Environment × Environment, and Gene × Environment interactions were associated with different patterns of respiratory sinus arrhythmia reactivity. The implications for future research and evidence-based intervention are discussed.

  9. Role of ionotropic GABA, glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

    Directory of Open Access Journals (Sweden)

    Goodchild Ann K

    2010-10-01

    Full Text Available Abstract Background Cardiac vagal preganglionic neurons (CVPN are responsible for the tonic, reflex and respiratory modulation of heart rate (HR. Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve. Results Microinjection of the GABAA antagonist picrotoxin into CVPN decreased HR but did not affect baroreflex bradycardia. The glycine antagonist strychnine did not alter HR or baroreflex bradycardia. Combined microinjection of the NMDA antagonist, MK801, and AMPA antagonist, CNQX, into CVPN evoked a small bradycardia and abolished baroreflex bradycardia. MK801 attenuated whereas CNQX abolished baroreceptor bradycardia. Control intravenous injections of the 5-HT1A agonist 8-OH-DPAT evoked a small bradycardia and potentiated baroreflex bradycardia. These effects were still observed following microinjection of picrotoxin but not strychnine into CVPN. Conclusions We conclude that activation of GABAA receptors set the level of HR whereas AMPA to a greater extent than NMDA receptors elicit baroreflex changes in HR. Furthermore, activation of 5-HT1A receptors evokes bradycardia and enhances baroreflex changes in HR due to interactions with glycinergic neurons involving strychnine receptors. This study provides reference for future studies investigating how diseases alter neurochemical inputs to CVPN.

  10. [Effect of damage integrity rat brain synaptic membranes on the functional activity GABA(A)-receptor/Cl(-)-ionophore complex in the CNC].

    Science.gov (United States)

    Rebrov, I G; Kalinina, M V

    2013-01-01

    Functional activity of the CGABA(A)-receptor/Cl(-) ionophore complex was investigated the muscimol-stimulated entry of the radioactive isotope 36Cl(-) in synaptoneurosomes in changing the structure and permeability of neuronal membranes. Integrity of the membranes was damaged by removal of Ca(+2) and Mg(+2) from the incubation medium and by the method of freezing-thawing synaptoneurosomes. In both cases, an increase in basal 36Cl(-) entry into synaptoneurosomes, indicating increased nonspecific permeability of neuronal membranes, and decreased activity the CABA(A)-receptor/Cl(-) ionophore complex. The conclusion about the relationship of processes damage neuronal membranes and reducing the inhibitory processes in the epileptic focus.

  11. Synthesis, Anticonvulsant, Sedative and Anxiolytic Activities of Novel Annulated Pyrrolo[1,4]benzodiazepines

    Directory of Open Access Journals (Sweden)

    Kumaraswamy Sorra

    2014-09-01

    Full Text Available Four new pentacyclic benzodiazepine derivatives (PBDTs 13–16 were synthesized by conventional thermal heating and microwave-assisted intramolecular cyclocondensation. Their anticonvulsant, sedative and anxiolytic activities were evaluated by drug-induced convulsion models, a pentobarbital-induced hypnotic model and an elevated plus maze in mice. PBDT 13, a triazolopyrrolo[2,1-c][1,4]benzodiazepin-8-one fused with a thiadiazolone ring, exhibited the best anticonvulsant, sedative and anxiolytic effects in our tests. There was no significant difference in potency between PBDT 13 and diazepam, and we proposed that the action mechanism of PBDT 13 could be similar to that of diazepam via benzodiazepine receptors.

  12. Differential distribution of GABAA receptor subunits in soma and processes of cerebellar granule cells: effects of maturation and a GABA agonist

    DEFF Research Database (Denmark)

    Elster, L; Hansen, Gert Helge; Belhage, B

    1995-01-01

    or absence of the GABAA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4c]pyridin-3-ol (THIP). THIP (150 microM) induced a 2-fold increase in the number of alpha 1 and beta 2/3 subunits in both cell bodies and processes in 4-day-old cultures. Extending the culture period to 8 days led to a polarization......Quantitative analysis of the density of alpha 1 and beta 2/3 GABAA receptor subunits was performed at the electron microscope level after indirect pre-embedding immunogold labeling with subunit-specific antibodies of rat cerebellar granule cell cultures grown for 4 or 8 days and in the presence...... of the receptor expression, since the increase in the number of subunits selectively was observed in the processes. Moreover, a general subcellular differentiation of the receptor population was observed in all culture conditions, since the ratio between the two subunits (beta 2/3; alpha 1) was four times higher...

  13. Flumazenil decreases surface expression of α4β2δ GABAA receptors by increasing the rate of receptor internalization.

    Science.gov (United States)

    Kuver, Aarti; Smith, Sheryl S

    2016-01-01

    Increases in expression of α4βδ GABAA receptors (GABARs), triggered by fluctuations in the neurosteroid THP (3α-OH-5α[β]-pregnan-20-one), are associated with changes in mood and cognition. We tested whether α4βδ trafficking and surface expression would be altered by in vitro exposure to flumazenil, a benzodiazepine ligand which reduces α4βδ expression in vivo. We first determined that flumazenil (100 nM-100 μM, IC50=∼1 μM) acted as a negative modulator, reducing GABA (10 μM)-gated current in the presence of 100 nM THP (to increase receptor efficacy), assessed with whole cell patch clamp recordings of recombinant α4β2δ expressed in HEK-293 cells. Surface expression of recombinant α4β2δ receptors was detected using a 3XFLAG reporter at the C-terminus of α4 (α4F) using confocal immunocytochemical techniques following 48 h exposure of cells to GABA (10 μM)+THP (100 nM). Flumazenil (10 μM) decreased surface expression of α4F by ∼60%, while increasing its intracellular accumulation, after 48 h. Reduced surface expression of α4β2δ after flumazenil treatment was confirmed by decreases in the current responses to 100 nM of the GABA agonist gaboxadol. Flumazenil-induced decreases in surface expression of α4β2δ were prevented by the dynamin blocker, dynasore, and by leupeptin, which blocks lysosomal enzymes, suggesting that flumazenil is acting to increase endocytosis and lysosomal degradation of the receptor. Flumazenil increased the rate of receptor removal from the cell surface by 2-fold, assessed using botulinum toxin B to block insertion of new receptors. These findings may suggest new therapeutic strategies for regulation of α4β2δ expression using flumazenil. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Enhanced phasic GABA inhibition during the repair phase of stroke: a novel therapeutic target

    Science.gov (United States)

    Paz, Jeanne T.; Wang, Eric Hou Jen; Badgely, Corrine; Olson, Andrew; Micheva, Kristina D.; Wang, Gordon; Lemmens, Robin; Tran, Kevin V.; Nishiyama, Yasuhiro; Liang, Xibin; Hamilton, Scott A.; O’Rourke, Nancy; Smith, Stephen J.; Huguenard, John R.; Bliss, Tonya M.

    2016-01-01

    Abstract Ischaemic stroke is the leading cause of severe long-term disability yet lacks drug therapies that promote the repair phase of recovery. This repair phase of stroke occurs days to months after stroke onset and involves brain remapping and plasticity within the peri-infarct zone. Elucidating mechanisms that promote this plasticity is critical for the development of new therapeutics with a broad treatment window. Inhibiting tonic (extrasynaptic) GABA signalling during the repair phase was reported to enhance functional recovery in mice suggesting that GABA plays an important function in modulating brain repair. While tonic GABA appears to suppress brain repair after stroke, less is known about the role of phasic (synaptic) GABA during the repair phase. We observed an increase in postsynaptic phasic GABA signalling in mice within the peri-infarct cortex specific to layer 5; we found increased numbers of α1 receptor subunit-containing GABAergic synapses detected using array tomography, and an associated increased efficacy of spontaneous and miniature inhibitory postsynaptic currents in pyramidal neurons. Furthermore, we demonstrate that enhancing phasic GABA signalling using zolpidem, a Food and Drug Administration (FDA)-approved GABA-positive allosteric modulator, during the repair phase improved behavioural recovery. These data identify potentiation of phasic GABA signalling as a novel therapeutic strategy, indicate zolpidem’s potential to improve recovery, and underscore the necessity to distinguish the role of tonic and phasic GABA signalling in stroke recovery. PMID:26685158

  15. Synthesis of substituted [{sup 123}I]imidazo[1,2-a]pyridines as potential probes for the study of the peripheral benzodiazepine receptors using SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, A.; Mattner, F.; Dikic, B.; Papazian, V. [Radiopharmaceuticals Div. R and D, ANSTO, Menai, NSW (Australia)

    2000-07-01

    The imidazo[1,2-a]pyridines N,N'-dimethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 1. N,N'-diethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 2, and N-methyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 3, are high affinity and selective ligands for the peripheral benzodiazepineodiazepine receptors (PBR). The [{sup 123}I]1-3 labelled analogues of these compounds were subsequently synthesised for the potential study of the PBR in vivo using SPECT. Radioiodination was achieved by iododestannylation reactions of the corresponding tributyl tin precursors with Na[{sup 123}I] in the presence of peracetic acid, chloramine-T or Iodogen. Purification of the crude product was achieved by semipreparative C-18 RP HPLC to give the products in radiochemical yields of 40-85%. The products were obtained in >97% chemical and radiochemical purity and with specific activities >80 GBq/{mu}mol. (orig.)

  16. Quality components and antidepressant-like effects of GABA green tea.

    Science.gov (United States)

    Teng, Jie; Zhou, Wen; Zeng, Zhen; Zhao, Wenfang; Huang, Yahui; Zhang, Xu

    2017-09-20

    Gamma (γ)-aminobutyric acid (GABA) green tea, with high GABA content, is a kind of special green tea. The goals of this study are to analyze the changes in quality components of green tea during anaerobic treatment, and to investigate whether or not the extract of GABA present in green tea can prevent depression or improve the depressive state of animals. Results showed that GABA content in green tea had increased significantly after anaerobic treatment. The contents of tea polysaccharides, total free amino acids, and water extracts were also increased whereas tea polyphenols were reduced. More importantly, the extract of GABA green tea could alleviate mouse depression and stress from desperate environments through the forced swim test (FST), tail suspension test (TST), mRNA and protein expression levels of GABA A receptors. Therefore, these results indicate that GABA green tea may have a health effect on prevention and alleviation of depression, and it works on the GABAergic neurotransmission of mouse cerebral cortex via up-regulating expression of the GABA A receptor α1 subunit, thus ameliorating depression.

  17. Conditional gene deletion reveals functional redundancy of GABAB receptors in peripheral nociceptors in vivo

    NARCIS (Netherlands)

    Gangadharan, Vijayan; Agarwal, Nitin; Brugger, Stefan; Tegeder, Imgard; Bettler, Bernhard; Kuner, Rohini; Kurejova, Martina

    2009-01-01

    BACKGROUND: gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter which mainly mediates its effects on neurons via ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. GABA(B) receptors are widely expressed in the central and the peripheral nervous system. Although there

  18. Tolerance to the sedative and anxiolytic effects of diazepam is associated with different alterations of GABAA receptors in rat cerebral cortex.

    Science.gov (United States)

    Ferreri, M C; Gutiérrez, M L; Gravielle, M C

    2015-12-03

    The clinical use of benzodiazepines is limited by the development of tolerance to their pharmacological effects. Tolerance to each of the pharmacological actions of benzodiazepines develops at different rates. The aim of this work was to investigate the mechanism of tolerance by performing behavioral tests in combination with biochemical studies. To this end, we administered prolonged treatments of diazepam to rats for 7 or 14 days. Tolerance to the sedative effects of diazepam was detected by means of the open field test after the 7- and 14-day treatments, whereas tolerance to the anxiolytic actions of benzodiazepine manifested following only the 14-day treatment in the elevated plus maze. The cerebral cortical concentrations of diazepam did not decline after the diazepam treatments, indicating that tolerance was not due to alterations in pharmacokinetic factors. The uncoupling of GABA/benzodiazepine site interactions and an increase in the degree of phosphorylation of the GABAA receptor γ2 subunit at serine 327 in the cerebral cortex were produced by day 7 of diazepam treatment and persisted after 14 days of exposure to benzodiazepine. Thus, these alterations could be part of the mechanism of tolerance to the sedative effects of diazepam. An increase in the percentage of α1-containing GABAA receptors in the cerebral cortex was observed following the 14-day treatment with diazepam but not the 7-day treatment, suggesting that tolerance to the anxiolytic effects is associated with a change in receptor subunit composition. The understanding of the molecular bases of tolerance could be important for the development of new drugs that maintain their efficacies over long-term treatments. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Upregulated GABA Inhibitory Function in ADHD Children with Child Behavior Checklist–Dysregulation Profile: 123I-Iomazenil SPECT Study

    Science.gov (United States)

    Nagamitsu, Shinichiro; Yamashita, Yushiro; Tanigawa, Hitoshi; Chiba, Hiromi; Kaida, Hayato; Ishibashi, Masatoshi; Kakuma, Tatsuyuki; Croarkin, Paul E.; Matsuishi, Toyojiro

    2015-01-01

    The child behavior checklist–dysregulation profile (CBCL–DP) refers to a pattern of elevated scores on the attention problems, aggression, and anxiety/depression subscales of the child behavior checklist. The aim of the present study was to investigate the potential role of GABA inhibitory neurons in children with attention deficit/hyperactivity disorder (ADHD) and dysregulation assessed with a dimensional measure. Brain single photon emission computed tomography (SPECT) was performed in 35 children with ADHD using 123I-iomazenil, which binds with high affinity to benzodiazepine receptors. Iomazenil binding activities were assessed with respect to the presence or absence of a threshold CBCL–DP (a score ≥210 for the sum of the three subscales: Attention Problems, Aggression, and Anxiety/Depression). We then attempted to identify which CBCL–DP subscale explained the most variance with respect to SPECT data, using “age,” “sex,” and “history of maltreatment” as covariates. Significantly higher iomazenil binding activity was seen in the posterior cingulate cortex (PCC) of ADHD children with a significant CBCL–DP. The Anxiety/Depression subscale on the CBCL had significant effects on higher iomazenil binding activity in the left superior frontal, middle frontal, and temporal regions, as well as in the PCC. The present brain SPECT findings suggest that GABAergic inhibitory neurons may play an important role in the neurobiology of the CBCL–DP, in children with ADHD. PMID:26082729

  20. Visualization of specific binding sites of benzodiazepine in human brain

    International Nuclear Information System (INIS)

    Shinotoh, H.; Yamasaki, T.; Inoue, O.; Itoh, T.; Suzuki, K.; Hashimoto, K.; Tateno, Y.; Ikehira, H.

    1986-01-01

    Using 11C-labeled Ro15-1788 and positron emission tomography, studies of benzodiazepine binding sites in the human brain were performed on four normal volunteers. Rapid and high accumulation of 11C activity was observed in the brain after i.v. injection of [11C]Ro15-1788, the maximum of which was within 12 min. Initial distribution of 11C activity in the brain was similar to the distribution of the normal cerebral blood flow. Ten minutes after injection, however, a high uptake of 11C activity was observed in the cerebral cortex and moderate uptake was seen in the cerebellar cortex, the basal ganglia, and the thalamus. The accumulation of 11C activity was low in the brain stem. This distribution of 11C activity was approximately parallel to the known distribution of benzodiazepine receptors. Saturation experiments were performed on four volunteers with oral administration of 0.3-1.8 mg/kg of cold Ro15-1788 prior to injection. Initial distribution of 11C activity following injection peaked within 2 min and then the accumulation of 11C activity decreased rapidly and remarkably throughout the brain. The results indicated that [11C] Ro15-1788 associates and dissociates to specific and nonspecific binding sites rapidly and has a high ratio of specific receptor binding to nonspecific binding in vivo. Carbon-11 Ro15-1788 is a suitable radioligand for the study of benzodiazepine receptors in vivo in humans

  1. An Overview of the CNS-Pharmacodynamic Profiles of Nonselective and Selective GABA Agonists

    Directory of Open Access Journals (Sweden)

    Xia Chen

    2012-01-01

    Full Text Available Various 2,3 subtype selective partial GABA-A agonists are in development to treat anxiety disorders. These compounds are expected to be anxiolytic with fewer undesirable side effects, compared to nonselective GABA-A agonists like benzodiazepines. Several 2,3 subtype selective and nonselective GABA-A agonists have been examined in healthy volunteers, using a battery addressing different brain domains. Data from five placebo-controlled double-blind studies were pooled. Lorazepam 2 mg was the comparator in three studies. Three 2,3-selective GABAA agonists (i.e., TPA023, TPACMP2, SL65.1498, one 1-selective GABAA agonists (zolpidem, and another full agonist (alprazolam were examined. Pharmacological selectivity was assessed by determination of regression lines for the change from baseline of saccadic-peak-velocity- (ΔSPV- relative effect, relative to changes in different pharmacodynamic endpoints (ΔPD. SPV was chosen for its sensitivity to the anxiolysis of benzodiazepines. Slopes of the ΔSPV-ΔPD relations were consistently lower with the 2,3 selective GABA-A agonists than with lorazepam, indicating that their PD effects are less than their SPV-effects. The ΔSPV-ΔPD relations of lorazepam were comparable to alprazolam. Zolpidem showed relatively higher impairments in ΔPD relative to ΔSPV, but did not significantly differ from lorazepam. These PD results support the pharmacological selectivity of the 2,3-selective GABA-A agonists, implying an improved therapeutic window.

  2. Regulation of (/sup 3/H)GABA release from strips of guinea pig urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Shirakawa, J.; Taniyama, K.; Iwai, S.; Tanaka, C.

    1988-12-01

    The presence of receptors that regulate the release of gamma-aminobutyric acid (GABA) was studied in strips of the guinea pig urinary bladder. GABA (10(-8)-10(-5) M) and muscimol (10(-8)-10(-5) M), but not baclofen (10(-5) M), reduced the Ca2+-dependent, tetrodotoxin-resistant release of (/sup 3/H)GABA evoked by high K+ from the urinary bladder strips preloaded with (/sup 3/H)GABA. The inhibitory effect of muscimol was antagonized by bicuculline and potentiated by diazepam, clonazepam, and pentobarbital sodium. The potentiating effect of clonazepam was antagonized by Ro 15-1788. Acetylcholine (ACh) inhibited the high K+-evoked release of (/sup 3/H)GABA. The inhibitory effect of ACh was antagonized by atropine sulfate and pirenzepine but not by hexamethonium. Norepinephrine (NE) inhibited the evoked release of (/sup 3/H)GABA. The inhibitory effect of NE was mimicked by clonidine, but not by phenylephrine, and was antagonized by yohimbine but not by prazosin. These results provide evidence that the release of GABA from strips of guinea pig urinary bladder is regulated via the bicuculline-sensitive GABAA receptor, M1-muscarinic, and alpha 2-adrenergic receptors.

  3. Repeated intermittent alcohol exposure during the third trimester-equivalent increases expression of the GABA(A) receptor δ subunit in cerebellar granule neurons and delays motor development in rats.

    Science.gov (United States)

    Diaz, Marvin R; Vollmer, Cyndel C; Zamudio-Bulcock, Paula A; Vollmer, William; Blomquist, Samantha L; Morton, Russell A; Everett, Julie C; Zurek, Agnieszka A; Yu, Jieying; Orser, Beverley A; Valenzuela, C Fernando

    2014-04-01

    Exposure to ethanol (EtOH) during fetal development can lead to long-lasting alterations, including deficits in fine motor skills and motor learning. Studies suggest that these are, in part, a consequence of cerebellar damage. Cerebellar granule neurons (CGNs) are the gateway of information into the cerebellar cortex. Functionally, CGNs are heavily regulated by phasic and tonic GABAergic inhibition from Golgi cell interneurons; however, the effect of EtOH exposure on the development of GABAergic transmission in immature CGNs has not been investigated. To model EtOH exposure during the 3rd trimester-equivalent of human pregnancy, neonatal pups were exposed intermittently to high levels of vaporized EtOH from postnatal day (P) 2 to P12. This exposure gradually increased pup serum EtOH concentrations (SECs) to ∼60 mM (∼0.28 g/dl) during the 4 h of exposure. EtOH levels gradually decreased to baseline 8 h after the end of exposure. Surprisingly, basal tonic and phasic GABAergic currents in CGNs were not significantly affected by postnatal alcohol exposure (PAE). However, PAE increased δ subunit expression at P28 as detected by immunohistochemical and western blot analyses. Also, electrophysiological studies with an agonist that is highly selective for δ-containing GABA(A) receptors, 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-ol (THIP), showed an increase in THIP-induced tonic current. Behavioral studies of PAE rats did not reveal any deficits in motor coordination, except for a delay in the acquisition of the mid-air righting reflex that was apparent at P15 to P18. These findings demonstrate that repeated intermittent exposure to high levels of EtOH during the equivalent of the last trimester of human pregnancy has significant but relatively subtle effects on motor coordination and GABAergic transmission in CGNs in rats. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Liver biomarker and in vitro assessment confirm the hepatic origin of aminotransferase elevations lacking histopathological correlate in beagle dogs treated with GABA{sub A} receptor antagonist NP260

    Energy Technology Data Exchange (ETDEWEB)

    Harrill, Alison H., E-mail: ahharrill@uams.edu [College of Public Health, The University of Arkansas for Medical Sciences, Little Rock, AR 72205 (United States); The Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Eaddy, John S. [The Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Rose, Kelly [The Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Cullen, John M. [College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607 (United States); Ramanathan, Lakshmi [QPS, Newark, DE 19711 (United States); Wanaski, Stephen; Collins, Stephen; Ho, Yu [NeuroTherapeutics Pharma, Inc., Chicago, IL 60631 (United States); Watkins, Paul B. [The Hamner-University of North Carolina Institute for Drug Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Schools of Pharmacy and Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); LeCluyse, Edward L. [The Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States)

    2014-06-01

    NP260 was designed as a first-in-class selective antagonist of α4-subtype GABA{sub A} receptors that had promising efficacy in animal models of pain, epilepsy, psychosis, and anxiety. However, development of NP260 was complicated following a 28-day safety study in dogs in which pronounced elevations of serum aminotransferase levels were observed, although there was no accompanying histopathological indication of hepatocellular injury. To further investigate the liver effects of NP260, we assayed stored serum samples from the 28-day dog study for liver specific miRNA (miR-122) as well as enzymatic biomarkers glutamate dehydrogenase and sorbitol dehydrogenase, which indicate liver necrosis. Cytotoxicity assessments were conducted in hepatocytes derived from dog, rat, and human liver samples to address the species specificity of the liver response to NP260. All biomarkers, except ALT, returned toward baseline by Day 29 despite continued drug treatment, suggesting adaptation to the initial injury. In vitro analysis of the toxicity potential of NP260 to primary hepatocytes indicated a relative sensitivity of dog > human > rat, which may explain, in part, why the liver effects were not evident in the rodent safety studies. Taken together, the data indicate that a diagnostic biomarker approach, coupled with sensitive in vitro screening strategies, may facilitate interpretation of toxicity potential when an adaptive event masks the underlying toxicity. - Highlights: • NP260 caused ALT elevations in dogs without evidence of hepatocellular injury. • SDH, GLDH, and miRNA-122 elevations occurred, confirming hepatocellular necrosis. • NP260 toxicity is greater in dog and human hepatocytes than in rat hepatocytes. • Species sensitivity may explain why the rodent studies failed to indicate risk. • Diagnostic biomarkers and hepatocyte studies aid interpretation of hepatotoxicity.

  5. Expression of GABAergic receptors in mouse taste receptor cells.

    Directory of Open Access Journals (Sweden)

    Margaret R Starostik

    Full Text Available BACKGROUND: Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD for gamma-aminobutyric acid (GABA is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABA(A and GABA(C or metabotropic receptors (GABA(B while it is terminated by the re-uptake of GABA through transporters (GATs. METHODOLOGY/PRINCIPAL FINDINGS: Using reverse transcriptase-PCR (RT-PCR analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs in the circumvallate papillae express multiple subunits of the GABA(A and GABA(B receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABA(A-and GABA(B- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds. CONCLUSIONS/SIGNIFICANCE: The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.

  6. Neuronal and non-neuronal GABA transporters as targets for antiepileptic drugs

    DEFF Research Database (Denmark)

    Madsen, Karsten K; White, H Steve; Schousboe, Arne

    2010-01-01

    Epileptic seizure activity is associated with an imbalance between excitatory and inhibitory synaptic activities. The latter is mediated by GABA, and several currently used antiepileptic drugs target entities of the GABAergic synapse such as the receptors or the inactivation mechanism consisting...... of transmembrane transport and enzymatic degradation. The development of tiagabine selectively inhibiting the GABA transporter GAT1 constitutes a proof of concept that the GABA transporters are interesting drug targets in the context of antiepileptic drugs. The review provides a detailed analysis of the role...... of such transporters pointing in particular to an interesting role of the transporters located extrasynaptically. It is suggested that the betaine-GABA transporter BGT1 should receive particular interest in this context as the GABA analogue EF 1502 (N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-4-(methylamino)-4...

  7. GAD65 is essential for synthesis of GABA destined for tonic inhibition regulating epileptiform activity

    DEFF Research Database (Denmark)

    Walls, Anne B; Nilsen, Linn Hege; Eyjolfsson, Elvar M

    2010-01-01

    ABSTRACT: GABA is synthesized from glutamate by glutamate decarboxylase (GAD), which exists in two isoforms, that is, GAD65 and GAD67. In line with GAD65 being located in the GABAergic synapse, several studies have demonstrated that this isoform is important during sustained synaptic transmission....... In contrast, the functional significance of GAD65 in the maintenance of GABA destined for extrasynaptic tonic inhibition is less well studied. Using GAD65-/- and wild type GAD65+/+ mice, this was examined employing the cortical wedge preparation, a model suitable for investigating extrasynaptic GABA......(A) receptor activity. An impaired tonic inhibition in GAD65-/- mice was revealed demonstrating a significant role of GAD65 in the synthesis of GABA acting extrasynaptically. The correlation between an altered tonic inhibition and metabolic events as well as the functional and metabolic role of GABA...

  8. Genotype-to-phenotype analysis: Search for clinical characteristics of a missense change in the GABA{sub A}-{beta}1 receptor gene

    Energy Technology Data Exchange (ETDEWEB)

    Sobell, J.L.; Sigurdson, D.C.; Sommer, S.S. [Univ. of Washington, Seattle (United States)] [and others

    1996-02-16

    Genotype-to-phenotype analysis reverses the classical approach to genetic disease in which an unknown genotype is sought for a known phenotype. This paper provides an example of genotype-to-phenotype analysis for the possible psychiatric effects of a missense mutation (H396Q) at a highly conserved residue of the {Beta}1 subunit gene of the gamma aminobutyric acid type A receptor. DNA samples from 1,507 Caucasians of Western European descent were screened, and 10 heterozygotes for H396Q were identified. These individuals were matched to homozygous normal individuals by age, gender, and length of available medical records. The complete medical records of these 20 individuals were reviewed blindly by two psychiatrists (D.C.S., L.L.H.) to assess psychiatric symptomatology, with an emphasis on anxiety and related disorders. However, no association was found between this missense change at a conserved amino acid and a dominant neuropsychiatric disease phenotype. Thus, this missense change may be neutral or only mildly deleterious, may only cause recessive disease in rare individuals, or may interact epistatically with some other gene(s). 17 refs.

  9. Conformational, vibrational and DFT studies of a newly synthesized arylpiperazine-based drug and evaluation of its reactivity towards the human GABA receptor

    Science.gov (United States)

    Onawole, A. T.; Al-Ahmadi, A. F.; Mary, Y. S.; Panicker, C. Y.; Ullah, N.; Armaković, S.; Armaković, S. J.; Van Alsenoy, C.; Al-Saadi, A. A.

    2017-11-01

    This study reports a computational assessment of important biochemical properties and vibrational assignments for the synthesized 1-(4-(3-methoxy-4-nitrophenyl)piperazin-1-yl)ethanone (MNPE). MNPE is related to the commonly used arylpiperazine-based drugs that exhibit a wide range of pharmacological activities. The characterization of MNPE is based on the readily sighted 1363 cm-1 infrared band (associated with piperazine ring stretching), 1308 cm-1 Raman line (associated with the phenyl ring breathing), 1242 cm-1 Raman line and 1092 cm-1 infrared band (both associated with Csbnd N stretching) as key modes in its vibrational spectra. First principle calculations revealed that MNPE could exist in sixteen different plausible conformations, which were used as basis to understand the possible molecular docking mechanism of the molecule as an agonist in the human GABAA receptor. The best binding scenarios showed the presence of intramolecular hydrogen bonding in MNPE and was comparable with the most stable configuration. It was further evaluated for its reactivity properties by utilizing the concepts of Average Local Ionization Energies (ALIE) and Fukui functions. The autoxidation and hydrolysis degradation likelihood of MNPE estimated from the computed bond dissociation energies and radial distribution functions predicted that MNPE is to be readily biodegradable in aqueous solutions.

  10. Paradoxical effects of GABA-A modulators may explain sex steroid induced negative mood symptoms in some persons

    NARCIS (Netherlands)

    Bäckström, T.; Haage, D.; Löfgren, M.; Johansson, I. M.; Strömberg, J.; Nyberg, S.; Andréen, L.; Ossewaarde, L.; van Wingen, G. A.; Turkmen, S.; Bengtsson, S. K.

    2011-01-01

    Some women have negative mood symptoms, caused by progestagens in hormonal contraceptives or sequential hormone therapy or by progesterone in the luteal phase of the menstrual cycle, which may be attributed to metabolites acting on the GABA-A receptor. The GABA system is the major inhibitory system

  11. Does extracellular calcium determine what pool of GABA is the target for alpha-latrotoxin?

    Science.gov (United States)

    Storchak, L G; Linetska, M V; Himmelreich, N H

    2002-04-01

    Presynaptic neurotoxin alpha-latrotoxin, from the venom of Latrodectus mactans tredecimguttatus, causes massive [(3)H]GABA release from rat brain synaptosomes, irrespective of calcium presence in the extracellular medium. Whether the binding of alpha-latrotoxin to Ca(2+)-dependent (neurexin 1 alpha) or to Ca(2+)-independent (latrophilin) receptor triggers [(3)H]GABA release by the same mechanisms or different ones, inducing either exocytotic process or outflow by mobile membrane GABA transporter, is unknown. We examined alpha-latrotoxin-evoked [(3)H]GABA release from synaptosomes which cytosolic [(3)H]GABA pool was depleted either by applying competitive inhibitors of the GABA transporter, nipecotic acid and 2,4-diaminobutyric acid, or by permeation with digitonin. We also compared the effect of the GABA transporter inhibitors on depolarisation-evoked and alpha-latrotoxin-evoked [(3)H]GABA release using as depolarising agents 4-aminopyridine and high KCl in the Ca(2+)-containing and in Ca(2+)-free medium, respectively. Incubation of synaptosomes with nipecotic acid induced the essential acceleration of unstimulated [(3)H]GABA release and deep inhibition of high KCl-evoked Ca(2+)-independent [(3)H]GABA release. In contrast, at the similar conditions the effect of alpha-latrotoxin was greatly augmented with respect to the control response. Another way to assay what GABA pool was involved in alpha-latrotoxin-induced release lays in an analysis of the effects of depolarisation and alpha-latrotoxin in consecutive order. The preliminary 4-aminopyridine-stimulated [(3)H]GABA release attenuated the toxin effect. But when depolarisation occurred in Ca(2+)-free medium, no influence on alpha-latrotoxin effect was revealed. Employing digitonin-permeated synaptosomes, we have shown that alpha-latrotoxin could stimulate [3H]GABA release in the medium with 1mM EGTA, this effect of the toxin was blocked by concanavalin A and was ATP-dependent. The latter suggests that alpha

  12. Quantitative autoradiographic characterization of GA-BAB receptors in mammalian central nervous system

    International Nuclear Information System (INIS)

    Chu, D.Chin-Mei.

    1989-01-01

    The inhibitory effects of the amino acid neurotransmitter γ-aminobutyric acid (GABA) within the nervous system appear to be mediated through two distinct classes of receptors: GABA A and GABA B receptors. A quantitative autoradiographic method with 3 H-GABA was developed to examine the hypotheses that GABA A and GABA B sites have distinct anatomical distributions, pharmacologic properties, and synaptic localizations within the rodent nervous system. The method was also applied to a comparative study of these receptors in postmortem human brain from individuals afflicted with Alzheimer's disease and those without neurologic disease. The results indicated that GABA B receptors occur in fewer numbers and have a lower affinity for GABA than GABA A receptors in both rodent and human brain. Within rodent brain, the distribution of these two receptor populations were clearly distinct. GABA B receptors were enriched in the medial habenula, interpeduncular nucleus, cerebellar molecular layer and olfactory glomerular layer. After selective lesions of postsynaptic neurons of the corticostriatal and perforant pathway, both GABA B and GABA A receptors were significantly decreased in number. Lesions of the presynaptic limbs of the perforant but not the corticostriatal pathway resulted in upregulation of both GABA receptors in the area of innervation. GABA B receptors were also upregulated in CA3 dendritic regions after destruction of dentate granule neurons

  13. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons

    Science.gov (United States)

    Korol, Sergiy V.; Jin, Zhe; Birnir, Bryndis

    2015-01-01

    Glucagon-like peptide-1 (GLP-1) is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM), an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC) amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM) plus diazepam (1 μM), only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons. PMID:25927918

  14. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons.

    Directory of Open Access Journals (Sweden)

    Sergiy V Korol

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM, an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM plus diazepam (1 μM, only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons.

  15. Attention Span, Anxiety and Benzodiazepine Receptors

    Science.gov (United States)

    1991-02-26

    represent a new class of nootropic druos witn a s9intricant clinical potential. 2 FINAL TECHNICAL REPORT ON GRANT AFOSR-87-0364 ENTITLED "ATTENTION SPAN...acquisition and retention of novel aversively motivated goal-directed behavior. This nootropic action may be linked to the flumazenil enhanced brain...metabolism, as revealed by oxygen utilization in the rat forebrain [32]. The nootropic effect may also be linked to increased protein synthesis in the CNS, an

  16. Reducing Prescriptions of Long-acting Benzodiazepine Drugs in Denmark

    DEFF Research Database (Denmark)

    Eriksen, Sophie Isabel; Bjerrum, Lars

    2015-01-01

    Prolonged consumption of benzodiazepine drugs (BZD) and benzodiazepine receptor agonists (zolpidem, zaleplon, zopiclone; altogether Z drugs) is related to potential physiological and psychological dependence along with other adverse effects. This study aimed to analyse the prescribing of long......-acting BZD (half-life >10 hr), compared to short-acting BZD in Denmark during a 10-year period. Descriptive analysis of total sales data from the Danish Register of Medicinal Product Statistics, to individuals in the primary healthcare sector, of all BZD and Z-drugs in the period of 2003-2013. Prescription...... inhabitants/day in 2003 to 16.4 DDD/1000 inhabitants/day in 2013; a relative reduction of 37%. Prescription data in this study did not include information about indications for initiating treatments. In addition, due to compliance problems, some of the prescribed drugs may not have been consumed according...

  17. Effects of chronic delta-9-tetrahydrocannabinol (THC) administration on neurotransmitter concentrations and receptor binding in the rat brain

    International Nuclear Information System (INIS)

    Ali, S.F.; Newport, G.D.; Scallet, A.C.; Gee, K.W.; Paule, M.G.; Brown, R.M.; Slikker, W. Jr.

    1989-01-01

    THC is the major psychoactive constituent of marijuana and is also known as an hallucinogenic compound. Numerous reports have shown that large doses of THC produce significant alterations in various neurotransmitter systems. The present study was designed to determine whether chronic exposure to THC produces significant alterations in selected neurotransmitter systems (dopamine, serotonin, acetylcholine, GABAergic, benzodiazepine, and opiate) in the rat brain. In Experiment 1, male Sprague-Dawley rats were gavaged with vehicle, 10 or 20 mg THC/kg body weight daily, 5 days/week for 90 days. Animals were killed either 24 hours or two months after the last dose. Brains were dissected into different regions for neurochemical analyses. Two months after the cessation of chronic administration, there was a significant decrease in GABA receptor binding in the hippocampus of animals in the high dose group. However, no other significant changes were found in neurotransmitter receptor binding characteristics in the hippocampus or in neurotransmitter concentrations in the caudate nucleus, hypothalamus or septum after chronic THC administration. In an attempt to replicate the GABA receptor binding changes and also to determine the [35S]TBPS binding in hippocampus, we designed Experiment 2. In this experiment, we dosed the animals by gavage with 0, 5, 10 or 20 mg THC/kg daily, 5 days/week or with 20 mg THC/kg Monday through Thursday and 60 mg/kg on Friday for 90 days. Results from this experiment failed to replicate the dose-dependent effect of THC on GABA receptor binding in hippocampus. Modulation of [35S]TBPS binding by GABA or 3 alpha-OH-DHP or inhibition by cold TBPS in frontal cortex did not show any significant dose-related effects

  18. Effects of chronic delta-9-tetrahydrocannabinol (THC) administration on neurotransmitter concentrations and receptor binding in the rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S.F.; Newport, G.D.; Scallet, A.C.; Gee, K.W.; Paule, M.G.; Brown, R.M.; Slikker, W. Jr. (National Center for Toxicological Research, Jefferson, Arkansas (USA))

    THC is the major psychoactive constituent of marijuana and is also known as an hallucinogenic compound. Numerous reports have shown that large doses of THC produce significant alterations in various neurotransmitter systems. The present study was designed to determine whether chronic exposure to THC produces significant alterations in selected neurotransmitter systems (dopamine, serotonin, acetylcholine, GABAergic, benzodiazepine, and opiate) in the rat brain. In Experiment 1, male Sprague-Dawley rats were gavaged with vehicle, 10 or 20 mg THC/kg body weight daily, 5 days/week for 90 days. Animals were killed either 24 hours or two months after the last dose. Brains were dissected into different regions for neurochemical analyses. Two months after the cessation of chronic administration, there was a significant decrease in GABA receptor binding in the hippocampus of animals in the high dose group. However, no other significant changes were found in neurotransmitter receptor binding characteristics in the hippocampus or in neurotransmitter concentrations in the caudate nucleus, hypothalamus or septum after chronic THC administration. In an attempt to replicate the GABA receptor binding changes and also to determine the (35S)TBPS binding in hippocampus, we designed Experiment 2. In this experiment, we dosed the animals by gavage with 0, 5, 10 or 20 mg THC/kg daily, 5 days/week or with 20 mg THC/kg Monday through Thursday and 60 mg/kg on Friday for 90 days. Results from this experiment failed to replicate the dose-dependent effect of THC on GABA receptor binding in hippocampus. Modulation of (35S)TBPS binding by GABA or 3 alpha-OH-DHP or inhibition by cold TBPS in frontal cortex did not show any significant dose-related effects.

  19. Synthesis and anticonvulsant activity of N-3 substituted 2,3-benzodiazepines.

    Science.gov (United States)

    Quartarone, Silvana; Caruso, Roberta; Orlando, Valèrie; Russo, Emilio; De Sarro, Giovambattista; Chimirri, Alba

    2004-05-01

    A series of new 3-alkylcarbamoyl-1-aryl-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-ones was synthesized starting from the corresponding 3-N-unsubstituted derivatives, previously described as noncompetitive AMPA-type glutamate receptor antagonists. The new compounds proved to protect against seizures induced by means of auditory stimulation in DBA/2 mice and some of them showed anticonvulsant properties comparable or better than those of GYKI 52466, the prototype of 2,3-benzodiazepine noncompetitive AMPA receptor antagonists. Copyright 2004 Elsevier SAS

  20. Muscarinic control of rostromedial tegmental nucleus GABA neurons and morphine-induced locomotion.

    Science.gov (United States)

    Wasserman, David I; Tan, Joel M J; Kim, Jun Chul; Yeomans, John S

    2016-07-01

    Opioids induce rewarding and locomotor effects by inhibiting rostromedial tegmental GABA neurons that express μ-opioid and nociceptin receptors. These GABA neurons then strongly inhibit dopamine neurons. Opioid-induced reward, locomotion and dopamine release also depend on pedunculopontine and laterodorsal tegmental cholinergic and glutamate neurons, many of which project to and activate ventral tegmental area dopamine neurons. Here we show that laterodorsal tegmental and pedunculopontine cholinergic neurons project to both rostromedial tegmental nucleus and ventral tegmental area, and that M4 muscarinic receptors are co-localized with μ-opioid receptors associated with rostromedial tegmental GABA neurons. To inhibit or excite rostromedial tegmental GABA neurons, we utilized adeno-associated viral vectors and DREADDs to express designed muscarinic receptors (M4D or M3D respectively) in GAD2::Cre mice. In M4D-expressing mice, clozapine-N-oxide increased morphine-induced, but not vehicle-induced, locomotion. In M3D-expressing mice, clozapine-N-oxide blocked morphine-induced, but not vehicle-induced, locomotion. We propose that cholinergic inhibition of rostromedial tegmental GABA neurons via M4 muscarinic receptors facilitates opioid inhibition of the same neurons. This model explains how mesopontine cholinergic systems and muscarinic receptors in the rostromedial tegmental nucleus and ventral tegmental area are important for dopamine-dependent and dopamine-independent opioid-induced rewards and locomotion. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  1. GABA(A) Increases Calcium in Subventricular Zone Astrocyte-Like Cells Through L- and T-Type Voltage-Gated Calcium Channels

    DEFF Research Database (Denmark)

    Young, Stephanie Z; Platel, Jean-Claude; Nielsen, Jakob V

    2010-01-01

    intracellular Ca(2+) dynamics in SVZ astrocytes. To monitor Ca(2+) activity selectively in astrocyte-like cells, we used two lines of transgenic mice expressing either GFP fused to a Gq-coupled receptor or DsRed under the human glial fibrillary acidic protein (hGFAP) promoter. GABA(A) receptor activation......In the adult neurogenic subventricular zone (SVZ), the behavior of astrocyte-like cells and some of their functions depend on changes in intracellular Ca(2+) levels and tonic GABA(A) receptor activation. However, it is unknown whether, and if so how, GABA(A) receptor activity regulates......-like cells to 75%, suggesting that the majority of SVZ astrocytes express functional VGCCs. SVZ astrocytes also displayed spontaneous Ca(2+) activity, the frequency of which was regulated by tonic GABA(A) receptor activation. These data support a role for ambient GABA in tonically regulating intracellular Ca...

  2. Benzodiazepines and postoperative cognitive dysfunction in the elderly

    DEFF Research Database (Denmark)

    Rasmussen, L.S.; Steentoft, Anni; Rasmussen, H.

    1999-01-01

    hypnotics benzodiazepine,diazepam,age factor,anaesthesia,geriatric,psychological responses,postoperative......hypnotics benzodiazepine,diazepam,age factor,anaesthesia,geriatric,psychological responses,postoperative...

  3. (R)-(3-amino-2-fluoropropyl) phosphinic acid (AZD3355), a novel GABAB receptor agonist, inhibits transient lower esophageal sphincter relaxation through a peripheral mode of action

    DEFF Research Database (Denmark)

    Lehmann, Anders; Antonsson, Madeleine; Holmberg, Ann Aurell

    2009-01-01

    recombinant human GABA transporters. AR-H061719 [(R/S)-(3-amino-2-fluoropropyl)phosphinic acid], (the racemate of AZD3355) inhibited the response of ferret mechanoreceptors to gastric distension, further supporting its peripheral site of action on TLESR. In summary, AZD3355 probably inhibits TLESR through...

  4. Mapping of the {alpha}{sub 4} subunit gene (GABRA4) to human chromosome 4 defines an {alpha}{sub 2}-{alpha}{sub 4}-{beta}{sub 1}-{gamma}{sub 1} gene cluster: Further evidence that modern GABA{sub a} receptor gene clusters are derived from an ancestral cluster

    Energy Technology Data Exchange (ETDEWEB)

    McLean, P.J.; Farb, D.H.; Russek, S.J. [Boston Univ. School of Medicine, MA (United States)] [and others

    1995-04-10

    We demonstrated previously that an {alpha}{sub 1}-{beta}{sub 2}-{gamma}{sub 2} gene cluster of the {gamma}-aminobutyric acid (GABA{sub A}) receptor is located on human chromosome 5q34-q35 and that an ancestral {alpha}-{beta}-{gamma} gene cluster probably spawned clusters on chromosomes 4, 5, and 15. Here, we report that the {alpha}{sub 4} gene (GABRA4) maps to human chromosome 4p14-q12, defining a cluster comprising the {alpha}{sub 2}, {alpha}{sub 4}, {beta}{sub 1}, and {gamma}{sub 1} genes. The existence of an {alpha}{sub 2}-{alpha}{sub 4}-{beta}{sub 1}-{gamma}{sub 2} cluster on chromosome 4 and an {alpha}{sub 1}-{alpha}{sub 6}-{beta}{sub 2}-{gamma}{sub 2} cluster on chromosome 5 provides further evidence that the number of ancestral GABA{sub A} receptor subunit genes has been expanded by duplication within an ancestral gene cluster. Moreover, if duplication of the {alpha} gene occurred before duplication of the ancestral gene cluster, then a heretofore undiscovered subtype of a subunit should be located on human chromosome 15q11-q13 within an {alpha}{sub 5}-{alpha}{sub x}-{beta}{sub 3}-{gamma}{sub 3} gene cluster at the locus for Angelman and Prader-Willi syndromes. 34 refs., 6 figs., 1 tab.

  5. Anaesthetic Impairment of Immune Function Is Mediated via GABAA Receptors

    Science.gov (United States)

    Wheeler, Daniel W.; Thompson, Andrew J.; Corletto, Federico; Reckless, Jill; Loke, Justin C. T.; Lapaque, Nicolas; Grant, Andrew J.; Mastroeni, Pietro; Grainger, David J.; Padgett, Claire L.; O'Brien, John A.; Miller, Nigel G. A.; Trowsdale, John

    2011-01-01

    Background GABAA receptors are members of the Cys-loop family of neurotransmitter receptors, proteins which are responsible for fast synaptic transmission, and are the site of action of wide range of drugs [1]. Recent work has shown that Cys-loop receptors are present on immune cells, but their physiological roles and the effects of drugs that modify their function in the innate immune system are currently unclear [2]. We are interested in how and why anaesthetics increase infections in intensive care patients; a serious problem as more than 50% of patients with severe sepsis will die [3]–[6]. As many anaesthetics act via GABAA receptors [7], the aim of this study was to determine if these receptors are present on immune cells, and could play a role in immunocompromising patients. Principal Findings We demonstrate, using RT-PCR, that monocytes express GABAA receptors constructed of α1, α4, β2, γ1 and/or δ subunits. Whole cell patch clamp electrophysiological studies show that GABA can activate these receptors, resulting in the opening of a chloride-selective channel; activation is inhibited by the GABAA receptor antagonists bicuculline and picrotoxin, but not enhanced by the positive modulator diazepam. The anaesthetic drugs propofol and thiopental, which can act via GABAA receptors, impaired monocyte function in classic immunological chemotaxis and phagocytosis assays, an effect reversed by bicuculline and picrotoxin. Significance Our results show that functional GABAA receptors are present on monocytes with properties similar to CNS GABAA receptors. The functional data provide a possible explanation as to why chronic propofol and thiopental administration can increase the risk of infection in critically ill patients: their action on GABAA receptors inhibits normal monocyte behaviour. The data also suggest a potential solution: monocyte GABAA receptors are insensitive to diazepam, thus the use of benzodiazepines as an alternative anesthetising agent may be

  6. GABA and Topiramate Inhibit the Formation of Human Macrophage-Derived Foam Cells by Modulating Cholesterol-Metabolism-Associated Molecules

    Directory of Open Access Journals (Sweden)

    Ying Yang

    2014-04-01

    Full Text Available Aims: γ-aminobutyric acid (GABA, the principal inhibitory neurotransmitter, acts on GABA receptors to play an important role in the modulation of macrophage functions. The present study examined the effects of GABA and a GABA receptor agonist on modulating cholesterol-metabolism-associated molecules in human monocyte-derived macrophages (HMDMs. Methods: ORO stain, HPLC, qRT-PCR, Western blot and EMSA were carried out using HMDMs exposed to ox-LDL with or without GABAergic agents as the experimental model. Results: GABA and topiramate reduced the percentage of cholesterol ester in lipid-laden HMDMs by down-regulating SR-A, CD36 and LOX-1 expression and up-regulating ABCA1, ABCG1 and SR-BI expression in lipid-laden HMDMs. The production of TNF-a was decreased in GABA-and topiramate-treated lipid-laden HMDMs, and levels of interleukin (IL-6 did not change. The activation of two signaling pathways, p38MAPK and NF-γB, was repressed by GABA and topiramate in lipid-laden HMDMs. Conclusion: GABA and topiramate inhibit the formation of human macrophage-derived foam cells and may be a possibility for macrophage targeted therapy of atherosclerotic lesions.

  7. GABA Shunt in Durum Wheat

    Directory of Open Access Journals (Sweden)

    Petronia Carillo

    2018-02-01

    Full Text Available Plant responses to salinity are complex, especially when combined with other stresses, and involve many changes in gene expression and metabolic fluxes. Until now, plant stress studies have been mainly dealt only with a single stress approach. However, plants exposed to multiple stresses at the same time, a combinatorial approach reflecting real-world scenarios, show tailored responses completely different from the response to the individual stresses, due to the stress-related plasticity of plant genome and to specific metabolic modifications. In this view, recently it has been found that γ-aminobutyric acid (GABA but not glycine betaine (GB is accumulated in durum wheat plants under salinity only when it is combined with high nitrate and high light. In these conditions, plants show lower reactive oxygen species levels and higher photosynthetic efficiency than plants under salinity at low light. This is certainly relevant because the most of drought or salinity studies performed on cereal seedlings have been done in growth chambers under controlled culture conditions and artificial lighting set at low light. However, it is very difficult to interpret these data. To unravel the reason of GABA accumulation and its possible mode of action, in this review, all possible roles for GABA shunt under stress are considered, and an additional mechanism of action triggered by salinity and high light suggested.

  8. GABA Shunt in Durum Wheat.

    Science.gov (United States)

    Carillo, Petronia

    2018-01-01

    Plant responses to salinity are complex, especially when combined with other stresses, and involve many changes in gene expression and metabolic fluxes. Until now, plant stress studies have been mainly dealt only with a single stress approach. However, plants exposed to multiple stresses at the same time, a combinatorial approach reflecting real-world scenarios, show tailored responses completely different from the response to the individual stresses, due to the stress-related plasticity of plant genome and to specific metabolic modifications. In this view, recently it has been found that γ-aminobutyric acid (GABA) but not glycine betaine (GB) is accumulated in durum wheat plants under salinity only when it is combined with high nitrate and high light. In these conditions, plants show lower reactive oxygen species levels and higher photosynthetic efficiency than plants under salinity at low light. This is certainly relevant because the most of drought or salinity studies performed on cereal seedlings have been done in growth chambers under controlled culture conditions and artificial lighting set at low light. However, it is very difficult to interpret these data. To unravel the reason of GABA accumulation and its possible mode of action, in this review, all possible roles for GABA shunt under stress are considered, and an additional mechanism of action triggered by salinity and high light suggested.

  9. Inflammatory mediators potentiate high affinity GABA(A) currents in rat dorsal root ganglion neurons.

    Science.gov (United States)

    Lee, Kwan Yeop; Gold, Michael S

    2012-06-19

    Following acute tissue injury action potentials may be initiated in afferent processes terminating in the dorsal horn of the spinal cord that are propagated back out to the periphery, a process referred to as a dorsal root reflex (DRR). The DRR is dependent on the activation of GABA(A) receptors. The prevailing hypothesis is that DRR is due to a depolarizing shift in the chloride equilibrium potential (E(Cl)) following an injury-induced activation of the Na(+)-K(+)-Cl(-)-cotransporter. Because inflammatory mediators (IM), such as prostaglandin E(2) are also released in the spinal cord following tissue injury, as well as evidence that E(Cl) is already depolarized in primary afferents, an alternative hypothesis is that an IM-induced increase in GABA(A) receptor mediated current (I(GABA)) could underlie the injury-induced increase in DRR. To test this hypothesis, we explored the impact of IM (prostaglandin E(2) (1 μM), bradykinin (10 μM), and histamine (1 μM)) on I(GABA) in dissociated rat dorsal root ganglion (DRG) neurons with standard whole cell patch clamp techniques. IM potentiated I(GABA) in a subpopulation of medium to large diameter capsaicin insensitive DRG neurons. This effect was dependent on the concentration of GABA, manifest only at low concentrations (emergence of injury-induced DRR. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  10. The role of GABA in the hypoxia tolerance of the epaulette shark

    International Nuclear Information System (INIS)

    Wise, G.; Mulvey, J.; Renshaw, G.M.C.; Dodd, P.R.

    1998-01-01

    Full text: The epaulette shark responds to hypoxia with brain hypometabolism which is correlated with increased levels of gamma-aminobutyric acid (GABA). We examined GABA-like immunoreactivity (GABA-IR) and the density and binding characteristics of GABA A receptors in the Epaulette shark brainstem. These studies were conducted to investigate changes in response to hypoxia. Experimental animals were exposed to eight cycles of an extreme hypoxic regimen (5% of normoxia). Animals were anaesthetised with 80mg/L of MS222 and the brain was dissected and processed either for immunohistochemistry or receptor ligand binding. Membranes were prepared at 4 deg C according to a previously reported protocol and the binding characteristics of [ 3 H]flunitrazeparn ([ 3 H]FNZ) were examined using an in vitro centrifugation assay. We report on the effect of hypoxia on specific [ 3 H]FNZ binding characteristics. GABA-IR was detected using a primary antibody dilution of 1:15 000 and the Vector ABC method. We report that an overall increase in the optical density of GABA-IR occurs with significant increases in three out of the four brainstem nuclei examined in experimental animals. The results of these studies are discussed in conjunction with the hypoxia-tolerance .of the epaulette shark. Copyright (1998) Australian Neuroscience Society

  11. A selective, non-peptide CRF receptor 1 antagonist prevents sodium lactate-induced acute panic-like responses.

    Science.gov (United States)

    Shekhar, Anantha; Johnson, Philip L; Fitz, Stephanie D; Nakazato, Atsuro; Chaki, Shigeyuki; Steckler, Thomas; Schmidt, Mark

    2011-04-01

    Corticotropin releasing factor (CRF) is implicated in a variety of stress-related disorders such as depression and anxiety, and blocking CRF receptors is a putative strategy for treating such disorders. Using a well-studied animal model of panic, we tested the efficacy of JNJ19567470/CRA5626, a selective, non-peptidergic CRF type 1 receptor (CRF1) antagonist (3, 10 and 40 mg/kg intraperitoneal injection), in preventing the sodium lactate (NaLac)-induced panic-like behavioural and cardiovascular responses. Adult male rats with chronic reduction of GABA levels (by inhibition of GABA synthesis with l-allyglycine, a glutamic acid decarboxylase inhibitor) in the dorsomedial/perifornical hypothalamus are highly anxious and exhibit physiological and behavioural responses to intravenous NaLac infusions similar to patients with panic disorder. These 'panic-prone' rats pre-treated with vehicle injections displayed NaLac-induced increases in autonomic responses (i.e. tachycardia and hypertensive responses), anxiety-like behaviour in the social interaction test, and flight-like increases in locomotor activity. However, systemically injecting such panic-prone rats with the highest dose of CRF1 receptor antagonist prior to NaLac infusions blocked all NaLac-induced behaviour and cardiovascular responses. These data suggest that selective CRF1 receptor antagonists could be a novel target for developing anti-panic drugs that are as effective as benzodiazepines in acute treatment of a panic attack without the deleterious side-effects (e.g. sedation and cognitive impairment) associated with benzodiazepines.

  12. Sleep-promoting effects of the GABA/5-HTP mixture in vertebrate models.

    Science.gov (United States)

    Hong, Ki-Bae; Park, Yooheon; Suh, Hyung Joo

    2016-09-01

    The aim of this study was to investigate the sleep-promoting effect of combined γ-aminobutyric acid (GABA) and 5-hydroxytryptophan (5-HTP) on sleep quality and quantity in vertebrate models. Pentobarbital-induced sleep test and electroencephalogram (EEG) analysis were applied to investigate sleep latency, duration, total sleeping time and sleep quality of two amino acids and GABA/5-HTP mixture. In addition, real-time PCR and HPLC analysis were applied to analyze the signaling pathway. The GABA/5-HTP mixture significantly regulated the sleep latency, duration (pHTP mixture modulates both GABAergic and serotonergic signaling. Moreover, the sleep architecture can be controlled by the regulation of GABAA receptor and GABA content with 5-HTP. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. [Local GABA-ergic modulation of serotonergic neuron activity in the nucleus raphe magnus].

    Science.gov (United States)

    Iniushkin, A N; Merkulova, N A; Orlova, A O; Iniushkina, E M

    2009-07-01

    In voltage-clamp experimental on slices of the rat brainstem the effects of 5-HT and GABA on serotonergic neurons of nucleus raphe magnus were investigated. Local applications of 5-HT induced an increase in IPCSs frequency and amplitude in 45% of serotonergic cells. The effect suppressed by the blocker of fast sodium channels tetradotoxin. Antagonist of GABA receptor gabazine blocked IPSCs in neurons both sensitive and non-sensitive to 5-HT action. Applications of GABA induced a membrane current (I(GABA)), which was completely blocked by gabazine. The data suggest self-control of the activity of serotonergic neurons in nucleus raphe magnus by negative feedback loop via local GABAergic interneurons.

  14. Uptake and release of [14C] GABA from rabbit retina synaptosomes

    International Nuclear Information System (INIS)

    Redburn, D.A.

    1977-01-01

    A partial separation of two synaptosomal fractions was achieved using modifications of conventional homogenization and centrifugation techniques. The two fractions contained morphologically distinct synaptosomal populations, receptor cell synaptosomes (large synaptosomes, P 1 ), and synaptosomes from the other cell types (smaller, conventional-sized synaptosomes, P 2 ). [ 14 C]GABA was bound and released from subcellular fractions from retina under conditions which support its role as a neurotransmitter in retina. On the other hand, [ 3 H]leucine, which is very likely a non-transmitter compound, was bound by retinal fractions but not released to the appropriate stimulation. [ 14 C]GABA binding and release sites were more prevalent in P 2 fractions. [ 14 C]GABA was bound by P 1 fractions containing photoreceptor synaptosomes; however, the K + stimulated release of [ 14 C]GABA appeared to be insensitive to external Ca 2+ . Possible mechanisms are discussed. (author)

  15. Upregulated GABA inhibitory function in AD/HD children with Child Behavior Checklist–Dysregulation Profile: 123I-iomazenil SPECT study

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    Shinichiro eNagamitsu

    2015-06-01

    Full Text Available The Child Behavior Checklist–Dysregulation Profile (CBCL-DP refers to a pattern of elevated scores on the Attention Problems, Aggression, and Anxiety/Depression subscales of the Child Behavior Checklist. The aim of the present study was to investigate the potential role of GABA inhibitory neurons in children with attention deficit/hyperactivity disorder (AD/HD and dysregulation assessed with a dimensional measure. Brain single photon emission computed tomography (SPECT was performed in 35 children with AD/HD using 123I-iomazenil, which binds with high affinity to benzodiazepine receptors. Iomazenil binding activities were assessed with respect to the presence or absence of a threshold CBCL-DP (a score ≥210 for the sum of the three subscales Attention Problems, Aggression, and Anxiety/Depression. We then attempted to identify which CBCL-DP subscale explained the most variance with respect to SPECT data, using age, sex, and history of maltreatment as covariates. Significantly higher iomazenil binding activity was seen in the posterior cingulate cortex (PCC of AD/HD children with a significant CBCL-DP. The Anxiety/Depression subscale on the CBCL had significant effects on higher iomazenil binding activity in the left superior frontal, middle frontal, and temporal regions, as well as in the PCC. The present brain SPECT findings suggest that GABAergic inhibitory neurons may play an important role in the neurobiology of the CBCL-DP, in children with ADHD.

  16. The glutamate/GABA-glutamine cycle

    DEFF Research Database (Denmark)

    Bak, Lasse K; Schousboe, Arne; Waagepetersen, Helle S

    2006-01-01

    or GABA from neurons and subsequent uptake into astrocytes. In return, astrocytes release glutamine to be taken up into neurons for use as neurotransmitter precursor. In this review, the basic properties of the glutamate/GABA-glutamine cycle will be discussed, including aspects of transport and metabolism...... of intercellular transfer of ammonia produced in neurons (when glutamine is deamidated to glutamate) and utilized in astrocytes (for amidation of glutamate) when the glutamate/GABA-glutamine cycle is operating. A main objective of this review is to endorse the view that the glutamate/GABA-glutamine cycle must...

  17. Benzodiazepines and related drugs for insomnia in palliative care.

    Science.gov (United States)

    Hirst, A; Sloan, R

    2002-01-01

    Insomnia, a subjective complaint of poor sleep and associated impairment in daytime function, is a common problem. Currently, benzodiazepines are the most used pharmacological treatment for this complaint. They are considered helpful for occasional short-term use up to four weeks but longer term use is not advised due to potential problems regarding tolerance, dosing escalation, psychological addiction and physical dependence. There is no consensus on their utility in patients with progressive incurable conditions who may require assistance with sleep for many weeks as their condition deteriorates. To assess the effectiveness and safety of benzodiazepines or benzodiazepine receptor agonists such as Zolpidem, Zopiclone and Zaleplon for insomnia in palliative care. Several electronic databases were searched including Cochrane PaPaS Group specialized register, Cochrane Library Issue 4, 2001, MEDLINE, EMBASE, BNI plus, CINAHL, BIOLOGICAL ABSTRACTS, PSYCINFO, CANCERLIT, HEALTHSTAR, WEB OF SCIENCE, SIGLE, Dissertation Abstracts, ZETOC and the MetaRegister of ongoing trials. These were searched from 1960 to 2001 or as much of this range as possible. Additional articles were sought by handsearching reference lists in standard textbooks and reviews in the field and by contacting academic centres in palliative care and pharmaceutical companies. There were no language restrictions. Studies considered for inclusion were randomized controlled trials of adult patients in any setting, receiving palliative care or suffering an incurable progressive medical condition. (For example, cancers, AIDS, Motor Neurone Disease, Multiple Sclerosis, Parkinson's Disease, Chronic Obstructive Pulmonary Disease). There had to be an explicit complaint of insomnia in study participants, diagnosed by any of the three main classification systems (DSM-IV (APA 1994), ICSD (AASD 1990) or ICD (WHO 1992)), or as described in the study if it involved a subjective complaint of poor sleep. Studies had to

  18. Endogenous GABA controls oligodendrocyte lineage cell number, myelination, and CNS internode length.

    Science.gov (United States)

    Hamilton, Nicola B; Clarke, Laura E; Arancibia-Carcamo, I Lorena; Kougioumtzidou, Eleni; Matthey, Moritz; Káradóttir, Ragnhildur; Whiteley, Louise; Bergersen, Linda H; Richardson, William D; Attwell, David

    2017-02-01

    Adjusting the thickness and internodal length of the myelin sheath is a mechanism for tuning the conduction velocity of axons to match computational needs. Interactions between oligodendrocyte precursor cells (OPCs) and developing axons regulate the formation of myelin around axons. We now show, using organotypic cerebral cortex slices from mice expressing eGFP in Sox10-positive oligodendrocytes, that endogenously released GABA, acting on GABA A receptors, greatly reduces the number of oligodendrocyte lineage cells. The decrease in oligodendrocyte number correlates with a reduction in the amount of myelination but also an increase in internode length, a parameter previously thought to be set by the axon diameter or to be a property intrinsic to oligodendrocytes. Importantly, while TTX block of neuronal activity had no effect on oligodendrocyte lineage cell number when applied alone, it was able to completely abolish the effect of blocking GABA A receptors, suggesting that control of myelination by endogenous GABA may require a permissive factor to be released from axons. In contrast, block of AMPA/KA receptors had no effect on oligodendrocyte lineage cell number or myelination. These results imply that, during development, GABA can act as a local environmental cue to control myelination and thus influence the conduction velocity of action potentials within the CNS. GLIA 2017;65:309-321. © 2016 The Authors Glia Published by Wiley Periodicals, Inc.

  19. Benzodiazepine dependence potential: current studies and trends.

    Science.gov (United States)

    Smith, D E

    1984-01-01

    The appearance of newer, short-acting benzodiazepines has produced misconceptions regarding the potential addictive quality of these drugs. Following a review of the Smith and Wesson (1983) barbiturate withdrawal technique, application of this procedure to the withdrawal of individuals addicted to short-acting benzodiazepines is reviewed. Attention is also given to the emergence of "look-alike" drugs, and the resultant implications for substance abuse treatment personnel.

  20. GABA Levels Are Decreased After Stroke and GABA Changes During Rehabilitation Correlate With Motor Improvement

    Science.gov (United States)

    Blicher, Jakob Udby; Near, Jamie; Næss-Schmidt, Erhard; Stagg, Charlotte J.; Johansen-Berg, Heidi; Nielsen, Jørgen Feldbæk; Østergaard, Leif; Ho, Yi-Ching Lynn

    2017-01-01

    Background and Objective γ-Aminobutyric acid (GABA) is the dominant inhibitory neurotransmitter in the brain and is important in motor learning. We aimed to measure GABA content in primary motor cortex poststroke (using GABA-edited magnetic resonance spectroscopy [MRS]) and in relation to motor recovery during 2 weeks of constraint-induced movement therapy (CIMT). Methods Twenty-one patients (3-12 months poststroke) and 20 healthy subjects were recruited. Magnetic resonance imaging structural T1 and GABA-edited MRS were performed at baseline and after CIMT, and once in healthy subjects. GABA:creatine (GABA:Cr) ratio was measured by GABA-edited MRS. Motor function was measured using Wolf Motor Function Test (WMFT). Results Baseline comparison between stroke patients (n = 19) and healthy subjects showed a significantly lower GABA:Cr ratio in stroke patients (P < .001) even after correcting for gray matter content in the voxel (P < .01) and when expressing GABA relative to N-acetylaspartic acid (NAA; P = .03). After 2 weeks of CIMT patients improved significantly on WMFT, but no consistent change across the group was observed for the GABA:Cr ratio (n = 17). However, the extent of improvement on WMFT correlated significantly with the magnitude of GABA:Cr changes (P < .01), with decreases in GABA:Cr ratio being associated with better improvements in motor function. Conclusions In patients 3 to 12 months poststroke, GABA levels are lower in the primary motor cortex than in healthy subjects. The observed association between GABA and recovery warrants further studies on the potential use of GABA MRS as a biomarker in poststroke recovery. PMID:25055837

  1. Decreased Hepatocyte Growth Factor (HGF) and Gamma Aminobutyric Acid (GABA) in Individuals with Obsessive-Compulsive Disorder (OCD).

    Science.gov (United States)

    Russo, Anthony J; Pietsch, Stefanie C

    2013-01-01

    There is support for the role of gamma aminobutyric acid (GABA) in the etiology of mood disorders. Recent research has shown that hepatocyte growth factor (HGF) modulates GABAergic inhibition and seizure susceptibility. This study was designed to determine and correlate plasma levels of HGF and GABA as well as symptom severity in individuals with obsessive-compulsive disorder (OCD). Plasma from 15 individuals with OCD (9 males, 6 females;, mean age 38.7 years) and 17 neurotypical controls (10 males, 7 females; mean age 35.2 years) was assessed for HGF, GABA, urokinase plasminogen activator (uPA), and urokinase plasminogen activator receptor (uPAR) concentration using enzyme-linked immunosorbest assays ELISAs. Symptom severity was assessed in these OCD individuals and compared with HGF and GABA concentrations. In this preliminary study, individuals with OCD had significantly decreased HGF levels, decreased plasma levels of GABA and decreased uPA. We found that both uPA and uPAR levels correlate with HGF. Both low uPA and low uPAR levels correlate with high symptom severity in individuals with OCD. Low GABA levels in OCD individuals also correlate with high symptom severity. These results demonstrate a preliminary association between HGF, GABA, uPA levels, and OCD and suggest that plasma GABA and uPA levels are related to symptom severity in individuals with OCD.

  2. GABA localization in the nematode Ascaris

    Energy Technology Data Exchange (ETDEWEB)

    Guastella, J.

    1988-01-01

    A histochemical approach was used to examine the distribution of GABA-associated neurons in the nematode Ascaris, an organism whose small number of morphologically simple neurons make it an excellent preparation for analyzing neuronal phenotypes. Two GABAergic markers were examined: GABA-like immunoreactivity (GLIR), a marker for endogenous stores of GABA; and ({sup 3}H)-GABA uptake, a marker for GABA uptake sites. Strong GLIR was present in the cell bodies, neurites and commissures of dorsal and ventral inhibitory motorneurons present in this region. Strong GLIR was also present in the cell bodies and processes of the four RME neurons in the nerve ring and in several other ganglionic neurons. Staining was absent in excitatory motorneurons, in ventral cord interneurons and in muscle cells and hypodermis. GABA uptake sites were found in single neural processes in both the ventral and dorsal nerve cords. ({sup 3}H)-GABA labeling was also observed in the other two RME cells and several other cephalic neurons. Four putative cholinergic excitatory motorneurons in the retrovesicular ganglion (RVG) were heavily labeled. Ventral and dorsal nerve cord inhibitory motorneurons did not take up ({sup 3}H)-GABA. Labeling of the ventral cord excitatory motorneuron somata and cell bodies was at or slightly above background. Heavy labeling of muscle cells was also observed.

  3. Prefrontal Cortical GABA Transmission Modulates Discrimination and Latent Inhibition of Conditioned Fear: Relevance for Schizophrenia

    Science.gov (United States)

    Piantadosi, Patrick T; Floresco, Stan B

    2014-01-01

    Inhibitory gamma-aminobutyric acid (GABA) transmission within the prefrontal cortex (PFC) regulates numerous functions, and perturbations in GABAergic transmission within this region have been proposed to contribute to some of the cognitive and behavioral abnormalities associated with disorders such as schizophrenia. These abnormalities include deficits in emotional regulation and aberrant attributions of affective salience. Yet, how PFC GABA regulates these types of emotional processes are unclear. To address this issue, we investigated the contribution of PFC GABA transmission to different aspects of Pavlovian emotional learning in rats using translational discriminative fear conditioning and latent inhibition (LI) assays. Reducing prelimbic PFC GABAA transmission via infusions of the antagonist bicuculline before the acquisition or expression of fear conditioning eliminated the ability to discriminate between an aversive conditioned stimulus (CS+) paired with footshock vs a neutral CS–, resembling similar deficits observed in schizophrenic patients. In a separate experiment, blockade of PFC GABAA receptors before CS preexposure (PE) and conditioning did not affect subsequent expression of LI, but did enhance fear in rats that were not preexposed to the CS. In contrast, PFC GABA-blockade before a fear expression test disrupted the recall of learned irrelevance and abolished LI. These data suggest that normal PFC GABA transmission is critical for regulating and mitigating multiple aspects of aversive learning, including discrimination between fear vs safety signals and recall of information about the irrelevance of stimuli. Furthermore, they suggest that similar deficits in emotional regulation observed in schizophrenia may be driven in part by deficient PFC GABA activity. PMID:24784549

  4. Assembly of the outer retina in the absence of GABA synthesis in horizontal cells

    Directory of Open Access Journals (Sweden)

    Parker Edward

    2010-06-01

    Full Text Available Abstract Background The inhibitory neurotransmitter gamma-amino-butyric acid (GABA not only modulates excitability in the mature nervous system but also regulates neuronal differentiation and circuit development. Horizontal cells, a subset of interneurons in the outer retina, are transiently GABAergic during the period of cone photoreceptor synaptogenesis. In rodents, both horizontal cells and cone axonal terminals express GABAA receptors. To explore the possibility that transient GABA expression in mouse neonatal horizontal cells influences the structural development of synaptic connectivity in the outer retina, we examined a mutant in which expression of GAD67, the major synthesizing enzyme for GABA, is selectively knocked out in the retina. Results Immunocytochemistry and electron microscopy revealed that the assembly of triad synapses involving cone axonal pedicles and the dendrites of horizontal and bipolar cells is unaffected in the mutant retina. Moreover, loss of GABA synthesis in the outer retina did not perturb the spatial distributions and cell densities of cones and horizontal cells. However, there were some structural alterations at the cellular level: the average size of horizontal cell dendritic clusters was larger in the mutant, and there was also a small but significant increase in cone photoreceptor pedicle area. Moreover, metabotropic glutamate receptor 6 (mGluR6 receptors on the dendrites of ON bipolar cells occupied a slightly larger proportion of the cone pedicle in the mutant. Conclusions Together, our analysis shows that transient GABA synthesis in horizontal cells is not critical for synapse assembly and axonal and dendritic lamination in the outer retina. However, pre- and postsynaptic structures are somewhat enlarged in the absence of GABA in the developing outer retina, providing for a modest increase in potential contact area between cone photoreceptors and their targets. These findings differ from previous results

  5. Status epilepticus: Role for etiology in determining response to benzodiazepines.

    Science.gov (United States)

    Joshi, Suchitra; Rajasekaran, Karthik; Hawk, Kyle M; Chester, Stephen J; Goodkin, Howard P

    2018-04-01

    Clinical factors contributing to benzodiazepine failure in treating status epilepticus (SE) include suboptimal dosing and seizure duration. As many benzodiazepine-refractory episodes of SE arise from acute etiologies, we sought to determine whether etiology impacts SE treatment. The potency of diazepam to terminate SE induced by lithium-pilocarpine (LiPilo-SE) or kainic acid (KA-SE) in 3-week-old rats was studied by video-electroencephalography. Synaptic γ-aminobutyric acid type A receptor (GABAR)-mediated currents were recorded from dentate granule cells using voltage-clamp electrophysiology. Surface expression of γ2 subunit-containing GABARs and Kv4.2 potassium channels in hippocampal slices was determined using a biotinylation assay. Expression of phosphorylated forms of β2/3 and γ2 subunits was determined using phosphospecific antibodies and Western blotting. Diazepam failed to terminate late SE in LiPilo-SE animals but was successful in terminating KA-SE of 1- and 3-hour duration. One hour after SE onset, GABAR-mediated synaptic inhibition and γ2 subunit-containing GABAR surface expression were reduced in LiPilo-SE animals. These were unchanged in KA-SE animals at 1 and 3 hours. Phosphorylation of γ2 subunit residue S327 was unchanged in both models, although GABAR β3 subunit S408/409 residues were dephosphorylated in the LiPilo-SE animals. Kv4.2 potassium channel surface expression was increased in LiPilo-SE animals but reduced in KA-SE animals. SE-model-dependent differences support a novel hypothesis that the development of benzodiazepine pharmacoresistance may be etiologically predetermined. Further studies are required to investigate the mechanisms that underlie such etiological differences during SE and whether etiology-dependent protocols for the treatment of SE need to be developed. Ann Neurol 2018;83:830-841. © 2018 American Neurological Association.

  6. Effects of glutamate decarboxylase and gamma-aminobutyric acid (GABA) transporter on the bioconversion of GABA in engineered Escherichia coli.

    Science.gov (United States)

    Le Vo, Tam Dinh; Kim, Tae Wan; Hong, Soon Ho

    2012-05-01

    Gamma-aminobutyric acid (GABA) is a non-essential amino acid and a precursor of pyrrolidone, a monomer of nylon 4. GABA can be biosynthesized through the decarboxylation of L: -glutamate by glutamate decarboxylase. In this study, the effects of glutamate decarboxylase (gadA, gadB), glutamate/GABA antiporter (gadC) and GABA aminotransferase (gabT) on GABA production were investigated in Escherichia coli. Glutamate decarboxylase was overexpressed alone or with the glutamate/GABA antiporter to enhance GABA synthesis. GABA aminotransferase, which redirects GABA into the TCA cycle, was knock-out mutated. When gadB and gadC were co-overexpressed in the gabT mutant strain, a final GABA concentration of 5.46 g/l was obtained from 10 g/l of monosodium glutamate (MSG), which corresponded to a GABA yield of 89.5%.

  7. Reversed synaptic effects of hypocretin and NPY mediated by excitatory GABA-dependent synaptic activity in developing MCH neurons.

    Science.gov (United States)

    Li, Ying; Xu, Youfen; van den Pol, Anthony N

    2013-03-01

    In mature neurons, GABA is the primary inhibitory neurotransmitter. In contrast, in developing neurons, GABA exerts excitatory actions, and in some neurons GABA-mediated excitatory synaptic activity is more prevalent than glutamate-mediated excitation. Hypothalamic neuropeptides that modulate cognitive arousal and energy homeostasis, hypocretin/orexin and neuropeptide Y (NPY), evoked reversed effects on synaptic actions that were dependent on presynaptic GABA release onto melanin-concentrating hormone (MCH) neurons. MCH neurons were identified by selective green fluorescent protein (GFP) expression in transgenic mice. In adults, hypocretin increased GABA release leading to reduced excitation. In contrast, in the developing brain as studied here with analysis of miniature excitatory postsynaptic currents, paired-pulse ratios, and evoked potentials, hypocretin acted presynaptically to enhance the excitatory actions of GABA. The ability of hypocretin to enhance GABA release increases inhibition in adult neurons but paradoxically enhances excitation in developing MCH neurons. In contrast, NPY attenuation of GABA release reduced inhibition in mature neurons but enhanced inhibition during development by attenuating GABA excitation. Both hypocretin and NPY also evoked direct actions on developing MCH neurons. Hypocretin excited MCH cells by activating a sodium-calcium exchanger and by reducing potassium currents; NPY reduced activity by increasing an inwardly rectifying potassium current. These data for the first time show that both hypocretin and NPY receptors are functional presynaptically during early postnatal hypothalamic development and that both neuropeptides modulate GABA actions during development with a valence of enhanced excitation or inhibition opposite to that of the adult state, potentially allowing neuropeptide modulation of use-dependent synapse stabilization.

  8. GABA-Mediated Presynaptic Inhibition Is Required for Precision of Long-Term Memory

    Science.gov (United States)

    Cullen, Patrick K.; Dulka, Brooke N.; Ortiz, Samantha; Riccio, David C.; Jasnow, Aaron M.

    2014-01-01

    Though much attention has been given to the neural structures that underlie the long-term consolidation of contextual memories, little is known about the mechanisms responsible for the maintenance of memory precision. Here, we demonstrate a rapid time-dependent decline in memory precision in GABA [subscript B(1a)] receptor knockout mice. First, we…

  9. Electrocardiographic Manifestations of Benzodiazepine Toxicity

    Directory of Open Access Journals (Sweden)

    Nahid Kazemzadeh

    2014-11-01

    Full Text Available Background: The aim of this study was to evaluate and compare the clinical and electrocardiographic (ECG manifestations of benzodiazepines (BZs. Methods: In this retrospective study, all BZ-poisoned patients hospitalized at Loghman Hakim Hospital between September 2010 and March 2011 were evaluated. Patients’ information including age, sex, time elapsed between the ingestion and presentation, and type of the BZ used were extracted from the patients' charts and recorded. ECGs on presentation to the emergency department (ED were evaluated and parameters such as PR interval, QRS duration, corrected QT, amplitude of S wave in lead I, height of R wave and R/S ratio in the lead aVR were also measured and recorded. Results: Oxazepam, chlordiazepoxide, lorazepam, alprazolam, diazepam, and clonazepam were ingested by 9 (3%, 13 (4.4%, 29 (9.9%, 105 (35.8%, 65 (22.2%, and 72 (24.6% patients, respectively. Mean PR interval was reported to be 0.16 ± 0.03 sec and PR interval of greater than 200 msec was detected in 12 (4.5% patients. Mean QRS duration was 0.07 ± 0.01sec and QRS≥120 msec was observed in 7 (2.6% cases. Conclusion: Diazepam is the only BZ that does not cause QRS widening and oxazepam is the only one not causing PR prolongation. It can be concluded that if a patient refers with a decreased level of consciousness and accompanying signs of BZ toxicity, QRS widening in ECG rules out diazepam, whereas PR prolongation rules out oxazepam toxicity.

  10. Benzodiazepine Initiation and Dose Escalation.

    Science.gov (United States)

    Skinner, Brian W; Johnston, Elizabeth V; Saum, Lindsay M

    2017-04-01

    Benzodiazepines (BZDs) place patients at a significant risk of falling. The current literature does not address if this risk is increased during initiation or dose escalations of BZDs. To determine if initiation or dose escalations of BZD regimens are associated with an increased risk of falls in hospitalized patients compared with patients maintained on their home dose or who had their dose decreased from baseline. This retrospective case-control study evaluated hospitalized patients aged 45 years or older who received a BZD. Patients who did not fall were collected in a 3:1 ratio to patients who fell. Comparisons were made between BZD regimens prior to admission and those 48 hours prior to the index date. The date of fall served as the index date for patients who fell, and the median time-to-fall served as the index date for all other patients. A total of 132 patients were included in the study (33 falls and 99 without a fall). No significant differences were noted in demographics, baseline mobility, or past medical history. Patients who fell had a significantly longer median length of stay (15 vs 10 days; P = 0.025). Additionally, patients who fell were more likely to have had their BZD regimen initiated or dose escalated compared with patients who did not fall (63.6% vs 41.4%; P = 0.043). The risk of falling while on a BZD is increased on initiation and dose escalations. Hospitals should ensure judicious use of BZDs in inpatients to reduce the risk of falls.

  11. Synthesis of 3-Substituted 1,4-Benzodiazepin-2-ones

    Directory of Open Access Journals (Sweden)

    Kyungjin Kim

    1998-01-01

    Full Text Available The preparation of 3-substituted 1,4-benzodiazepines by benzodiazepine enolate alkylation has been explored. Employing this approach, multigram quantities of benzodiazepine 1 have been prepared for animal studies to evaluate a new approach for the treatment of the autoimmune disease systemic lupus erythematosus (SLE.

  12. Turnover and release of GABA in rat cortical slices: effect of a GABA-T inhibitor, gabaculine

    International Nuclear Information System (INIS)

    Szerb, J.C.

    1982-01-01

    The turnover and release of endogenous and labeled GABA were followed in rat cortical slices after incubation with [ 3 H]GABA. High performance liquid chromatography was used to measure endogenous GABA and to separate [ 3 H]GABA from its metabolites. During superfusion with 3 mM K + the slices rapidly lost their [ 3 H]GABA content while maintaining constant GABA levels. Exposure to 50 mM K + for 25 min caused an initial rapid rise in the release of both endogenous and [ 3 H]GABA followed by a more rapid decline in the release of the latter. The specific activity of released GABA was two to four times higher than that in the slices. Depolarization lead to a net synthesis of GABA. The GABA -T inhibitor, gabaculine, (5 micrometers) in vitro arrested the metabolism of [ 3 H]GABA and rapidly doubled the GABA content but did not significantly increase the high K + evoked release of endogenous GABA. In vivo pretreatment with 0.5 mM/kg gabaculine quadrupled GABA content and increased both the spontaneous and evoked release of endogenous GABA but while its Ca 2 + -dependent release increased by 50%, the Ca 2 + -independent release was enhanced sevenfold. This large Ca 2 + -independent release of GABA is likely to have different functional significance from the normal Ca 2 + -dependent release

  13. Action of bicyclic isoxazole GABA analogues on GABA transporters and its relation to anticonvulsant activity

    DEFF Research Database (Denmark)

    Bolvig, T; Larsson, O M; Pickering, D S

    1999-01-01

    The inhibitory action of bicyclic isoxazole gamma-aminobutyric acid (GABA) analogues and their 4,4-diphenyl-3-butenyl (DPB) substituted derivatives has been investigated in cortical neurones and astrocytes as well as in human embryonic kidney (HEK 293) cells transiently expressing either mouse GABA...... anticonvulsant activity, lack of proconvulsant activity and the ability of THPO to increase extracellular GABA concentration, indicate that these bicyclic isoxazole GABA analogues and their DPB derivatives may be useful lead structures in future search for new antiepileptic drugs....

  14. GABA regulates the multidirectional tangential migration of GABAergic interneurons in living neonatal mice.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Inada

    Full Text Available Cortical GABAergic interneurons originate from ganglionic eminences and tangentially migrate into the cortical plate at early developmental stages. To elucidate the characteristics of this migration of GABAergic interneurons in living animals, we established an experimental design specialized for in vivo time-lapse imaging of the neocortex of neonate mice with two-photon laser-scanning microscopy. In vesicular GABA/glycine transporter (VGAT-Venus transgenic mice from birth (P0 through P3, we observed multidirectional tangential migration of genetically-defined GABAergic interneurons in the neocortical marginal zone. The properties of this migration, such as the motility rate (distance/hr, the direction moved, and the proportion of migrating neurons to stationary neurons, did not change through P0 to P3, although the density of GABAergic neurons at the marginal zone decreased with age. Thus, the characteristics of the tangential motility of individual GABAergic neurons remained constant in development. Pharmacological block of GABA(A receptors and of the Na⁺-K⁺-Cl⁻ cotransporters, and chelating intracellular Ca²⁺, all significantly reduced the motility rate in vivo. The motility rate and GABA content within the cortex of neonatal VGAT-Venus transgenic mice were significantly greater than those of GAD67-GFP knock-in mice, suggesting that extracellular GABA concentration could facilitate the multidirectional tangential migration. Indeed, diazepam applied to GAD67-GFP mice increased the motility rate substantially. In an in vitro neocortical slice preparation, we confirmed that GABA induced a NKCC sensitive depolarization of GABAergic interneurons in VGAT-Venus mice at P0-P3. Thus, activation of GABA(AR by ambient GABA depolarizes GABAergic interneurons, leading to an acceleration of their multidirectional motility in vivo.

  15. Imaging of peripheral-type benzodiazepine receptor in tumor: in vitro binding and in vivo biodistribution of N-benzyl-N-[(11)C]methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide.

    Science.gov (United States)

    Yamasaki, Tomoteru; Kumata, Katsushi; Yanamoto, Kazuhiko; Hatori, Akiko; Takei, Makoto; Nakamura, Yukio; Koike, Sachiko; Ando, Koichi; Suzuki, Kazutoshi; Zhang, Ming-Rong

    2009-10-01

    The aim of this study was to evaluate N-benzyl-N-[(11)C]methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide ([(11)C]DAC) as a novel peripheral-type benzodiazepine receptor (PBR) ligand for tumor imaging. [(11)C]DAC was synthesized by the reaction of a desmethyl precursor with [(11)C]CH(3)I. In vitro uptake of [(11)C]DAC was examined in PBR-expressing C6 glioma and intact murine fibrosarcoma (NFSa) cells. In vivo distribution of [(11)C]DAC was determined using NFSa-bearing mice and small-animal positron emission tomography (PET). [(11)C]DAC showed specific binding to PBR in C6 glioma cells, a standard cell line with high PBR expression. Specific binding of [(11)C]DAC was also confirmed in NFSa cells, a target tumor cell line in this study. Results of PET experiments using NFSa-bearing mice, showed that [(11)C]DAC was taken up specifically into the tumor, and pretreatment with PK11195 abolished the uptake. [(11)C]DAC was taken up into PBR-expressing NFSa. [(11)C]DAC is a promising PET ligand that can be used for imaging PBR in tumor-bearing mice.

  16. CXCL12 chemokine and GABA neurotransmitter systems crosstalk and their putative roles

    Directory of Open Access Journals (Sweden)

    Guyon eAlice

    2014-04-01

    Full Text Available Since CXCL12 and its receptors, CXCR4 and CXCR7, have been found in the brain, the role of this chemokine has been expanded from chemoattractant in the immune system to neuromodulatory in the brain. Several pieces of evidence suggest that this chemokine system could crosstalk with the GABAergic system, known to be the main inhibitory neurotransmitter system in the brain. Indeed, GABA and CXCL12 as well as their receptors are colocalized in many cell types including neurons and there are several examples in which these two systems interact. Several mechanisms can be proposed to explain how these systems interact, including receptor-receptor interactions, crosstalk at the level of second messenger cascades, or direct pharmacological interactions, as GABA and GABAB receptor agonists/antagonists have been shown to be allosteric modulators of CXCR4.The interplay between CXCL12/CXCR4-CXCR7 and GABA/GABAA-GABAB receptors systems could have many physiological implications in neurotransmission, cancer and inflammation. In addition, the GABAB agonist baclofen is currently used in medicine to treat spasticity in patients with spinal cord injury, cerebral palsy, traumatic brain injury, multiple sclerosis and other disorders. More recently it has also been used in the treatment of alcohol dependence and withdrawal. The allosteric effects of this agent on CXCR4 could contribute to these beneficial effects or at the opposite, to its side effects.

  17. Benzodiazepine maintenance for alcohol dependence: A case series

    Directory of Open Access Journals (Sweden)

    Shivanand Kattimani

    2017-01-01

    Full Text Available Alcohol addiction is a chronic relapsing syndrome. Benzodiazepines remain as the mainstay for detoxification, taking care of the acute withdrawal syndrome. There is fear of dependence and abuse of benzodiazepines on prolonged use. Here, we selectively interviewed ten cases who were on longer duration of benzodiazepines to elicit their potential perceived benefits, attitudes, and any adverse effect. Three patients experienced adverse effects. None of them had features of benzodiazepine dependence. We opine that in select cases, benzodiazepine use should persist beyond detox period, and its benefits continue beyond the acute withdrawal phase while monitoring their safety/adverse effects.

  18. Benzodiazepine Synthesis and Rapid Toxicity Assay

    Science.gov (United States)

    Fletcher, James T.; Boriraj, Grit

    2010-01-01

    A second-year organic chemistry laboratory experiment to introduce students to general concepts of medicinal chemistry is described. Within a single three-hour time window, students experience the synthesis of a biologically active small molecule and the assaying of its biological toxicity. Benzodiazepine rings are commonly found in antidepressant…

  19. Benzodiazepines: minder gebruiken is beter gebruiken

    NARCIS (Netherlands)

    Oei, T.T.; Loonen, A.J.M.

    1981-01-01

    The benzodiazepines take an important place in the treatment of anxiety and sleep-disorders. The pharmacokinetic, pharmacodynamic and therapeutic properties of these drugs are shortly dealt with, whereafter the development of tolerance and dependence is considered in more detail. The clinical

  20. Chronic Treatment with a Promnesiant GABA-A α5-Selective Inverse Agonist Increases Immediate Early Genes Expression during Memory Processing in Mice and Rectifies Their Expression Levels in a Down Syndrome Mouse Model

    Science.gov (United States)

    Braudeau, J.; Dauphinot, L.; Duchon, A.; Loistron, A.; Dodd, R. H.; Hérault, Y.; Delatour, B.; Potier, M. C.

    2011-01-01

    Decrease of GABAergic transmission has been proposed to improve memory functions. Indeed, inverse agonists selective for α5 GABA-A-benzodiazepine receptors (α5IA) have promnesiant activity. Interestingly, we have recently shown that α5IA can rescue cognitive deficits in Ts65Dn mice, a Down syndrome mouse model with altered GABAergic transmission. Here, we studied the impact of chronic treatment with α5IA on gene expression in the hippocampus of Ts65Dn and control euploid mice after being trained in the Morris water maze task. In euploid mice, chronic treatment with α5IA increased IEGs expression, particularly of c-Fos and Arc genes. In Ts65Dn mice, deficits of IEGs activation were completely rescued after treatment with α5IA. In addition, normalization of Sod1 overexpression in Ts65Dn mice after α5IA treatment was observed. IEG expression regulation after α5IA treatment following behavioral stimulation could be a contributing factor for both the general promnesiant activity of α5IA and its rescuing effect in Ts65Dn mice alongside signaling cascades that are critical for memory consolidation and cognition. PMID:22028705

  1. Application of radioreceptor assay of benzodiazepines for toxicology

    International Nuclear Information System (INIS)

    Aaltonen, L.; Scheinin, M.

    1982-01-01

    A radioreceptor assay (RRA) for determining benzodiazepines (BZ) has been developed and applied to toxicological analysis of serum samples from 21 patients with acute BZ overdosage. The method was sensitive (e.g., lorazepam 17 nM, diazepam 41 nM), and specific for pharmacologically active BZ derivatives. The reproducibility of the results was good (intra-assay variation < 8%, inter-assay variation < 10%). Concentrations measured by the RRA showed a good correlation with those obtained by gas-liquid chromatographic analysis of the same samples. The quantitative results represent the sum of one or several parent substances and all biologically active metabolites, in proportion to their receptor binding affinities. (author)

  2. The neuropsychology of anxiety: an enquiry into the functions of the septo-hippocampal system

    National Research Council Canada - National Science Library

    Gray, Jeffrey Alan; McNaughton, Neil

    2000-01-01

    ... that the diverse behavioural and physiological effects of the benzodiazepine class of anxiolytic drugs are mediated in general by action at receptors allosterically coupled to the GABA A receptor. It is now clear that different classes of these effects are mediated by benzodiazepine binding sites that are coupled to GABA A receptors of different subunit compositions. In particular, studies of mice with point mutations in specific sub