Loss of cannabinoid receptor CB1 induces preterm birth.

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Haibin Wang

2008-10-01

Full Text Available Preterm birth accounting approximate 10% of pregnancies in women is a tremendous social, clinical and economic burden. However, its underlying causes remain largely unknown. Emerging evidence suggests that endocannabinoid signaling via cannabinoid receptor CB1 play critical roles in multiple early pregnancy events in both animals and humans. Since our previous studies demonstrated that loss of CB1 defers the normal implantation window in mice, we surmised that CB1 deficiency would influence parturition events.Exploiting mouse models with targeted deletion of Cnr1, Cnr2 and Ptgs1 encoding CB1, CB2 and cyclooxygenase-1, respectively, we examined consequences of CB1 or CB2 silencing on the onset of parturition. We observed that genetic or pharmacological inactivation of CB1, but not CB2, induced preterm labor in mice. Radioimmunoassay analysis of circulating levels of ovarian steroid hormones revealed that premature birth resulting from CB1 inactivation is correlated with altered progesterone/estrogen ratios prior to parturition. More strikingly, the phenotypic defects of prolonged pregnancy length and parturition failure in mice missing Ptgs1 were corrected by introducing CB1 deficiency into Ptgs1 null mice. In addition, loss of CB1 resulted in aberrant secretions of corticotrophin-releasing hormone and corticosterone during late gestation. The pathophysiological significance of this altered corticotrophin-releasing hormone-driven endocrine activity in the absence of CB1 was evident from our subsequent findings that a selective corticotrophin-releasing hormone antagonist was able to restore the normal parturition timing in Cnr1 deficient mice. In contrast, wild-type females receiving excessive levels of corticosterone induced preterm birth.CB1 deficiency altering normal progesterone and estrogen levels induces preterm birth in mice. This defect is independent of prostaglandins produced by cyclooxygenase-1. Moreover, CB1 inactivation resulted in

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

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Ken Soderstrom

2017-10-01

Full Text Available Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

Peripheral and central CB1 cannabinoid receptors control stress-induced impairment of memory consolidation.

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Busquets-Garcia, Arnau; Gomis-González, Maria; Srivastava, Raj Kamal; Cutando, Laura; Ortega-Alvaro, Antonio; Ruehle, Sabine; Remmers, Floortje; Bindila, Laura; Bellocchio, Luigi; Marsicano, Giovanni; Lutz, Beat; Maldonado, Rafael; Ozaita, Andrés

2016-08-30

Stressful events can generate emotional memories linked to the traumatic incident, but they also can impair the formation of nonemotional memories. Although the impact of stress on emotional memories is well studied, much less is known about the influence of the emotional state on the formation of nonemotional memories. We used the novel object-recognition task as a model of nonemotional memory in mice to investigate the underlying mechanism of the deleterious effect of stress on memory consolidation. Systemic, hippocampal, and peripheral blockade of cannabinoid type-1 (CB1) receptors abolished the stress-induced memory impairment. Genetic deletion and rescue of CB1 receptors in specific cell types revealed that the CB1 receptor population specifically in dopamine β-hydroxylase (DBH)-expressing cells is both necessary and sufficient for stress-induced impairment of memory consolidation, but CB1 receptors present in other neuronal populations are not involved. Strikingly, pharmacological manipulations in mice expressing CB1 receptors exclusively in DBH(+) cells revealed that both hippocampal and peripheral receptors mediate the impact of stress on memory consolidation. Thus, CB1 receptors on adrenergic and noradrenergic cells provide previously unrecognized cross-talk between central and peripheral mechanisms in the stress-dependent regulation of nonemotional memory consolidation, suggesting new potential avenues for the treatment of cognitive aspects on stress-related disorders.

Cannabinoid receptor CB2 modulates axon guidance

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Duff, Gabriel; Argaw, Anteneh; Cecyre, Bruno

2013-01-01

on axon guidance. These effects are specific to CB2R since no changes were observed in mice where the gene coding for this receptor was altered (cnr2 (-/-)). The CB2R induced morphological changes observed at the growth cone are PKA dependent and require the presence of the netrin-1 receptor, Deleted...... CB2R's implication in retinothalamic development. Overall, this study demonstrates that the contribution of endocannabinoids to brain development is not solely mediated by CB1R, but also involves CB2R....

Cannabinoid CB1 receptors in distinct circuits of the extended amygdala determine fear responsiveness to unpredictable threat.

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Lange, M D; Daldrup, T; Remmers, F; Szkudlarek, H J; Lesting, J; Guggenhuber, S; Ruehle, S; Jüngling, K; Seidenbecher, T; Lutz, B; Pape, H C

2017-10-01

The brain circuits underlying behavioral fear have been extensively studied over the last decades. Although the vast majority of experimental studies assess fear as a transient state of apprehension in response to a discrete threat, such phasic states of fear can shift to a sustained anxious apprehension, particularly in face of diffuse cues with unpredictable environmental contingencies. Unpredictability, in turn, is considered an important variable contributing to anxiety disorders. The networks of the extended amygdala have been suggested keys to the control of phasic and sustained states of fear, although the underlying synaptic pathways and mechanisms remain poorly understood. Here, we show that the endocannabinoid system acting in synaptic circuits of the extended amygdala can explain the fear response profile during exposure to unpredictable threat. Using fear training with predictable or unpredictable cues in mice, combined with local and cell-type-specific deficiency and rescue of cannabinoid type 1 (CB1) receptors, we found that presynaptic CB1 receptors on distinct amygdala projections to bed nucleus of the stria terminalis (BNST) are both necessary and sufficient for the shift from phasic to sustained fear in response to an unpredictable threat. These results thereby identify the causal role of a defined protein in a distinct brain pathway for the temporal development of a sustained state of anxious apprehension during unpredictability of environmental influences, reminiscent of anxiety symptoms in humans.

Role of CB1 cannabinoid receptors on GABAergic neurons in brain aging.

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Albayram, Onder; Alferink, Judith; Pitsch, Julika; Piyanova, Anastasia; Neitzert, Kim; Poppensieker, Karola; Mauer, Daniela; Michel, Kerstin; Legler, Anne; Becker, Albert; Monory, Krisztina; Lutz, Beat; Zimmer, Andreas; Bilkei-Gorzo, Andras

2011-07-05

Brain aging is associated with cognitive decline that is accompanied by progressive neuroinflammatory changes. The endocannabinoid system (ECS) is involved in the regulation of glial activity and influences the progression of age-related learning and memory deficits. Mice lacking the Cnr1 gene (Cnr1(-/-)), which encodes the cannabinoid receptor 1 (CB1), showed an accelerated age-dependent deficit in spatial learning accompanied by a loss of principal neurons in the hippocampus. The age-dependent decrease in neuronal numbers in Cnr1(-/-) mice was not related to decreased neurogenesis or to epileptic seizures. However, enhanced neuroinflammation characterized by an increased density of astrocytes and activated microglia as well as an enhanced expression of the inflammatory cytokine IL-6 during aging was present in the hippocampus of Cnr1(-/-) mice. The ongoing process of pyramidal cell degeneration and neuroinflammation can exacerbate each other and both contribute to the cognitive deficits. Deletion of CB1 receptors from the forebrain GABAergic, but not from the glutamatergic neurons, led to a similar neuronal loss and increased neuroinflammation in the hippocampus as observed in animals lacking CB1 receptors in all cells. Our results suggest that CB1 receptor activity on hippocampal GABAergic neurons protects against age-dependent cognitive decline by reducing pyramidal cell degeneration and neuroinflammation.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB1 receptor blockade

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Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-01-01

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors. PMID:23487769

Effects of caffeine on striatal neurotransmission: focus on cannabinoid CB1 receptors.

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Rossi, Silvia; De Chiara, Valentina; Musella, Alessandra; Mataluni, Giorgia; Sacchetti, Lucia; Siracusano, Alberto; Bernardi, Giorgio; Usiello, Alessandro; Centonze, Diego

2010-04-01

Caffeine is the most commonly self-administered psychoactive substance worldwide. At usual doses, the effects of caffeine on vigilance, attention, mood and arousal largely depend on the modulation of central adenosine receptors. The present review article describes the action of caffeine within the striatum, to provide a possible molecular mechanism at the basis of the psychomotor and reinforcing properties of this pharmacological agent. The striatum is in fact a subcortical area involved in sensorimotor, cognitive, and emotional processes, and recent experimental findings showed that chronic caffeine consumption enhances the sensitivity of striatal GABAergic synapses to the stimulation of cannabinoid CB1 receptors. The endocannabinoid system is involved in the psychoactive effects of many compounds, and adenosine A2A receptors (the main receptor target of caffeine) elicit a permissive effect towards CB1 receptors, thus suggesting that A2A-CB1 receptor interaction plays a major role in the generation and maintenance of caffeine reinforcing behavior. Aim of this review is to describe the effects of caffeine on striatal neurotransmission with special reference to the modulation of the endocannabinoid system.

Spatial distribution of cannabinoid receptor type 1 (CB1 in normal canine central and peripheral nervous system.

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Jessica Freundt-Revilla

Full Text Available The endocannabinoid system is a regulatory pathway consisting of two main types of cannabinoid receptors (CB1 and CB2 and their endogenous ligands, the endocannabinoids. The CB1 receptor is highly expressed in the central and peripheral nervous systems (PNS in mammalians and is involved in neuromodulatory functions. Since endocannabinoids were shown to be elevated in cerebrospinal fluid of epileptic dogs, knowledge about the species specific CB receptor expression in the nervous system is required. Therefore, we assessed the spatial distribution of CB1 receptors in the normal canine CNS and PNS. Immunohistochemistry of several regions of the brain, spinal cord and peripheral nerves from a healthy four-week-old puppy, three six-month-old dogs, and one ten-year-old dog revealed strong dot-like immunoreactivity in the neuropil of the cerebral cortex, Cornu Ammonis (CA and dentate gyrus of the hippocampus, midbrain, cerebellum, medulla oblongata and grey matter of the spinal cord. Dense CB1 expression was found in fibres of the globus pallidus and substantia nigra surrounding immunonegative neurons. Astrocytes were constantly positive in all examined regions. CB1 labelled neurons and satellite cells of the dorsal root ganglia, and myelinating Schwann cells in the PNS. These results demonstrate for the first time the spatial distribution of CB1 receptors in the healthy canine CNS and PNS. These results can be used as a basis for further studies aiming to elucidate the physiological consequences of this particular anatomical and cellular distribution.

Human orexin/hypocretin receptors form constitutive homo- and heteromeric complexes with each other and with human CB1 cannabinoid receptors

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Jäntti, Maria H.; Mandrika, Ilona; Kukkonen, Jyrki P.

2014-01-01

Highlights: • OX 1 and OX 2 orexin and CB 1 cannabinoid receptor dimerization was investigated. • Bioluminescence resonance energy transfer method was used. • All receptors readily formed constitutive homo- and heteromeric complexes. - Abstract: Human OX 1 orexin receptors have been shown to homodimerize and they have also been suggested to heterodimerize with CB 1 cannabinoid receptors. The latter has been suggested to be important for orexin receptor responses and trafficking. In this study, we wanted to assess the ability of the other combinations of receptors to also form similar complexes. Vectors for expression of human OX 1 , OX 2 and CB 1 receptors, C-terminally fused with either Renilla luciferase or GFP 2 green fluorescent protein variant, were generated. The constructs were transiently expressed in Chinese hamster ovary cells, and constitutive dimerization between the receptors was assessed by bioluminescence energy transfer (BRET). Orexin receptor subtypes readily formed homo- and hetero(di)mers, as suggested by significant BRET signals. CB 1 receptors formed homodimers, and they also heterodimerized with both orexin receptors. Interestingly, BRET efficiency was higher for homodimers than for almost all heterodimers. This is likely to be due to the geometry of the interaction; the putatively symmetric dimers may place the C-termini in a more suitable orientation in homomers. Fusion of luciferase to an orexin receptor and GFP 2 to CB 1 produced more effective BRET than the opposite fusions, also suggesting differences in geometry. Similar was seen for the OX 1 –OX 2 interaction. In conclusion, orexin receptors have a significant propensity to make homo- and heterodi-/oligomeric complexes. However, it is unclear whether this affects their signaling. As orexin receptors efficiently signal via endocannabinoid production to CB 1 receptors, dimerization could be an effective way of forming signal complexes with optimal cannabinoid concentrations

Association of cannabis use during adolescence, prefrontal CB1 receptor signaling and schizophrenia

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Adriana eCaballero

2012-05-01

Full Text Available The cannabinoid receptor 1 (CB1R is the G-protein coupled receptor responsible for the majority of the endocannabinoid signaling in the human brain. It is widely distributed in the limbic system, basal ganglia, and cerebellum, which are areas responsible for cognition, memory, and motor control. Because of this widespread distribution, it is not surprising that drugs that co-opt CB1R have expected behavioral outcomes consistent with dysregulated signaling from these areas (e.g. memory loss, cognitive deficits, etc. In the context of this review, we present evidence for the role of CB1R signaling in the prefrontal cortex (PFC, an area involved in executive functions, with emphasis on the developmental regulation of CB1R signaling in the acquisition of mature PFC function. We further hypothesize how alterations of CB1R signaling specifically during adolescent maturation might confer liability to psychiatric disorders.

Molecular basis of cannabinoid CB1 receptor coupling to the G protein heterotrimer Gαiβγ: identification of key CB1 contacts with the C-terminal helix α5 of Gαi.

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Shim, Joong-Youn; Ahn, Kwang H; Kendall, Debra A

2013-11-08

The cannabinoid (CB1) receptor is a member of the rhodopsin-like G protein-coupled receptor superfamily. The human CB1 receptor, which is among the most expressed receptors in the brain, has been implicated in several disease states, including drug addiction, anxiety, depression, obesity, and chronic pain. Different classes of CB1 agonists evoke signaling pathways through the activation of specific subtypes of G proteins. The molecular basis of CB1 receptor coupling to its cognate G protein is unknown. As a first step toward understanding CB1 receptor-mediated G protein signaling, we have constructed a ternary complex structural model of the CB1 receptor and Gi heterotrimer (CB1-Gi), guided by the x-ray structure of β2-adrenergic receptor (β2AR) in complex with Gs (β2AR-Gs), through 824-ns duration molecular dynamics simulations in a fully hydrated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer environment. We identified a group of residues at the juxtamembrane regions of the intracellular loops 2 and 3 (IC2 and IC3) of the CB1 receptor, including Ile-218(3.54), Tyr-224(IC2), Asp-338(6.30), Arg-340(6.32), Leu-341(6.33), and Thr-344(6.36), as potential key contacts with the extreme C-terminal helix α5 of Gαi. Ala mutations of these residues at the receptor-Gi interface resulted in little G protein coupling activity, consistent with the present model of the CB1-Gi complex, which suggests tight interactions between CB1 and the extreme C-terminal helix α5 of Gαi. The model also suggests that unique conformational changes in the extreme C-terminal helix α5 of Gα play a crucial role in the receptor-mediated G protein activation.

Presynaptic selectivity of a ligand for serotonin 1A receptors revealed by in vivo PET assays of rat brain.

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Takeaki Saijo

Full Text Available A novel investigational antidepressant with high affinity for the serotonin transporter and the serotonin 1A (5-HT(1A receptor, called Wf-516 (structural formula: (2S-1-[4-(3,4-dichlorophenylpiperidin-1-yl]-3-[2-(5-methyl-1,3,4-oxadiazol-2-ylbenzo[b]furan-4-yloxy]propan-2-ol monohydrochloride, has been found to exert a rapid therapeutic effect, although the mechanistic basis for this potential advantage remains undetermined. We comparatively investigated the pharmacokinetics and pharmacodynamics of Wf-516 and pindolol by positron emission tomographic (PET and autoradiographic assays of rat brains in order to elucidate their molecular interactions with presynaptic and postsynaptic 5-HT(1A receptors. In contrast to the full receptor occupancy by pindolol in PET measurements, the binding of Wf-516 to 5-HT(1A receptors displayed limited capacity, with relatively high receptor occupancy being achieved in regions predominantly containing presynaptic receptors. This selectivity was further proven by PET scans of neurotoxicant-treated rats deficient in presynaptic 5-HT(1A receptors. In addition, [(35S]guanosine 5'-O-[γ-thio]triphosphate autoradiography indicated a partial agonistic ability of Wf-516 for 5-HT(1A receptors. This finding has lent support to reports that diverse partial agonists for 5-HT(1A receptors exert high sensitivity for presynaptic components. Thus, the present PET data suggest a relatively high capacity of presynaptic binding sites for partial agonists. Since our in vitro and ex vivo autoradiographies failed to illustrate these distinct features of Wf-516, in vivo PET imaging is considered to be, thus far, the sole method capable of pharmacokinetically demonstrating the unique actions of Wf-516 and similar new-generation antidepressants.

Presynaptic selectivity of a ligand for serotonin 1A receptors revealed by in vivo PET assays of rat brain.

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Saijo, Takeaki; Maeda, Jun; Okauchi, Takashi; Maeda, Jun-ichi; Morio, Yasunori; Kuwahara, Yasuhiro; Suzuki, Masayuki; Goto, Nobuharu; Fukumura, Toshimitsu; Suhara, Tetsuya; Higuchi, Makoto

2012-01-01

A novel investigational antidepressant with high affinity for the serotonin transporter and the serotonin 1A (5-HT(1A)) receptor, called Wf-516 (structural formula: (2S)-1-[4-(3,4-dichlorophenyl)piperidin-1-yl]-3-[2-(5-methyl-1,3,4-oxadiazol-2-yl)benzo[b]furan-4-yloxy]propan-2-ol monohydrochloride), has been found to exert a rapid therapeutic effect, although the mechanistic basis for this potential advantage remains undetermined. We comparatively investigated the pharmacokinetics and pharmacodynamics of Wf-516 and pindolol by positron emission tomographic (PET) and autoradiographic assays of rat brains in order to elucidate their molecular interactions with presynaptic and postsynaptic 5-HT(1A) receptors. In contrast to the full receptor occupancy by pindolol in PET measurements, the binding of Wf-516 to 5-HT(1A) receptors displayed limited capacity, with relatively high receptor occupancy being achieved in regions predominantly containing presynaptic receptors. This selectivity was further proven by PET scans of neurotoxicant-treated rats deficient in presynaptic 5-HT(1A) receptors. In addition, [(35)S]guanosine 5'-O-[γ-thio]triphosphate autoradiography indicated a partial agonistic ability of Wf-516 for 5-HT(1A) receptors. This finding has lent support to reports that diverse partial agonists for 5-HT(1A) receptors exert high sensitivity for presynaptic components. Thus, the present PET data suggest a relatively high capacity of presynaptic binding sites for partial agonists. Since our in vitro and ex vivo autoradiographies failed to illustrate these distinct features of Wf-516, in vivo PET imaging is considered to be, thus far, the sole method capable of pharmacokinetically demonstrating the unique actions of Wf-516 and similar new-generation antidepressants.

Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers.

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Hirvonen, J; Goodwin, R S; Li, C-T; Terry, G E; Zoghbi, S S; Morse, C; Pike, V W; Volkow, N D; Huestis, M A; Innis, R B

2012-06-01

Chronic cannabis (marijuana, hashish) smoking can result in dependence. Rodent studies show reversible downregulation of brain cannabinoid CB(1) (cannabinoid receptor type 1) receptors after chronic exposure to cannabis. However, whether downregulation occurs in humans who chronically smoke cannabis is unknown. Here we show, using positron emission tomography imaging, reversible and regionally selective downregulation of brain cannabinoid CB(1) receptors in human subjects who chronically smoke cannabis. Downregulation correlated with years of cannabis smoking and was selective to cortical brain regions. After ∼4 weeks of continuously monitored abstinence from cannabis on a secure research unit, CB(1) receptor density returned to normal levels. This is the first direct demonstration of cortical cannabinoid CB(1) receptor downregulation as a neuroadaptation that may promote cannabis dependence in human brain.

Regulation of hippocampal cannabinoid CB1 receptor actions by adenosine A1 receptors and chronic caffeine administration: implications for the effects of Δ9-tetrahydrocannabinol on spatial memory.

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Sousa, Vasco C; Assaife-Lopes, Natália; Ribeiro, Joaquim A; Pratt, Judith A; Brett, Ros R; Sebastião, Ana M

2011-01-01

The cannabinoid CB(1) receptor-mediated modulation of γ-aminobutyric acid (GABA) release from inhibitory interneurons is important for the integrity of hippocampal-dependent spatial memory. Although adenosine A(1) receptors have a central role in fine-tuning excitatory transmission in the hippocampus, A(1) receptors localized in GABAergic cells do not directly influence GABA release. CB(1) and A(1) receptors are the main targets for the effects of two of the most heavily consumed psychoactive substances worldwide: Δ(9)-tetrahydrocannabinol (THC, a CB(1) receptor agonist) and caffeine (an adenosine receptor antagonist). We first tested the hypothesis that an A(1)-CB(1) interaction influences GABA and glutamate release in the hippocampus. We found that A(1) receptor activation attenuated the CB(1)-mediated inhibition of GABA and glutamate release and this interaction was manifested at the level of G-protein activation. Using in vivo and in vitro approaches, we then investigated the functional implications of the adenosine-cannabinoid interplay that may arise following chronic caffeine consumption. Chronic administration of caffeine in mice (intraperitoneally, 3 mg/kg/day, for 15 days, >12 h before trials) led to an A(1)-mediated enhancement of the CB(1)-dependent acute disruptive effects of THC on a short-term spatial memory task, despite inducing a reduction in cortical and hippocampal CB(1) receptor number and an attenuation of CB(1) coupling with G protein. A(1) receptor levels were increased following chronic caffeine administration. This study shows that A(1) receptors exert a negative modulatory effect on CB(1)-mediated inhibition of GABA and glutamate release, and provides the first evidence of chronic caffeine-induced alterations on the cannabinoid system in the cortex and hippocampus, with functional implications in spatial memory.

Human orexin/hypocretin receptors form constitutive homo- and heteromeric complexes with each other and with human CB{sub 1} cannabinoid receptors

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Jäntti, Maria H., E-mail: maria.jantti@helsinki.fi [Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki (Finland); Mandrika, Ilona, E-mail: ilona@biomed.lu.lv [Latvian Biomedical Research and Study Centre, Ratsupites Str. 1, Riga LV 1067 (Latvia); Kukkonen, Jyrki P., E-mail: jyrki.kukkonen@helsinki.fi [Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki (Finland)

2014-03-07

Highlights: • OX{sub 1} and OX{sub 2} orexin and CB{sub 1} cannabinoid receptor dimerization was investigated. • Bioluminescence resonance energy transfer method was used. • All receptors readily formed constitutive homo- and heteromeric complexes. - Abstract: Human OX{sub 1} orexin receptors have been shown to homodimerize and they have also been suggested to heterodimerize with CB{sub 1} cannabinoid receptors. The latter has been suggested to be important for orexin receptor responses and trafficking. In this study, we wanted to assess the ability of the other combinations of receptors to also form similar complexes. Vectors for expression of human OX{sub 1}, OX{sub 2} and CB{sub 1} receptors, C-terminally fused with either Renilla luciferase or GFP{sup 2} green fluorescent protein variant, were generated. The constructs were transiently expressed in Chinese hamster ovary cells, and constitutive dimerization between the receptors was assessed by bioluminescence energy transfer (BRET). Orexin receptor subtypes readily formed homo- and hetero(di)mers, as suggested by significant BRET signals. CB{sub 1} receptors formed homodimers, and they also heterodimerized with both orexin receptors. Interestingly, BRET efficiency was higher for homodimers than for almost all heterodimers. This is likely to be due to the geometry of the interaction; the putatively symmetric dimers may place the C-termini in a more suitable orientation in homomers. Fusion of luciferase to an orexin receptor and GFP{sup 2} to CB{sub 1} produced more effective BRET than the opposite fusions, also suggesting differences in geometry. Similar was seen for the OX{sub 1}–OX{sub 2} interaction. In conclusion, orexin receptors have a significant propensity to make homo- and heterodi-/oligomeric complexes. However, it is unclear whether this affects their signaling. As orexin receptors efficiently signal via endocannabinoid production to CB{sub 1} receptors, dimerization could be an effective way

Age-dependent changes of presynaptic neuromodulation via A1-adenosine receptors in rat hippocampal slices.

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Sperlágh, B; Zsilla, G; Baranyi, M; Kékes-Szabó, A; Vizi, E S

1997-10-01

The presynaptic neuromodulation of stimulation-evoked release of [3H]-acetylcholine by endogenous adenosine, via A1-adenosine receptors, was studied in superfused hippocampal slices taken from 4-, 12- and 24-month-old rats. 8-Cyclopentyl-1,3-dimethylxanthine (0.25 microM), a selective A1-receptor antagonist, increased significantly the electrical field stimulation-induced release of [3H]-acetylcholine in slices prepared from 4- and 12-month-old rats, showing a tonic inhibitory action of endogenous adenosine via stimulation of presynaptic A1-adenosine receptors. In contrast, 8-cyclopentyl-1,3-dimethylxanthine had no effect in 24-month-old rats. 2-Chloroadenosine (10 microM), an adenosine receptor agonist decreased the release of [3H]-acetylcholine in slices taken from 4- and 12-month-old rats, and no significant change was observed in slices taken from 24-month-old rats. In order to show whether the number/or affinity of the A1-receptors was affected in aged rats, [3H]-8-cyclopentyl-1,3-dimethylxanthine binding was studied in hippocampal membranes prepared from rats of different ages. Whereas the Bmax value was significantly lower in 2-year-old rats than in younger counterparts, the dissociation constant (Kd) was not affected by aging, indicating that the density rather than the affinity of adenosine receptors was altered. Endogenous adenosine levels present in the extracellular space were also measured in the superfusate by high performance liquid chromatography (HPLC) coupled with ultraviolet detection, and an age-related increase in the adenosine level was found. In summary, our results indicate that during aging the level of adenosine in the extracellular fluid is increased in the hippocampus. There is a downregulation and reduced responsiveness of presynaptic adenosine A1-receptors, and it seems likely that these changes are due to the enhanced adenosine level in the extracellular space.

Cannabinoid receptor CB1 mediates baseline and activity-induced survival of new neurons in adult hippocampal neurogenesis

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Müller Anke

2010-06-01

Full Text Available Abstract Background Adult neurogenesis is a particular example of brain plasticity that is partially modulated by the endocannabinoid system. Whereas the impact of synthetic cannabinoids on the neuronal progenitor cells has been described, there has been lack of information about the action of plant-derived extracts on neurogenesis. Therefore we here focused on the effects of Δ9-tetrahydrocannabinol (THC and Cannabidiol (CBD fed to female C57Bl/6 and Nestin-GFP-reporter mice on proliferation and maturation of neuronal progenitor cells and spatial learning performance. In addition we used cannabinoid receptor 1 (CB1 deficient mice and treatment with CB1 antagonist AM251 in Nestin-GFP-reporter mice to investigate the role of the CB1 receptor in adult neurogenesis in detail. Results THC and CBD differed in their effects on spatial learning and adult neurogenesis. CBD did not impair learning but increased adult neurogenesis, whereas THC reduced learning without affecting adult neurogenesis. We found the neurogenic effect of CBD to be dependent on the CB1 receptor, which is expressed over the whole dentate gyrus. Similarly, the neurogenic effect of environmental enrichment and voluntary wheel running depends on the presence of the CB1 receptor. We found that in the absence of CB1 receptors, cell proliferation was increased and neuronal differentiation reduced, which could be related to CB1 receptor mediated signaling in Doublecortin (DCX-expressing intermediate progenitor cells. Conclusion CB1 affected the stages of adult neurogenesis that involve intermediate highly proliferative progenitor cells and the survival and maturation of new neurons. The pro-neurogenic effects of CBD might explain some of the positive therapeutic features of CBD-based compounds.

Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers

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Hirvonen, J; Goodwin, RS; Li, C-T; Terry, GE; Zoghbi, SS; Morse, C; Pike, VW; Volkow, ND; Huestis, MA; Innis, RB

2011-01-01

Chronic cannabis (marijuana, hashish) smoking can result in dependence. Rodent studies show reversible downregulation of brain cannabinoid CB1 (cannabinoid receptor type 1) receptors after chronic exposure to cannabis. However, whether downregulation occurs in humans who chronically smoke cannabis is unknown. Here we show, using positron emission tomography imaging, reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in human subjects who chronically smoke ca...

Phencyclidine-Induced Social Withdrawal Results from Deficient Stimulation of Cannabinoid CB1 Receptors: Implications for Schizophrenia

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Seillier, Alexandre; Martinez, Alex A; Giuffrida, Andrea

2013-01-01

The neuronal mechanisms underlying social withdrawal, one of the core negative symptoms of schizophrenia, are not well understood. Recent studies suggest an involvement of the endocannabinoid system in the pathophysiology of schizophrenia and, in particular, of negative symptoms. We used biochemical, pharmacological, and behavioral approaches to investigate the role played by the endocannabinoid system in social withdrawal induced by sub-chronic administration of phencyclidine (PCP). Pharmacological enhancement of endocannabinoid levels via systemic administration of URB597, an inhibitor of endocannabinoid degradation, reversed social withdrawal in PCP-treated rats via stimulation of CB1 receptors, but reduced social interaction in control animals through activation of a cannabinoid/vanilloid-sensitive receptor. In addition, the potent CB agonist CP55,940 reversed PCP-induced social withdrawal in a CB1-dependent manner, whereas pharmacological blockade of CB1 receptors by either AM251 or SR141716 reduced the time spent in social interaction in control animals. PCP-induced social withdrawal was accompanied by a decrease of anandamide (AEA) levels in the amygdala and prefrontal cortex, and these deficits were reversed by URB597. As CB1 receptors are predominantly expressed on GABAergic interneurons containing the anxiogenic peptide cholecystokinin (CCK), we also examined whether the PCP-induced social withdrawal resulted from deficient CB1-mediated modulation of CCK transmission. The selective CCK2 antagonist LY225910 blocked both PCP- and AM251-induced social withdrawal, but not URB597 effect in control rats. Taken together, these findings indicate that AEA-mediated activation of CB1 receptors is crucial for social interaction, and that PCP-induced social withdrawal results from deficient endocannabinoid transmission. PMID:23563893

The CB1 Receptor as an Important Mediator of Hedonic Reward Processing

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Friemel, Chris M; Zimmer, Andreas; Schneider, Miriam

2014-01-01

The endocannabinoid (ECB) system has emerged recently as a key mediator for reward processing. It is well known that cannabinoids affect appetitive learning processes and can induce reinforcing and rewarding effects. However, the involvement of the ECB system in hedonic aspects of reward-related behavior is not completely understood. With the present study, we investigated the modulatory role of the ECB system on hedonic perception, measured by the pleasure attenuated startle (PAS) paradigm for a palatable food reward. Here, a conditioned odor is thought to induce a pleasant affective state that attenuates an aversive reflex—the acoustic startle response. Modulatory effects of the CB1 receptor antagonist/inverse agonist SR1411716 and the cannabinoid agonist WIN 55 212-2 on PAS were examined in rats. PAS was also measured in CB1 receptor knockout (KO) and wild-type (WT) mice. Pharmacological inhibition as well as the absence of CB1 receptors was found to reduce PAS, whereas WIN 55 212-2 administration increased PAS. Finally, presentation of a conditioned reward cue was found to induce striatal FosB/ΔFosB expression in WT mice, but not in KO mice, indicating a reduced stimulation of reward-related brain regions in conditioned KO mice by odor presentation. We here show that in addition to our previous studies in rats, PAS may also serve as a valuable and suitable measure to assess hedonic processing in mice. Our data further indicate that the ECB system, and in particular CB1 receptor signaling, appears to be highly important for the mediation of hedonic aspects of reward processing. PMID:24718372

Participation of hypothalamic CB1 receptors in reproductive axis disruption during immune challenge.

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Surkin, P N; Di Rosso, M E; Correa, F; Elverdin, J C; Genaro, A M; De Laurentiis, A; Fernández-Solari, J

2017-08-01

Immune challenge inhibits reproductive function and endocannabinoids (eCB) modulate sexual hormones. However, no studies have been performed to assess whether the eCB system mediates the inhibition of hormones that control reproduction as a result of immune system activation during systemic infections. For that reason, we evaluated the participation of the hypothalamic cannabinoid receptor CB1 on the hypothalamic-pituitary-gonadal (HPG) axis activity in rats submitted to immune challenge. Male adult rats were treated i.c.v. administration with a CB1 antagonist/inverse agonist (AM251) (500 ng/5 μL), followed by an i.p. injection of lipopolysaccharide (LPS) (5 mg/kg) 15 minutes later. Plasmatic, hypothalamic and adenohypophyseal pro-inflammatory cytokines, hormones and neuropeptides were assessed 90 or 180 minutes post-LPS. The plasma concentration of tumour necrosis factor α and adenohypophyseal mRNA expression of Tnfα and Il1β increased 90 and 180 minutes post i.p. administration of LPS. However, cytokine mRNA expression in the hypothalamus increased only 180 minutes post-LPS, suggesting an inflammatory delay in this organ. CB1 receptor blockade with AM251 increased LPS inflammatory effects, particularly in the hypothalamus. LPS also inhibited the HPG axis by decreasing gonadotrophin-releasing hormone hypothalamic content and plasma levels of luteinising hormone and testosterone. These disruptor effects were accompanied by decreased hypothalamic Kiss1 mRNA expression and prostaglandin E2 content, as well as by increased gonadotrophin-inhibitory hormone (Rfrp3) mRNA expression. All these disruptive effects were prevented by the presence of AM251. In summary, our results suggest that, in male rats, eCB mediate immune challenge-inhibitory effects on reproductive axis at least partially via hypothalamic CB1 activation. In addition, this receptor also participates in homeostasis recovery by modulating the inflammatory process taking place after LPS

Facilitation of neocortical presynaptic terminal development by NMDA receptor activation

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Sceniak Michael P

2012-02-01

Full Text Available Abstract Background Neocortical circuits are established through the formation of synapses between cortical neurons, but the molecular mechanisms of synapse formation are only beginning to be understood. The mechanisms that control synaptic vesicle (SV and active zone (AZ protein assembly at developing presynaptic terminals have not yet been defined. Similarly, the role of glutamate receptor activation in control of presynaptic development remains unclear. Results Here, we use confocal imaging to demonstrate that NMDA receptor (NMDAR activation regulates accumulation of multiple SV and AZ proteins at nascent presynaptic terminals of visual cortical neurons. NMDAR-dependent regulation of presynaptic assembly occurs even at synapses that lack postsynaptic NMDARs. We also provide evidence that this control of presynaptic terminal development is independent of glia. Conclusions Based on these data, we propose a novel NMDAR-dependent mechanism for control of presynaptic terminal development in excitatory neocortical neurons. Control of presynaptic development by NMDARs could ultimately contribute to activity-dependent development of cortical receptive fields.

Presynaptic Glycine Receptors Increase GABAergic Neurotransmission in Rat Periaqueductal Gray Neurons

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Kwi-Hyung Choi

2013-01-01

Full Text Available The periaqueductal gray (PAG is involved in the central regulation of nociceptive transmission by affecting the descending inhibitory pathway. In the present study, we have addressed the functional role of presynaptic glycine receptors in spontaneous glutamatergic transmission. Spontaneous EPSCs (sEPSCs were recorded in mechanically dissociated rat PAG neurons using a conventional whole-cell patch recording technique under voltage-clamp conditions. The application of glycine (100 µM significantly increased the frequency of sEPSCs, without affecting the amplitude of sEPSCs. The glycine-induced increase in sEPSC frequency was blocked by 1 µM strychnine, a specific glycine receptor antagonist. The results suggest that glycine acts on presynaptic glycine receptors to increase the probability of glutamate release from excitatory nerve terminals. The glycine-induced increase in sEPSC frequency completely disappeared either in the presence of tetrodotoxin or Cd2+, voltage-gated Na+, or Ca2+ channel blockers, suggesting that the activation of presynaptic glycine receptors might depolarize excitatory nerve terminals. The present results suggest that presynaptic glycine receptors can regulate the excitability of PAG neurons by enhancing glutamatergic transmission and therefore play an important role in the regulation of various physiological functions mediated by the PAG.

Cannabinoid-1 receptor (CB1R) blockers as medicines: beyond obesity and cardiometabolic disorders to substance abuse/drug addiction with CB1R neutral antagonists.

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Janero, David R

2012-03-01

Addiction to chemical substances with abuse potential presents medical needs largely unsolved by extant therapeutic strategies. Signal transmission through the cannabinoid-1 receptor (CB1R) in the central nervous system (CNS) modulates neurotransmitters/neuronal pathways contributing to the rewarding properties and hedonic effects of certain nondrug stimuli (e.g., food) and many prototypical addictive drugs, promoting excessive intake and its pathological consequences. Typical CB1R antagonists/inverse agonists reduce the rewarding effects and normalize behavioral phenotypes associated with food and abused drugs, but carry an unacceptable adverse-event profile that may reflect, at least partly, their intrinsic ability to alter basal homeostatic CB1R signaling in the CNS and elicit a negative efficacy response. Alternatively, peripherally biased CB1R inverse agonists with limited CNS permeability and putative CB1R neutral antagonists expressing modest (if any) inverse-agonist efficacy are garnering attention for treating obesity and related cardiometabolic complications with a potentially enhanced benefit-to-risk profile. This mini-review calls attention to the proposition that CB1R neutral antagonists offer attractive opportunities for pharmacotherapeutic exploitation in the substance abuse/drug addiction space, whereas the restricted CNS accessibility of peripherally biased CB1R inverse agonists circumscribes their therapeutic utility for this indication. The unique preclinical pharmacology, efficacy profiles, and reduced adverse-event risk of CB1R neutral antagonists make them worthy of translational study for their potential therapeutic application beyond obesity/cardiometabolic disease to include substance-abuse/drug-addiction disorders.

Cannabinoid CB1 receptor antagonist rimonabant disrupts nicotine reward-associated memory in rats.

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Fang, Qin; Li, Fang-Qiong; Li, Yan-Qin; Xue, Yan-Xue; He, Ying-Ying; Liu, Jian-Feng; Lu, Lin; Wang, Ji-Shi

2011-10-01

Exposure to cues previously associated with drug intake leads to relapse by activating previously acquired memories. Based on previous findings, in which cannabinoid CB(1) receptors were found to be critically involved in specific aspects of learning and memory, we investigated the role of CB(1) receptors in nicotine reward memory using a rat conditioned place preference (CPP) model. In Experiment 1, rats were trained for CPP with alternating injections of nicotine (0.5mg/kg, s.c.) and saline to acquire the nicotine-conditioned memory. To examine the effects of rimonabant on the reconsolidation of nicotine reward memory, rats were administered rimonabant (0, 0.3, and 3.0mg/kg, i.p.) immediately after reexposure to the drug-paired context. In Experiment 2, rats were trained for CPP similarly to Experiment 1. To examine the effects of rimonabant on the reinstatement of nicotine reward memory, rimonabant (0, 0.3, and 3.0mg/kg, i.p.) was administered before the test of nicotine-induced CPP reinstatement. In Experiment 3, to evaluate whether rimonabant itself produces a reward memory, rats were trained for CPP with alternating injections of different doses of rimonabant (0, 0.3, and 3.0mg/kg) and saline. Rimonabant at a dose of 3.0mg/kg significantly disrupted the reconsolidation of nicotine memory and significantly blocked the reinstatement of nicotine-induced CPP. However, rimonabant itself did not produce CPP. These findings provide clear evidence that CB(1) receptors play a role in nicotine reward memory, suggesting that CB(1) receptor antagonists may be a potential target for managing nicotine addiction. Copyright © 2011 Elsevier Inc. All rights reserved.

Acute cannabinoids impair working memory through astroglial CB1 receptor modulation of hippocampal LTD.

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Han, Jing; Kesner, Philip; Metna-Laurent, Mathilde; Duan, Tingting; Xu, Lin; Georges, Francois; Koehl, Muriel; Abrous, Djoher Nora; Mendizabal-Zubiaga, Juan; Grandes, Pedro; Liu, Qingsong; Bai, Guang; Wang, Wei; Xiong, Lize; Ren, Wei; Marsicano, Giovanni; Zhang, Xia

2012-03-02

Impairment of working memory is one of the most important deleterious effects of marijuana intoxication in humans, but its underlying mechanisms are presently unknown. Here, we demonstrate that the impairment of spatial working memory (SWM) and in vivo long-term depression (LTD) of synaptic strength at hippocampal CA3-CA1 synapses, induced by an acute exposure of exogenous cannabinoids, is fully abolished in conditional mutant mice lacking type-1 cannabinoid receptors (CB(1)R) in brain astroglial cells but is conserved in mice lacking CB(1)R in glutamatergic or GABAergic neurons. Blockade of neuronal glutamate N-methyl-D-aspartate receptors (NMDAR) and of synaptic trafficking of glutamate α-amino-3-hydroxy-5-methyl-isoxazole propionic acid receptors (AMPAR) also abolishes cannabinoid effects on SWM and LTD induction and expression. We conclude that the impairment of working memory by marijuana and cannabinoids is due to the activation of astroglial CB(1)R and is associated with astroglia-dependent hippocampal LTD in vivo. Copyright © 2012 Elsevier Inc. All rights reserved.

The Structure–Function Relationships of Classical Cannabinoids: CB1/CB2 Modulation

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Bow, Eric W.; Rimoldi, John M.

2016-01-01

The cannabinoids are members of a deceptively simple class of terpenophenolic secondary metabolites isolated from Cannabis sativa highlighted by (−)-Δ9-tetrahydrocannabinol (THC), eliciting distinct pharmacological effects mediated largely by cannabinoid receptor (CB1 or CB2) signaling. Since the initial discovery of THC and related cannabinoids, synthetic and semisynthetic classical cannabinoid analogs have been evaluated to help define receptor binding modes and structure–CB1/CB2 functional activity relationships. This perspective will examine the classical cannabinoids, with particular emphasis on the structure–activity relationship of five regions: C3 side chain, phenolic hydroxyl, aromatic A-ring, pyran B-ring, and cyclohexenyl C-ring. Cumulative structure–activity relationship studies to date have helped define the critical structural elements required for potency and selectivity toward CB1 and CB2 and, more importantly, ushered the discovery and development of contemporary nonclassical cannabinoid modulators with enhanced physicochemical and pharmacological profiles. PMID:27398024

Controlled-Deactivation CB1 Receptor Ligands as a Novel Strategy to Lower Intraocular Pressure

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Sally Miller

2018-05-01

Full Text Available Nearly half a century has passed since the demonstration that cannabis and its chief psychoactive component Δ9-THC lowers intraocular pressure (IOP. Elevated IOP remains the chief hallmark and therapeutic target for glaucoma, a condition that places millions at risk of blindness. It is likely that Δ9-THC exerts much of its IOP-lowering effects via the activation of CB1 cannabinoid receptors. However, the initial promise of CB1 as a target for treating glaucoma has not thus far translated into a credible therapeutic strategy. We have recently shown that blocking monoacylglycerol lipase (MAGL, an enzyme that breaks the endocannabinoid 2-arachidonoyl glycerol (2-AG, substantially lowers IOP. Another strategy is to develop cannabinoid CB1 receptor agonists that are optimized for topical application to the eye. Recently we have reported on a controlled-deactivation approach where the “soft” drug concept of enzymatic deactivation was combined with a “depot effect” that is commonly observed with Δ9-THC and other lipophilic cannabinoids. This approach allowed us to develop novel cannabinoids with a predictable duration of action and is particularly attractive for the design of CB1 activators for ophthalmic use with limited or no psychoactive effects. We have tested a novel class of compounds using a combination of electrophysiology in autaptic hippocampal neurons, a well-characterized model of endogenous cannabinoid signaling, and measurements of IOP in a mouse model. We now report that AM7410 is a reasonably potent and efficacious agonist at CB1 in neurons and that it substantially (30% lowers IOP for as long as 5 h after a single topical treatment. This effect is absent in CB1 knockout mice. Our results indicate that the direct targeting of CB1 receptors with controlled-deactivation ligands is a viable approach to lower IOP in a murine model and merits further study in other model systems.

Gz mediates the long-lasting desensitization of brain CB1 receptors and is essential for cross-tolerance with morphine

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Rodríguez-Muñoz María

2009-03-01

Full Text Available Abstract Background Although the systemic administration of cannabinoids produces antinociception, their chronic use leads to analgesic tolerance as well as cross-tolerance to morphine. These effects are mediated by cannabinoids binding to peripheral, spinal and supraspinal CB1 and CB2 receptors, making it difficult to determine the relevance of each receptor type to these phenomena. However, in the brain, the CB1 receptors (CB1Rs are expressed at high levels in neurons, whereas the expression of CB2Rs is marginal. Thus, CB1Rs mediate the effects of smoked cannabis and are also implicated in emotional behaviors. We have analyzed the production of supraspinal analgesia and the development of tolerance at CB1Rs by the direct injection of a series of cannabinoids into the brain. The influence of the activation of CB1Rs on supraspinal analgesia evoked by morphine was also evaluated. Results Intracerebroventricular (icv administration of cannabinoid receptor agonists, WIN55,212-2, ACEA or methanandamide, generated a dose-dependent analgesia. Notably, a single administration of these compounds brought about profound analgesic tolerance that lasted for more than 14 days. This decrease in the effect of cannabinoid receptor agonists was not mediated by depletion of CB1Rs or the loss of regulated G proteins, but, nevertheless, it was accompanied by reduced morphine analgesia. On the other hand, acute morphine administration produced tolerance that lasted only 3 days and did not affect the CB1R. We found that both neural mu-opioid receptors (MORs and CB1Rs interact with the HINT1-RGSZ module, thereby regulating pertussis toxin-insensitive Gz proteins. In mice with reduced levels of these Gz proteins, the CB1R agonists produced no such desensitization or morphine cross-tolerance. On the other hand, experimental enhancement of Gz signaling enabled an acute icv administration of morphine to produce a long-lasting tolerance at MORs that persisted for more than

Paranoid schizophrenia is characterized by increased CB1 receptor binding in the dorsolateral prefrontal cortex.

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Dalton, Victoria S; Long, Leonora E; Weickert, Cyndi Shannon; Zavitsanou, Katerina

2011-07-01

A number of studies suggest a dysregulation of the endogenous cannabinoid system in schizophrenia (SCZ). In the present study, we examined cannabinoid CB(1) receptor (CB(1)R) binding and mRNA expression in the dorsolateral prefrontal cortex (DLPFC) (Brodmann's area 46) of SCZ patients and controls, post-mortem. Receptor density was investigated using autoradiography with the CB(1)R ligand [(3)H] CP 55,940 and CB(1)R mRNA expression was measured using quantitative RT-PCR in a cohort of 16 patients with paranoid SCZ, 21 patients with non-paranoid SCZ and 37 controls matched for age, post-mortem interval and pH. All cases were obtained from the University of Sydney Tissue Resource Centre. Results were analyzed using one-way analysis of variance (ANOVA) and post hoc Bonferroni tests and with analysis of covariance (ANCOVA) to control for demographic factors that would potentially influence CB(1)R expression. There was a main effect of diagnosis on [(3)H] CP 55,940 binding quantified across all layers of the DLPFC (F(2,71) = 3.740, p = 0.029). Post hoc tests indicated that this main effect was due to patients with paranoid SCZ having 22% higher levels of CB(1)R binding compared with the control group. When ANCOVA was employed, this effect was strengthened (F(2,67) = 6.048, p = 0.004) with paranoid SCZ patients differing significantly from the control (p = 0.004) and from the non-paranoid group (p = 0.016). In contrast, no significant differences were observed in mRNA expression between the different disease subtypes and the control group. Our findings confirm the existence of a CB(1)R dysregulation in SCZ and underline the need for further investigation of the role of this receptor particularly in those diagnosed with paranoid SCZ.

The cannabinoid-1 receptor is abundantly expressed in striatal striosomes and striosome-dendron bouquets of the substantia nigra.

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Margaret I Davis

Full Text Available Presynaptic cannabinoid-1 receptors (CB1-R bind endogenous and exogenous cannabinoids to modulate neurotransmitter release. CB1-Rs are expressed throughout the basal ganglia, including striatum and substantia nigra, where they play a role in learning and control of motivated actions. However, the pattern of CB1-R expression across different striatal compartments, microcircuits and efferent targets, and the contribution of different CB1-R-expressing neurons to this pattern, are unclear. We use a combination of conventional techniques and novel genetic models to evaluate CB1-R expression in striosome (patch and matrix compartments of the striatum, and in nigral targets of striatal medium spiny projection neurons (MSNs. CB1-R protein and mRNA follow a descending dorsolateral-to-ventromedial intensity gradient in the caudal striatum, with elevated expression in striosomes relative to the surrounding matrix. The lateral predominance of striosome CB1-Rs contrasts with that of the classical striosomal marker, the mu opioid receptor (MOR, which is expressed most prominently in rostromedial striosomes. The dorsolateral-to-ventromedial CB1-R gradient is similar to Drd2 dopamine receptor immunoreactivity and opposite to Substance P. This topology of CB1-R expression is maintained downstream in the globus pallidus and substantia nigra. Dense CB1-R-expressing striatonigral fibers extend dorsally within the substantia nigra pars reticulata, and colocalize with bundles of ventrally extending, striosome-targeted, dendrites of dopamine-containing neurons in the substantia nigra pars compacta (striosome-dendron bouquets. Within striatum, CB1-Rs colocalize with fluorescently labeled MSN collaterals within the striosomes. Cre recombinase-mediated deletion of CB1-Rs from cortical projection neurons or MSNs, and MSN-selective reintroduction of CB1-Rs in knockout mice, demonstrate that the principal source of CB1-Rs in dorsolateral striosomes is local MSN collaterals

Comparative effects of chlorpyrifos in wild type and cannabinoid Cb1 receptor knockout mice

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Baireddy, Praveena; Liu, Jing; Hinsdale, Myron; Pope, Carey, E-mail: carey.pope@okstate.edu

2011-11-15

Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55.212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (-/-) mice. Mice of both genotypes (n = 5-6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82-95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 {mu}M) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20-23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner. -- Highlights: Black-Right-Pointing-Pointer C57Bl/6 mice showed dose-related cholinergic toxicity following subcutaneous chlorpyrifos exposure. Black-Right-Pointing-Pointer Wild type and

Comparative effects of chlorpyrifos in wild type and cannabinoid Cb1 receptor knockout mice

International Nuclear Information System (INIS)

Baireddy, Praveena; Liu, Jing; Hinsdale, Myron; Pope, Carey

2011-01-01

Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55.212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (−/−) mice. Mice of both genotypes (n = 5–6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82–95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 μM) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20–23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner. -- Highlights: ► C57Bl/6 mice showed dose-related cholinergic toxicity following subcutaneous chlorpyrifos exposure. ► Wild type and cannabinoid CB1 receptor knockout littermates

Involvement of Gaba and Cannabinoid Receptors in Central Food Intake Regulation in Neonatal Layer Chicks: Role of CB1 and Gabaa Receptors

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M Zendehdel

Full Text Available ABSTRACT Feeding behavior is regulated via a complex network which interacts via diverse signals from central and peripheral tissues. Endocannabinoids modulate release of GABA in a variety of regions of the central nervous system. Endocannabinoids and GABAergic system have an important role in the central regulation of appetite. Thus, the present study examines the possible interaction of central canabinoidergic and GABAergic systems on food intake in 3-h food-deprived (FD3 neonatal layer-type chicks. The results of this study showed that intracerebroventricular (ICV injection of 2-AG (2-Arachidonoylglycerol, selective CB1 receptors agonist, 2µg significantly increased food intake and this effect of 2-AG was attenuated by Picrotoxin (GABAA antagonist, 0.5µg (P0.05. Also, hyperphagic effect of CB65 (CB2 receptors agonist, 1.25µg was not affected by Picrotoxin or CGP54626 (p>0.05. Moreover, the food intake of chicks was significantly increased by ICV injection of GABAA agonist (Gaboxadol, 0.2 µg and SR141716A (CB1 receptors antagonist, 6.25µg significantly decreased Gaboxadol-induced hyperphagia (P0.05. These data showed there might be an interaction between central cannabinoidergic and GABAergic systems via CB1 and GABAA receptors in control of food intake in neonatal layer chicks.

Regulation of Hippocampal Cannabinoid CB1 Receptor Actions by Adenosine A1 Receptors and Chronic Caffeine Administration: Implications for the Effects of Δ9-Tetrahydrocannabinol on Spatial Memory

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Sousa, Vasco C; Assaife-Lopes, Natália; Ribeiro, Joaquim A; Pratt, Judith A; Brett, Ros R; Sebastião, Ana M

2010-01-01

Abstract The cannabinoid CB1 receptor-mediated modulation of ?-aminobutyric acid (GABA) release from inhibitory interneurons is important for the integrity of hippocampal-dependent spatial memory. Although adenosine A1 receptors have a central role in fine-tuning excitatory transmission in the hippocampus, A1 receptors localized in GABAergic cells do not directly influence GABA release. CB1 and A1 receptors are the main targets for the effects of two of the most heavily consumed ps...

Effects of cannabinoid CB1 receptor antagonist rimonabant in consolidation and reconsolidation of methamphetamine reward memory in mice.

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Yu, Lu-lu; Wang, Xue-yi; Zhao, Mei; Liu, Yu; Li, Yan-qin; Li, Fang-qiong; Wang, Xiaoyi; Xue, Yan-xue; Lu, Lin

2009-06-01

Previous studies have shown that cannabinoid CB1 receptors play an important role in specific aspects of learning and memory, yet there has been no systematic study focusing on the involvement of cannabinoid CB1 receptors in methamphetamine-related reward memory. The purpose of this study was to examine whether rimonabant, a cannabinoid CB1 receptor antagonist, would disrupt the consolidation and reconsolidation of methamphetamine-related reward memory, using conditioned place preference paradigm (CPP). Separate groups of male Kunming mice were trained to acquire methamphetamine CPP. Vehicle or rimonabant (1 mg/kg or 3 mg/kg, i.p.) was given at different time points: immediately after each CPP training session (consolidation), 30 min before the reactivation of CPP (retrieval), or immediately after the reactivation of CPP (reconsolidation). Methamphetamine CPP was retested 24 h and 1 and 2 weeks after rimonabant administration. Rimonabant at doses of 1 and 3 mg/kg significantly inhibited the consolidation of methamphetamine CPP. Only high-dose rimonabant (3 mg/kg) disrupted the retrieval and reconsolidation of methamphetamine CPP. Rimonabant had no effect on methamphetamine CPP in the absence of methamphetamine CPP reactivation. Our findings suggest that cannabinoid CB1 receptors play a major role in methamphetamine reward memory, and cannabinoid CB1 receptor antagonists may be a potential pharmacotherapy to manage relapse associated with drug-reward-related memory.

Mapping CB1 cannabinoid receptors with [3H]OMAR in the Flinders rodent model of depression

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Nahimi, A.; Gjedde, A.; Wong, D. F.

2012-01-01

not significantly different. Conclusions: Although changes in CB1 receptor expression have been demonstrated in human suicide victims with depression and in animal models of depression, the present maps of [3H]OMAR binding revealed no difference between FSL and FRL rats. We used a single concentration of [3H......Background: The endocannabinoid system regulates cognitive and emotional processes and pathology of this system is implicated in psychiatric disorders, including depression and schizophrenia. The precise role of the endocannabinoid system in psychiatric disorders remains unclear, but changes...... in expression of CB1 receptors and subsequent altered modulation of monoamines is suggested in depression (Esteban & Garcia-Sevilla, 2011). CB1 receptor agonists, such as WIN55,212-2 and CP55,940 regulate synthesis and release of monoamines and are suggested as a novel therapy in the treatment of depression...

Chronic and acute adenosine A2A receptor blockade prevents long-term episodic memory disruption caused by acute cannabinoid CB1 receptor activation.

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Mouro, Francisco M; Batalha, Vânia L; Ferreira, Diana G; Coelho, Joana E; Baqi, Younis; Müller, Christa E; Lopes, Luísa V; Ribeiro, Joaquim A; Sebastião, Ana M

2017-05-01

Cannabinoid-mediated memory impairment is a concern in cannabinoid-based therapies. Caffeine exacerbates cannabinoid CB 1 receptor (CB 1 R)-induced memory deficits through an adenosine A 1 receptor-mediated mechanism. We now evaluated how chronic or acute blockade of adenosine A 2A receptors (A 2A Rs) affects long-term episodic memory deficits induced by a single injection of a selective CB 1 R agonist. Long-term episodic memory was assessed by the novel object recognition (NOR) test. Mice received an intraperitoneal (i.p.) injection of the CB 1 /CB 2 receptor agonist WIN 55,212-2 (1 mg/kg) immediately after the NOR training, being tested for novelty recognition 24 h later. Anxiety levels were assessed by the Elevated Plus Maze test, immediately after the NOR. Mice were also tested for exploratory behaviour at the Open Field. For chronic A 2A R blockade, KW-6002 (istradefylline) (3 mg/kg/day) was administered orally for 30 days; acute blockade of A 2A Rs was assessed by i.p. injection of SCH 58261 (1 mg/kg) administered either together with WIN 55,212-2 or only 30 min before the NOR test phase. The involvement of CB 1 Rs was assessed by using the CB 1 R antagonist, AM251 (3 mg/kg, i.p.). WIN 55,212-2 caused a disruption in NOR, an action absent in mice also receiving AM251, KW-6002 or SCH 58261 during the encoding/consolidation phase; SCH 58251 was ineffective if present during retrieval only. No effects were detected in the Elevated Plus maze or Open Field Test. The finding that CB 1 R-mediated memory disruption is prevented by antagonism of adenosine A 2A Rs, highlights a possibility to prevent cognitive side effects when therapeutic application of CB 1 R drugs is desired. Copyright © 2017 Elsevier Ltd. All rights reserved.

Candidate PET radioligands for cannabinoid CB1 receptors: [18F]AM5144 and related pyrazole compounds

International Nuclear Information System (INIS)

Li Zizhong; Gifford, Andrew; Liu Qian; Thotapally, Rajesh; Ding Yushin; Makriyannis, Alexandros; Gatley, S. John

2005-01-01

Introduction: The mammalian brain contains abundant G protein-coupled cannabinoid CB 1 receptors that respond to Δ 9 -tetrahydrocannabinol, the active ingredient of cannabis. The availability of a positron emission tomography (PET) radioligand would facilitate studies of the addictive and medicinal properties of compounds that bind to this receptor. Among the known classes of ligands for CB 1 receptors, the pyrazoles are attractive targets for radiopharmaceutical development because they are antagonists and are generally less lipophilic than the other classes. Methods: A convenient high-yield synthesis of N-(4-[ 18 F]fluorophenyl)-5-(4-bromophenyl)-1-(2,4-dichlorophenyl)- 1H-pyrazole-3-carboxamide (AM5144) was devised by coupling the appropriate pyrazole-3-carboxyl chloride compound with 4-[ 18 F]fluoroaniline. The labeled precursor was synthesized from 1-[ 18 F]fluoro-4-nitrobenzene in 60% radiochemical yield for 10 min using an improved procedure involving sodium borohydride reduction with cobalt chloride catalysis. The product was purified by HPLC to give a specific activity >400 mCi/μmol and a radiochemical purity >95%, and a PET study was conducted in a baboon. Results: Although the regional uptake of AM5144 in baboon brain was consistent with binding to cannabinoid CB 1 receptors, absolute uptake at 1 receptor ligands is not surprising because of their high lipophilicity as compared with most brain PET radiotracers. However, for nine pyrazole compounds for which rodent data are available, brain uptake and calculated logP values are not correlated. Thus, high logP values should not preclude evaluation of radiotracers for targets such as the CB 1 receptor that may require very lipophilic ligands

The Combined Inhibitory Effect of the Adenosine A1 and Cannabinoid CB1 Receptors on cAMP Accumulation in the Hippocampus Is Additive and Independent of A1 Receptor Desensitization

OpenAIRE

Serpa, Andr?; Correia, Sara; Ribeiro, Joaquim A.; Sebasti?o, Ana M.; Cascalheira, Jos? F.

2015-01-01

Adenosine A1 and cannabinoid CB1 receptors are highly expressed in hippocampus where they trigger similar transduction pathways. We investigated how the combined acute activation of A1 and CB1 receptors modulates cAMP accumulation in rat hippocampal slices. The CB1 agonist WIN55212-2 (0.3?30??M) decreased forskolin-stimulated cAMP accumulation with an EC50 of 6.6 ? 2.7??M and an E max? of 31% ? 2%, whereas for the A1 agonist, N6-cyclopentyladenosine (CPA, 10?150?nM), an EC50 of 35 ? 19?nM, an...

Involvement of the cannabinoid CB1 receptor in modulation of dopamine output in the prefrontal cortex associated with food restriction in rats.

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Laura Dazzi

Full Text Available Increase in dopamine output on corticolimbic structures, such as medial prefrontal cortex (mPFC and nucleus accumbens, has been related to reward effects associated with palatable food or food presentation after a fasting period. The endocannabinoid system regulates feeding behavior through a modulatory action on different neurotransmitter systems, including the dopaminergic system. To elucidate the involvement of type 1 cannabinoid receptors in the regulation of dopamine output in the mPFC associated with feeding in hungry rats, we restricted the food availability to a 2-h period daily for 3 weeks. In food-restricted rats the extracellular dopamine concentration in the mPFC increased starting 80 min before food presentation and returned to baseline after food removal. These changes were attenuated in animals treated with the CB1 receptor antagonist SR141716. To better understand how food restriction can change the response of mesocortical dopaminergic neurons, we studied several components of the neuronal circuit that regulates dopamine output in the mPFC. Patch-clamp experiments revealed that the inhibitory effect of the CB1 receptor agonist WIN 55,212-2 on GABAergic sIPSC frequency was diminished in mPFC neurons of FR compared to fed ad libitum rats. The basal sIPSC frequency resulted reduced in mPFC neurons of food-restricted rats, suggestive of an altered regulation of presynaptic GABA release; these changes were accompanied by an enhanced excitability of mPFC and ventral tegmental area neurons. Finally, type 1 cannabinoid receptor expression in the mPFC was reduced in food-restricted rats. Together, our data support an involvement of the endocannabinoid system in regulation of dopamine release in the mPFC through changes in GABA inhibitory synapses and suggest that the emphasized feeding-associated increase in dopamine output in the mPFC of food-restricted rats might be correlated with an altered expression and function of type 1

Involvement of the cannabinoid CB1 receptor in modulation of dopamine output in the prefrontal cortex associated with food restriction in rats.

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Dazzi, Laura; Talani, Giuseppe; Biggio, Francesca; Utzeri, Cinzia; Lallai, Valeria; Licheri, Valentina; Lutzu, Stefano; Mostallino, Maria Cristina; Secci, Pietro Paolo; Biggio, Giovanni; Sanna, Enrico

2014-01-01

Increase in dopamine output on corticolimbic structures, such as medial prefrontal cortex (mPFC) and nucleus accumbens, has been related to reward effects associated with palatable food or food presentation after a fasting period. The endocannabinoid system regulates feeding behavior through a modulatory action on different neurotransmitter systems, including the dopaminergic system. To elucidate the involvement of type 1 cannabinoid receptors in the regulation of dopamine output in the mPFC associated with feeding in hungry rats, we restricted the food availability to a 2-h period daily for 3 weeks. In food-restricted rats the extracellular dopamine concentration in the mPFC increased starting 80 min before food presentation and returned to baseline after food removal. These changes were attenuated in animals treated with the CB1 receptor antagonist SR141716. To better understand how food restriction can change the response of mesocortical dopaminergic neurons, we studied several components of the neuronal circuit that regulates dopamine output in the mPFC. Patch-clamp experiments revealed that the inhibitory effect of the CB1 receptor agonist WIN 55,212-2 on GABAergic sIPSC frequency was diminished in mPFC neurons of FR compared to fed ad libitum rats. The basal sIPSC frequency resulted reduced in mPFC neurons of food-restricted rats, suggestive of an altered regulation of presynaptic GABA release; these changes were accompanied by an enhanced excitability of mPFC and ventral tegmental area neurons. Finally, type 1 cannabinoid receptor expression in the mPFC was reduced in food-restricted rats. Together, our data support an involvement of the endocannabinoid system in regulation of dopamine release in the mPFC through changes in GABA inhibitory synapses and suggest that the emphasized feeding-associated increase in dopamine output in the mPFC of food-restricted rats might be correlated with an altered expression and function of type 1 cannabinoid receptor in this

Integrated cannabinoid CB1 receptor transmission within the amygdala-prefrontal cortical pathway modulates neuronal plasticity and emotional memory encoding.

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Tan, Huibing; Lauzon, Nicole M; Bishop, Stephanie F; Bechard, Melanie A; Laviolette, Steven R

2010-06-01

The cannabinoid CB1 receptor system is functionally involved in the processing and encoding of emotionally salient sensory information, learning and memory. The CB1 receptor is found in high concentrations in brain structures that are critical for emotional processing, including the basolateral amygdala (BLA) and the medial prefrontal cortex (mPFC). In addition, synaptic plasticity in the form of long-term potentiation (LTP) within the BLA > mPFC pathway is an established correlate of exposure to emotionally salient events. We performed a series of in vivo LTP studies by applying tetanic stimulation to the BLA combined with recordings of local field potentials within prelimbic cortical (PLC) region of the rat mPFC. Systemic pretreatment with AM-251 dose dependently blocked LTP along the BLA-PLC pathway and also the behavioral acquisition of conditioned fear memories. We next performed a series of microinfusion experiments wherein CB1 receptor transmission within the BLA > PLC circuit was pharmacologically blocked. Asymmetrical, interhemispheric blockade of CB1 receptor transmission along the BLA > PLC pathway prevented the acquisition of emotionally salient associative memory. Our results indicate that coordinated CB1 receptor transmission within the BLA > PLC pathway is critically involved in the encoding of emotional fear memories and modulates neural plasticity related to the encoding of emotionally salient associative learning.

Interactions of CB1 and mGlu5 receptor antagonists in food intake, anxiety and memory models in rats.

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Varga, Balázs; Kassai, Ferenc; Gyertyán, István

2012-12-01

CB(1) receptor antagonists proved to be effective anti-obesity drugs, however, their depressive and anxiogenic effects became also evident. Finding solution to overcome these psychiatric side effects is still in focus of research. Based on the available clinical and preclinical results we hypothesized that the combination of CB(1) and mGlu(5) receptor antagonisms may result in a pharmacological intervention, where the anxiolytic mGlu(5) receptor inhibition may counteract the anxiogenic psychiatric side effects of CB(1) antagonism, while CB(1) antagonism may ameliorate the memory impairing effect of mGlu(5) receptor antagonism. Further, the two components will synergistically interact in blocking food-intake and reducing obesity. For testing the interaction of mGlu(5) and CB(1) receptor antagonism MTEP [3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pridine; SIB-1757, 6-methyl-2-(phenylazo)-3-pyridinol)] (mGlu(5) antagonist) and rimonabant [(5-(4-Chlorophenyl)-1-(2,4-dichloro-phenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide)hydrochloride] (CB(1) antagonist) were used. All experiments were carried out in rats. Effects of the compounds on anxiety were tested in two foot shock induced ultrasonic vocalization paradigms, appetite suppression was assessed in the food intake test, while memory effects were tested in a context conditioned ultrasonic vocalization setup. MTEP abolished the anxiogenic effect of rimonabant, while there was an additive cooperation in suppressing appetite. However, rimonabant did not ameliorate the memory impairing effect of MTEP. By combination of CB(1) and mGluR5 antagonism, anxiety related side effects might be attenuated, appetite suppression maintained, nevertheless, the possible emergence of unwanted memory impairments can overshadow its therapeutic success. Copyright © 2012 Elsevier Inc. All rights reserved.

Müller cells express the cannabinoid CB2 receptor in the vervet monkey retina

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Bouskila, Joseph; Javadi, Pasha; Casanova, Christian

2013-01-01

The presence of the cannabinoid receptor type 1 (CB1R) has been largely documented in the rodent and primate retinae in recent years. There is, however, some controversy concerning the presence of the CB2 receptor (CB2R) within the central nervous system. Only recently, CB2R has been found in the...

Elevated Brain Cannabinoid CB1 Receptor Availability in Posttraumatic Stress Disorder: A Positron Emission Tomography Study

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Neumeister, Alexander; Normandin, Marc D.; Pietrzak, Robert H.; Piomelli, Daniele; Zheng, Ming-Qiang; Gujarro-Anton, Ana; Potenza, Marc N.; Bailey, Christopher R.; Lin, Shu-fei; Najafzadeh, Soheila; Ropchan, Jim; Henry, Shannan; Corsi-Travali, Stefani; Carson, Richard E.; Huang, Yiyun

2013-01-01

Endocannabinoids and their attending cannabinoid type 1 receptor (CB1) have been implicated in animal models of posttraumatic stress disorder (PTSD). However, their specific role has not been studied in people with PTSD. Herein, we present an in vivo imaging study using positron emission tomography (PET) and the CB1-selective radioligand [11C]OMAR in individuals with PTSD, and healthy controls with lifetime histories of trauma (trauma controls [TC]) and those without such histories (healthy controls [HC]). Untreated individuals with PTSD (N=25) with non-combat trauma histories, and TC (N=12) and HC (N=23) participated in a magnetic resonance (MR) imaging scan and a resting PET scan with the CB1 receptor antagonist radiotracer [11C]OMAR, which measures volume of distribution (VT) linearly related to CB1 receptor availability. Peripheral levels of anandamide, 2-arachidonoylglycerol (2-AG), oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and cortisol were also assessed. In the PTSD group, relative to the HC and TC groups, we found elevated brain-wide [11C]OMAR VT values (F(2,53)=7.96, p=.001; 19.5% and 14.5% higher, respectively) which were most pronounced in women (F(1,53)=5.52, p=.023). Anandamide concentrations were reduced in the PTSD relative to the TC (53.1% lower) and HC (58.2% lower) groups. Cortisol levels were lower in the PTSD and TC groups relative to the HC group. Three biomarkers examined collectively—OMAR VT, anandamide, and cortisol—correctly classified nearly 85% of PTSD cases. These results suggest that abnormal CB1 receptor-mediated anandamide signaling is implicated in the etiology of PTSD, and provide a promising neurobiological model to develop novel, evidence-based pharmacotherapies for this disorder. PMID:23670490

Immunohistochemical characterisation and localisation of cannabinoid CB1 receptor protein in the rat vestibular nucleus complex and the effects of unilateral vestibular deafferentation.

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Ashton, John C; Zheng, Yiwen; Liu, Ping; Darlington, Cynthia L; Smith, Paul F

2004-09-24

CB1 receptor expression has been reported to be low in the brainstem compared with the forebrain, and low in the vestibular nucleus complex (VNC) compared with other regions in the brainstem. However, a frequent effect of cannabis is dizziness and loss of balance. This may be due to the activation of cannabinoid receptors in the central vestibular pathways. We used immunohistochemistry to study the distribution of CB1 receptor protein in the VNC, and Western blotting to measure CB1 receptor expression in the VNC following unilateral vestibular deafferentation (UVD); the hippocampal CA1, CA2/3 and dentate gyrus (DG) regions were also analysed for comparison. This study confirms a previous electrophysiological demonstration that CB1 receptors exist in significant densities in the VNC and are likely to contribute to the neurochemical control of the vestibular reflexes. Nonetheless, CB1 receptor expression did not change significantly in the VNC during vestibular compensation. In addition, despite some small but significant changes in CB1 receptor expression in the CA2/3 and the DG following UVD, in no case were these differences statistically significant in comparison to both control groups.

Activation of type 2 cannabinoid receptors (CB2R) promotes fatty acid oxidation through the SIRT1/PGC-1α pathway

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Zheng, Xuqin [Department of Endocrinology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province 210029 (China); Sun, Tao [Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu Province 210002 (China); Wang, Xiaodong, E-mail: xdwang666@hotmail.com [Department of Endocrinology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu Province 210029 (China)

2013-07-05

Highlights: •TC, a CB2R specific agonist, stimulates SIRT1 activity by PKA/CREB pathway. •TC promotes PGC-1α transcriptional activity by increasing its deacetylation. •TC increases the expression of genes linked to FAO and promotes the rate of FAO. •The effects of TC in FAO are dependent on CB2R. •Suggesting CB2R as a target to treat diseases with lipid dysregulation. -- Abstract: Abnormal fatty acid oxidation has been associated with obesity and type 2 diabetes. At the transcriptional level, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) has been reported to strongly increase the ability of hormone nuclear receptors PPARα and ERRα to drive transcription of fatty acid oxidation enzymes. In this study, we report that a specific agonist of the type 2 cannabinoid receptor (CB2R) can lead to fatty acid oxidation through the PGC-1α pathway. We have found that CB2R is expressed in differentiated C2C12 myotubes, and that use of the specific agonist trans-caryophyllene (TC) stimulates sirtuin 1 (SIRT1) deacetylase activity by increasing the phosphorylation of cAMP response element-binding protein (CREB), thus leading to increased levels of PGC-1α deacetylation. This use of TC treatment increases the expression of genes linked to the fatty acid oxidation pathway in a SIRT1/PGC-1α-dependent mechanism and also drastically accelerates the rate of complete fatty acid oxidation in C2C12 myotubes, neither of which occur when CB2R mRNA is knocked down using siRNA. These results reveal that activation of CB2R by a selective agonist promotes lipid oxidation through a signaling/transcriptional pathway. Our findings imply that pharmacological manipulation of CB2R may provide therapeutic possibilities to treat metabolic diseases associated with lipid dysregulation.

Neurophysiological evidence for the presence of cannabinoid CB1 receptors in the laterodorsal tegmental nucleus

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Soni, Neeraj; Satpathy, Shankha; Kohlmeier, Kristi Anne

2014-01-01

Marijuana, which acts within the endocannabinoid (eCB) system as an agonist of the cannabinoid type 1 receptor (CB1R), exhibits addictive properties and has powerful actions on the state of arousal of an organism. The laterodorsal tegmental nucleus (LDT), as a component of the reticular activating...... the firing frequency and synaptic activity of neurons in this nucleus. Therefore, endogenous eCB transmission could play a role in processes involving the LDT, such as cortical activation and motivated behaviours and, further, behavioural actions of marijuana are probably mediated, in part, via cellular...

Targeting the endocannabinoid/CB1 receptor system for treating obesity in Prader–Willi syndrome

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Ibrahim Knani

2016-12-01

Full Text Available Objective: Extreme obesity is a core phenotypic feature of Prader–Willi syndrome (PWS. Among numerous metabolic regulators, the endocannabinoid (eCB system is critically involved in controlling feeding, body weight, and energy metabolism, and a globally acting cannabinoid-1 receptor (CB1R blockade reverses obesity both in animals and humans. The first-in-class CB1R antagonist rimonabant proved effective in inducing weight loss in adults with PWS. However, it is no longer available for clinical use because of its centrally mediated, neuropsychiatric, adverse effects. Methods: We studied eCB ‘tone’ in individuals with PWS and in the Magel2-null mouse model that recapitulates the major metabolic phenotypes of PWS and determined the efficacy of a peripherally restricted CB1R antagonist, JD5037 in treating obesity in these mice. Results: Individuals with PWS had elevated circulating levels of 2-arachidonoylglycerol and its endogenous precursor and breakdown ligand, arachidonic acid. Increased hypothalamic eCB ‘tone’, manifested by increased eCBs and upregulated CB1R, was associated with increased fat mass, reduced energy expenditure, and decreased voluntary activity in Magel2-null mice. Daily chronic treatment of obese Magel2-null mice and their littermate wild-type controls with JD5037 (3 mg/kg/d for 28 days reduced body weight, reversed hyperphagia, and improved metabolic parameters related to their obese phenotype. Conclusions: Dysregulation of the eCB/CB1R system may contribute to hyperphagia and obesity in Magel2-null mice and in individuals with PWS. Our results demonstrate that treatment with peripherally restricted CB1R antagonists may be an effective strategy for the management of severe obesity in PWS. Author Video: Author Video Watch what authors say about their articles Keywords: Endocannabinoids, PWS, Magel2, Peripheral CB1 blockade, Metabolic syndrome

The central cannabinoid CB1 receptor is required for diet-induced obesity and rimonabant's antiobesity effects in mice.

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Pang, Zhen; Wu, Nancy N; Zhao, Weiguang; Chain, David C; Schaffer, Erica; Zhang, Xin; Yamdagni, Preeti; Palejwala, Vaseem A; Fan, Chunpeng; Favara, Sarah G; Dressler, Holly M; Economides, Kyriakos D; Weinstock, Daniel; Cavallo, Jean S; Naimi, Souad; Galzin, Anne-Marie; Guillot, Etienne; Pruniaux, Marie-Pierre; Tocci, Michael J; Polites, H Greg

2011-10-01

Cannabinoid receptor CB1 is expressed abundantly in the brain and presumably in the peripheral tissues responsible for energy metabolism. It is unclear if the antiobesity effects of rimonabant, a CB1 antagonist, are mediated through the central or the peripheral CB1 receptors. To address this question, we generated transgenic mice with central nervous system (CNS)-specific knockdown (KD) of CB1, by expressing an artificial microRNA (AMIR) under the control of the neuronal Thy1.2 promoter. In the mutant mice, CB1 expression was reduced in the brain and spinal cord, whereas no change was observed in the superior cervical ganglia (SCG), sympathetic trunk, enteric nervous system, and pancreatic ganglia. In contrast to the neuronal tissues, CB1 was undetectable in the brown adipose tissue (BAT) or the liver. Consistent with the selective loss of central CB1, agonist-induced hypothermia was attenuated in the mutant mice, but the agonist-induced delay of gastrointestinal transit (GIT), a primarily peripheral nervous system-mediated effect, was not. Compared to wild-type (WT) littermates, the mutant mice displayed reduced body weight (BW), adiposity, and feeding efficiency, and when fed a high-fat diet (HFD), showed decreased plasma insulin, leptin, cholesterol, and triglyceride levels, and elevated adiponectin levels. Furthermore, the therapeutic effects of rimonabant on food intake (FI), BW, and serum parameters were markedly reduced and correlated with the degree of CB1 KD. Thus, KD of CB1 in the CNS recapitulates the metabolic phenotype of CB1 knockout (KO) mice and diminishes rimonabant's efficacy, indicating that blockade of central CB1 is required for rimonabant's antiobesity actions.

A key agonist-induced conformational change in the cannabinoid receptor CB1 is blocked by the allosteric ligand Org 27569.

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Fay, Jonathan F; Farrens, David L

2012-09-28

Allosteric ligands that modulate how G protein-coupled receptors respond to traditional orthosteric drugs are an exciting and rapidly expanding field of pharmacology. An allosteric ligand for the cannabinoid receptor CB1, Org 27569, exhibits an intriguing effect; it increases agonist binding, yet blocks agonist-induced CB1 signaling. Here we explored the mechanism behind this behavior, using a site-directed fluorescence labeling approach. Our results show that Org 27569 blocks conformational changes in CB1 that accompany G protein binding and/or activation, and thus inhibit formation of a fully active CB1 structure. The underlying mechanism behind this behavior is that simultaneous binding of Org 27569 produces a unique agonist-bound conformation, one that may resemble an intermediate structure formed on the pathway to full receptor activation.

Developmental and visual input-dependent regulation of the CB1 cannabinoid receptor in the mouse visual cortex.

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Taisuke Yoneda

Full Text Available The mammalian visual system exhibits significant experience-induced plasticity in the early postnatal period. While physiological studies have revealed the contribution of the CB1 cannabinoid receptor (CB1 to developmental plasticity in the primary visual cortex (V1, it remains unknown whether the expression and localization of CB1 is regulated during development or by visual experience. To explore a possible role of the endocannabinoid system in visual cortical plasticity, we examined the expression of CB1 in the visual cortex of mice. We found intense CB1 immunoreactivity in layers II/III and VI. CB1 mainly localized at vesicular GABA transporter-positive inhibitory nerve terminals. The amount of CB1 protein increased throughout development, and the specific laminar pattern of CB1 appeared at P20 and remained until adulthood. Dark rearing from birth to P30 decreased the amount of CB1 protein in V1 and altered the synaptic localization of CB1 in the deep layer. Dark rearing until P50, however, did not influence the expression of CB1. Brief monocular deprivation for 2 days upregulated the localization of CB1 at inhibitory nerve terminals in the deep layer. Taken together, the expression and the localization of CB1 are developmentally regulated, and both parameters are influenced by visual experience.

Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation?

OpenAIRE

Zlebnik, Natalie E.; Cheer, Joseph F.

2016-01-01

The Cannabis sativa plant has been used to treat various physiological and psychiatric conditions for millennia. Current research is focused on isolating potentially therapeutic chemical constituents from the plant for use in the treatment of many central nervous system disorders. Of particular interest is the primary nonpsychoactive constituent cannabidiol (CBD). Unlike Δ9-tetrahydrocannabinol (THC), CBD does not act through the cannabinoid type 1 (CB1) receptor but has many other receptor t...

Singular Location and Signaling Profile of Adenosine A2A-Cannabinoid CB1 Receptor Heteromers in the Dorsal Striatum.

Science.gov (United States)

Moreno, Estefanía; Chiarlone, Anna; Medrano, Mireia; Puigdellívol, Mar; Bibic, Lucka; Howell, Lesley A; Resel, Eva; Puente, Nagore; Casarejos, María J; Perucho, Juan; Botta, Joaquín; Suelves, Nuria; Ciruela, Francisco; Ginés, Silvia; Galve-Roperh, Ismael; Casadó, Vicent; Grandes, Pedro; Lutz, Beat; Monory, Krisztina; Canela, Enric I; Lluís, Carmen; McCormick, Peter J; Guzmán, Manuel

2018-04-01

The dorsal striatum is a key node for many neurobiological processes such as motor activity, cognitive functions, and affective processes. The proper functioning of striatal neurons relies critically on metabotropic receptors. Specifically, the main adenosine and endocannabinoid receptors present in the striatum, ie, adenosine A 2A receptor (A 2A R) and cannabinoid CB 1 receptor (CB 1 R), are of pivotal importance in the control of neuronal excitability. Facilitatory and inhibitory functional interactions between striatal A 2A R and CB 1 R have been reported, and evidence supports that this cross-talk may rely, at least in part, on the formation of A 2A R-CB 1 R heteromeric complexes. However, the specific location and properties of these heteromers have remained largely unknown. Here, by using techniques that allowed a precise visualization of the heteromers in situ in combination with sophisticated genetically modified animal models, together with biochemical and pharmacological approaches, we provide a high-resolution expression map and a detailed functional characterization of A 2A R-CB 1 R heteromers in the dorsal striatum. Specifically, our data unveil that the A 2A R-CB 1 R heteromer (i) is essentially absent from corticostriatal projections and striatonigral neurons, and, instead, is largely present in striatopallidal neurons, (ii) displays a striking G protein-coupled signaling profile, where co-stimulation of both receptors leads to strongly reduced downstream signaling, and (iii) undergoes an unprecedented dysfunction in Huntington's disease, an archetypal disease that affects striatal neurons. Altogether, our findings may open a new conceptual framework to understand the role of coordinated adenosine-endocannabinoid signaling in the indirect striatal pathway, which may be relevant in motor function and neurodegenerative diseases.

Stimulation of cannabinoid receptor 2 (CB2 suppresses microglial activation

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Fernandez Francisco

2005-12-01

Full Text Available Abstract Background Activated microglial cells have been implicated in a number of neurodegenerative disorders, including Alzheimer's disease (AD, multiple sclerosis (MS, and HIV dementia. It is well known that inflammatory mediators such as nitric oxide (NO, cytokines, and chemokines play an important role in microglial cell-associated neuron cell damage. Our previous studies have shown that CD40 signaling is involved in pathological activation of microglial cells. Many data reveal that cannabinoids mediate suppression of inflammation in vitro and in vivo through stimulation of cannabinoid receptor 2 (CB2. Methods In this study, we investigated the effects of a cannabinoid agonist on CD40 expression and function by cultured microglial cells activated by IFN-γ using RT-PCR, Western immunoblotting, flow cytometry, and anti-CB2 small interfering RNA (siRNA analyses. Furthermore, we examined if the stimulation of CB2 could modulate the capacity of microglial cells to phagocytise Aβ1–42 peptide using a phagocytosis assay. Results We found that the selective stimulation of cannabinoid receptor CB2 by JWH-015 suppressed IFN-γ-induced CD40 expression. In addition, this CB2 agonist markedly inhibited IFN-γ-induced phosphorylation of JAK/STAT1. Further, this stimulation was also able to suppress microglial TNF-α and nitric oxide production induced either by IFN-γ or Aβ peptide challenge in the presence of CD40 ligation. Finally, we showed that CB2 activation by JWH-015 markedly attenuated CD40-mediated inhibition of microglial phagocytosis of Aβ1–42 peptide. Taken together, these results provide mechanistic insight into beneficial effects provided by cannabinoid receptor CB2 modulation in neurodegenerative diseases, particularly AD.

SR 144528, the first potent and selective antagonist of the CB2 cannabinoid receptor.

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Rinaldi-Carmona, M; Barth, F; Millan, J; Derocq, J M; Casellas, P; Congy, C; Oustric, D; Sarran, M; Bouaboula, M; Calandra, B; Portier, M; Shire, D; Brelière, J C; Le Fur, G L

1998-02-01

Based on both binding and functional data, this study introduces SR 144528 as the first, highly potent, selective and orally active antagonist for the CB2 receptor. This compound which displays subnanomolar affinity (Ki = 0.6 nM) for both the rat spleen and cloned human CB2 receptors has a 700-fold lower affinity (Ki = 400 nM) for both the rat brain and cloned human CB1 receptors. Furthermore it shows no affinity for any of the more than 70 receptors, ion channels or enzymes investigated (IC50 > 10 microM). In vitro, SR 144528 antagonizes the inhibitory effects of the cannabinoid receptor agonist CP 55,940 on forskolin-stimulated adenylyl cyclase activity in cell lines permanently expressing the h CB2 receptor (EC50 = 10 nM) but not in cells expressing the h CB1 (no effect at 10 microM). Furthermore, SR 144528 is able to selectively block the mitogen-activated protein kinase activity induced by CP 55,940 in cell lines expressing h CB2 (IC50 = 39 nM) whereas in cells expressing h CB1 an IC50 value of more than 1 microM is found. In addition, SR 144528 is shown to antagonize the stimulating effects of CP 55,940 on human tonsillar B-cell activation evoked by cross-linking of surface Igs (IC50 = 20 nM). In vivo, after oral administration SR 144528 totally displaced the ex vivo [3H]-CP 55,940 binding to mouse spleen membranes (ED50 = 0.35 mg/kg) with a long duration of action. In contrast, after the oral route it does not interact with the cannabinoid receptor expressed in the mouse brain (CB1). It is expected that SR 144528 will provide a powerful tool to investigate the in vivo functions of the cannabinoid system in the immune response.

Candidate PET radioligands for cannabinoid CB{sub 1} receptors: [{sup 18}F]AM5144 and related pyrazole compounds

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Zizhong, Li [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Gifford, Andrew [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Qian, Liu [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Thotapally, Rajesh [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Yushin, Ding [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States); Makriyannis, Alexandros [Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States); Gatley, S John [Center for Translational Neuroimaging, Brookhaven National Laboratory, Upton, NY 11973 (United States) and Center for Drug Discovery, Northeastern University, Boston, MA 02115 (United States)

2005-05-01

Introduction: The mammalian brain contains abundant G protein-coupled cannabinoid CB{sub 1} receptors that respond to {delta}{sup 9}-tetrahydrocannabinol, the active ingredient of cannabis. The availability of a positron emission tomography (PET) radioligand would facilitate studies of the addictive and medicinal properties of compounds that bind to this receptor. Among the known classes of ligands for CB{sub 1} receptors, the pyrazoles are attractive targets for radiopharmaceutical development because they are antagonists and are generally less lipophilic than the other classes. Methods: A convenient high-yield synthesis of N-(4-[{sup 18}F]fluorophenyl)-5-(4-bromophenyl)-1-(2,4-dichlorophenyl)- 1H-pyrazole-3-carboxamide (AM5144) was devised by coupling the appropriate pyrazole-3-carboxyl chloride compound with 4-[{sup 18}F]fluoroaniline. The labeled precursor was synthesized from 1-[{sup 18}F]fluoro-4-nitrobenzene in 60% radiochemical yield for 10 min using an improved procedure involving sodium borohydride reduction with cobalt chloride catalysis. The product was purified by HPLC to give a specific activity >400 mCi/{mu}mol and a radiochemical purity >95%, and a PET study was conducted in a baboon. Results: Although the regional uptake of AM5144 in baboon brain was consistent with binding to cannabinoid CB{sub 1} receptors, absolute uptake at <0.003% injected radioactivity per cubic centimeter was lower than the previously reported uptake of the radioiodinated pyrazole AM281. Conclusions: The relatively poor brain uptake of AM5144 and other pyrazole CB{sub 1} receptor ligands is not surprising because of their high lipophilicity as compared with most brain PET radiotracers. However, for nine pyrazole compounds for which rodent data are available, brain uptake and calculated logP values are not correlated. Thus, high logP values should not preclude evaluation of radiotracers for targets such as the CB{sub 1} receptor that may require very lipophilic ligands.

Modulación del tono vascular por la sobre-expresión de receptores a canabinoides CB1 y CB2 en arterioesclerosis inducida en ratas

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Espinoza P., María Rosa

2013-01-01

La arteriosclerosis, es un proceso degenerativo responsable de la mayor parte de las enfermedades cardiovasculares, es una enfermedad compleja que se produce a partir de múltiples factores de riesgo. Se ha observado que los compuestos derivados de la planta cannabis sativa provocan efectos vasorelajantes por medio de receptores específicos CB1 y CB2. ACPA y JWH 133 son potentes agonistas a estos receptores, se desconoce el papel que desempeñan en la arteriosclerosis provocando una relajación ...

Presynaptic CRF1 Receptors Mediate the Ethanol Enhancement of GABAergic Transmission in the Mouse Central Amygdala

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Zhiguo Nie

2009-01-01

Full Text Available Corticotropin-releasing factor (CRF is a 41-amino-acid neuropeptide involved in stress responses initiated from several brain areas, including the amygdala formation. Research shows a strong relationship between stress, brain CRF, and excessive alcohol consumption. Behavioral studies suggest that the central amygdala (CeA is significantly involved in alcohol reward and dependence. We recently reported that the ethanol augmentation of GABAergic synaptic transmission in rat CeA involves CRF1 receptors, because both CRF and ethanol significantly enhanced the amplitude of evoked GABAergic inhibitory postsynaptic currents (IPSCs in CeA neurons from wild-type (WT and CRF2 knockout (KO mice, but not in neurons of CRF1 KO mice. The present study extends these findings using selective CRF receptor ligands, gene KO models, and miniature IPSC (mIPSC analysis to assess further a presynaptic role for the CRF receptors in mediating ethanol effects in the CeA. In whole-cell patch recordings of pharmacologically isolated GABAAergic IPSCs from slices of mouse CeA, both CRF and ethanol augmented evoked IPSCs in a concentration-dependent manner, with low EC50s. A CRF1 (but not CRF2 KO construct and the CRF1-selective nonpeptide antagonist NIH-3 (LWH-63 blocked the augmenting effect of both CRF and ethanol on evoked IPSCs. Furthermore, the new selective CRF1 agonist stressin1, but not the CRF2 agonist urocortin 3, also increased evoked IPSC amplitudes. Both CRF and ethanol decreased paired-pulse facilitation (PPF of evoked IPSCs and significantly enhanced the frequency, but not the amplitude, of spontaneous miniature GABAergic mIPSCs in CeA neurons of WT mice, suggesting a presynaptic site of action. The PPF effect of ethanol was abolished in CeA neurons of CRF1 KO mice. The CRF1 antagonist NIH-3 blocked the CRF- and ethanol-induced enhancement of mIPSC frequency in CeA neurons. These data indicate that presynaptic CRF1 receptors play a critical role in permitting

Cannabinoid CB1 /CB2 receptor agonists attenuate hyperactivity and body weight loss in a rat model of activity-based anorexia.

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Scherma, Maria; Satta, Valentina; Collu, Roberto; Boi, Maria Francesca; Usai, Paolo; Fratta, Walter; Fadda, Paola

2017-08-01

Anorexia nervosa (AN) is a serious psychiatric condition characterized by excessive body weight loss and disturbed perceptions of body shape and size, often associated with excessive physical activity. There is currently no effective drug-related therapy of this disease and this leads to high relapse rate. Clinical data suggest that a promising therapy to treat and reduce reoccurrence of AN may be based on the use of drugs that target the endocannabinoid (EC) system, which appears dysregulated in AN patients. The activity-based anorexia (ABA) rodent model mimics the severe body weight loss and increased physical activity, as well as the neuroendocrine disturbances (i.e. hypoleptinaemia and hypercortisolaemia) in AN. This study investigated whether cannabinoid agonists can effectively modify anorexic-like behaviours and neuroendocrine changes in rats subjected to a repeated ABA regime that mimics the human condition in which patients repeatedly undergo a recovery and illness cycle. Our data show that subchronic treatment with both the natural CB 1 /CB 2 receptor agonist Δ 9 -tetrahydrocannabinol and the synthetic CB 1 /CB 2 receptor agonist CP-55,940 significantly reduced body weight loss and running wheel activity in ABA rats. These behavioural effects were accompanied by an increase in leptin signalling and a decrease in plasma levels of corticosterone. Taken together, our results further demonstrate the involvement of the EC system in AN pathophysiology and that strategies which modulate EC signalling are useful to treat this disorder, specifically in patients where physical hyperactivity plays a central role in its progression and maintenance. © 2017 The British Pharmacological Society.

Cytotoxicity of synthetic cannabinoids on primary neuronal cells of the forebrain: the involvement of cannabinoid CB1 receptors and apoptotic cell death

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Tomiyama, Ken-ichi; Funada, Masahiko

2014-01-01

The abuse of herbal products containing synthetic cannabinoids has become an issue of public concern. The purpose of this paper was to evaluate the acute cytotoxicity of synthetic cannabinoids on mouse brain neuronal cells. Cytotoxicity induced by synthetic cannabinoid (CP-55,940, CP-47,497, CP-47,497-C8, HU-210, JWH-018, JWH-210, AM-2201, and MAM-2201) was examined using forebrain neuronal cultures. These synthetic cannabinoids induced cytotoxicity in the forebrain cultures in a concentration-dependent manner. The cytotoxicity was suppressed by preincubation with the selective CB 1 receptor antagonist AM251, but not with the selective CB 2 receptor antagonist AM630. Furthermore, annexin-V-positive cells were found among the treated forebrain cells. Synthetic cannabinoid treatment induced the activation of caspase-3, and preincubation with a caspase-3 inhibitor significantly suppressed the cytotoxicity. These synthetic cannabinoids induced apoptosis through a caspase-3-dependent mechanism in the forebrain cultures. Our results indicate that the cytotoxicity of synthetic cannabinoids towards primary neuronal cells is mediated by the CB 1 receptor, but not by the CB 2 receptor, and further suggest that caspase cascades may play an important role in the apoptosis induced by these synthetic cannabinoids. In conclusion, excessive synthetic cannabinoid abuse may present a serious acute health concern due to neuronal damage or deficits in the brain. - Highlights: • Synthetic cannabinoids (classical cannabinoids, non-classical cannabinoids, and aminoalkylindole derivatives) induce cytotoxicity in mouse forebrain cultures. • Synthetic cannabinoid-induced cytotoxicity towards forebrain cultures is mediated by the CB 1 receptor, but not by the CB 2 receptor, and involves caspase-dependent apoptosis. • A high concentration of synthetic cannabinoids may be toxic to neuronal cells that express CB 1 receptors

CB1 receptor-mediated signaling underlies the hippocampal synaptic, learning, and memory deficits following treatment with JWH-081, a new component of spice/K2 preparations.

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Basavarajappa, Balapal S; Subbanna, Shivakumar

2014-02-01

Recently, synthetic cannabinoids have been sprayed onto plant material, which is subsequently packaged and sold as "Spice" or "K2" to mimic the effects of marijuana. A recent report identified several synthetic additives in samples of "Spice/K2", including JWH-081, a synthetic ligand for the cannabinoid receptor 1 (CB1). The deleterious effects of JWH-081 on brain function are not known, particularly on CB1 signaling, synaptic plasticity, learning and memory. Here, we evaluated the effects of JWH-081 on pCaMKIV, pCREB, and pERK1/2 signaling events followed by long-term potentiation (LTP), hippocampal-dependent learning and memory tasks using CB1 receptor wild-type (WT) and knockout (KO) mice. Acute administration of JWH-081 impaired CaMKIV phosphorylation in a dose-dependent manner, whereas inhibition of CREB phosphorylation in CB1 receptor WT mice was observed only at higher dose of JWH-081 (1.25 mg/kg). JWH-081 at higher dose impaired CaMKIV and CREB phosphorylation in a time-dependent manner in CB1 receptor WT mice but not in KO mice and failed to alter ERK1/2 phosphorylation. In addition, SR treated or CB1 receptor KO mice have a lower pCaMKIV/CaMKIV ratio and higher pCREB/CREB ratio compared with vehicle or WT littermates. In hippocampal slices, JWH-081 impaired LTP in CB1 receptor WT but not in KO littermates. Furthermore, JWH-081 at higher dose impaired object recognition, spontaneous alternation and spatial memory on the Y-maze in CB1 receptor WT mice but not in KO mice. Collectively our findings suggest that deleterious effects of JWH-081 on hippocampal function involves CB1 receptor mediated impairments in CaMKIV and CREB phosphorylation, LTP, learning and memory in mice. © 2013 Wiley Periodicals, Inc.

Cognitive Impairment Induced by Delta9-tetrahydrocannabinol Occurs through Heteromers between Cannabinoid CB1 and Serotonin 5-HT2A Receptors.

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Xavier Viñals

2015-07-01

Full Text Available Activation of cannabinoid CB1 receptors (CB1R by delta9-tetrahydrocannabinol (THC produces a variety of negative effects with major consequences in cannabis users that constitute important drawbacks for the use of cannabinoids as therapeutic agents. For this reason, there is a tremendous medical interest in harnessing the beneficial effects of THC. Behavioral studies carried out in mice lacking 5-HT2A receptors (5-HT2AR revealed a remarkable 5-HT2AR-dependent dissociation in the beneficial antinociceptive effects of THC and its detrimental amnesic properties. We found that specific effects of THC such as memory deficits, anxiolytic-like effects, and social interaction are under the control of 5-HT2AR, but its acute hypolocomotor, hypothermic, anxiogenic, and antinociceptive effects are not. In biochemical studies, we show that CB1R and 5-HT2AR form heteromers that are expressed and functionally active in specific brain regions involved in memory impairment. Remarkably, our functional data shows that costimulation of both receptors by agonists reduces cell signaling, antagonist binding to one receptor blocks signaling of the interacting receptor, and heteromer formation leads to a switch in G-protein coupling for 5-HT2AR from Gq to Gi proteins. Synthetic peptides with the sequence of transmembrane helices 5 and 6 of CB1R, fused to a cell-penetrating peptide, were able to disrupt receptor heteromerization in vivo, leading to a selective abrogation of memory impairments caused by exposure to THC. These data reveal a novel molecular mechanism for the functional interaction between CB1R and 5-HT2AR mediating cognitive impairment. CB1R-5-HT2AR heteromers are thus good targets to dissociate the cognitive deficits induced by THC from its beneficial antinociceptive properties.

Cognitive Impairment Induced by Delta9-tetrahydrocannabinol Occurs through Heteromers between Cannabinoid CB1 and Serotonin 5-HT2A Receptors.

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Viñals, Xavier; Moreno, Estefanía; Lanfumey, Laurence; Cordomí, Arnau; Pastor, Antoni; de La Torre, Rafael; Gasperini, Paola; Navarro, Gemma; Howell, Lesley A; Pardo, Leonardo; Lluís, Carmen; Canela, Enric I; McCormick, Peter J; Maldonado, Rafael; Robledo, Patricia

2015-07-01

Activation of cannabinoid CB1 receptors (CB1R) by delta9-tetrahydrocannabinol (THC) produces a variety of negative effects with major consequences in cannabis users that constitute important drawbacks for the use of cannabinoids as therapeutic agents. For this reason, there is a tremendous medical interest in harnessing the beneficial effects of THC. Behavioral studies carried out in mice lacking 5-HT2A receptors (5-HT2AR) revealed a remarkable 5-HT2AR-dependent dissociation in the beneficial antinociceptive effects of THC and its detrimental amnesic properties. We found that specific effects of THC such as memory deficits, anxiolytic-like effects, and social interaction are under the control of 5-HT2AR, but its acute hypolocomotor, hypothermic, anxiogenic, and antinociceptive effects are not. In biochemical studies, we show that CB1R and 5-HT2AR form heteromers that are expressed and functionally active in specific brain regions involved in memory impairment. Remarkably, our functional data shows that costimulation of both receptors by agonists reduces cell signaling, antagonist binding to one receptor blocks signaling of the interacting receptor, and heteromer formation leads to a switch in G-protein coupling for 5-HT2AR from Gq to Gi proteins. Synthetic peptides with the sequence of transmembrane helices 5 and 6 of CB1R, fused to a cell-penetrating peptide, were able to disrupt receptor heteromerization in vivo, leading to a selective abrogation of memory impairments caused by exposure to THC. These data reveal a novel molecular mechanism for the functional interaction between CB1R and 5-HT2AR mediating cognitive impairment. CB1R-5-HT2AR heteromers are thus good targets to dissociate the cognitive deficits induced by THC from its beneficial antinociceptive properties.

The effect of coniine on presynaptic nicotinic receptors.

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Erkent, Ulkem; Iskit, Alper B; Onur, Rustu; Ilhan, Mustafa

2016-01-01

Toxicity of coniine, an alkaloid of Conium maculatum (poison hemlock), is manifested by characteristic nicotinic clinical signs including excitement, depression, hypermetria, seizures, opisthotonos via postsynaptic nicotinic receptors. There is limited knowledge about the role of presynaptic nicotinic receptors on the pharmacological and toxicological effects of coniine in the literature. The present study was undertaken to evaluate the possible role of presynaptic nicotinic receptors on the pharmacological and toxicological effects of coniine. For this purpose, the rat anococcygeus muscle and guinea-pig atria were used in vitro. Nicotine (100 μM) elicited a biphasic response composed of a relaxation followed by contraction through the activation of nitrergic and noradrenergic nerve terminals in the phenylephrine-contracted rat anococcygeus muscle. Coniine inhibited both the nitrergic and noradrenergic response in the muscle (-logIC(50) = 3.79 ± 0.11 and -logIC(50) = 4.57 ± 0.12 M, respectively). The effect of coniine on nicotinic receptor-mediated noradrenergic transmission was also evaluated in the guinea-pig atrium (-logIC(50) = 4.47 ± 0.12 M) and did not differ from the -logIC(50) value obtained in the rat anococcygeus muscle. This study demonstrated that coniine exerts inhibitory effects on nicotinic receptor-mediated nitrergic and noradrenergic transmitter response.

The cannabinoid receptor CB1 contributes to the development of ectopic lesions in a mouse model of endometriosis.

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Sanchez, Ana-Maria; Quattrone, Federica; Pannese, Maria; Ulisse, Adele; Candiani, Massimo; Diaz-Alonso, Javier; Velasco, Guillermo; Panina-Bordignon, Paola

2017-01-01

Does signaling via the cannabinoid (CB 1 ) receptor play a role in the pathogenesis of endometriosis in a mouse model? Mice treated with a CB 1 agonist developed larger ectopic lesions, while less severe lesions developed in the absence of functional CB 1 expression. The expression of components of the endocannabinoid system has been demonstrated in both mouse and human uteri. CB 1 receptors are expressed in human epithelial and stromal cell lines derived from eutopic endometrium and deep infiltrating endometriosis nodules. This was a randomized study in a mouse model of endometriosis. In a first set of experiments, mice with endometriosis were treated with the CB 1 receptor agonist methanandamide (MET) (5 mg/kg, n = 20) on Days 1-5 and 8-12. In a second set of experiments, endometriosis development was evaluated in CB 1 -/- mice and in their wild-type (WT) littermates. Endometriosis-like lesions were induced in Balb/c and C57/Bl6 mice. Two weeks after disease induction, the lesions were counted, measured and either included for immunohistochemistry analysis or frozen for gene expression profiling by semi-quantitative real-time PCR. To limit the role of chance, the experiments were conducted under standardized laboratory conditions with appropriate controls. The lesion total volume was significantly higher in MET-treated compared with vehicle-treated mice (P endometriosis in a mouse model. However, the relative contribution of the CB 1 -mediated signaling pathways active in inflammatory, uterine and peritoneal cells remains to be ascertained. Since the study was performed in a mouse model, the significance of the findings in the human system warrants further investigation. Clarifying the function and regulation of CB 1 and its molecular interactions with endogenous ligands, and how endocannabinoids levels are regulated in women with endometriosis, represent critical areas of research for the potential development of a novel medical treatment of the disease. A

The cannabinoid CB1 receptor and mTORC1 signalling pathways interact to modulate glucose homeostasis in mice

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Francisco J. Bermudez-Silva

2016-01-01

Full Text Available The endocannabinoid system (ECS is an intercellular signalling mechanism that is present in the islets of Langerhans and plays a role in the modulation of insulin secretion and expansion of the β-cell mass. The downstream signalling pathways mediating these effects are poorly understood. Mammalian target of rapamycin complex 1 (mTORC1 signalling is a key intracellular pathway involved in energy homeostasis and is known to importantly affect the physiology of pancreatic islets. We investigated the possible relationship between cannabinoid type 1 (CB1 receptor signalling and the mTORC1 pathway in the endocrine pancreas of mice by using pharmacological analysis as well as mice genetically lacking the CB1 receptor or the downstream target of mTORC1, the kinase p70S6K1. In vitro static secretion experiments on islets, western blotting, and in vivo glucose and insulin tolerance tests were performed. The CB1 receptor antagonist rimonabant decreased glucose-stimulated insulin secretion (GSIS at 0.1 µM while increasing phosphorylation of p70S6K1 and ribosomal protein S6 (rpS6 within the islets. Specific pharmacological blockade of mTORC1 by 3 nM rapamycin, as well as genetic deletion of p70S6K1, impaired the CB1-antagonist-mediated decrease in GSIS. In vivo experiments showed that 3 mg/kg body weight rimonabant decreased insulin levels and induced glucose intolerance in lean mice without altering peripheral insulin sensitivity; this effect was prevented by peripheral administration of low doses of rapamycin (0.1 mg/kg body weight, which increased insulin sensitivity. These findings suggest a functional interaction between the ECS and the mTORC1 pathway within the endocrine pancreas and at the whole-organism level, which could have implications for the development of new therapeutic approaches for pancreatic β-cell diseases.

Mice expressing a "hyper-sensitive" form of the CB1 cannabinoid receptor (CB1 show modestly enhanced alcohol preference and consumption.

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David J Marcus

Full Text Available We recently characterized S426A/S430A mutant mice expressing a desensitization-resistant form of the CB1 receptor. These mice display an enhanced response to endocannabinoids and ∆9-THC. In this study, S426A/S430A mutants were used as a novel model to test whether ethanol consumption, morphine dependence, and reward for these drugs are potentiated in mice with a "hyper-sensitive" form of CB1. Using an unlimited-access, two-bottle choice, voluntary drinking paradigm, S426A/S430A mutants exhibit modestly increased intake and preference for low (6% but not higher concentrations of ethanol. S426A/S430A mutants and wild-type mice show similar taste preference for sucrose and quinine, exhibit normal sensitivity to the hypothermic and ataxic effects of ethanol, and have normal blood ethanol concentrations following administration of ethanol. S426A/S430A mutants develop robust conditioned place preference for ethanol (2 g/kg, morphine (10 mg/kg, and cocaine (10 mg/kg, demonstrating that drug reward is not changed in S426A/S430A mutants. Precipitated morphine withdrawal is also unchanged in opioid-dependent S426A/S430A mutant mice. Although ethanol consumption is modestly changed by enhanced CB1 signaling, reward, tolerance, and acute sensitivity to ethanol and morphine are normal in this model.

Upregulation of CB2 receptors in reactive astrocytes in canine degenerative myelopathy, a disease model of amyotrophic lateral sclerosis

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Fernández-Trapero, María; Espejo-Porras, Francisco; Rodríguez-Cueto, Carmen; Coates, Joan R.; Pérez-Díaz, Carmen; de Lago, Eva; Fernández-Ruiz, Javier

2017-01-01

ABSTRACT Targeting of the CB2 receptor results in neuroprotection in the SOD1G93A mutant mouse model of amyotrophic lateral sclerosis (ALS). The neuroprotective effects of CB2 receptors are facilitated by their upregulation in the spinal cord of the mutant mice. Here, we investigated whether similar CB2 receptor upregulation, as well as parallel changes in other endocannabinoid elements, is evident in the spinal cord of dogs with degenerative myelopathy (DM), caused by mutations in the superoxide dismutase 1 gene (SOD1). We used well-characterized post-mortem spinal cords from unaffected and DM-affected dogs. Tissues were used first to confirm the loss of motor neurons using Nissl staining, which was accompanied by glial reactivity (elevated GFAP and Iba-1 immunoreactivity). Next, we investigated possible differences in the expression of endocannabinoid genes measured by qPCR between DM-affected and control dogs. We found no changes in expression of the CB1 receptor (confirmed with CB1 receptor immunostaining) or NAPE-PLD, DAGL, FAAH and MAGL enzymes. In contrast, CB2 receptor levels were significantly elevated in DM-affected dogs determined by qPCR and western blotting, which was confirmed in the grey matter using CB2 receptor immunostaining. Using double-labelling immunofluorescence, CB2 receptor immunolabelling colocalized with GFAP but not Iba-1, indicating upregulation of CB2 receptors on astrocytes in DM-affected dogs. Our results demonstrate a marked upregulation of CB2 receptors in the spinal cord in canine DM, which is concentrated in activated astrocytes. Such receptors could be used as a potential target to enhance the neuroprotective effects exerted by these glial cells. PMID:28069688

Upregulation of CB2 receptors in reactive astrocytes in canine degenerative myelopathy, a disease model of amyotrophic lateral sclerosis

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María Fernández-Trapero

2017-05-01

Full Text Available Targeting of the CB2 receptor results in neuroprotection in the SOD1G93A mutant mouse model of amyotrophic lateral sclerosis (ALS. The neuroprotective effects of CB2 receptors are facilitated by their upregulation in the spinal cord of the mutant mice. Here, we investigated whether similar CB2 receptor upregulation, as well as parallel changes in other endocannabinoid elements, is evident in the spinal cord of dogs with degenerative myelopathy (DM, caused by mutations in the superoxide dismutase 1 gene (SOD1. We used well-characterized post-mortem spinal cords from unaffected and DM-affected dogs. Tissues were used first to confirm the loss of motor neurons using Nissl staining, which was accompanied by glial reactivity (elevated GFAP and Iba-1 immunoreactivity. Next, we investigated possible differences in the expression of endocannabinoid genes measured by qPCR between DM-affected and control dogs. We found no changes in expression of the CB1 receptor (confirmed with CB1 receptor immunostaining or NAPE-PLD, DAGL, FAAH and MAGL enzymes. In contrast, CB2 receptor levels were significantly elevated in DM-affected dogs determined by qPCR and western blotting, which was confirmed in the grey matter using CB2 receptor immunostaining. Using double-labelling immunofluorescence, CB2 receptor immunolabelling colocalized with GFAP but not Iba-1, indicating upregulation of CB2 receptors on astrocytes in DM-affected dogs. Our results demonstrate a marked upregulation of CB2 receptors in the spinal cord in canine DM, which is concentrated in activated astrocytes. Such receptors could be used as a potential target to enhance the neuroprotective effects exerted by these glial cells.

AAV-mediated overexpression of the CB1 receptor in the mPFC of adult rats alters cognitive flexibility, social behavior and emotional reactivity

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Matthias eKlugmann

2011-07-01

Full Text Available The endocannabinoid (ECB system is strongly involved in the regulation of cognitive processing and emotional behavior and evidence indicates that ECB signaling might affect these behavioral abilities by modulations of prefrontal cortical functions. The aim of the present study was to examine the role of the CB1 receptor in the medial prefrontal cortex (mPFC on cognitive flexibility and emotional behavior. Therefore, the CB1 receptor was overexpressed by adeno-associated virus (AAV vector-mediated gene transfer specifically in the mPFC of adult Wistar rats. Animals were then tested in different anxiety-related paradigms for emotional reactivity (e.g. elevated plus maze (EPM, light/dark emergence test (EMT, social interaction and the attentional set shift task (ASST - an adaptation of the human Wisconsin card sorting test - for cognitive abilities and behavioral flexibility. A subtle increase in exploratory behavior was found in CB1 receptor overexpressing animals (CB1-R compared to empty vector injected controls (Empty in the EMT and EPM, although general locomotor activity did not differ between the groups. During social interaction testing, social contact behavior towards the unknown conspecific was found to be decreased, whereas social withdrawal was increased in CB1-R animals and they showed an inadequate increase in exploratory behavior compared to control animals. In the ASST, impaired reversal learning abilities were detected in CB1-R animals compared to controls, indicating reduced behavioral flexibility. In conclusion, upregulation of the CB1 receptor specifically in the rat mPFC induces alterations in emotional reactivity, leads to inadequate social behavior and impairs cognitive flexibility. These findings might be relevant for neuropsychiatric disorders, since higher cortical CB1 receptor expression levels as well as similar behavioral impairments as observed in the present study have been described in schizophrenic patients.

Cytotoxicity of synthetic cannabinoids on primary neuronal cells of the forebrain: the involvement of cannabinoid CB{sub 1} receptors and apoptotic cell death

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Tomiyama, Ken-ichi; Funada, Masahiko, E-mail: mfunada@ncnp.go.jp

2014-01-01

The abuse of herbal products containing synthetic cannabinoids has become an issue of public concern. The purpose of this paper was to evaluate the acute cytotoxicity of synthetic cannabinoids on mouse brain neuronal cells. Cytotoxicity induced by synthetic cannabinoid (CP-55,940, CP-47,497, CP-47,497-C8, HU-210, JWH-018, JWH-210, AM-2201, and MAM-2201) was examined using forebrain neuronal cultures. These synthetic cannabinoids induced cytotoxicity in the forebrain cultures in a concentration-dependent manner. The cytotoxicity was suppressed by preincubation with the selective CB{sub 1} receptor antagonist AM251, but not with the selective CB{sub 2} receptor antagonist AM630. Furthermore, annexin-V-positive cells were found among the treated forebrain cells. Synthetic cannabinoid treatment induced the activation of caspase-3, and preincubation with a caspase-3 inhibitor significantly suppressed the cytotoxicity. These synthetic cannabinoids induced apoptosis through a caspase-3-dependent mechanism in the forebrain cultures. Our results indicate that the cytotoxicity of synthetic cannabinoids towards primary neuronal cells is mediated by the CB{sub 1} receptor, but not by the CB{sub 2} receptor, and further suggest that caspase cascades may play an important role in the apoptosis induced by these synthetic cannabinoids. In conclusion, excessive synthetic cannabinoid abuse may present a serious acute health concern due to neuronal damage or deficits in the brain. - Highlights: • Synthetic cannabinoids (classical cannabinoids, non-classical cannabinoids, and aminoalkylindole derivatives) induce cytotoxicity in mouse forebrain cultures. • Synthetic cannabinoid-induced cytotoxicity towards forebrain cultures is mediated by the CB{sub 1} receptor, but not by the CB{sub 2} receptor, and involves caspase-dependent apoptosis. • A high concentration of synthetic cannabinoids may be toxic to neuronal cells that express CB{sub 1} receptors.

CB2 cannabinoid receptors contribute to bacterial invasion and mortality in polymicrobial sepsis.

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Balázs Csóka

2009-07-01

Full Text Available Sepsis is a major healthcare problem and current estimates suggest that the incidence of sepsis is approximately 750,000 annually. Sepsis is caused by an inability of the immune system to eliminate invading pathogens. It was recently proposed that endogenous mediators produced during sepsis can contribute to the immune dysfunction that is observed in sepsis. Endocannabinoids that are produced excessively in sepsis are potential factors leading to immune dysfunction, because they suppress immune cell function by binding to G-protein-coupled CB(2 receptors on immune cells. Here we examined the role of CB(2 receptors in regulating the host's response to sepsis.The role of CB(2 receptors was studied by subjecting CB(2 receptor wild-type and knockout mice to bacterial sepsis induced by cecal ligation and puncture. We report that CB(2 receptor inactivation by knockout decreases sepsis-induced mortality, and bacterial translocation into the bloodstream of septic animals. Furthermore, CB(2 receptor inactivation decreases kidney and muscle injury, suppresses splenic nuclear factor (NF-kappaB activation, and diminishes the production of IL-10, IL-6 and MIP-2. Finally, CB(2 receptor deficiency prevents apoptosis in lymphoid organs and augments the number of CD11b(+ and CD19(+ cells during CLP.Taken together, our results establish for the first time that CB(2 receptors are important contributors to septic immune dysfunction and mortality, indicating that CB(2 receptors may be therapeutically targeted for the benefit of patients suffering from sepsis.

Sphingosine-1-Phosphate (S1P) Impacts Presynaptic Functions by Regulating Synapsin I Localization in the Presynaptic Compartment.

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Riganti, Loredana; Antonucci, Flavia; Gabrielli, Martina; Prada, Ilaria; Giussani, Paola; Viani, Paola; Valtorta, Flavia; Menna, Elisabetta; Matteoli, Michela; Verderio, Claudia

2016-04-20

Growing evidence indicates that sphingosine-1-P (S1P) upregulates glutamate secretion in hippocampal neurons. However, the molecular mechanisms through which S1P enhances excitatory activity remain largely undefined. The aim of this study was to identify presynaptic targets of S1P action controlling exocytosis. Confocal analysis of rat hippocampal neurons showed that S1P applied at nanomolar concentration alters the distribution of Synapsin I (SynI), a presynaptic phosphoprotein that controls the availability of synaptic vesicles for exocytosis. S1P induced SynI relocation to extrasynaptic regions of mature neurons, as well as SynI dispersion from synaptic vesicle clusters present at axonal growth cones of developing neurons. S1P-induced SynI relocation occurred in a Ca(2+)-independent but ERK-dependent manner, likely through the activation of S1P3 receptors, as it was prevented by the S1P3 receptor selective antagonist CAY1044 and in neurons in which S1P3 receptor was silenced. Our recent evidence indicates that microvesicles (MVs) released by microglia enhance the metabolism of endogenous sphingolipids in neurons and stimulate excitatory transmission. We therefore investigated whether MVs affect SynI distribution and whether endogenous S1P could be involved in the process. Analysis of SynI immunoreactivity showed that exposure to microglial MVs induces SynI mobilization at presynaptic sites and growth cones, whereas the use of inhibitors of sphingolipid cascade identified S1P as the sphingolipid mediating SynI redistribution. Our data represent the first demonstration that S1P induces SynI mobilization from synapses, thereby indicating the phosphoprotein as a novel target through which S1P controls exocytosis. Growing evidence indicates that the bioactive lipid sphingosine and its metabolite sphingosine-1-P (S1P) stimulate excitatory transmission. While it has been recently clarified that sphingosine influences directly the exocytotic machinery by activating the

Mice expressing a “hyper-sensitive” form of the CB1 cannabinoid receptor (CB1) show modestly enhanced alcohol preference and consumption

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Gonek, Maciej; Zee, Michael L.; Farnsworth, Jill C.; Amin, Randa A.; Andrews, Mary-Jeanette; Davis, Brian J.; Mackie, Ken; Morgan, Daniel J.

2017-01-01

We recently characterized S426A/S430A mutant mice expressing a desensitization-resistant form of the CB1 receptor. These mice display an enhanced response to endocannabinoids and ∆9-THC. In this study, S426A/S430A mutants were used as a novel model to test whether ethanol consumption, morphine dependence, and reward for these drugs are potentiated in mice with a “hyper-sensitive” form of CB1. Using an unlimited-access, two-bottle choice, voluntary drinking paradigm, S426A/S430A mutants exhibit modestly increased intake and preference for low (6%) but not higher concentrations of ethanol. S426A/S430A mutants and wild-type mice show similar taste preference for sucrose and quinine, exhibit normal sensitivity to the hypothermic and ataxic effects of ethanol, and have normal blood ethanol concentrations following administration of ethanol. S426A/S430A mutants develop robust conditioned place preference for ethanol (2 g/kg), morphine (10 mg/kg), and cocaine (10 mg/kg), demonstrating that drug reward is not changed in S426A/S430A mutants. Precipitated morphine withdrawal is also unchanged in opioid-dependent S426A/S430A mutant mice. Although ethanol consumption is modestly changed by enhanced CB1 signaling, reward, tolerance, and acute sensitivity to ethanol and morphine are normal in this model. PMID:28426670

Cannabinoid Type 1 Receptor (CB1) Ligands with Therapeutic Potential for Withdrawal Syndrome in Chemical Dependents of Cannabis sativa.

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Ferreira, Jaderson V; Chaves, Gisele A; Marino, Bianca L B; Sousa, Kessia P A; Souza, Lucilene R; Brito, Maiara F B; Teixeira, Hueldem R C; da Silva, Carlos H T P; Santos, Cleydson B R; Hage-Melim, Lorane I S

2017-08-22

Cannabis sativa withdrawal syndrome is characterized mainly by psychological symptoms. By using computational tools, the aim of this study was to propose drug candidates for treating withdrawal syndrome based on the natural ligands of the cannabinoid type 1 receptor (CB1). One compound in particular, 2-n-butyl-5-n-pentylbenzene-1,3-diol (ZINC1730183, also known as stemphol), showed positive predictions as a human CB1 ligand and for facile synthetic accessibility. Therefore, ZINC1730183 is a favorable candidate scaffold for further research into pharmacotherapeutic alternatives to treat C. sativa withdrawal syndrome. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

GABAergic and cortical and subcortical glutamatergic axon terminals contain CB1 cannabinoid receptors in the ventromedial nucleus of the hypothalamus.

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Leire Reguero

Full Text Available BACKGROUND: Type-1 cannabinoid receptors (CB(1R are enriched in the hypothalamus, particularly in the ventromedial hypothalamic nucleus (VMH that participates in homeostatic and behavioral functions including food intake. Although CB(1R activation modulates excitatory and inhibitory synaptic transmission in the brain, CB(1R contribution to the molecular architecture of the excitatory and inhibitory synaptic terminals in the VMH is not known. Therefore, the aim of this study was to investigate the precise subcellular distribution of CB(1R in the VMH to better understand the modulation exerted by the endocannabinoid system on the complex brain circuitries converging into this nucleus. METHODOLOGY/PRINCIPAL FINDINGS: Light and electron microscopy techniques were used to analyze CB(1R distribution in the VMH of CB(1R-WT, CB(1R-KO and conditional mutant mice bearing a selective deletion of CB(1R in cortical glutamatergic (Glu-CB(1R-KO or GABAergic neurons (GABA-CB(1R-KO. At light microscopy, CB(1R immunolabeling was observed in the VMH of CB(1R-WT and Glu-CB(1R-KO animals, being remarkably reduced in GABA-CB(1R-KO mice. In the electron microscope, CB(1R appeared in membranes of both glutamatergic and GABAergic terminals/preterminals. There was no significant difference in the percentage of CB(1R immunopositive profiles and CB(1R density in terminals making asymmetric or symmetric synapses in CB(1R-WT mice. Furthermore, the proportion of CB(1R immunopositive terminals/preterminals in CB(1R-WT and Glu-CB(1R-KO mice was reduced in GABA-CB(1R-KO mutants. CB(1R density was similar in all animal conditions. Finally, the percentage of CB(1R labeled boutons making asymmetric synapses slightly decreased in Glu-CB(1R-KO mutants relative to CB(1R-WT mice, indicating that CB(1R was distributed in cortical and subcortical excitatory synaptic terminals. CONCLUSIONS/SIGNIFICANCE: Our anatomical results support the idea that the VMH is a relevant hub candidate in

Blockade of cannabinoid CB receptor function protects against in vivo disseminating brain damage following NMDA-induced excitotoxicity

DEFF Research Database (Denmark)

Hansen, H.H.; Ramos, J.A.; Fernández-Ruiz, J.

2002-01-01

-induced excitotoxic damage in the ipsilateral forebrain was not influenced by agonist-stimulated CB receptor function. In contrast, blockade of CB, but not CB, receptor activity evoked a robust neuroprotective response by reducing the infarct area and the number of cortical degenerating neurons. These results suggest...... receptor function on NMDA-induced excitotoxicity. Neonatal (6-day-old) rat pups received a systemic injection of a mixed CB/CB receptor agonist (WIN55,212-2) or their respective antagonists (SR141716A for CB and SR144528 for CB) prior to an unilateral intrastriatal microinjection of NMDA. The NMDA...... a critical involvement of CB receptor tonus on neuronal survival following NMDA receptor-induced excitotoxicity in vivo....

Polymorphisms of the dopamine D4 receptor gene (DRD4 VNTR) and cannabinoid CB1 receptor gene (CNR1) are not strongly related to cue-reactivity after alcohol exposure

NARCIS (Netherlands)

Wildenberg, E. van den; Janssen, R.G.J.H.; Hutchison, K.E.; Breukelen, G.J.P. van; Wiers, R.W.H.J.

2007-01-01

Polymorphisms in the D4 dopamine receptor gene (DRD4) and the CB1 cannabinoid receptor gene (CNR1) have been associated with a differential response to alcohol after consumption. The goal of the present study was to investigate whether heavy drinkers with these polymorphisms would respond with

METHODS FOR RECOMBINANT EXPRESSION AND FUNCTIONAL CHARACTERIZATION OF HUMAN CANNABINOID RECEPTOR CB2

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Alexei A. Yeliseev

2013-03-01

Full Text Available Cannabinoid receptor CB2 is a seven transmembrane-domain integral membrane protein that belongs to a large superfamily of G protein-coupled receptors (GPCR. CB2 is a part of the endocannabinoid system that plays vital role in regulation of immune response, inflammation, pain sensitivity, obesity and other physiological responses. Information about the structure and mechanisms of functioning of this receptor in cell membranes is essential for the rational development of specific pharmaceuticals. Here we review the methodology for recombinant expression, purification, stabilization and biochemical characterization of CB2 suitable for preparation of multi-milligram quantities of functionally active receptor. The biotechnological protocols include expression of the recombinant CB2 in E. coli cells as a fusion with the maltose binding protein, stabilization with a high affinity ligand and a derivative of cholesterol in detergent micelles, efficient purification by tandem affinity chromatography, and reconstitution of the receptor into lipid bilayers. The purified recombinant CB2 receptor is amenable to functional and structural studies including nuclear magnetic resonance spectroscopy and a wide range of biochemical and biophysical techniques.

Biodistribution and dosimetry in humans of two inverse agonists to image cannabinoid CB1 receptors using positron emission tomography

International Nuclear Information System (INIS)

Terry, Garth E.; Hirvonen, Jussi; Liow, Jeih-San; Seneca, Nicholas; Morse, Cheryl L.; Pike, Victor W.; Innis, Robert B.; Tauscher, Johannes T.; Schaus, John M.; Phebus, Lee; Felder, Christian C.; Halldin, Christer

2010-01-01

Cannabinoid subtype 1 (CB 1 ) receptors are found in nearly every organ in the body, may be involved in several neuropsychiatric and metabolic disorders, and are therefore an active target for pharmacotherapy and biomarker development. We recently reported brain imaging of CB 1 receptors with two PET radioligands: 11 C-MePPEP and 18 F-FMPEP-d 2 . Here we describe the biodistribution and dosimetry estimates for these two radioligands. Seven healthy subjects (four men and three women) underwent whole-body PET scans for 120 min after injection with 11 C-MePPEP. Another seven healthy subjects (two men and five women) underwent whole-body PET scans for 300 min after injection with 18 F-FMPEP-d 2 . Residence times were acquired from regions of interest drawn on tomographic images of visually identifiable organs for both radioligands and from radioactivity excreted in urine for 18 F-FMPEP-d 2 . The effective doses of 11 C-MePPEP and 18 F-FMPEP-d 2 are 4.6 and 19.7 μSv/MBq, respectively. Both radioligands demonstrated high uptake of radioactivity in liver, lung, and brain shortly after injection and accumulated radioactivity in bone marrow towards the end of the scan. After injection of 11 C-MePPEP, radioactivity apparently underwent hepatobiliary excretion only, while radioactivity from 18 F-FMPEP-d 2 showed both hepatobiliary and urinary excretion. 11 C-MePPEP and 18 F-FMPEP-d 2 yield an effective dose similar to other PET radioligands labeled with either 11 C or 18 F. The high uptake in brain confirms the utility of these two radioligands to image CB 1 receptors in brain, and both may also be useful to image CB 1 receptors in the periphery. (orig.)

Cannabis Users Show Enhanced Expression of CB1-5HT2A Receptor Heteromers in Olfactory Neuroepithelium Cells.

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Galindo, Liliana; Moreno, Estefanía; López-Armenta, Fernando; Guinart, Daniel; Cuenca-Royo, Aida; Izquierdo-Serra, Mercè; Xicota, Laura; Fernandez, Cristina; Menoyo, Esther; Fernández-Fernández, José M; Benítez-King, Gloria; Canela, Enric I; Casadó, Vicent; Pérez, Víctor; de la Torre, Rafael; Robledo, Patricia

2018-01-02

Cannabinoid CB1 receptors (CB 1 R) and serotonergic 2A receptors (5HT 2A R) form heteromers in the brain of mice where they mediate the cognitive deficits produced by delta-9-tetrahydrocannabinol. However, it is still unknown whether the expression of this heterodimer is modulated by chronic cannabis use in humans. In this study, we investigated the expression levels and functionality of CB 1 R-5HT 2A R heteromers in human olfactory neuroepithelium (ON) cells of cannabis users and control subjects, and determined their molecular characteristics through adenylate cyclase and the ERK 1/2 pathway signaling studies. We also assessed whether heteromer expression levels correlated with cannabis consumption and cognitive performance in neuropsychological tests. ON cells from controls and cannabis users expressed neuronal markers such as βIII-tubulin and nestin, displayed similar expression levels of genes related to cellular self-renewal, stem cell differentiation, and generation of neural crest cells, and showed comparable Na + currents in patch clamp recordings. Interestingly, CB 1 R-5HT 2A R heteromer expression was significantly increased in cannabis users and positively correlated with the amount of cannabis consumed, and negatively with age of onset of cannabis use. In addition, a negative correlation was found between heteromer expression levels and attention and working memory performance in cannabis users and control subjects. Our findings suggest that cannabis consumption regulates the formation of CB 1 R-5HT 2A R heteromers, and may have a key role in cognitive processing. These heterodimers could be potential new targets to develop treatment alternatives for cognitive impairments.

Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

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Navarro, Gemma; Carriba, Paulina; Gandí, Jorge; Ciruela, Francisco; Casadó, Vicent; Cortés, Antoni; Mallol, Josefa; Canela, Enric I.; Lluis, Carmen; Franco, Rafael

2008-01-01

Functional interactions in signaling occur between dopamine D2 (D2R) and cannabinoid CB1 (CB1R) receptors, between CB1R and adenosine A2A (A2AR) receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells. PMID:18956124

Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

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Gemma Navarro

2008-01-01

Full Text Available Functional interactions in signaling occur between dopamine D2 (D2R and cannabinoid CB1 (CB1R receptors, between CB1R and adenosine A2A (A2AR receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells.

Cannabinoid CB2 receptor agonists protect the striatum against malonate toxicity: relevance for Huntington’s disease

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Sagredo, Onintza; González, Sara; Aroyo, Ilia; Pazos, María Ruth; Benito, Cristina; Lastres-Becker, Isabel; Romero, Juan P.; Tolón, Rosa M.; Mechoulam, Raphael; Brouillet, Emmanuel; Romero, Julián; Fernández-Ruiz, Javier

2009-01-01

Cannabinoid agonists might serve as neuroprotective agents in neurodegenerative disorders. Here, we examined this hypothesis in a rat model of Huntington’s disease (HD) generated by intrastriatal injection of the mitochondrial complex II inhibitor malonate. Our results showed that only compounds able to activate CB2 receptors were capable of protecting striatal projection neurons from malonate-induced death. That CB2 receptor agonists are neuroprotective was confirmed by using the selective CB2 receptor antagonist, SR144528, and by the observation that mice deficient in CB2 receptor were more sensitive to malonate than wild-type animals. CB2 receptors are scarce in the striatum in healthy conditions but they are markedly up-regulated after the lesion with malonate. Studies of double immunostaining revealed a significant presence of CB2 receptors in cells labelled with the marker of reactive microglia OX-42, and also in cells labelled with GFAP (a marker of astrocytes). We further showed that the activation of CB2 receptors significantly reduced the levels of tumor necrosis factor-α (TNF-α) that had been increased by the lesion with malonate. In summary, our results demonstrate that stimulation of CB2 receptors protect the striatum against malonate toxicity, likely through a mechanism involving glial cells, in particular reactive microglial cells in which CB2 receptors would be up-regulated in response to the lesion. Activation of these receptors would reduce the generation of proinflammatory molecules like TNF-α. Altogether our results support the hypothesis that CB2 receptors could constitute a therapeutic target to slowdown neurodegeneration in HD. PMID:19115380

Cannabinoid CB2 receptor potentiates obesity-associated inflammation, insulin resistance and hepatic steatosis.

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Vanessa Deveaux

Full Text Available BACKGROUND: Obesity-associated inflammation is of critical importance in the development of insulin resistance and non-alcoholic fatty liver disease. Since the cannabinoid receptor CB2 regulates innate immunity, the aim of the present study was to investigate its role in obesity-induced inflammation, insulin resistance and fatty liver. METHODOLOGY: Murine obesity models included genetically leptin-deficient ob/ob mice and wild type (WT mice fed a high fat diet (HFD, that were compared to their lean counterparts. Animals were treated with pharmacological modulators of CB2 receptors. Experiments were also performed in mice knock-out for CB2 receptors (Cnr2 -/-. PRINCIPAL FINDINGS: In both HFD-fed WT mice and ob/ob mice, Cnr2 expression underwent a marked induction in the stromal vascular fraction of epididymal adipose tissue that correlated with increased fat inflammation. Treatment with the CB2 agonist JWH-133 potentiated adipose tissue inflammation in HFD-fed WT mice. Moreover, cultured fat pads isolated from ob/ob mice displayed increased Tnf and Ccl2 expression upon exposure to JWH-133. In keeping, genetic or pharmacological inactivation of CB2 receptors decreased adipose tissue macrophage infiltration associated with obesity, and reduced inductions of Tnf and Ccl2 expressions. In the liver of obese mice, Cnr2 mRNA was only weakly induced, and CB2 receptors moderately contributed to liver inflammation. HFD-induced insulin resistance increased in response to JWH-133 and reduced in Cnr2 -/- mice. Finally, HFD-induced hepatic steatosis was enhanced in WT mice treated with JWH-133 and blunted in Cnr2 -/- mice. CONCLUSION/SIGNIFICANCE: These data unravel a previously unrecognized contribution of CB2 receptors to obesity-associated inflammation, insulin resistance and non-alcoholic fatty liver disease, and suggest that CB2 receptor antagonists may open a new therapeutic approach for the management of obesity-associated metabolic disorders.

Pharmacological blockade of either cannabinoid CB1 or CB2 receptors prevents both cocaine-induced conditioned locomotion and cocaine-induced reduction of cell proliferation in the hippocampus of adult male rat

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Blanco-Calvo, Eduardo; Rivera, Patricia; Arrabal, Sergio; Vargas, Antonio; Pavón, Francisco Javier; Serrano, Antonia; Castilla-Ortega, Estela; Galeano, Pablo; Rubio, Leticia; Suárez, Juan; Rodriguez de Fonseca, Fernando

2014-01-01

Addiction to major drugs of abuse, such as cocaine, has recently been linked to alterations in adult neurogenesis in the hippocampus. The endogenous cannabinoid system modulates this proliferative response as demonstrated by the finding that pharmacological activation/blockade of cannabinoid CB1 and CB2 receptors not only modulates neurogenesis but also modulates cell death in the brain. In the present study, we evaluated whether the endogenous cannabinoid system affects cocaine-induced alterations in cell proliferation. To this end, we examined whether pharmacological blockade of either CB1 (Rimonabant, 3 mg/kg) or CB2 receptors (AM630, 3 mg/kg) would affect cell proliferation [the cells were labeled with 5-bromo-2′-deoxyuridine (BrdU)] in the subventricular zone (SVZ) of the lateral ventricle and the dentate subgranular zone (SGZ). Additionally, we measured cell apoptosis (as monitored by the expression of cleaved caspase-3) and glial activation [by analyzing the expression of glial fibrillary acidic protein (GFAP) and Iba-1] in the striatum and hippocampus during acute and repeated (4 days) cocaine administration (20 mg/kg). The results showed that acute cocaine exposure decreased the number of BrdU-immunoreactive (ir) cells in the SVZ and SGZ. In contrast, repeated cocaine exposure reduced the number of BrdU-ir cells only in the SVZ. Both acute and repeated cocaine exposure increased the number of cleaved caspase-3-, GFAP- and Iba1-ir cells in the hippocampus, and this effect was counteracted by AM630 or Rimonabant, which increased the number of BrdU-, GFAP-, and Iba1-ir cells in the hippocampus. These results indicate that the changes in neurogenic, apoptotic and gliotic processes that were produced by repeated cocaine administration were normalized by pharmacological blockade of CB1 and CB2. The restorative effects of cannabinoid receptor blockade on hippocampal cell proliferation were associated with the prevention of the induction of conditioned

Presynaptic Ionotropic Receptors Controlling and Modulating the Rules for Spike Timing-Dependent Plasticity

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Matthijs B. Verhoog

2011-01-01

Full Text Available Throughout life, activity-dependent changes in neuronal connection strength enable the brain to refine neural circuits and learn based on experience. In line with predictions made by Hebb, synapse strength can be modified depending on the millisecond timing of action potential firing (STDP. The sign of synaptic plasticity depends on the spike order of presynaptic and postsynaptic neurons. Ionotropic neurotransmitter receptors, such as NMDA receptors and nicotinic acetylcholine receptors, are intimately involved in setting the rules for synaptic strengthening and weakening. In addition, timing rules for STDP within synapses are not fixed. They can be altered by activation of ionotropic receptors located at, or close to, synapses. Here, we will highlight studies that uncovered how network actions control and modulate timing rules for STDP by activating presynaptic ionotropic receptors. Furthermore, we will discuss how interaction between different types of ionotropic receptors may create “timing” windows during which particular timing rules lead to synaptic changes.

The CB1 receptor antagonist AM251 impairs reconsolidation of pavlovian fear memory in the rat basolateral amygdala.

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Ratano, Patrizia; Everitt, Barry J; Milton, Amy L

2014-10-01

We have investigated the requirement for signaling at CB1 receptors in the reconsolidation of a previously consolidated auditory fear memory, by infusing the CB1 receptor antagonist AM251, or the FAAH inhibitor URB597, directly into the basolateral amygdala (BLA) in conjunction with memory reactivation. AM251 disrupted memory restabilization, but only when administered after reactivation. URB597 produced a small, transient enhancement of memory restabilization when administered after reactivation. The amnestic effect of AM251 was rescued by coadministration of the GABAA receptor antagonist bicuculline at reactivation, indicating that the disruption of reconsolidation was mediated by altered GABAergic transmission in the BLA. These data show that the endocannabinoid system in the BLA is an important modulator of fear memory reconsolidation and that its effects on memory are mediated by an interaction with the GABAergic system. Thus, targeting the endocannabinoid system may have therapeutic potential to reduce the impact of maladaptive memories in neuropsychiatric disorders such as posttraumatic stress disorder.

Elevation of endogenous anandamide impairs LTP, learning, and memory through CB1 receptor signaling in mice.

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Basavarajappa, Balapal S; Nagre, Nagaraja N; Xie, Shan; Subbanna, Shivakumar

2014-07-01

In rodents, many exogenous and endogenous cannabinoids, such as anandamide (AEA) and 2-arachidonyl glycerol (2-AG), have been shown to play an important role in certain hippocampal memory processes. However, the mechanisms by which endogenous AEA regulate this processes are not well understood. Here the effects of AEA on long-term potentiation (LTP), hippocampal-dependent learning and memory tasks, pERK1/2, pCaMKIV, and pCREB signaling events in both cannabinoid receptor type 1 (CB1R) wild-type (WT) and knockout (KO) mice were assessed following administration of URB597, an inhibitor of the fatty acid amide hydrolase (FAAH). Acute administration of URB597 enhanced AEA levels without affecting the levels of 2-AG or CB1R in the hippocampus and neocortex as compared to vehicle. In hippocampal slices, URB597 impaired LTP in CB1R WT but not in KO littermates. URB597 impaired object recognition, spontaneous alternation and spatial memory in the Y-maze test in CB1R WT mice but not in KO mice. Furthermore, URB597 enhanced ERK phosphorylation in WT without affecting total ERK levels in WT or KO mice. URB597 impaired CaMKIV and CREB phosphorylation in WT but not in KO mice. CB1R KO mice have a lower pCaMKIV/CaMKIV ratio and higher pCREB/CREB ratio as compared to WT littermates. Our results indicate that pharmacologically elevated AEA impair LTP, learning and memory and inhibit CaMKIV and CREB phosphorylation, via the activation of CB1Rs. Collectively, these findings also suggest that pharmacological elevation of AEA beyond normal concentrations is also detrimental for the underlying physiological responses. © 2014 Wiley Periodicals, Inc.

Blockade of Cannabinoid CB1 Receptors in the Dorsal Periaqueductal Gray Unmasks the Antinociceptive Effect of Local Injections of Anandamide in Mice

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Diego C. Mascarenhas

2017-10-01

Full Text Available Divergent results in pain management account for the growing number of studies aiming at elucidating the pharmacology of the endocannabinoid/endovanilloid anandamide (AEA within several pain-related brain structures. For instance, the stimulation of both Transient Receptor Potential Vanilloid type 1 (TRPV1 and Cannabinoid type 1 (CB1 receptors led to paradoxical effects on nociception. Here, we attempted to propose a clear and reproducible methodology to achieve the antinociceptive effect of exogenous AEA within the dorsal periaqueductal gray (dPAG of mice exposed to the tail-flick test. Accordingly, male Swiss mice received intra-dPAG injection of AEA (CB1/TRPV1 agonist, capsaicin (TRPV1 agonist, WIN (CB1 agonist, AM251 (CB1 antagonist, and 6-iodonordihydrocapsaicin (6-IODO (TRPV1 selective antagonist and their nociceptive response was assessed with the tail-flick test. In order to assess AEA effects on nociception specifically at vanilloid or cannabinoid (CB substrates into the dPAG, mice underwent an intrinsically inactive dose of AM251 or 6-IODO followed by local AEA injections and were subjected to the same test. While intra-dPAG AEA did not change acute pain, local injections of capsaicin or WIN induced a marked TRPV1- and CB1-dependent antinociceptive effect, respectively. Regarding the role of AEA specifically at CB/vanilloid substrates, while the blockade of TRPV1 did not change the lack of effects of intra-dPAG AEA on nociception, local pre-treatment of AM251, a CB1 antagonist, led to a clear AEA-induced antinociception. It seems that the exogenous AEA-induced antinociception is unmasked when it selectively binds to vanilloid substrates, which might be useful to address acute pain in basic and perhaps clinical trials.

Biodistribution and dosimetry in humans of two inverse agonists to image cannabinoid CB{sub 1} receptors using positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Terry, Garth E. [National Institute of Mental Health, Molecular Imaging Branch, Bethesda, MD (United States); Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Stockholm (Sweden); Hirvonen, Jussi; Liow, Jeih-San; Seneca, Nicholas; Morse, Cheryl L.; Pike, Victor W.; Innis, Robert B. [National Institute of Mental Health, Molecular Imaging Branch, Bethesda, MD (United States); Tauscher, Johannes T.; Schaus, John M.; Phebus, Lee; Felder, Christian C. [Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN (United States); Halldin, Christer [Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Stockholm (Sweden)

2010-08-15

Cannabinoid subtype 1 (CB{sub 1}) receptors are found in nearly every organ in the body, may be involved in several neuropsychiatric and metabolic disorders, and are therefore an active target for pharmacotherapy and biomarker development. We recently reported brain imaging of CB{sub 1} receptors with two PET radioligands: {sup 11}C-MePPEP and {sup 18}F-FMPEP-d{sub 2}. Here we describe the biodistribution and dosimetry estimates for these two radioligands. Seven healthy subjects (four men and three women) underwent whole-body PET scans for 120 min after injection with {sup 11}C-MePPEP. Another seven healthy subjects (two men and five women) underwent whole-body PET scans for 300 min after injection with {sup 18}F-FMPEP-d{sub 2}. Residence times were acquired from regions of interest drawn on tomographic images of visually identifiable organs for both radioligands and from radioactivity excreted in urine for {sup 18}F-FMPEP-d{sub 2}. The effective doses of {sup 11}C-MePPEP and {sup 18}F-FMPEP-d{sub 2} are 4.6 and 19.7 {mu}Sv/MBq, respectively. Both radioligands demonstrated high uptake of radioactivity in liver, lung, and brain shortly after injection and accumulated radioactivity in bone marrow towards the end of the scan. After injection of {sup 11}C-MePPEP, radioactivity apparently underwent hepatobiliary excretion only, while radioactivity from {sup 18}F-FMPEP-d{sub 2} showed both hepatobiliary and urinary excretion. {sup 11}C-MePPEP and {sup 18}F-FMPEP-d{sub 2} yield an effective dose similar to other PET radioligands labeled with either {sup 11}C or {sup 18}F. The high uptake in brain confirms the utility of these two radioligands to image CB{sub 1} receptors in brain, and both may also be useful to image CB{sub 1} receptors in the periphery. (orig.)

The anabolic steroid nandrolone alters cannabinoid self-administration and brain CB1 receptor density and function.

Science.gov (United States)

Struik, Dicky; Fadda, Paola; Zara, Tamara; Zamberletti, Erica; Rubino, Tiziana; Parolaro, Daniela; Fratta, Walter; Fattore, Liana

2017-01-01

Clinical and pre-clinical observations indicate that anabolic-androgenic steroids can induce neurobiological changes that alter the rewarding effects of drugs of abuse. In this study, we investigated the effect of the anabolic steroid nandrolone on the rewarding properties of the cannabinoid CB 1 receptor agonist WIN55,212-2 (WIN) in rats. Lister Hooded male rats were treated intramuscularly with nandrolone (15mg/kg) or vehicle for 14 consecutive days, and then allowed to self-administer WIN (12.5μg/kg/infusion) intravenously. After reaching stable drug intake, self-administration behavior was extinguished to examine drug- and cue-induced reinstatement of cannabinoid-seeking behavior. Other behavioral parameters presumed to influence drug-taking and drug-seeking behaviors were examined to gain more insight into the behavioral specificity of nandrolone treatment. Finally, animals were sacrificed for analysis of CB 1 receptor density and function in selected brain areas. We found that nandrolone-treated rats self-administered up to 2 times more cannabinoid than vehicle-treated rats, but behaved similarly to control rats when tested for drug- and cue-induced reinstatement of cannabinoid-seeking behavior. Enhanced cannabinoid intake by nandrolone-treated rats was not accompanied by changes in locomotor activity, sensorimotor gating, or memory function. However, our molecular data show that after chronic WIN self-administration nandrolone-treated rats display altered CB 1 receptor density and function in selected brain areas. We hypothesize that increased cannabinoid self-administration in nandrolone-treated rats results from a nandrolone-induced decrease in reward function, which rats seem to compensate by voluntarily increasing their cannabinoid intake. Altogether, our findings corroborate the hypothesis that chronic exposure to anabolic-androgenic steroids induces dysfunction of the reward pathway in rats and might represent a potential risk factor for abuse of

Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation?

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Zlebnik, Natalie E; Cheer, Joseph F

2016-07-08

The Cannabis sativa plant has been used to treat various physiological and psychiatric conditions for millennia. Current research is focused on isolating potentially therapeutic chemical constituents from the plant for use in the treatment of many central nervous system disorders. Of particular interest is the primary nonpsychoactive constituent cannabidiol (CBD). Unlike Δ(9)-tetrahydrocannabinol (THC), CBD does not act through the cannabinoid type 1 (CB1) receptor but has many other receptor targets that may play a role in psychiatric disorders. Here we review preclinical and clinical data outlining the therapeutic efficacy of CBD for the treatment of motivational disorders such as drug addiction, anxiety, and depression. Across studies, findings suggest promising treatment effects and potentially overlapping mechanisms of action for CBD in these disorders and indicate the need for further systematic investigation of the viability of CBD as a psychiatric pharmacotherapy.

Anandamide inhibits Theiler's virus induced VCAM-1 in brain endothelial cells and reduces leukocyte transmigration in a model of blood brain barrier by activation of CB1 receptors

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Loría Frida

2011-08-01

Full Text Available Abstract Background VCAM-1 represents one of the most important adhesion molecule involved in the transmigration of blood leukocytes across the blood-brain barrier (BBB that is an essential step in the pathogenesis of MS. Several evidences have suggested the potential therapeutic value of cannabinoids (CBs in the treatment of MS and their experimental models. However, the effects of endocannabinoids on VCAM-1 regulation are poorly understood. In the present study we investigated the effects of anandamide (AEA in the regulation of VCAM-1 expression induced by Theiler's virus (TMEV infection of brain endothelial cells using in vitro and in vivo approaches. Methods i in vitro: VCAM-1 was measured by ELISA in supernatants of brain endothelial cells infected with TMEV and subjected to AEA and/or cannabinoid receptors antagonist treatment. To evaluate the functional effect of VCAM-1 modulation we developed a blood brain barrier model based on a system of astrocytes and brain endothelial cells co-culture. ii in vivo: CB1 receptor deficient mice (Cnr1-/- infected with TMEV were treated with the AEA uptake inhibitor UCM-707 for three days. VCAM-1 expression and microglial reactivity were evaluated by immunohistochemistry. Results Anandamide-induced inhibition of VCAM-1 expression in brain endothelial cell cultures was mediated by activation of CB1 receptors. The study of leukocyte transmigration confirmed the functional relevance of VCAM-1 inhibition by AEA. In vivo approaches also showed that the inhibition of AEA uptake reduced the expression of brain VCAM-1 in response to TMEV infection. Although a decreased expression of VCAM-1 by UCM-707 was observed in both, wild type and CB1 receptor deficient mice (Cnr1-/-, the magnitude of VCAM-1 inhibition was significantly higher in the wild type mice. Interestingly, Cnr1-/- mice showed enhanced microglial reactivity and VCAM-1 expression following TMEV infection, indicating that the lack of CB1 receptor

Human immunodeficiency virus-1 protein Tat induces excitotoxic loss of presynaptic terminals in hippocampal cultures.

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Shin, Angela H; Thayer, Stanley A

2013-05-01

Human immunodeficiency virus (HIV) infection of the CNS produces dendritic damage that correlates with cognitive decline in patients with HIV-associated neurocognitive disorders (HAND). HIV-induced neurotoxicity results in part from viral proteins shed from infected cells, including the HIV transactivator of transcription (Tat). We previously showed that Tat binds to the low density lipoprotein receptor-related protein (LRP), resulting in overactivation of NMDA receptors, activation of the ubiquitin-proteasome pathway, and subsequent loss of postsynaptic densities. Here, we show that Tat also induces a loss of presynaptic terminals. The number of presynaptic terminals was quantified using confocal imaging of synaptophysin fused to green fluorescent protein (Syn-GFP). Tat-induced loss of presynaptic terminals was secondary to excitatory postsynaptic mechanisms because treatment with an LRP antagonist or an NMDA receptor antagonist inhibited this loss. Treatment with nutlin-3, an E3 ligase inhibitor, prevented Tat-induced loss of presynaptic terminals. These data suggest that Tat-induced loss of presynaptic terminals is a consequence of excitotoxic postsynaptic activity. We previously found that ifenprodil, an NR2B subunit-selective NMDA receptor antagonist, induced recovery of postsynaptic densities. Here we show that Tat-induced loss of presynaptic terminals was reversed by ifenprodil treatment. Thus, Tat-induced loss of presynaptic terminals is reversible, and this recovery can be initiated by inhibiting a subset of postsynaptic NMDA receptors. Understanding the dynamics of synaptic changes in response to HIV infection of the CNS may lead to the design of improved pharmacotherapies for HAND patients. Copyright © 2012 Elsevier Inc. All rights reserved.

Targeting CB2-GPR55 Receptor Heteromers Modulates Cancer Cell Signaling*

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Moreno, Estefanía; Andradas, Clara; Medrano, Mireia; Caffarel, María M.; Pérez-Gómez, Eduardo; Blasco-Benito, Sandra; Gómez-Cañas, María; Pazos, M. Ruth; Irving, Andrew J.; Lluís, Carme; Canela, Enric I.; Fernández-Ruiz, Javier; Guzmán, Manuel; McCormick, Peter J.; Sánchez, Cristina

2014-01-01

The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. Because a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells. Here we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo. These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology. PMID:24942731

A search for presynaptic inhibitory histamine receptors in guinea-pig tissues: Further H3 receptors but no evidence for H4 receptors.

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Petri, Doris; Schlicker, Eberhard

2016-07-01

The histamine H4 receptor is coupled to Gi/o proteins and expressed on inflammatory cells and lymphoid tissues; it was suggested that this receptor also occurs in the brain or on peripheral neurones. Since many Gi/o protein-coupled receptors, including the H3 receptor, serve as presynaptic inhibitory receptors, we studied whether the sympathetic neurones supplying four peripheral tissues and the cholinergic neurones in the hippocampus from the guinea-pig are equipped with release-modulating H4 and H3 receptors. For this purpose, we preincubated tissue pieces from the aorta, atrium, renal cortex and vas deferens with (3)H-noradrenaline and hippocampal slices with (3)H-choline and determined the electrically evoked tritium overflow. The stimulation-evoked overflow in the five superfused tissues was inhibited by the muscarinic receptor agonist oxotremorine, which served as a positive control, but not affected by the H4 receptor agonist 4-methylhistamine. The H3 receptor agonist R-α-methylhistamine inhibited noradrenaline release in the peripheral tissues without affecting acetylcholine release in the hippocampal slices. Thioperamide shifted the concentration-response curve of histamine in the aorta and the renal cortex to the right, yielding apparent pA2 values of 8.0 and 8.1, respectively, which are close to its affinity at other H3 receptors but higher by one log unit than its pKi at the H4 receptor of the guinea-pig. In conclusion, histamine H4 receptors could not be identified in five experimental models of the guinea-pig that are suited for the detection of presynaptic inhibitory receptors whereas H3 receptors could be shown in the peripheral tissues but not in the hippocampus. This article is part of the Special Issue entitled 'Histamine Receptors'. Copyright © 2015 Elsevier Ltd. All rights reserved.

Presynaptic localization of histamine H3-receptors in rat brain

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Fujimoto, K.; Mizuguchi, H.; Fukui, H.; Wada, H.

1991-01-01

The localization of histamine H3-receptors in subcellular fractions from the rat brain was examined in a [3H] (R) alpha-methylhistamine binding assay and compared with those of histamine H1- and adrenaline alpha 1- and alpha 2-receptors. Major [3H](R) alpha-methylhistamine binding sites with increased specific activities ([3H]ligand binding vs. protein amount) were recovered from the P2 fraction by differential centrifugation. Minor [3H](R)alpha-methylhistamine binding sites with increased specific activities were also detected in the P3 fraction. Further subfractionation of the P2 fraction by discontinuous sucrose density gradient centrifugation showed major recoveries of [3H](R)alpha-methylhistamine binding in myelin (MYE) and synaptic plasma membrane (SPM) fractions. A further increase in specific activity was observed in the MYE fraction, but the SPM fraction showed no significant increase in specific activity. Adrenaline alpha 2-receptors, the pre-synaptic autoreceptors, in a [3H] yohimbine binding assay showed distribution patterns similar to histamine H3-receptors. On the other hand, post-synaptic histamine H1- and adrenaline alpha 1-receptors were closely localized and distributed mainly in the SPM fraction with increased specific activity. Only a negligible amount was recovered in the MYE fraction, unlike the histamine H3- and adrenaline alpha 2-receptors

Evidence against a critical role of CB1 receptors in adaptation of the hypothalamic-pituitary-adrenal axis and other consequences of daily repeated stress.

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Rabasa, Cristina; Pastor-Ciurana, Jordi; Delgado-Morales, Raúl; Gómez-Román, Almudena; Carrasco, Javier; Gagliano, Humberto; García-Gutiérrez, María S; Manzanares, Jorge; Armario, Antonio

2015-08-01

There is evidence that endogenous cannabinoids (eCBs) play a role in the control of the hypothalamic-pituitary-adrenal (HPA) axis, although they appear to have dual, stimulatory and inhibitory, effects. Recent data in rats suggest that eCBs, acting through CB1 receptors (CB1R), may be involved in adaptation of the HPA axis to daily repeated stress. In the present study we analyze this issue in male mice and rats. Using a knock-out mice for the CB1 receptor (CB1-/-) we showed that mutant mice presented similar adrenocorticotropic hormone (ACTH) response to the first IMO as wild-type mice. Daily repeated exposure to 1h of immobilization reduced the ACTH response to the stressor, regardless of the genotype, demonstrating that adaptation occurred to the same extent in absence of CB1R. Prototypical changes observed after repeated stress such as enhanced corticotropin releasing factor (CRH) gene expression in the paraventricular nucleus of the hypothalamus, impaired body weight gain and reduced thymus weight were similarly observed in both genotypes. The lack of effect of CB1R in the expression of HPA adaptation to another similar stressor (restraint) was confirmed in wild-type CD1 mice by the lack of effect of the CB1R antagonist AM251 just before the last exposure to stress. Finally, the latter drug did not blunt the HPA, glucose and behavioral adaptation to daily repeated forced swim in rats. Thus, the present results indicate that CB1R is not critical for overall effects of daily repeated stress or proper adaptation of the HPA axis in mice and rats. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

Intracellular postsynaptic cannabinoid receptors link thyrotropin-releasing hormone receptors to TRPC-like channels in thalamic paraventricular nucleus neurons.

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Zhang, L; Kolaj, M; Renaud, L P

2015-12-17

postsynaptic currents, suggesting presynaptic CB receptors are not involved in this situation. Collectively, the data imply that activation of TRH receptors in these midline thalamic neurons engages novel signaling pathways that include postsynaptic intracellular CB1 and CB2 receptors in the activation of TRPC4/5-like channels. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Distinct roles of presynaptic dopamine receptors in the differential modulation of the intrinsic synapses of medium-spiny neurons in the nucleus accumbens

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Schmauss Claudia

2007-01-01

Full Text Available Abstract Background In both schizophrenia and addiction, pathological changes in dopamine release appear to induce alterations in the circuitry of the nucleus accumbens that affect coordinated thought and motivation. Dopamine acts principally on medium-spiny GABA neurons, which comprise 95% of accumbens neurons and give rise to the majority of inhibitory synapses in the nucleus. To examine dopamine action at single medium-spiny neuron synapses, we imaged Ca2+ levels in their presynaptic varicosities in the acute brain slice using two-photon microscopy. Results Presynaptic Ca2+ rises were differentially modulated by dopamine. The D1/D5 selective agonist SKF81297 was exclusively facilitatory. The D2/D3 selective agonist quinpirole was predominantly inhibitory, but in some instances it was facilitatory. Studies using D2 and D3 receptor knockout mice revealed that quinpirole inhibition was either D2 or D3 receptor-mediated, while facilitation was mainly D3 receptor-mediated. Subsets of varicosities responded to both D1 and D2 agonists, showing that there was significant co-expression of these receptor families in single medium-spiny neurons. Neighboring presynaptic varicosities showed strikingly heterogeneous responses to DA agonists, suggesting that DA receptors may be differentially trafficked to individual varicosities on the same medium-spiny neuron axon. Conclusion Dopamine receptors are present on the presynaptic varicosities of medium-spiny neurons, where they potently control GABAergic synaptic transmission. While there is significant coexpression of D1 and D2 family dopamine receptors in individual neurons, at the subcellular level, these receptors appear to be heterogeneously distributed, potentially explaining the considerable controversy regarding dopamine action in the striatum, and in particular the degree of dopamine receptor segregation on these neurons. Assuming that post-receptor signaling is restricted to the microdomains of

Endogenous vs Exogenous Allosteric Modulators in GPCRs: A dispute for shuttling CB1 among different membrane microenvironments

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Stornaiuolo, Mariano; Bruno, Agostino; Botta, Lorenzo; Regina, Giuseppe La; Cosconati, Sandro; Silvestri, Romano; Marinelli, Luciana; Novellino, Ettore

2015-10-01

A Cannabinoid Receptor 1 (CB1) binding site for the selective allosteric modulator ORG27569 is here identified through an integrate approach of consensus pocket prediction, mutagenesis studies and Mass Spectrometry. This unprecedented ORG27569 pocket presents the structural features of a Cholesterol Consensus Motif, a cholesterol interacting region already found in other GPCRs. ORG27569 and cholesterol affects oppositely CB1 affinity for orthosteric ligands. Moreover, the rise in cholesterol intracellular level results in CB1 trafficking to the axonal region of neuronal cells, while, on the contrary, ORG27568 binding induces CB1 enrichment at the soma. This control of receptor migration among functionally different membrane regions of the cell further contributes to downstream signalling and adds a previously unknown mechanism underpinning CB1 modulation by ORG27569 , that goes beyond a mere control of receptor affinity for orthosteric ligands.

Changes in interleukin-1 signal modulators induced by 3,4-methylenedioxymethamphetamine (MDMA: regulation by CB2 receptors and implications for neurotoxicity

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O'Shea Esther

2011-05-01

Full Text Available Abstract Background 3,4-Methylenedioxymethamphetamine (MDMA produces a neuroinflammatory reaction in rat brain characterized by an increase in interleukin-1 beta (IL-1β and microglial activation. The CB2 receptor agonist JWH-015 reduces both these changes and partially protects against MDMA-induced neurotoxicity. We have examined MDMA-induced changes in IL-1 receptor antagonist (IL-1ra levels and IL-1 receptor type I (IL-1RI expression and the effects of JWH-015. The cellular location of IL-1β and IL-1RI was also examined. MDMA-treated animals were given the soluble form of IL-1RI (sIL-1RI and neurotoxic effects examined. Methods Dark Agouti rats received MDMA (12.5 mg/kg, i.p. and levels of IL-1ra and expression of IL-1RI measured 1 h, 3 h or 6 h later. JWH-015 (2.4 mg/kg, i.p. was injected 48 h, 24 h and 0.5 h before MDMA and IL-1ra and IL-1RI measured. For localization studies, animals were sacrificed 1 h or 3 h following MDMA and stained for IL-1β or IL-1RI in combination with neuronal and microglial markers. sIL-1RI (3 μg/animal; i.c.v. was administered 5 min before MDMA and 3 h later. 5-HT transporter density was determined 7 days after MDMA injection. Results MDMA produced an increase in IL-ra levels and a decrease in IL-1RI expression in hypothalamus which was prevented by CB2 receptor activation. IL-1RI expression was localized on neuronal cell bodies while IL-1β expression was observed in microglial cells following MDMA. sIL-1RI potentiated MDMA-induced neurotoxicity. MDMA also increased IgG immunostaining indicating that blood brain-barrier permeability was compromised. Conclusions In summary, MDMA produces changes in IL-1 signal modulators which are modified by CB2 receptor activation. These results indicate that IL-1β may play a partial role in MDMA-induced neurotoxicity.

Role of cannabinoid receptor CB2 in HER2 pro-oncogenic signaling in breast cancer.

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Pérez-Gómez, Eduardo; Andradas, Clara; Blasco-Benito, Sandra; Caffarel, María M; García-Taboada, Elena; Villa-Morales, María; Moreno, Estefanía; Hamann, Sigrid; Martín-Villar, Ester; Flores, Juana M; Wenners, Antonia; Alkatout, Ibrahim; Klapper, Wolfram; Röcken, Christoph; Bronsert, Peter; Stickeler, Elmar; Staebler, Annette; Bauer, Maret; Arnold, Norbert; Soriano, Joaquim; Pérez-Martínez, Manuel; Megías, Diego; Moreno-Bueno, Gema; Ortega-Gutiérrez, Silvia; Artola, Marta; Vázquez-Villa, Henar; Quintanilla, Miguel; Fernández-Piqueras, José; Canela, Enric I; McCormick, Peter J; Guzmán, Manuel; Sánchez, Cristina

2015-06-01

Pharmacological activation of cannabinoid receptors elicits antitumoral responses in different cancer models. However, the biological role of these receptors in tumor physio-pathology is still unknown. We analyzed CB2 cannabinoid receptor protein expression in two series of 166 and 483 breast tumor samples operated in the University Hospitals of Kiel, Tübingen, and Freiburg between 1997 and 2010 and CB2 mRNA expression in previously published DNA microarray datasets. The role of CB2 in oncogenesis was studied by generating a mouse line that expresses the human V-Erb-B2 Avian Erythroblastic Leukemia Viral Oncogene Homolog 2 (HER2) rat ortholog (neu) and lacks CB2 and by a variety of biochemical and cell biology approaches in human breast cancer cells in culture and in vivo, upon modulation of CB2 expression by si/shRNAs and overexpression plasmids. CB2-HER2 molecular interaction was studied by colocalization, coimmunoprecipitation, and proximity ligation assays. Statistical tests were two-sided. We show an association between elevated CB2 expression in HER2+ breast tumors and poor patient prognosis (decreased overall survival, hazard ratio [HR] = 0.29, 95% confidence interval [CI] = 0.09 to 0.71, P = .009) and higher probability to suffer local recurrence (HR = 0.09, 95% CI = 0.049 to 0.54, P = .003) and to develop distant metastases (HR = 0.33, 95% CI = 0.13 to 0.75, P = .009). We also demonstrate that genetic inactivation of CB2 impairs tumor generation and progression in MMTV-neu mice. Moreover, we show that HER2 upregulates CB2 expression by activating the transcription factor ELK1 via the ERK cascade and that an increased CB2 expression activates the HER2 pro-oncogenic signaling at the level of the tyrosine kinase c-SRC. Finally, we show HER2 and CB2 form heteromers in cancer cells. Our findings reveal an unprecedented role of CB2 as a pivotal regulator of HER2 pro-oncogenic signaling in breast cancer, and they suggest that CB2 may be a biomarker with

Depression of presynaptic excitation by the activation of vanilloid receptor 1 in the rat spinal dorsal horn revealed by optical imaging

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Ikeda Hiroshi

2006-02-01

Full Text Available Abstract In this study, we show that capsaicin (CAP depresses primary afferent fiber terminal excitability by acting on vanilloid receptor 1 (TRPV1 channels of primary afferent fibers in adenosine 5'-triphosphate (ATP- and temperature-dependent manner using two optical imaging methods. First, transverse slices of spinal cord were stained with a voltage-sensitive dye and the net excitation in the spinal dorsal horn was recorded. Prolonged treatment (>20 min with the TRPV1 channel agonist, CAP, resulted in a long-lasting inhibition of the net excitation evoked by single-pulse stimulation of C fiber-activating strength. A shorter application of CAP inhibited the excitation in a concentration-dependent manner and the inhibition was reversed within several minutes. This inhibition was Ca++-dependent, was antagonized by the TRPV1 channel antagonist, capsazepine (CPZ, and the P2X and P2Y antagonist, suramin, and was facilitated by the P2Y agonist, uridine 5'-triphosphate (UTP. The inhibition of excitation was unaffected by bicuculline and strychnine, antagonists of GABAA and glycine receptors, respectively. Raising the perfusate temperature to 39°C from 27°C inhibited the excitation (-3%/°C. This depressant effect was antagonized by CPZ and suramin, but not by the P2X antagonist, 2', 3'-O-(2,4,6-trinitrophenyl adenosine 5'-triphosphate (TNP-ATP. Second, in order to record the presynaptic excitation exclusively, we stained the primary afferent fibers anterogradely from the dorsal root. CAP application and a temperature increase from 27°C to 33°C depressed the presynaptic excitation, and CPZ antagonized these effects. Thus, this study showed that presynaptic excitability is modulated by CAP, temperature, and ATP under physiological conditions, and explains the reported central actions of CAP. These results may have clinical importance, especially for the control of pain.

Stabilization of functional recombinant cannabinoid receptor CB(2 in detergent micelles and lipid bilayers.

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Krishna Vukoti

Full Text Available Elucidation of the molecular mechanisms of activation of G protein-coupled receptors (GPCRs is among the most challenging tasks for modern membrane biology. For studies by high resolution analytical methods, these integral membrane receptors have to be expressed in large quantities, solubilized from cell membranes and purified in detergent micelles, which may result in a severe destabilization and a loss of function. Here, we report insights into differential effects of detergents, lipids and cannabinoid ligands on stability of the recombinant cannabinoid receptor CB(2, and provide guidelines for preparation and handling of the fully functional receptor suitable for a wide array of downstream applications. While we previously described the expression in Escherichia coli, purification and liposome-reconstitution of multi-milligram quantities of CB(2, here we report an efficient stabilization of the recombinant receptor in micelles - crucial for functional and structural characterization. The effects of detergents, lipids and specific ligands on structural stability of CB(2 were assessed by studying activation of G proteins by the purified receptor reconstituted into liposomes. Functional structure of the ligand binding pocket of the receptor was confirmed by binding of (2H-labeled ligand measured by solid-state NMR. We demonstrate that a concerted action of an anionic cholesterol derivative, cholesteryl hemisuccinate (CHS and high affinity cannabinoid ligands CP-55,940 or SR-144,528 are required for efficient stabilization of the functional fold of CB(2 in dodecyl maltoside (DDM/CHAPS detergent solutions. Similar to CHS, the negatively charged phospholipids with the serine headgroup (PS exerted significant stabilizing effects in micelles while uncharged phospholipids were not effective. The purified CB(2 reconstituted into lipid bilayers retained functionality for up to several weeks enabling high resolution structural studies of this GPCR at

Structural basis of G protein-coupled receptor-Gi protein interaction: formation of the cannabinoid CB2 receptor-Gi protein complex.

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Mnpotra, Jagjeet S; Qiao, Zhuanhong; Cai, Jian; Lynch, Diane L; Grossfield, Alan; Leioatts, Nicholas; Hurst, Dow P; Pitman, Michael C; Song, Zhao-Hui; Reggio, Patricia H

2014-07-18

In this study, we applied a comprehensive G protein-coupled receptor-Gαi protein chemical cross-linking strategy to map the cannabinoid receptor subtype 2 (CB2)-Gαi interface and then used molecular dynamics simulations to explore the dynamics of complex formation. Three cross-link sites were identified using LC-MS/MS and electrospray ionization-MS/MS as follows: 1) a sulfhydryl cross-link between C3.53(134) in TMH3 and the Gαi C-terminal i-3 residue Cys-351; 2) a lysine cross-link between K6.35(245) in TMH6 and the Gαi C-terminal i-5 residue, Lys-349; and 3) a lysine cross-link between K5.64(215) in TMH5 and the Gαi α4β6 loop residue, Lys-317. To investigate the dynamics and nature of the conformational changes involved in CB2·Gi complex formation, we carried out microsecond-time scale molecular dynamics simulations of the CB2 R*·Gαi1β1γ2 complex embedded in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer, using cross-linking information as validation. Our results show that although molecular dynamics simulations started with the G protein orientation in the β2-AR*·Gαsβ1γ2 complex crystal structure, the Gαi1β1γ2 protein reoriented itself within 300 ns. Two major changes occurred as follows. 1) The Gαi1 α5 helix tilt changed due to the outward movement of TMH5 in CB2 R*. 2) A 25° clockwise rotation of Gαi1β1γ2 underneath CB2 R* occurred, with rotation ceasing when Pro-139 (IC-2 loop) anchors in a hydrophobic pocket on Gαi1 (Val-34, Leu-194, Phe-196, Phe-336, Thr-340, Ile-343, and Ile-344). In this complex, all three experimentally identified cross-links can occur. These findings should be relevant for other class A G protein-coupled receptors that couple to Gi proteins. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Monoclonal antibody 1.6.1 against human MPL receptor allows HSC enrichment of CB and BM CD34(+)CD38(-) populations.

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Petit Cocault, Laurence; Fleury, Maud; Clay, Denis; Larghero, Jérôme; Vanneaux, Valérie; Souyri, Michèle

2016-04-01

Thrombopoietin (TPO) and its receptor Mpl (CD110) play a crucial role in the regulation of hematopoietic stem cells (HSCs). Functional study of Mpl-expressing HSCs has, however, been hampered by the lack of efficient monoclonal antibodies, explaining the very few data available on Mpl(+) HSCs during human embryonic development and after birth. Investigating the main monoclonal antibodies used so far to sort CD110(+) cells from cord blood (CB) and adult bone marrow (BM), we found that only the recent monoclonal antibody 1.6.1 engineered by Immunex Corporation was specific. Using in vitro functional assays, we found that this antibody can be used to sort a CD34(+)CD38(-)CD110(+) population enriched in hematopoietic progenitor stem cells, both in CB and in adult BM. In vivo injection into NSG mice further indicated that the CB CD34(+)CD38(-)CD110(+) population is highly enriched in HSCs compared with both CD34(+)CD38(-)CD110(-) and CD34(+)CD38(-) populations. Together our results validate MAb1.6.1 as an important tool, which has so far been lacking, in the HSC field. Copyright © 2016 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

CB2 cannabinoid receptors modulate HIF-1α and TIM-3 expression in a hypoxia-ischemia mouse model.

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Kossatz, Elk; Maldonado, Rafael; Robledo, Patricia

2016-12-01

The role of CB2 cannabinoid receptors (CB 2 R) in global brain lesions induced by hypoxia-ischemia (HI) insult is still unresolved. The aim of this study was to evaluate the involvement of CB 2 R in the behavioural and biochemical underpinnings related to brain damage induced by HI in adult mice, and the mechanisms involved. CB 2 R knockout (KO) mice and wild-type littermates (WT) underwent permanent ligation of the left common carotid artery and hypoxia. Behavioural measurements in the rotarod, beam walking, object recognition, open field, and Irwin tests were carried out 24h, 72h and 7 days. In KO mice, more extensive brain injury was observed. Behavioural deficits in the Irwin test were observed in both genotypes; while WT mice showed progressive recovery by day 7, KO mice did not. Only KO mice showed alterations in motor learning, coordination and balance, and did not recover over time. A higher expression of microglia and astrocytes was observed in several brain areas of lesioned WT and KO mice. The possible alteration of the inflammatory-related factors HIF-1α and TIM-3 was evaluated in these animals. In both genotypes, HIF-1α and TIM-3 expression was observed in lesioned areas associated with activated microglia. However, the expression levels of these proteins were exacerbated in KO mice in several lesioned and non-lesioned brain structures. Our results indicate that CB 2 R may have a crucial neuroprotective role following HI insult through the modulation of the inflammatory-related HIF-1α/TIM-3 signalling pathway in microglia. Copyright © 2016 Elsevier B.V. and ECNP. All rights reserved.

Antagonism of presynaptic dopamine receptors by phenothiazine drug metabolites

International Nuclear Information System (INIS)

Nowak, J.Z.; Arbilla, S.; Langer, S.Z.; Dahl, S.G.

1990-01-01

Electrically evoked release of dopamine from the caudate nucleus is reduced by the dopamine receptor agonists, apomorphine and bromocriptine, and facilitated by neuroleptic drugs, which act as dopamine autoreceptor antagonists. The potencies of chlorpromazine, fluphenazine, levomepromazine and their hydroxy-metabolites in modulating electrically evoked release of dopamine were examined by superfusion of rabbit caudate nucleus slices pre-incubated with 3 H-dopamine. O-Desmethyl levomepromazine, 3-hydroxy- and 7-hydroxy metabolites of chlorpromazine and levomepromazine facilitated electrically evoked release of 3 H-dopamine, having potencies similar to that of the parent compounds. 7-Hydroxy fluphenazine was less active than fluphenazine in this system. These results indicate that phenolic metabolites of chlorpromazine and levomepromazine, but not of fluphenazine, may contribute to effects of the drugs mediated by presynaptic dopamine receptors

Paradoxical effects of the cannabinoid CB2 receptor agonist GW405833 on rat osteoarthritic knee joint pain.

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Schuelert, N; Zhang, C; Mogg, A J; Broad, L M; Hepburn, D L; Nisenbaum, E S; Johnson, M P; McDougall, J J

2010-11-01

The present study examined whether local administration of the cannabinoid-2 (CB(2)) receptor agonist GW405833 could modulate joint nociception in control rat knee joints and in an animal model of osteoarthritis (OA). OA was induced in male Wistar rats by intra-articular injection of sodium monoiodo-acetate with a recovery period of 14 days. Immunohistochemistry was used to evaluate the expression of CB(2) and transient receptor potential vanilloid channel-1 (TRPV1) receptors in the dorsal root ganglion (DRG) and synovial membrane of sham- and sodium mono-iodoacetate (MIA)-treated animals. Electrophysiological recordings were made from knee joint primary afferents in response to rotation of the joint both before and following close intra-arterial injection of different doses of GW405833. The effect of intra-articular GW405833 on joint pain perception was determined by hindlimb incapacitance. An in vitro neuronal release assay was used to see if GW405833 caused release of an inflammatory neuropeptide (calcitonin gene-related peptide - CGRP). CB(2) and TRPV1 receptors were co-localized in DRG neurons and synoviocytes in both sham- and MIA-treated animals. Local application of the GW405833 significantly reduced joint afferent firing rate by up to 31% in control knees. In OA knee joints, however, GW405833 had a pronounced sensitising effect on joint mechanoreceptors. Co-administration of GW405833 with the CB(2) receptor antagonist AM630 or pre-administration of the TRPV1 ion channel antagonist SB366791 attenuated the sensitising effect of GW405833. In the pain studies, intra-articular injection of GW405833 into OA knees augmented hindlimb incapacitance, but had no effect on pain behaviour in saline-injected control joints. GW405833 evoked increased CGRP release via a TRPV1 channel-dependent mechanism. These data indicate that GW405833 reduces the mechanosensitivity of afferent nerve fibres in control joints but causes nociceptive responses in OA joints. The observed

Genetic background can result in a marked or minimal effect of gene knockout (GPR55 and CB2 receptor in experimental autoimmune encephalomyelitis models of multiple sclerosis.

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Sofia Sisay

Full Text Available Endocannabinoids and some phytocannabinoids bind to CB1 and CB2 cannabinoid receptors, transient receptor potential vanilloid one (TRPV1 receptor and the orphan G protein receptor fifty-five (GPR55. Studies using C57BL/10 and C57BL/6 (Cnr2 (tm1Zim CB2 cannabinoid receptor knockout mice have demonstrated an immune-augmenting effect in experimental autoimmune encephalomyelitis (EAE models of multiple sclerosis. However, other EAE studies in Biozzi ABH mice often failed to show any treatment effect of either CB2 receptor agonism or antagonism on inhibition of T cell autoimmunity. The influence of genetic background on the induction of EAE in endocannabinoid system-related gene knockout mice was examined. It was found that C57BL/6.GPR55 knockout mice developed less severe disease, notably in female mice, following active induction with myelin oligodendrocyte glycoprotein 35-55 peptide. In contrast C57BL/6.CB2 (Cnr2 (Dgen receptor knockout mice developed augmented severity of disease consistent with the genetically and pharmacologically-distinct, Cnr2 (tm1Zim mice. However, when the knockout gene was bred into the ABH mouse background and EAE induced with spinal cord autoantigens the immune-enhancing effect of CB2 receptor deletion was lost. Likewise CB1 receptor and transient receptor potential vanilloid one knockout mice on the ABH background demonstrated no alteration in immune-susceptibility, in terms of disease incidence and severity of EAE, in contrast to that reported in some C57BL/6 mouse studies. Furthermore the immune-modulating influence of GPR55 was marginal on the ABH mouse background. Whilst sedative doses of tetrahydrocannabinol could induce immunosuppression, this was associated with a CB1 receptor rather than a CB2 receptor-mediated effect. These data support the fact that non-psychoactive doses of medicinal cannabis have a marginal influence on the immune response in MS. Importantly, it adds a note of caution for the translational

Differential effects of presynaptic versus postsynaptic adenosine A2A receptor blockade on Δ9-tetrahydrocannabinol (THC) self-administration in squirrel monkeys.

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Justinová, Zuzana; Redhi, Godfrey H; Goldberg, Steven R; Ferré, Sergi

2014-05-07

Different doses of an adenosine A2A receptor antagonist MSX-3 [3,7-dihydro-8-[(1E)-2-(3-ethoxyphenyl)ethenyl]-7 methyl-3-[3-(phosphooxy)propyl-1-(2 propynil)-1H-purine-2,6-dione] were found previously to either decrease or increase self-administration of cannabinoids delta-9-tetrahydrocannabinol (THC) or anandamide in squirrel monkeys. It was hypothesized that the decrease observed with a relatively low dose of MSX-3 was related to blockade of striatal presynaptic A2A receptors that modulate glutamatergic neurotransmission, whereas the increase observed with a higher dose was related to blockade of postsynaptic A2A receptors localized in striatopallidal neurons. This hypothesis was confirmed in the present study by testing the effects of the preferential presynaptic and postsynaptic A2A receptor antagonists SCH-442416 [2-(2-furanyl)-7-[3-(4-methoxyphenyl)propyl]-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] and KW-6002 [(E)-1, 3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione], respectively, in squirrel monkeys trained to intravenously self-administer THC. SCH-442416 produced a significant shift to the right of the THC self-administration dose-response curves, consistent with antagonism of the reinforcing effects of THC. Conversely, KW-6002 produced a significant shift to the left, consistent with potentiation of the reinforcing effects of THC. These results show that selectively blocking presynaptic A2A receptors could provide a new pharmacological approach to the treatment of marijuana dependence and underscore corticostriatal glutamatergic neurotransmission as a possible main mechanism involved in the rewarding effects of THC.

Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.

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De Luca, Maria Antonietta; Castelli, M Paola; Loi, Barbara; Porcu, Alessandra; Martorelli, Mariella; Miliano, Cristina; Kellett, Kathryn; Davidson, Colin; Stair, Jacqueline L; Schifano, Fabrizio; Di Chiara, Gaetano

2016-06-01

In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [(35)S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018. The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003-0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose-response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

Binding and Signaling Studies Disclose a Potential Allosteric Site for Cannabidiol in Cannabinoid CB2 Receptors.

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Martínez-Pinilla, Eva; Varani, Katia; Reyes-Resina, Irene; Angelats, Edgar; Vincenzi, Fabrizio; Ferreiro-Vera, Carlos; Oyarzabal, Julen; Canela, Enric I; Lanciego, José L; Nadal, Xavier; Navarro, Gemma; Borea, Pier Andrea; Franco, Rafael

2017-01-01

The mechanism of action of cannabidiol (CBD), the main non-psychotropic component of Cannabis sativa L., is not completely understood. First assumed that the compound was acting via cannabinoid CB 2 receptors (CB 2 Rs) it is now suggested that it interacts with non-cannabinoid G-protein-coupled receptors (GPCRs); however, CBD does not bind with high affinity to the orthosteric site of any GPCR. To search for alternative explanations, we tested CBD as a potential allosteric ligand of CB 2 R. Radioligand and non-radioactive homogeneous binding, intracellular cAMP determination and ERK1/2 phosphorylation assays were undertaken in heterologous systems expressing the human version of CB 2 R. Using membrane preparations from CB 2 R-expressing HEK-293T (human embryonic kidney 293T) cells, we confirmed that CBD does not bind with high affinity to the orthosteric site of the human CB 2 R where the synthetic cannabinoid, [ 3 H]-WIN 55,212-2, binds. CBD was, however, able to produce minor but consistent reduction in the homogeneous binding assays in living cells using the fluorophore-conjugated CB 2 R-selective compound, CM-157. The effect on binding to CB 2 R-expressing living cells was different to that exerted by the orthosteric antagonist, SR144528, which decreased the maximum binding without changing the K D . CBD at nanomolar concentrations was also able to significantly reduce the effect of the selective CB 2 R agonist, JWH133, on forskolin-induced intracellular cAMP levels and on activation of the MAP kinase pathway. These results may help to understand CBD mode of action and may serve to revisit its therapeutic possibilities.

Binding and Signaling Studies Disclose a Potential Allosteric Site for Cannabidiol in Cannabinoid CB2 Receptors

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Eva Martínez-Pinilla

2017-10-01

Full Text Available The mechanism of action of cannabidiol (CBD, the main non-psychotropic component of Cannabis sativa L., is not completely understood. First assumed that the compound was acting via cannabinoid CB2 receptors (CB2Rs it is now suggested that it interacts with non-cannabinoid G-protein-coupled receptors (GPCRs; however, CBD does not bind with high affinity to the orthosteric site of any GPCR. To search for alternative explanations, we tested CBD as a potential allosteric ligand of CB2R. Radioligand and non-radioactive homogeneous binding, intracellular cAMP determination and ERK1/2 phosphorylation assays were undertaken in heterologous systems expressing the human version of CB2R. Using membrane preparations from CB2R-expressing HEK-293T (human embryonic kidney 293T cells, we confirmed that CBD does not bind with high affinity to the orthosteric site of the human CB2R where the synthetic cannabinoid, [3H]-WIN 55,212-2, binds. CBD was, however, able to produce minor but consistent reduction in the homogeneous binding assays in living cells using the fluorophore-conjugated CB2R-selective compound, CM-157. The effect on binding to CB2R-expressing living cells was different to that exerted by the orthosteric antagonist, SR144528, which decreased the maximum binding without changing the KD. CBD at nanomolar concentrations was also able to significantly reduce the effect of the selective CB2R agonist, JWH133, on forskolin-induced intracellular cAMP levels and on activation of the MAP kinase pathway. These results may help to understand CBD mode of action and may serve to revisit its therapeutic possibilities.

Imidazopyridine CB2 agonists: optimization of CB2/CB1 selectivity and implications for in vivo analgesic efficacy.

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Trotter, B Wesley; Nanda, Kausik K; Burgey, Christopher S; Potteiger, Craig M; Deng, James Z; Green, Ahren I; Hartnett, John C; Kett, Nathan R; Wu, Zhicai; Henze, Darrell A; Della Penna, Kimberly; Desai, Reshma; Leitl, Michael D; Lemaire, Wei; White, Rebecca B; Yeh, Suzie; Urban, Mark O; Kane, Stefanie A; Hartman, George D; Bilodeau, Mark T

2011-04-15

A new series of imidazopyridine CB2 agonists is described. Structural optimization improved CB2/CB1 selectivity in this series and conferred physical properties that facilitated high in vivo exposure, both centrally and peripherally. Administration of a highly selective CB2 agonist in a rat model of analgesia was ineffective despite substantial CNS exposure, while administration of a moderately selective CB2/CB1 agonist exhibited significant analgesic effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

Enhanced novelty-induced corticosterone spike and upregulated serotonin 5-HT1A and cannabinoid CB1 receptors in adolescent BTBR mice.

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Gould, Georgianna G; Burke, Teresa F; Osorio, Miguel D; Smolik, Corey M; Zhang, Wynne Q; Onaivi, Emmanuel S; Gu, Ting-Ting; DeSilva, Mauris N; Hensler, Julie G

2014-01-01

Hypothalamic pituitary adrenal (HPA) axis responses to change and social challenges during adolescence can influence mental health and behavior into adulthood. To examine how HPA tone in adolescence may contribute to psychopathology, we challenged male adolescent (5 weeks) and adult (16 weeks) BTBR T(+)tf/J (BTBR) and 129S1/SvImJ (129S) mice with novelty in sociability tests. In prior studies these strains had exaggerated or altered HPA stress responses and low sociability relative to C57BL/6J mice in adulthood. In adolescence these strains already exhibited similar or worse sociability deficits than adults or age-matched C57 mice. Yet BTBR adolescents were less hyperactive and buried fewer marbles than adults. Novelty-induced corticosterone (CORT) spikes in adolescent BTBR were double adult levels, and higher than 129S or C57 mice at either age. Due to their established role in HPA feedback, we hypothesized that hippocampal Gαi/o-coupled serotonin 5-HT1A and cannabinoid CB1 receptor function might be upregulated in BTBR mice. Adolescent BTBR mice had higher hippocampal 5-HT1A density as measured by [(3)H] 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) binding than C57 mice, and adult BTBR 8-OH-DPAT-stimulated GTPγS binding was higher than in either C57 or 129S mice in this region. Further, BTBR hippocampal CB1 density measured by [(3)H]CP55,940 binding was 15-20% higher than in C57. CP55,940-stimulated GTPγS binding in adult BTBR dentate gyrus was 30% higher then 129S (p<0.05), but was not a product of greater neuronal or cell density defined by NeuN and DAPI staining. Hence hyperactive HPA responsiveness during adolescence may underlie 5-HT1A and CB1 receptor up-regulation and behavioral phenotype of BTBR mice. Copyright © 2013 Elsevier Ltd. All rights reserved.

The future of type 1 cannabinoid receptor allosteric ligands.

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Alaverdashvili, Mariam; Laprairie, Robert B

2018-02-01

Allosteric modulation of the type 1 cannabinoid receptor (CB1R) holds great therapeutic potential. This is because allosteric modulators do not possess intrinsic efficacy, but instead augment (positive allosteric modulation) or diminish (negative allosteric modulation) the receptor's response to endogenous ligand. Consequently, CB1R allosteric modulators have an effect ceiling which allows for the tempering of CB1R signaling without the desensitization, tolerance, dependence, and psychoactivity associated with orthosteric compounds. Pain, movement disorders, epilepsy, obesity are all potential therapeutic targets for CB1R allosteric modulation. Several challenges exist for the development of CB1R allosteric modulators, such as receptor subtype specificity, translation to in vivo systems, and mixed allosteric/agonist/inverse agonist activity. Despite these challenges, elucidation of crystal structures of CB1R and compound design based on structure-activity relationships will advance the field. In this review, we will cover recent progress for CB1R allosteric modulators and discuss the future promise of this research.

Temporal changes of CB1 cannabinoid receptor in the basal ganglia as a possible structure-specific plasticity process in 6-OHDA lesioned rats.

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Gabriela P Chaves-Kirsten

Full Text Available The endocannabinoid system has been implicated in several neurobiological processes, including neurodegeneration, neuroprotection and neuronal plasticity. The CB1 cannabinoid receptors are abundantly expressed in the basal ganglia, the circuitry that is mostly affected in Parkinson's Disease (PD. Some studies show variation of CB1 expression in basal ganglia in different animal models of PD, however the results are quite controversial, due to the differences in the procedures employed to induce the parkinsonism and the periods analyzed after the lesion. The present study evaluated the CB1 expression in four basal ganglia structures, namely striatum, external globus pallidus (EGP, internal globus pallidus (IGP and substantia nigra pars reticulata (SNpr of rats 1, 5, 10, 20, and 60 days after unilateral intrastriatal 6-hydroxydopamine injections, that causes retrograde dopaminergic degeneration. We also investigated tyrosine hydroxylase (TH, parvalbumin, calbindin and glutamic acid decarboxylase (GAD expression to verify the status of dopaminergic and GABAergic systems. We observed a structure-specific modulation of CB1 expression at different periods after lesions. In general, there were no changes in the striatum, decreased CB1 in IGP and SNpr and increased CB1 in EGP, but this increase was not sustained over time. No changes in GAD and parvalbumin expression were observed in basal ganglia, whereas TH levels were decreased and the calbindin increased in striatum in short periods after lesion. We believe that the structure-specific variation of CB1 in basal ganglia in the 6-hydroxydopamine PD model could be related to a compensatory process involving the GABAergic transmission, which is impaired due to the lack of dopamine. Our data, therefore, suggest that the changes of CB1 and calbindin expression may represent a plasticity process in this PD model.

Delta-9-tetrahydrocannabinol differentially suppresses cisplatin-induced emesis and indices of motor function via cannabinoid CB(1) receptors in the least shrew.

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Darmani, N A

2001-01-01

We have recently shown that the cannabinoid CB(1) receptor antagonist, SR 141716A, produces emesis in the least shrew (Cryptotis parva) in a dose- and route-dependent manner. This effect was blocked by delta-9-tetrahydrocannabinol (Delta(9)-THC). The present study investigates the cannabinoid receptor mechanisms by which Delta(9)-THC produces its antiemetic effects against cisplatin (20 mg/kg, i.p.)-induced emesis as well as its cannabimimetic activity profile (motor reduction) in the least shrew. Intraperitoneal administration of Delta(9)-THC (1, 2.5, 5 and 10 mg/kg) dose-dependently reduced both the percentage of animals vomiting (ID(50)=1.8+/-1.6 mg/kg) and the frequency of vomits (ID(50)=0.36+/-1.18 mg/kg) in a potent manner. The lowest significantly effective antiemetic dose of Delta(9)-THC for the latter emesis parameters was 2.5 mg/kg. Although Delta(9)-THC reduced the frequency of vomits up to 98%, it failed to completely protect all tested shrews from vomiting (80% protection). The cannabinoid CB(1) antagonist (SR 141716A) and not the CB(2) antagonist (SR 144528), reversed the antiemetic effects of Delta(9)-THC in a dose-dependent fashion. Delta(9)-THC (1, 5, 10 and 20 mg/kg, ip) suppressed locomotor parameters (spontaneous locomotor activity, duration of movement and rearing frequency) in a biphasic manner and only the 20-mg/kg dose simultaneously suppressed the triad of locomotor parameters to a significant degree. Subcutaneous (1-10 mg/kg) and intraperitoneal (0.05-40 mg/kg) injection of some doses of SR 141716A caused significant reductions in one or more components of the triad of locomotor parameters but these reductions were not dose dependent. Subcutaneous injection of SR 141716A (0.2, 1, 5 and 10 mg/kg) reversed the motor suppressant effects of a 20-mg/kg dose of Delta(9)-THC (ip) in a dose-dependent manner. Relative to its motor suppressant effects, Delta(9)-THC is a more potent antiemetic agent. Both effects are probably mediated via CB(1

Simultaneous Activation of Induced Heterodimerization between CXCR4 Chemokine Receptor and Cannabinoid Receptor 2 (CB2) Reveals a Mechanism for Regulation of Tumor Progression*

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Coke, Christopher J.; Scarlett, Kisha A.; Chetram, Mahandranauth A.; Jones, Kia J.; Sandifer, Brittney J.; Davis, Ahriea S.; Marcus, Adam I.

2016-01-01

The G-protein-coupled chemokine receptor CXCR4 generates signals that lead to cell migration, cell proliferation, and other survival mechanisms that result in the metastatic spread of primary tumor cells to distal organs. Numerous studies have demonstrated that CXCR4 can form homodimers or can heterodimerize with other G-protein-coupled receptors to form receptor complexes that can amplify or decrease the signaling capacity of each individual receptor. Using biophysical and biochemical approaches, we found that CXCR4 can form an induced heterodimer with cannabinoid receptor 2 (CB2) in human breast and prostate cancer cells. Simultaneous, agonist-dependent activation of CXCR4 and CB2 resulted in reduced CXCR4-mediated expression of phosphorylated ERK1/2 and ultimately reduced cancer cell functions such as calcium mobilization and cellular chemotaxis. Given that treatment with cannabinoids has been shown to reduce invasiveness of cancer cells as well as CXCR4-mediated migration of immune cells, it is plausible that CXCR4 signaling can be silenced through a physical heterodimeric association with CB2, thereby inhibiting subsequent functions of CXCR4. Taken together, the data illustrate a mechanism by which the cannabinoid system can negatively modulate CXCR4 receptor function and perhaps tumor progression. PMID:26841863

Presynaptic type III neuregulin1-ErbB signaling targets {alpha}7 nicotinic acetylcholine receptors to axons.

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Hancock, Melissa L; Canetta, Sarah E; Role, Lorna W; Talmage, David A

2008-05-05

Type III Neuregulin1 (Nrg1) isoforms are membrane-tethered proteins capable of participating in bidirectional juxtacrine signaling. Neuronal nicotinic acetylcholine receptors (nAChRs), which can modulate the release of a rich array of neurotransmitters, are differentially targeted to presynaptic sites. We demonstrate that Type III Nrg1 back signaling regulates the surface expression of alpha7 nAChRs along axons of sensory neurons. Stimulation of Type III Nrg1 back signaling induces an increase in axonal surface alpha7 nAChRs, which results from a redistribution of preexisting intracellular pools of alpha7 rather than from increased protein synthesis. We also demonstrate that Type III Nrg1 back signaling activates a phosphatidylinositol 3-kinase signaling pathway and that activation of this pathway is required for the insertion of preexisting alpha7 nAChRs into the axonal plasma membrane. These findings, in conjunction with prior results establishing that Type III Nrg1 back signaling controls gene transcription, demonstrate that Type III Nrg1 back signaling can regulate both short-and long-term changes in neuronal function.

Presynaptic type III neuregulin1-ErbB signaling targets alpha7 nicotinic acetylcholine receptors to axons.

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Hancock, Melissa L; Canetta, Sarah E; Role, Lorna W; Talmage, David A

2008-06-01

Type III Neuregulin1 (Nrg1) isoforms are membrane-tethered proteins capable of participating in bidirectional juxtacrine signaling. Neuronal nicotinic acetylcholine receptors (nAChRs), which can modulate the release of a rich array of neurotransmitters, are differentially targeted to presynaptic sites. We demonstrate that Type III Nrg1 back signaling regulates the surface expression of alpha7 nAChRs along axons of sensory neurons. Stimulation of Type III Nrg1 back signaling induces an increase in axonal surface alpha7 nAChRs, which results from a redistribution of preexisting intracellular pools of alpha7 rather than from increased protein synthesis. We also demonstrate that Type III Nrg1 back signaling activates a phosphatidylinositol 3-kinase signaling pathway and that activation of this pathway is required for the insertion of preexisting alpha7 nAChRs into the axonal plasma membrane. These findings, in conjunction with prior results establishing that Type III Nrg1 back signaling controls gene transcription, demonstrate that Type III Nrg1 back signaling can regulate both short-and long-term changes in neuronal function.

Presynaptic Type III Neuregulin1-ErbB signaling targets α7 nicotinic acetylcholine receptors to axons

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Hancock, Melissa L.; Canetta, Sarah E.; Role, Lorna W.; Talmage, David A.

2008-01-01

Type III Neuregulin1 (Nrg1) isoforms are membrane-tethered proteins capable of participating in bidirectional juxtacrine signaling. Neuronal nicotinic acetylcholine receptors (nAChRs), which can modulate the release of a rich array of neurotransmitters, are differentially targeted to presynaptic sites. We demonstrate that Type III Nrg1 back signaling regulates the surface expression of α7 nAChRs along axons of sensory neurons. Stimulation of Type III Nrg1 back signaling induces an increase in axonal surface α7 nAChRs, which results from a redistribution of preexisting intracellular pools of α7 rather than from increased protein synthesis. We also demonstrate that Type III Nrg1 back signaling activates a phosphatidylinositol 3-kinase signaling pathway and that activation of this pathway is required for the insertion of preexisting α7 nAChRs into the axonal plasma membrane. These findings, in conjunction with prior results establishing that Type III Nrg1 back signaling controls gene transcription, demonstrate that Type III Nrg1 back signaling can regulate both short-and long-term changes in neuronal function. PMID:18458158

Anandamide induces matrix metalloproteinase-2 production through cannabinoid-1 receptor and transient receptor potential vanilloid-1 in human dental pulp cells in culture.

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Miyashita, Keiko; Oyama, Tohru; Sakuta, Tetsuya; Tokuda, Masayuki; Torii, Mitsuo

2012-06-01

Anandamide (N-arachidonoylethanolamine [AEA]) is one of the main endocannabinoids. Endocannabinoids are implicated in various physiological and pathologic functions, inducing not only nociception but also regeneration and inflammation. The role of the endocannabinoid system in peripheral organs was recently described. The aim of this study was to investigate the effect of AEA on matrix metalloproteinase (MMP)-2 induction in human dental pulp cells (HPC). We examined AEA-induced MMP-2 production and the expression of AEA receptors (cannabinoid [CB] receptor-1, CB2, and transient receptor potential vanilloid-1 [TRPV1]) in HPC by Western blot. MMP-2 concentrations in supernatants were determined by enzyme-linked immunosorbent assay. We then investigated the role of the AEA receptors and mitogen-activated protein kinase in AEA-induced MMP-2 production in HPC. AEA significantly induced MMP-2 production in HPC. HPC expressed all 3 types of AEA receptor (CB1, CB2, and TRPV1). AEA-induced MMP-2 production was blocked by CB1 or TRPV1 antagonists and by small interfering RNA for CB1 or TRPV1. Furthermore, c-Jun N-terminal kinase inhibitor also reduced MMP-2 production. We demonstrated for the first time that AEA induced MMP-2 production via CB1 and TRPV1 in HPC. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

A cell population that strongly expresses the CB1 cannabinoid receptor in the ependyma of the rat spinal cord.

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Garcia-Ovejero, Daniel; Arevalo-Martin, Angel; Paniagua-Torija, Beatriz; Sierra-Palomares, Yolanda; Molina-Holgado, Eduardo

2013-01-01

The cells surrounding the central canal of the spinal cord are a source of stem/precursor cells that may give rise to neurons, astrocytes, or oligodendrocytes. However, they are a heterogeneous population that remains poorly understood. Here we describe a subpopulation characterized by their strong expression of the CB(1) cannabinoid receptor, oval/round soma, apical nucleus, a variable number of cilia (0, 1, or 2), and the presence of a single short and occasionally ramified basal process. These cells are mainly located in the lateral and dorsal central canal throughout the spinal cord. These CB(1)(HIGH) cells are closely related to the basal lamina labyrinths or fractones derived from subependymal microglia. In addition, CB(1)(HIGH) cells express some stem/precursor cell markers, including vimentin, nestin, Sox2, Sox9, and GLAST, but not others such as CD15 or GFAP. In addition, this cell population does not proliferate in the intact adult spinal cord, although up to 50% of these cells express the proliferation marker Ki67 in newly born rats or after a spinal cord contusion. The present findings contribute to our understanding of the spinal cord central canal structure and reveal the targets for endocannabinoids inside this neurogenic niche. Copyright © 2012 Wiley Periodicals, Inc.

Synthesis and preliminary biological evaluation of [{sup 123}I]Me{sub 2}Pyr, a new potential ligand for imaging of central cannabinoid CB{sub 1} receptors

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Gielow, P. [Department of Nuclear Medicine, University School of Medicine, Carl-Neuberg-Str. 1, D-30625 Hannover (Germany)]. E-mail: gielow.peter@mh-hannover.de; Klinge, P. [International Neuroscience Institute, Alexis Carrel Str. 4, D-30625 Hannover (Germany); Knapp, W.H. [Department of Nuclear Medicine, University School of Medicine, Carl-Neuberg-Str. 1, D-30625 Hannover (Germany); Berding, G. [Department of Nuclear Medicine, University School of Medicine, Carl-Neuberg-Str. 1, D-30625 Hannover (Germany)

2006-07-15

A synthesis of 1-(2,4-dichlorophenyl)-5-(4-[{sup 123}I]iodophenyl)-4-methyl-1H-pyrazole -3-carboxylic acid N',N'-dimethyl-hydrazide ([{sup 123}I]Me{sub 2}Pyr), a new radioiodinated analogue of the high-affinity cannabinoid CB{sub 1} receptor antagonist SR141716A, is described. Labelling was achieved by radioiododestannylation of the tributylstannyl precursor with [{sup 123}I]iodide in the presence of chloramine T. HPLC purification afforded the labelled product in 48% radiochemical yield. Preliminary rat brain biodistribution studies with the {sup 125}I labelled compound revealed high uptake in the substantia nigra, the globus pallidus externus and the cerebellum, which is consistent with the known distribution of CB{sub 1} receptors.

Mice Expressing a "Hyper-Sensitive" Form of the Cannabinoid Receptor 1 (CB1 Are Neither Obese Nor Diabetic.

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David J Marcus

Full Text Available Multiple lines of evidence implicate the endocannabinoid signaling system in the modulation of metabolic disease. Genetic or pharmacological inactivation of CB1 in rodents leads to reduced body weight, resistance to diet-induced obesity, decreased intake of highly palatable food, and increased energy expenditure. Cannabinoid agonists stimulate feeding in rodents and increased levels of endocannabinoids can disrupt lipid metabolism. Therefore, the hypothesis that sustained endocannabinoid signaling can lead to obesity and diabetes was examined in this study using S426A/S430A mutant mice expressing a desensitization-resistant CB1 receptor. These mice display exaggerated and prolonged responses to acute administration of phytocannabinoids, synthetic cannabinoids, and endocannabinoids. As a consequence these mice represent a novel model for determining the effect of enhanced endocannabinoid signaling on metabolic disease. S426A/S430A mutants consumed equivalent amounts of both high fat (45% and low fat (10% chow control diet compared to wild-type littermate controls. S426A/S430A mutants and wild-type mice fed either high or low fat control diet displayed similar fasting blood glucose levels and normal glucose clearance following a 2 g/kg glucose challenge. Furthermore, S426A/S430A mutants and wild-type mice consumed similar amounts of chow following an overnight fast. While both THC and JZL195 significantly increased food intake two hours after injection, this increase was similar between the S426A/S430A mutant and wildtype control mice Our results indicate that S426A/S430A mutant mice expressing the desensitization-resistant form of CB1 do not exhibit differences in body weight, food intake, glucose homeostasis, or re-feeding following a fast.

Effects of cannabinoid CB(1) receptor agonism and antagonism on SKF81297-induced dyskinesia and haloperidol-induced dystonia in Cebus apella monkeys

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Madsen, Morten V; Peacock, Linda P; Werge, Thomas

2011-01-01

81297 (SKF) and acute dystonia induced by the dopamine D(2) receptor antagonist haloperidol in Cebus apella monkeys. The monkeys were sensitised to EPS by prior exposure to D(2) receptor antagonists. SKF (0.3 mg/kg) was administered alone and in combination with the CB(1) agonist CP55,940 (0.......0025-0.01 mg/kg) or the CB(1) antagonist SR141716A (0.25-0.75 mg/kg). Haloperidol (individual doses at 0.01-0.02 mg/kg) was administered alone and in combination with CP55,940 (0.005 or 0.01 mg/kg) or SR141716A (0.5 or 0.75 mg/kg). Subsequently, the monkeys were videotaped, and the recordings were rated...... for oral dyskinesia or dystonia. SKF-induced oral dyskinesia was dose-dependently reduced by CP55,940, with no effect of SR141716A. Haloperidol-induced dystonia was not affected by either CP55,940 or SR141716A....

CB 1/2 dual agonists with 3-carbamoyl 2-pyridone derivatives as antipruritics: reduction of CNS side effects by introducing polar functional groups.

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Odan, Masahide; Ishizuka, Natsuki; Hiramatsu, Yoshiharu; Inagaki, Masanao; Hashizume, Hiroshi; Fujii, Yasuhiko; Mitsumori, Susumu; Morioka, Yasuhide; Soga, Masahiko; Deguchi, Masashi; Yasui, Kiyoshi; Arimura, Akinori

2012-04-15

Our lead compound 1 showed high affinity for both CB1 and CB2 receptors, suggesting the possibility of inducing psychoactive side effects through the CB1 receptor in the brain. To solve this issue, polar functional groups were introduced at the 3-position of the pyridone core of compound 1 to find CB1/2 dual agonists such as 17 and 20 which did not show any CNS side effects. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cannabinoid CB2 Receptors Contribute to Upregulation of β-endorphin in Inflamed Skin Tissues by Electroacupuncture

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Su Tang-feng

2011-12-01

Full Text Available Abstract Background Electroacupuncture (EA can produce analgesia by increasing the β-endorphin level and activation of peripheral μ-opioid receptors in inflamed tissues. Endogenous cannabinoids and peripheral cannabinoid CB2 receptors (CB2Rs are also involved in the antinociceptive effect of EA on inflammatory pain. However, little is known about how peripheral CB2Rs interact with the endogenous opioid system at the inflammatory site and how this interaction contributes to the antinociceptive effect of EA on inflammatory pain. In this study, we determined the role of peripheral CB2Rs in the effects of EA on the expression of β-endorphin in inflamed skin tissues and inflammatory pain. Results Inflammatory pain was induced by injection of complete Freund's adjuvant into the left hindpaw of rats. Thermal hyperalgesia was tested with a radiant heat stimulus, and mechanical allodynia was quantified using von Frey filaments. The mRNA level of POMC and protein level of β-endorphin were quantified by real-time PCR and Western blotting, respectively. The β-endorphin-containing keratinocytes and immune cells in the inflamed skin tissues were detected by double-immunofluorescence labeling. The CB2R agonist AM1241 or EA significantly reduced thermal hyperalgesia and mechanical allodynia, whereas the selective μ-opioid receptor antagonist β-funaltrexamine significantly attenuated the antinociceptive effect produced by them. AM1241 or EA significantly increased the mRNA level of POMC and the protein level of β-endorphin in inflamed skin tissues, and these effects were significantly attenuated by pretreatment with the CB2R antagonist AM630. AM1241 or EA also significantly increased the percentage of β-endorphin-immunoreactive keratinocytes, macrophages, and T-lymphocytes in inflamed skin tissues, and these effects were blocked by AM630. Conclusions EA and CB2R stimulation reduce inflammatory pain through activation of μ-opioid receptors. EA increases

Cannabinoid receptor type-1: breaking the dogmas [version 1; referees: 3 approved

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Arnau Busquets Garcia

2016-05-01

Full Text Available The endocannabinoid system (ECS is abundantly expressed in the brain. This system regulates a plethora of physiological functions and is composed of cannabinoid receptors, their endogenous ligands (endocannabinoids, and the enzymes involved in the metabolism of endocannabinoids. In this review, we highlight the new advances in cannabinoid signaling, focusing on a key component of the ECS, the type-1 cannabinoid receptor (CB1. In recent years, the development of new imaging and molecular tools has demonstrated that this receptor can be distributed in many cell types (e.g., neuronal or glial cells and intracellular compartments (e.g., mitochondria. Interestingly, cellular and molecular effects are differentially mediated by CB1 receptors according to their specific localization (e.g., glutamatergic or GABAergic neurons. Moreover, this receptor is expressed in the periphery, where it can modulate periphery-brain connections. Finally, the better understanding of the CB1 receptor structure led researchers to propose interesting and new allosteric modulators. Thus, the advances and the new directions of the CB1 receptor field will provide new insights and better approaches to profit from its interesting therapeutic profile.

Simultaneous Activation of Induced Heterodimerization between CXCR4 Chemokine Receptor and Cannabinoid Receptor 2 (CB2) Reveals a Mechanism for Regulation of Tumor Progression.

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Coke, Christopher J; Scarlett, Kisha A; Chetram, Mahandranauth A; Jones, Kia J; Sandifer, Brittney J; Davis, Ahriea S; Marcus, Adam I; Hinton, Cimona V

2016-05-06

The G-protein-coupled chemokine receptor CXCR4 generates signals that lead to cell migration, cell proliferation, and other survival mechanisms that result in the metastatic spread of primary tumor cells to distal organs. Numerous studies have demonstrated that CXCR4 can form homodimers or can heterodimerize with other G-protein-coupled receptors to form receptor complexes that can amplify or decrease the signaling capacity of each individual receptor. Using biophysical and biochemical approaches, we found that CXCR4 can form an induced heterodimer with cannabinoid receptor 2 (CB2) in human breast and prostate cancer cells. Simultaneous, agonist-dependent activation of CXCR4 and CB2 resulted in reduced CXCR4-mediated expression of phosphorylated ERK1/2 and ultimately reduced cancer cell functions such as calcium mobilization and cellular chemotaxis. Given that treatment with cannabinoids has been shown to reduce invasiveness of cancer cells as well as CXCR4-mediated migration of immune cells, it is plausible that CXCR4 signaling can be silenced through a physical heterodimeric association with CB2, thereby inhibiting subsequent functions of CXCR4. Taken together, the data illustrate a mechanism by which the cannabinoid system can negatively modulate CXCR4 receptor function and perhaps tumor progression. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

CB1 Receptor-Mediated Signaling Underlies the Hippocampal Synaptic, Learning and Memory Deficits Following Treatment with JWH-081, a New Component of Spice/K2 Preparations

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Basavarajappa, Balapal S.; Subbanna, Shivakumar

2014-01-01

Recently, synthetic cannabinoids have been sprayed onto plant material, which is subsequently packaged and sold as “Spice” or “K2” to mimic the effects of marijuana. A recent report identified several synthetic additives in samples of “Spice/K2”, including JWH-081, a synthetic ligand for the cannabinoid receptor 1 (CB1). The deleterious effects of JWH-081 on brain function are not known, particularly on CB1 signaling, synaptic plasticity, learning and memory. Here, we evaluated the effects of...

CB1 cannabinoid receptor-mediated anandamide signaling mechanisms of the inferior colliculus modulate the haloperidol-induced catalepsy.

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Medeiros, P; de Freitas, R L; Silva, M O; Coimbra, N C; Melo-Thomas, L

2016-11-19

The inferior colliculus (IC), a midbrain structure that processes acoustic information of aversive nature, is distinguished from other auditory nuclei in the brainstem by its connections with structures of the motor system. Previous evidence relating the IC to motor behavior shows that glutamatergic and GABAergic mechanisms in the IC exert influence on systemic haloperidol-induced catalepsy. There is substantial evidence supporting a role played by the endocannabinoid system as a modulator of the glutamatergic neurotransmission, as well as the dopaminergic activity in the basal nuclei and therefore it may be considered as a potential pharmacological target for the treatment of movement disorders. The present study evaluated if the endocannabinoid system in the IC plays a role in the elaboration of systemic haloperidol-induced catalepsy. Male Wistar rats received intracollicular microinjection of either the endogenous cannabinoid anandamide (AEA) at different concentrations (5, 50 or 100pmol/0.2μl), the CB 1 cannabinoid receptor antagonist AM251 at 50, 100 or 200pmol/0.2μl or vehicle, followed by intraperitoneal (IP) administration of either haloperidol at 0.5 or 1mg/kg or physiological saline. Systemic injection of haloperidol at both doses (0.5 or 1mg/kg, IP) produced a cataleptic state, compared to vehicle/physiological saline-treated group, lasting 30 and 50min after systemic administration of the dopaminergic receptors non-selective antagonist. The midbrain microinjection of AEA at 50pmol/0.2μl increased the latency for stepping down from the horizontal bar after systemic administration of haloperidol. Moreover, the intracollicular administration of AEA at 50pmol/0.2μl was able to increase the duration of catalepsy as compared to AEA at 100pmol/0.2-μl-treated group. Intracollicular pretreatment with AM251 at the intermediate concentration (100pmol/0.2μl) was able to decrease the duration of catalepsy after systemic administration of haloperidol. However

Effect of cannabinoids CB1 receptors blockade on hemodynamic parameters and endothelial function at the immobilization stress in the experiment

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S. V. Gavreliuk

2017-12-01

Full Text Available The aim of the study was to evaluate the response of hemodynamic parameters and changes in endothelial function in modeling of CB1 cannabinoid receptors blockade in chronic stress. Materials and мethods. The study was performed on four groups of hundred-day-old rats, which were examined by ultrasonic scanning during the ten-day period of the experiment. The first group consisted of intact animals; the second group – animals, which were exposed to immobilization stress; the third – animals which were given a solution of rimonabant hydrochloride at the rate of 10 mg×kg-1 of animal weight per day daily per os; the fourth group consisted of animals which daily received a solution of rimonabant hydrochloride at the rate of 10 mg×kg-1 of animal weight per day and were exposed to immobilization stress. The intraluminal vessel diameter, the intima-media complex thickness, endothelium-dependent and endothelium-independent dilation were quantified in the ultrasound examination. Quantitative characteristics of the blood flow were studied: peak systolic velocity, end diastolic velocity, resistive index and peak-systolic/end-diastolic ratio, and estimated mean blood flow velocity. Results. It has been found that the effect of chronic immobilization stress in 100-day-old male rats causes intima-media complex structure and thickness change, endothelial dysfunction and increase in the abdominal aorta intraluminal diameter. Hemodynamics changes are characterized by a decrease in the average blood flow velocity and an increase in the values of indices characterizing the vascular wall peripheral resistance. Prolonged blockade of cannabinoids CB1 receptors leads to endothelial dysfunction development, a decrease in the intraluminal diameter of the abdominal aorta and a decrease in the average blood flow velocity while vascular wall elastic properties maintaining. This affects the sensitivity of cardiovascular system to nitrogen oxide, which is manifested by

Computer modeling of Cannabinoid receptor type 1

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Sapundzhi Fatima

2018-01-01

Full Text Available Cannabinoid receptors are important class of receptors as they are involved in various physiological processes such as appetite, pain-sensation, mood, and memory. It is important to design receptor-selective ligands in order to treat a particular disorder. The aim of the present study is to model the structure of cannabinoid receptor CB1 and to perform docking between obtained models and known ligands. Two models of CBR1 were prepared with two different methods (Modeller of Chimera and MOE. They were used for docking with GOLD 5.2. It was established a high correlation between inhibitory constant Ki of CB1 cannabinoid ligands and the ChemScore scoring function of GOLD, which concerns both models. This suggests that the models of the CB1 receptors obtained could be used for docking studies and in further investigation and design of new potential, selective and active cannabinoids with the desired effects.

Prevention of drug priming- and cue-induced reinstatement of MDMA-seeking behaviors by the CB1 cannabinoid receptor antagonist AM251.

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Nawata, Yoko; Kitaichi, Kiyoyuki; Yamamoto, Tsuneyuki

2016-03-01

3,4-Methylenedioxymethamphetamine (MDMA), a methamphetamine (METH) derivative, exhibits METH-like actions at monoamine transporters and positive reinforcing effects in rodents and primates. The purposes of the present study were to determine whether cross-reinstatement would be observed between MDMA and METH and if the cannabinoid receptor, a receptor known to play critical roles in the brain reward system, could modulate MDMA craving. Rats were trained to press a lever for intravenous MDMA (0.3mg/infusion) or METH (0.02mg/infusion) infusions under a fixed ratio 1 schedule paired with drug-associated cues (light and tone). Following drug self-administration acquisition training, rats underwent extinction training (an infusion of saline). Reinstatement tests were performed once the extinction criteria were achieved. In MDMA-trained rats, the MDMA-priming injection (3.2mg/kg, i.p.) or re-exposure to MDMA-associated cues reinstated MDMA-seeking behavior. Additionally, a priming injection of METH (1.0mg/kg, i.p.) also reinstated MDMA-seeking behavior. In contrast, none of the MDMA doses reinstated METH-seeking behavior in the METH-trained rats. The CB1 cannabinoid receptor antagonist AM251 markedly attenuated the MDMA-seeking behaviors induced by MDMA-priming injection or re-exposure to MDMA-associated cues in a dose-dependent manner. These findings show that MDMA has obvious addictive potential for reinstating drug-seeking behavior and that METH can be an effective stimulus for reinstating MDMA-seeking behaviors. Furthermore, based on the attenuating effect of AM251 in the reinstatement of MDMA-seeking behaviors, drugs that suppress CB1 receptors may be used in treatment of MDMA dependence. Copyright © 2016. Published by Elsevier Ireland Ltd.

Presynaptic membrane receptors in acetylcholine release modulation in the neuromuscular synapse.

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Tomàs, Josep; Santafé, Manel M; Garcia, Neus; Lanuza, Maria A; Tomàs, Marta; Besalduch, Núria; Obis, Teresa; Priego, Mercedes; Hurtado, Erica

2014-05-01

Over the past few years, we have studied, in the mammalian neuromuscular junction (NMJ), the local involvement in transmitter release of the presynaptic muscarinic ACh autoreceptors (mAChRs), purinergic adenosine autoreceptors (P1Rs), and trophic factor receptors (TFRs; for neurotrophins and trophic cytokines) during development and in the adult. At any given moment, the way in which a synapse works is largely the logical outcome of the confluence of these (and other) metabotropic signalling pathways on intracellular kinases, which phosphorylate protein targets and materialize adaptive changes. We propose an integrated interpretation of the complementary function of these receptors in the adult NMJ. The activity of a given receptor group can modulate a given combination of spontaneous, evoked, and activity-dependent release characteristics. For instance, P1Rs can conserve resources by limiting spontaneous quantal leak of ACh (an A1 R action) and protect synapse function, because stimulation with adenosine reduces the magnitude of depression during repetitive activity. The overall outcome of the mAChRs seems to contribute to upkeep of spontaneous quantal output of ACh, save synapse function by decreasing the extent of evoked release (mainly an M2 action), and reduce depression. We have also identified several links among P1Rs, mAChRs, and TFRs. We found a close dependence between mAChR and some TFRs and observed that the muscarinic group has to operate correctly if the tropomyosin-related kinase B receptor (trkB) is also to operate correctly, and vice versa. Likewise, the functional integrity of mAChRs depends on P1Rs operating normally. Copyright © 2014 Wiley Periodicals, Inc.

Cellular mechanisms for presynaptic inhibition of sensory afferents

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Perrier, Jean-Francois Marie; delgado-lezama, rodolfo; Christensen, Rasmus Kordt

It is well established that presynaptic inhibition of primary afferents involves the activation of GABAA receptors located on presynaptic terminals. However, the source of GABA remains unknown. In an integrated preparation of the spinal cord of the adult turtle, we evoked dorsal root potentials...

Exercise reduces adipose tissue via cannabinoid receptor type 1 which is regulated by peroxisome proliferator-activated receptor-δ

International Nuclear Information System (INIS)

Yan Zhencheng; Liu Daoyan; Zhang Lili; Shen Chenyi; Ma Qunli; Cao Tingbing; Wang Lijuan; Nie Hai; Zidek, Walter; Tepel, Martin; Zhu Zhiming

2007-01-01

Obesity is one major cardiovascular risk factor. We tested effects of endurance exercise on cannabinoid receptor type 1 (CB1) and peroxisome proliferator-activated receptor-δ (PPAR-δ)-dependent pathways in adipose tissue. Male Wistar rats were randomly assigned to standard laboratory chow or a high-fat diet without and with regular endurance exercise. Exercise in rats on high-fat diet significantly reduced visceral fat mass, blood pressure, and adipocyte size (each p < 0.05). Adipocyte hypertrophy induced by high-fat diet was accompanied by increased CB1 expression in adipose tissue, whereas exercise significantly reduced CB1 expression (each p < 0.05). CB1 receptor expression and adipocyte differentiation were directly regulated by PPAR-δ. Adipocyte hypertrophy induced by high-fat diet was accompanied by reduced PPAR-δ. Furthermore, selective silencing of PPAR-δ by RNA interference in 3T3-L1-preadipocyte cells significantly increased CB1 expression from 1.00 ± 0.06 (n = 3) to 1.91 ± 0.06 (n = 3; p < 0.01) and increased adipocyte differentiation, whereas adenovirus-mediated overexpression of PPAR-δ significantly reduced CB1 expression to 0.39 ± 0.03 (n = 3; p < 0.01) and reduced adipocyte differentiation. In the presence of the CB1 antagonist rimonabant adipocyte differentiation in stimulated 3T3 L1 preadipocyte cells was significantly reduced. The study indicates that high-fat diet-induced hypertrophy of adipocytes is associated with increased CB1 receptor expression which is directly regulated by PPAR-δ. Both CB1 and PPAR-δ are intimately involved in therapeutic interventions against a most important cardiovascular risk factor

Electroacupuncture Inhibition of Hyperalgesia in Rats with Adjuvant Arthritis: Involvement of Cannabinoid Receptor 1 and Dopamine Receptor Subtypes in Striatum

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Yin Shou

2013-01-01

Full Text Available Electroacupuncture (EA has been regarded as an alternative treatment for inflammatory pain for several decades. However, the molecular mechanisms underlying the antinociceptive effect of EA have not been thoroughly clarified. Previous studies have shown that cannabinoid CB1 receptors are related to pain relief. Accumulating evidence has shown that the CB1 and dopamine systems sometimes interact and may operate synergistically in rat striatum. To our knowledge, dopamine D1/D2 receptors are involved in EA analgesia. In this study, we found that repeated EA at Zusanli (ST36 and Kunlun (BL60 acupoints resulted in marked improvements in thermal hyperalgesia. Both western blot assays and FQ-PCR analysis results showed that the levels of CB1 expression in the repeated-EA group were much higher than those in any other group (P=0.001. The CB1-selective antagonist AM251 inhibited the effects of repeated EA by attenuating the increases in CB1 expression. The two kinds of dopamine receptors imparted different actions on the EA-induced CB1 upregulation in AA rat model. These results suggested that the strong activation of the CB1 receptor after repeated EA resulted in the concomitant phenomenon of the upregulation of D1 and D2 levels of gene expression.

Contrasting effects of lithium chloride and CB1 receptor blockade on enduring changes in the valuation of reward.

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Giovanni eHernandez

2011-09-01

Full Text Available When an organism has been trained to respond for a reward, its learned behavior can be characterized as goal-directed or habitual based on whether or not it is susceptible to reward devaluation. Here, we evaluated whether instrumental responding for brain stimulation reward (BSR can devalued using a paradigm traditionally used for natural rewards. Rats were trained to lever press for BSR. Subsequently, BSR was paired with either lithium chloride (LiCl, 5 mg/kg, i.p, a pro-emetic, or AM251, a CB1 receptor antagonist (3 mg/kg, i.p.. Pairings of BSR with these two compounds or their respective vehicle were performed in a novel environment so that only unconditional effects of BSR were affected by the pharmacological manipulations. Subsequently, in a probe test, all rats were returned in the drug-free state to the boxes where they had received training instrumental responding was reassessed in the absence of BSR delivery. LiCl produced enduring decreases in the number of responses during the test session, whereas AM251 had no effect. These results show that instrumental responding for BSR is susceptible to devaluation, in accord with the proposal that this behavior is supported at least in part by associations between the response and the rewarding outcome. Furthermore, they suggest that the reward modulation observed in studies involving the use of CB1 receptor antagonists arises from changes in the organism’s motivation rather than due to drug-induced changes in the intrinsic value of reward.

Contrasting Effects of Lithium Chloride and CB1 Receptor Blockade on Enduring Changes in the Valuation of Reward.

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Hernandez, Giovanni; Bernstein, David; Schoenbaum, Geoffrey; Cheer, Joseph F

2011-01-01

When an organism responds for a reward, its learned behavior can be characterized as goal-directed or habitual based on whether or not it is susceptible to reward devaluation. Here, we evaluated whether instrumental responding for brain stimulation reward (BSR) can be devalued using a paradigm traditionally used for natural rewards. Rats were trained to lever press for BSR; afterward, BSR was paired with either lithium chloride (LiCl, 5 mg/kg, i.p.), a pro-emetic, or AM251, a CB1 receptor antagonist (3 mg/kg, i.p.) or the vehicle of these compounds. Pairings of BSR with these compounds and their vehicles were performed in a novel environment so that only unconditional effects of BSR would be affected by the pharmacological manipulations. Subsequently, in a probe test, all rats were returned in the drug-free state to the boxes where they had received training and instrumental responding was reassessed in the absence of BSR delivery. When compared to control, LiCl produced a significant decrease in the number of responses during the test session, whereas AM251 did not. These results show that instrumental responding for BSR is susceptible to devaluation, in accord with the proposal that this behavior is supported at least in part by associations between the response and the rewarding outcome. Further, they suggest that reward modulation observed in studies involving the use of CB1 receptor antagonists arises from changes in the organism's motivation rather than drug-induced changes in the intrinsic value of reward.

Phospho-dependent Accumulation of GABABRs at Presynaptic Terminals after NMDAR Activation.

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Hannan, Saad; Gerrow, Kim; Triller, Antoine; Smart, Trevor G

2016-08-16

Here, we uncover a mechanism for regulating the number of active presynaptic GABAB receptors (GABABRs) at nerve terminals, an important determinant of neurotransmitter release. We find that GABABRs gain access to axon terminals by lateral diffusion in the membrane. Their relative accumulation is dependent upon agonist activation and the presence of the two distinct sushi domains that are found only in alternatively spliced GABABR1a subunits. Following brief activation of NMDA receptors (NMDARs) using glutamate, GABABR diffusion is reduced, causing accumulation at presynaptic terminals in a Ca(2+)-dependent manner that involves phosphorylation of GABABR2 subunits at Ser783. This signaling cascade indicates how synaptically released glutamate can initiate, via a feedback mechanism, increased levels of presynaptic GABABRs that limit further glutamate release and excitotoxicity. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Expression Analysis of CB2-GFP BAC Transgenic Mice.

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Schmöle, Anne-Caroline; Lundt, Ramona; Gennequin, Benjamin; Schrage, Hanna; Beins, Eva; Krämer, Alexandra; Zimmer, Till; Limmer, Andreas; Zimmer, Andreas; Otte, David-Marian

2015-01-01

The endocannabinoid system (ECS) is a retrograde messenger system, consisting of lipid signaling molecules that bind to at least two G-protein-coupled receptors, Cannabinoid receptor 1 and 2 (CB1 and 2). As CB2 is primarily expressed on immune cells such as B cells, T cells, macrophages, dendritic cells, and microglia, it is of great interest how CB2 contributes to immune cell development and function in health and disease. Here, understanding the mechanisms of CB2 involvement in immune-cell function as well as the trafficking and regulation of CB2 expressing cells are crucial issues. Up to now, CB2 antibodies produce unclear results, especially those targeting the murine protein. Therefore, we have generated BAC transgenic GFP reporter mice (CB2-GFPTg) to trace CB2 expression in vitro and in situ. Those mice express GFP under the CB2 promoter and display GFP expression paralleling CB2 expression on the transcript level in spleen, thymus and brain tissue. Furthermore, by using fluorescence techniques we show that the major sources for GFP-CB2 expression are B cells in spleen and blood and microglia in the brain. This novel CB2-GFP transgenic reporter mouse line represents a powerful resource to study CB2 expression in different cell types. Furthermore, it could be used for analyzing CB2-mediated mobilization and trafficking of immune cells as well as studying the fate of recruited immune cells in models of acute and chronic inflammation.

Presynaptic inhibition of spontaneous acetylcholine release mediated by P2Y receptors at the mouse neuromuscular junction.

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De Lorenzo, S; Veggetti, M; Muchnik, S; Losavio, A

2006-09-29

At the neuromuscular junction, ATP is co-released with the neurotransmitter acetylcholine (ACh) and once in the synaptic space, it is degraded to the presynaptically active metabolite adenosine. Intracellular recordings were performed on diaphragm fibers of CF1 mice to determine the action of extracellular ATP (100 muM) and the slowly hydrolysable ATP analog 5'-adenylylimidodiphosphate lithium (betagamma-imido ATP) (30 muM) on miniature end-plate potential (MEPP) frequency. We found that application of ATP and betagamma-imido ATP decreased spontaneous secretion by 45.3% and 55.9% respectively. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A(1) adenosine receptor antagonist and alpha,beta-methylene ADP sodium salt (alphabeta-MeADP), which is an inhibitor of ecto-5'-nucleotidase, did not prevent the inhibitory effect of ATP, demonstrating that the nucleotide is able to modulate spontaneous ACh release through a mechanism independent of the action of adenosine. Blockade of Ca(2+) channels by both, Cd(2+) or the combined application of nitrendipine and omega-conotoxin GVIA (omega-CgTx) (L-type and N-type Ca(2+) channel antagonists, respectively) prevented the effect of betagamma-imido ATP, indicating that the nucleotide modulates Ca(2+) influx through the voltage-dependent Ca(2+) channels related to spontaneous secretion. betagamma-Imido ATP-induced modulation was antagonized by the non-specific P2 receptor antagonist suramin and the P2Y receptor antagonist 1-amino-4-[[4-[[4-chloro-6-[[3(or4)-sulfophenyl] amino]-1,3,5-triazin-2-yl]amino]-3-sulfophenyl] amino]-9,10-dihydro-9,10-dioxo-2-anthracenesulfonic acid (reactive blue-2), but not by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (PPADS), which has a preferential antagonist effect on P2X receptors. Pertussis toxin and N-ethylmaleimide (NEM), which are blockers of G(i/o) proteins, prevented the action of the nucleotide, suggesting that the effect is mediated by P2Y receptors

Suppressing effect of COR659 on alcohol, sucrose, and chocolate self-administration in rats: involvement of the GABAB and cannabinoid CB1 receptors.

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Maccioni, Paola; Colombo, Giancarlo; Lorrai, Irene; Zaru, Alessandro; Carai, Mauro A M; Gessa, Gian Luigi; Brizzi, Antonella; Mugnaini, Claudia; Corelli, Federico

2017-09-01

COR659 [methyl2-(4-chlorophenylcarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate] is a new, positive allosteric modulator (PAM) of the GABA B receptor. This study evaluated whether COR659 shared with previously tested GABA B PAMs the capacity to reduce alcohol self-administration in rats. Treatment with non-sedative doses of COR659 (2.5, 5, and 10 mg/kg; i.p.) suppressed lever-responding for alcohol (15% v/v) in Sardinian alcohol-preferring (sP) rats under the fixed ratio (FR) 4 (FR4) and progressive ratio (PR) schedules of reinforcement; COR659 was more potent and effective than the reference GABA B PAM, GS39783. Treatment with COR659, but not GS39783, suppressed (a) lever-responding for a sucrose solution (1-3% w/v) in sP rats under the FR4 and PR schedules, (b) lever-responding for a chocolate solution [5% (w/v) Nesquik®] in Wistar rats under the FR10 and PR schedules, and (c) cue-induced reinstatement of chocolate seeking in Wistar rats. Treatment with COR659 was completely ineffective on lever-responding (FR10) for regular food pellets in food-deprived Wistar rats. Pretreatment with the GABA B receptor antagonist, SCH50911, partially blocked COR659-induced reduction of alcohol self-administration, being ineffective on reduction of chocolate self-administration. Pretreatment with the cannabinoid CB 1 receptor antagonist, AM4113, fully blocked COR659-induced reduction of chocolate self-administration, being ineffective on reduction of alcohol self-administration. COR659 might exert its behavioral effects via a composite mechanism: (i) positive allosteric modulation of the GABA B receptor, responsible for a large proportion of reduction of alcohol self-administration; (ii) an action at other receptor system(s), including the cannabinoid CB 1 receptor, through which COR659 affects seeking and consumption of highly palatable foods.

Chronic ethanol exposure decreases CB1 receptor function at GABAergic synapses in the rat central amygdala

DEFF Research Database (Denmark)

Varodayan, Florence P.; Soni, Neeraj; Bajo, Michal

2016-01-01

release, and GABAergic dysregulation in the central nucleus of the amygdala (CeA) is critical in the transition to alcohol dependence. We investigated possible disruptions in CB1 signaling of rat CeA GABAergic transmission following intermittent ethanol exposure. In the CeA of alcohol-naive rats, CB1...

Stimulation of brain glucose uptake by cannabinoid CB2 receptors and its therapeutic potential in Alzheimer's disease.

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Köfalvi, Attila; Lemos, Cristina; Martín-Moreno, Ana M; Pinheiro, Bárbara S; García-García, Luis; Pozo, Miguel A; Valério-Fernandes, Ângela; Beleza, Rui O; Agostinho, Paula; Rodrigues, Ricardo J; Pasquaré, Susana J; Cunha, Rodrigo A; de Ceballos, María L

2016-11-01

Cannabinoid CB2 receptors (CB2Rs) are emerging as important therapeutic targets in brain disorders that typically involve neurometabolic alterations. We here addressed the possible role of CB2Rs in the regulation of glucose uptake in the mouse brain. To that aim, we have undertaken 1) measurement of (3)H-deoxyglucose uptake in cultured cortical astrocytes and neurons and in acute hippocampal slices; 2) real-time visualization of fluorescently labeled deoxyglucose uptake in superfused hippocampal slices; and 3) in vivo PET imaging of cerebral (18)F-fluorodeoxyglucose uptake. We now show that both selective (JWH133 and GP1a) as well as non-selective (WIN55212-2) CB2R agonists, but not the CB1R-selective agonist, ACEA, stimulate glucose uptake, in a manner that is sensitive to the CB2R-selective antagonist, AM630. Glucose uptake is stimulated in astrocytes and neurons in culture, in acute hippocampal slices, in different brain areas of young adult male C57Bl/6j and CD-1 mice, as well as in middle-aged C57Bl/6j mice. Among the endocannabinoid metabolizing enzymes, the selective inhibition of COX-2, rather than that of FAAH, MAGL or α,βDH6/12, also stimulates the uptake of glucose in hippocampal slices of middle-aged mice, an effect that was again prevented by AM630. However, we found the levels of the endocannabinoid, anandamide reduced in the hippocampus of TgAPP-2576 mice (a model of β-amyloidosis), and likely as a consequence, COX-2 inhibition failed to stimulate glucose uptake in these mice. Together, these results reveal a novel general glucoregulatory role for CB2Rs in the brain, raising therapeutic interest in CB2R agonists as nootropic agents. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Expression Analysis of CB2-GFP BAC Transgenic Mice.

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Anne-Caroline Schmöle

Full Text Available The endocannabinoid system (ECS is a retrograde messenger system, consisting of lipid signaling molecules that bind to at least two G-protein-coupled receptors, Cannabinoid receptor 1 and 2 (CB1 and 2. As CB2 is primarily expressed on immune cells such as B cells, T cells, macrophages, dendritic cells, and microglia, it is of great interest how CB2 contributes to immune cell development and function in health and disease. Here, understanding the mechanisms of CB2 involvement in immune-cell function as well as the trafficking and regulation of CB2 expressing cells are crucial issues. Up to now, CB2 antibodies produce unclear results, especially those targeting the murine protein. Therefore, we have generated BAC transgenic GFP reporter mice (CB2-GFPTg to trace CB2 expression in vitro and in situ. Those mice express GFP under the CB2 promoter and display GFP expression paralleling CB2 expression on the transcript level in spleen, thymus and brain tissue. Furthermore, by using fluorescence techniques we show that the major sources for GFP-CB2 expression are B cells in spleen and blood and microglia in the brain. This novel CB2-GFP transgenic reporter mouse line represents a powerful resource to study CB2 expression in different cell types. Furthermore, it could be used for analyzing CB2-mediated mobilization and trafficking of immune cells as well as studying the fate of recruited immune cells in models of acute and chronic inflammation.

A Feedforward Inhibitory Circuit Mediated by CB1-Expressing Fast-Spiking Interneurons in the Nucleus Accumbens.

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Wright, William J; Schlüter, Oliver M; Dong, Yan

2017-04-01

The nucleus accumbens (NAc) gates motivated behaviors through the functional output of principle medium spiny neurons (MSNs), whereas dysfunctional output of NAc MSNs contributes to a variety of psychiatric disorders. Fast-spiking interneurons (FSIs) are sparsely distributed throughout the NAc, forming local feedforward inhibitory circuits. It remains elusive how FSI-based feedforward circuits regulate the output of NAc MSNs. Here, we investigated a distinct subpopulation of NAc FSIs that express the cannabinoid receptor type-1 (CB1). Using a combination of paired electrophysiological recordings and pharmacological approaches, we characterized and compared feedforward inhibition of NAc MSNs from CB1 + FSIs and lateral inhibition from recurrent MSN collaterals. We observed that CB1 + FSIs exerted robust inhibitory control over a large percentage of nearby MSNs in contrast to local MSN collaterals that provided only sparse and weak inhibitory input to their neighboring MSNs. Furthermore, CB1 + FSI-mediated feedforward inhibition was preferentially suppressed by endocannabinoid (eCB) signaling, whereas MSN-mediated lateral inhibition was unaffected. Finally, we demonstrated that CB1 + FSI synapses onto MSNs are capable of undergoing experience-dependent long-term depression in a voltage- and eCB-dependent manner. These findings demonstrated that CB1 + FSIs are a major source of local inhibitory control of MSNs and a critical component of the feedforward inhibitory circuits regulating the output of the NAc.

Pharmacology of the hypothermic response to 5-HT1A receptor activation in humans.

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Lesch, K P; Poten, B; Söhnle, K; Schulte, H M

1990-01-01

The selective 5-HT1A receptor ligand ipsapirone (IPS) caused dose-related hypothermia in humans. The response was attenuated by the nonselective 5-HT1/2 receptor antagonist metergoline and was completely antagonized by the nonselective beta-adrenoceptor antagonist pindolol, which interacts stereoselectively with the 5-HT1A receptor. The selective beta 1-adrenergic antagonist betaxolol had no effect. The findings indicate that IPS-induced hypothermia specifically involves activation of (presynaptic) 5-HT1A receptors. Therefore, the hypothermic response to IPS may provide a convenient in vivo paradigma to assess the function of the presynaptic 5-HT receptor in affective disorders and its involvement in the effects of psychotropic drugs.

Upregulation of Cannabinoid Type 1 Receptors in Dopamine D2 Receptor Knockout Mice Is Reversed by Chronic Forced Ethanol Consumption

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Thanos, P.K.; Wang, G.; Thanos, P.K.; Gopez, V.; Delis, F.; Michaelides, M.; Grand, D.K.; Wang, G.-J.; Kunos, G.; Volkow, N.D.

2011-01-01

The anatomical proximity of the cannabinoid type 1 (CNR1/CB1R) and the dopamine D2 receptors (DRD2), their ability to form CB1R-DRD2 heteromers, their opposing roles in locomotion, and their involvement in ethanol's reinforcing and addictive properties prompted us to study the levels and distribution of CB1R after chronic ethanol intake, in the presence and absence of DRD2. We monitored the drinking patterns and locomotor activity of Drd2+/+ and Drd2-/- mice consuming either water or a 20% (v/v) ethanol solution (forced ethanol intake) for 6 months and used the selective CB1 receptor antagonist [{sup 3}H]SR141716A to quantify CB1R levels in different brain regions with in vitro receptor autoradiography. We found that the lack of DRD2 leads to a marked upregulation (approximately 2-fold increase) of CB1R in the cerebral cortex, the caudate-putamen, and the nucleus accumbens, which was reversed by chronic ethanol intake. The results suggest that DRD2-mediated dopaminergic neurotransmission and chronic ethanol intake exert an inhibitory effect on cannabinoid receptor expression in cortical and striatal regions implicated in the reinforcing and addictive properties of ethanol.

Immunohistochemical analysis of cannabinoid receptor 1 expression in steatotic rat livers.

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Zduniak, Krzysztof; Ziółkowski, Piotr; Regnell, Pontus; Tollet-Egnell, Petra; Åkesson, Lina; Cooper, Martin E

2016-04-01

The primary aim of the present study was to determine the expression levels of cannabinoid receptor type 1 (CB1) in steatotic rat livers. The secondary aim was to clarify whether steatosis and inflammation are more marked in areas with increased CB1 overexpression. For ethical and economic reasons, the present study investigated tissue from archived liver blocks, which were obtained from 38 rats that had been euthanized during the course of previous research at the Karolinska Institute of the Karolinska University Hospital (Stockholm, Sweden) and Lund University (Malmö, Sweden). Liver tissue fixed in formalin and embedded in paraffin was used that had been sourced from 36 male Sprague Dawley rats (age, 7 weeks) and 2 rats (age, 180 days) lacking normal leptin receptors. The rat liver tissue was stained with antibodies against CB1 and counterstained with hematoxylin. The expression of CB1 and the number of cells overexpressing CB1 were determined. Steatosis was scored according to the Dixon scoring system. CB1 overexpression and steatosis were detected in hepatocytes from all 38 livers sampled. The expression of CB1 was more marked in hepatocytes localized next to portal triads. Near the central veins, the expression was significantly weaker. Steatosis was more marked in areas of increased CB1 overexpression. Lymphocyte infiltration was more commonly observed in areas of increased CB1 overexpression. Therefore, the present results indicate that CB1 receptors are overexpressed in areas with steatosis, and indicate that CB1 in hepatocytes contributes to the formation of steatosis in rats, even prior to its progression to steatohepatitis. These results are consistent with publications reporting that CB1 in hepatocytes increases lipogenesis and contributes to inflammation.

Astrocytes regulate heterogeneity of presynaptic strengths in hippocampal networks

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Letellier, Mathieu; Park, Yun Kyung; Chater, Thomas E.; Chipman, Peter H.; Gautam, Sunita Ghimire; Oshima-Takago, Tomoko; Goda, Yukiko

2016-01-01

Dendrites are neuronal structures specialized for receiving and processing information through their many synaptic inputs. How input strengths are modified across dendrites in ways that are crucial for synaptic integration and plasticity remains unclear. We examined in single hippocampal neurons the mechanism of heterosynaptic interactions and the heterogeneity of synaptic strengths of pyramidal cell inputs. Heterosynaptic presynaptic plasticity that counterbalances input strengths requires N-methyl-d-aspartate receptors (NMDARs) and astrocytes. Importantly, this mechanism is shared with the mechanism for maintaining highly heterogeneous basal presynaptic strengths, which requires astrocyte Ca2+ signaling involving NMDAR activation, astrocyte membrane depolarization, and L-type Ca2+ channels. Intracellular infusion of NMDARs or Ca2+-channel blockers into astrocytes, conditionally ablating the GluN1 NMDAR subunit, or optogenetically hyperpolarizing astrocytes with archaerhodopsin promotes homogenization of convergent presynaptic inputs. Our findings support the presence of an astrocyte-dependent cellular mechanism that enhances the heterogeneity of presynaptic strengths of convergent connections, which may help boost the computational power of dendrites. PMID:27118849

Cannabinoid CB2 receptors are involved in the protection of RAW264.7 macrophages against the oxidative stress: an in vitro study

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Sabrina Giacoppo

2017-01-01

Full Text Available Research in the last decades has widely investigated the anti-oxidant properties of natural products as a therapeutic approach for the prevention and the treatment of oxidative-stress related disorders. In this context, several studies were aimed to evaluate the therapeutic potential of phytocannabinoids, the bioactive compounds of Cannabis sativa. Here, we examined the anti-oxidant ability of Cannabigerol (CBG, a non-psychotropic cannabinoid, still little known, into counteracting the hydrogen peroxide (H2O2-induced oxidative stress in murine RAW264.7 macrophages. In addition, we tested selective receptor antagonists for cannabinoid receptors and specifically CB1R (SR141716A and CB2R (AM630 in order to investigate through which CBG may exert its action. Taken together, our in vitro results showed that CBG is able to counteract oxidative stress by activation of CB2 receptors. CB2 antagonist pre-treatment indeed blocked the protective effects of CBG in H2O2 stimulated macrophages, while CB1R was not involved. Specifically, CBG exhibited a potent action in inhibiting oxidative stress, by down-regulation of the main oxidative markers (iNOS, nitrotyrosine and PARP-1, by preventing IκB-α phosphorylation and translocation of the nuclear factor-κB (NF-κB and also via the modulation of MAP kinases pathway. On the other hand, CBG was found to increase anti-oxidant defense of cells by modulating superoxide dismutase-1 (SOD-1 expression and thus inhibiting cell death (results focused on balance between Bax and Bcl-2. Based on its antioxidant activities, CBG may hold great promise as an anti-oxidant agent and therefore used in clinical practice as a new approach in oxidative-stress related disorders.

Prior stimulation of the endocannabinoid system prevents methamphetamine-induced dopaminergic neurotoxicity in the striatum through activation of CB2 receptors

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Nader, Joëlle; Rapino, Cinzia; Gennequin, Benjamin; Chavant, Francois; Francheteau, Maureen; Makriyannis, Alexandros; Duranti, Andrea; Maccarrone, Mauro; Solinas, Marcello; Thiriet, Nathalie

2016-01-01

Methamphetamine toxicity is associated with cell death and loss of dopamine neuron terminals in the striatum similar to what is found in some neurodegenerative diseases. Conversely, the endocannabinoid system (ECS) has been suggested to be neuroprotective in the brain, and new pharmacological tools have been developed to increase their endogenous tone. In this study, we evaluated whether ECS stimulation could reduce the neurotoxicity of high doses of methamphetamine on the dopamine system. We found that methamphetamine alters the levels of the major endocannabinoids, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) in the striatum, suggesting that the ECS participates in the brain responses to methamphetamine. Δ9-tetrahydrocannabinol (THC), a cannabis-derived agonist of both CB1 and CB2 cannabinoid receptors, or inhibitors of the main enzymes responsible for the degradation of AEA and 2-AG (URB597 and JZL184, respectively), blunted the decrease in striatal protein levels of tyrosine hydroxylase induced by methamphetamine. In addition, antagonists of CB2, but not of CB1, blocked the preventive effects of URB597 and JZL184, suggesting that only the former receptor subtype is engaged in neuroprotection exerted by ECS stimulation. Finally, we found that methamphetamine increases striatal levels of the cytokine tumor necrosis factor alpha, an effect that was blocked by ECS stimulation. Altogether, our results indicate that stimulation of ECS prior to the administration of an overdose of meth-amphetamine considerably reduces the neurotoxicity of the drug through CB2 receptor activation and highlight a protective function for the ECS against the toxicity induced by drugs and other external insults to the brain. This article is part of the Special Issue entitled ‘CNS Stimulants’. PMID:24709540

Leptin Receptor Deficiency is Associated With Upregulation of Cannabinoid 1 Receptors in Limbic Brain Regions

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THANOS, PANAYOTIS K.; RAMALHETE, ROBERTO C.; MICHAELIDES, MICHAEL; PIYIS, YIANNI K.; WANG, GENE-JACK; VOLKOW, NORA D.

2009-01-01

Leptin receptor dysfunction results in overeating and obesity. Leptin regulates hypothalamic signaling that underlies the motivation to hyperphagia, but the interaction between leptin and cannabinoid signaling is poorly understood. We evaluated the role of cannabinoid 1 receptors (CB1R) in overeating and the effects of food deprivation on CB1R in the brain. One-month-old Zucker rats were divided into unrestricted and restricted (fed 70% of unrestricted rats) diet groups and maintained until adulthood (4 months). Levels of relative binding sites of CB1R (CB1R binding levels) were assessed using [3H] SR141716A in vitro autoradiography. These levels were higher (except cerebellum and hypothalamus) at 4 months than at 1 month of age. One month CB1R binding levels for most brain regions did not differ between Ob and Lean (Le) rats (except in frontal and cingulate cortices in Le and in the hypothalamus in Ob). Four month Ob rats had higher CB1R binding levels than Le in most brain regions and food restriction was associated with higher CB1R levels in all brain regions in Ob, but not in Le rats. CB1R binding levels increased between adolescence and young adulthood which we believe was influenced by leptin and food availability. The high levels of CB1R in Ob rats suggest that leptin's inhibition of food-intake is in part mediated by downregulation of CB1R and that leptin interferes with CB1R upregulation under food-deprivation conditions. These results are consistent with prior findings showing increased levels of endogenous cannabinoids in the Ob rats corroborating the regulation of cannabinoid signaling by leptin. PMID:18563836

Perspectives of CB1 Antagonist in Treatment of Obesity: Experience of RIO-Asia

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Changyu Pan

2011-01-01

Full Text Available Rimonabant, a selective cannabinoid-1 (CB1 receptor antagonist, has been shown to reduce weight and enhance improvements in cardiometabolic risk parameters in Western populations. This study assessed these effects of rimonabant in Asian population. A total of 643 patients (BMI 25 kg/m2 or greater without diabetes from China, Republic of Korea, and Taiwan were prescribed a hypocaloric diet (600 kcal/day deficit and randomized to rimonabant 20 mg (n=318 or placebo (n=325 for 9months. The primary efficacy variable was weight change from baseline after 9 months of treatment. Results showed that rimonabant group lost more weight than placebo, (LSM ± SEM of −4.7 ± 0.3 kg vs. −1.7 ± 0.3 kg, P<.0001. The 5% and 10% responders were 2 or 3 folds more in the rimonabant group (53.0% vs. 20.0% and 21.5% vs. 5.7%, resp. (P<.0001. Rimonabant also significantly increased HDL-cholesterol, decreased triglycerides and waist circumference,by 7.1%, 10.6%, and 2.8 cm, respectively (P<.0001. This study confirmed the comparable efficacy and safety profile of rimonabant in Asian population to Caucasians. Owing to the recent suspension of all the CB1 antagonists off the pharmaceutical market for weight reduction in Europe and USA, a perspective in drug discovery for intervening peripheral CB1 receptor in the management of obesity is discussed.

Het endocannabinoïdsysteem, overgewicht en de CB1-endocannabinoïdreceptorblokker rimonabant

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Boekholdt, S. M.; Jukema, J. W.; Peters, R. J. G.

2007-01-01

--Obesity is an important healthcare issue. --Recent research has led to insights into the role of the endocannabinoid system in the regulation of body weight. --Rimonabant is a CB1-endocannabinoid-receptor antagonist. --Four trials were published recently on the efficacy and safety of rimonabant in

Pre-synaptic glycine GlyT1 transporter--NMDA receptor interaction: relevance to NMDA autoreceptor activation in the presence of Mg2+ ions.

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Musante, Veronica; Summa, Maria; Cunha, Rodrigo A; Raiteri, Maurizio; Pittaluga, Anna

2011-05-01

Rat hippocampal glutamatergic terminals possess NMDA autoreceptors whose activation by low micromolar NMDA elicits glutamate exocytosis in the presence of physiological Mg(2+) (1.2 mM), the release of glutamate being significantly reduced when compared to that in Mg(2+)-free condition. Both glutamate and glycine were required to evoke glutamate exocytosis in 1.2 mM Mg(2+), while dizocilpine, cis-4-[phosphomethyl]-piperidine-2-carboxylic acid and 7-Cl-kynurenic acid prevented it, indicating that occupation of both agonist sites is needed for receptor activation. D-serine mimicked glycine but also inhibited the NMDA/glycine-induced release of [(3H]D-aspartate, thus behaving as a partial agonist. The NMDA/glycine-induced release in 1.2 mM Mg(2+) strictly depended on glycine uptake through the glycine transporter type 1 (GlyT1), because the GlyT1 blocker N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine hydrochloride, but not the GlyT2 blocker Org 25534, prevented it. Accordingly, [(3)H]glycine was taken up during superfusion, while lowering the external concentration of Na(+), the monovalent cation co-transported with glycine by GlyT1, abrogated the NMDA-induced effect. Western blot analysis of subsynaptic fractions confirms that GlyT1 and NMDA autoreceptors co-localize at the pre-synaptic level, where GluN3A subunits immunoreactivity was also recovered. It is proposed that GlyT1s coexist with NMDA autoreceptors on rat hippocampal glutamatergic terminals and that glycine taken up by GlyT1 may permit physiological activation of NMDA pre-synaptic autoreceptors. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors.

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Vulfius, Catherine A; Kasheverov, Igor E; Kryukova, Elena V; Spirova, Ekaterina N; Shelukhina, Irina V; Starkov, Vladislav G; Andreeva, Tatyana V; Faure, Grazyna; Zouridakis, Marios; Tsetlin, Victor I; Utkin, Yuri N

2017-01-01

Phospholipases A2 (PLA2s) are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs) and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which should be proved by

Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors.

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Catherine A Vulfius

Full Text Available Phospholipases A2 (PLA2s are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which

Acetylcholine-induced inhibition of presynaptic calcium signals and transmitter release in the frog neuromuscular junction

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Eduard Khaziev

2016-12-01

Full Text Available Acetylcholine (ACh, released from axonal terminals of motor neurones in neuromuscular junctions regulates the efficacy of neurotransmission through activation of presynaptic nicotinic and muscarinic autoreceptors. Receptor-mediated presynaptic regulation could reflect either direct action on exocytotic machinery or modulation of Ca2+ entry and resulting intra-terminal Ca2+ dynamics. We have measured free intra-terminal cytosolic Ca2+ ([Ca2+]i using Oregon-Green 488 microfluorimetry, in parallel with voltage-clamp recordings of spontaneous (mEPC and evoked (EPC postsynaptic currents in post-junctional skeletal muscle fibre. Activation of presynaptic muscarinic and nicotinic receptors with exogenous acetylcholine and its non-hydrolized analogue carbachol reduced amplitude of the intra-terminal [Ca2+]i transients and decreased quantal content (calculated by dividing the area under EPC curve by the area under mEPC curve. Pharmacological analysis revealed the role of muscarinic receptors of M2 subtype as well as d-tubocurarine-sensitive nicotinic receptor in presynaptic modulation of [Ca2+]i transients. Modulation of synaptic transmission efficacy by ACh receptors was completely eliminated by pharmacological inhibition of N-type Ca2+ channels. We conclude that ACh receptor-mediated reduction of Ca2+ entry into the nerve terminal through N-type Ca2+ channels represents one of possible mechanism of presynaptic modulation in frog neuromuscular junction.

Resistance to diet-induced adiposity in cannabinoid receptor-1 deficient mice is not due to impaired adipocyte function

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Oosterveer, Maaike H.; Koolman, Anniek H.; de Boer, Pieter T.; Bos, Trijnie; Bleeker, Aycha; Bloks, Vincent W.; Kuipers, Folkert; Sauer, Pieter J. J.; van Dijk, Gertjan

2011-01-01

Background: Overactivity and/or dysregulation of the endocannabinoid system (ECS) contribute to development of obesity. In vitro studies indicate a regulatory role for the cannabinoid receptor 1 (CB1) in adipocyte function and CB1-receptor deficient (CB1-/-) mice are resistant to high fat

Clarifying CB2 receptor-dependent and independent effects of THC on human lung epithelial cells

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Sarafian, Theodore; Montes, Cindy; Harui, Airi; Beedanagari, Sudheer R.; Kiertscher, Sylvia; Stripecke, Renata; Hossepian, Derik; Kitchen, Christina; Kern, Rita; Belperio, John; Roth, Michael D.

2008-01-01

Marijuana smoking is associated with a number of abnormal findings in the lungs of habitual smokers. Previous studies revealed that Δ 9 -tetrahydrocannabinol (THC) caused mitochondrial injury in primary lung epithelial cells and in the cell line, A549 [Sarafian, T. A., Kouyoumjian, S., Khoshaghideh, F., Tashkin, D. P., and Roth, M. D. (2003). Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics. Am J Physiol Lung Cell Mol Physiol 284, L298-306; Sarafian, T., Habib, N., Mao, J. T., Tsu, I. H., Yamamoto, M. L., Hsu, E., Tashkin, D. P., and Roth, M. D. (2005). Gene expression changes in human small airway epithelial cells exposed to Delta9-tetrahydrocannabinol. Toxicol Lett 158, 95-107]. The role of cannabinoid receptors in this injury was unclear, as was the potential impact on cell function. In order to investigate these questions, A549 cells were engineered to over-express the type 2 cannabinoid receptor (CB2R) using a self-inactivating lentiviral vector. This transduction resulted in a 60-fold increase in CB2R mRNA relative to cells transduced with a control vector. Transduced cell lines were used to study the effects of THC on chemotactic activity and mitochondrial function. Chemotaxis in response to a 10% serum gradient was suppressed in a concentration-dependent manner by exposure to THC. CB2R-transduced cells exhibited less intrinsic chemotactic activity (p m ) in both control and CB2R-transduced cells. However, these decreases did not play a significant role in chemotaxis inhibition since cyclosporine A, which protected against ATP loss, did not increase cell migration. Moreover, CB2R-transduced cells displayed higher Ψ m than did control cells. Since both Ψ m and chemotaxis are regulated by intracellular signaling, we investigated the effects of THC on the activation of multiple signaling pathways. Serum exposure activated several signaling events of which phosphorylation of IκB-α and JNK was regulated in a CB2R- and THC

Role of endocannabinoids and cannabinoid-1 receptors in cerebrocortical blood flow regulation.

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András Iring

Full Text Available Endocannabinoids are among the most intensively studied lipid mediators of cardiovascular functions. In the present study the effects of decreased and increased activity of the endocannabinoid system (achieved by cannabinoid-1 (CB1 receptor blockade and inhibition of cannabinoid reuptake, respectively on the systemic and cerebral circulation were analyzed under steady-state physiological conditions and during hypoxia and hypercapnia (H/H.In anesthetized spontaneously ventilating rats the CB1-receptor antagonist/inverse agonist AM-251 (10 mg/kg, i.v. failed to influence blood pressure (BP, cerebrocortical blood flow (CoBF, measured by laser-Doppler flowmetry or arterial blood gas levels. In contrast, the putative cannabinoid reuptake inhibitor AM-404 (10 mg/kg, i.v. induced triphasic responses, some of which could be blocked by AM-251. Hypertension during phase I was resistant to AM-251, whereas the concomitant CoBF-increase was attenuated. In contrast, hypotension during phase III was sensitive to AM-251, whereas the concomitant CoBF-decrease was not. Therefore, CoBF autoregulation appeared to shift towards higher BP levels after CB1-blockade. During phase II H/H developed due to respiratory depression, which could be inhibited by AM-251. Interestingly, however, the concomitant rise in CoBF remained unchanged after AM-251, indicating that CB1-blockade potentially enhanced the reactivity of the CoBF to H/H. In accordance with this hypothesis, AM-251 induced a significant enhancement of the CoBF responses during controlled stepwise H/H.Under resting physiological conditions CB1-receptor mediated mechanisms appear to have limited influence on systemic or cerebral circulation. Enhancement of endocannabinoid levels, however, induces transient CB1-independent hypertension and sustained CB1-mediated hypotension. Furthermore, enhanced endocannabinoid activity results in respiratory depression in a CB1-dependent manner. Finally, our data indicate for the

Synapse-specific and compartmentalized expression of presynaptic homeostatic potentiation

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Li, Xiling; Goel, Pragya; Chen, Catherine; Angajala, Varun; Chen, Xun

2018-01-01

Postsynaptic compartments can be specifically modulated during various forms of synaptic plasticity, but it is unclear whether this precision is shared at presynaptic terminals. Presynaptic homeostatic plasticity (PHP) stabilizes neurotransmission at the Drosophila neuromuscular junction, where a retrograde enhancement of presynaptic neurotransmitter release compensates for diminished postsynaptic receptor functionality. To test the specificity of PHP induction and expression, we have developed a genetic manipulation to reduce postsynaptic receptor expression at one of the two muscles innervated by a single motor neuron. We find that PHP can be induced and expressed at a subset of synapses, over both acute and chronic time scales, without influencing transmission at adjacent release sites. Further, homeostatic modulations to CaMKII, vesicle pools, and functional release sites are compartmentalized and do not spread to neighboring pre- or post-synaptic structures. Thus, both PHP induction and expression mechanisms are locally transmitted and restricted to specific synaptic compartments. PMID:29620520

Brain neuronal CB2 cannabinoid receptors in drug abuse and depression: from mice to human subjects.

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Emmanuel S Onaivi

Full Text Available BACKGROUND: Addiction and major depression are mental health problems associated with stressful events in life with high relapse and reoccurrence even after treatment. Many laboratories were not able to detect the presence of cannabinoid CB2 receptors (CB2-Rs in healthy brains, but there has been demonstration of CB2-R expression in rat microglial cells and other brain associated cells during inflammation. Therefore, neuronal expression of CB2-Rs had been ambiguous and controversial and its role in depression and substance abuse is unknown. METHODOLOGY/PRINCIPAL FINDINGS: In this study we tested the hypothesis that genetic variants of CB2 gene might be associated with depression in a human population and that alteration in CB2 gene expression may be involved in the effects of abused substances including opiates, cocaine and ethanol in rodents. Here we demonstrate that a high incidence of (Q63R but not (H316Y polymorphism in the CB2 gene was found in Japanese depressed subjects. CB2-Rs and their gene transcripts are expressed in the brains of naïve mice and are modulated following exposure to stressors and administration of abused drugs. Mice that developed alcohol preference had reduced CB2 gene expression and chronic treatment with JWH015 a putative CB2-R agonist, enhanced alcohol consumption in stressed but not in control mice. The direct intracerebroventricular microinjection of CB2 anti-sense oligonucleotide into the mouse brain reduced mouse aversions in the plus-maze test, indicating the functional presence of CB2-Rs in the brain that modifies behavior. We report for the using electron microscopy the sub cellular localization of CB2-Rs that are mainly on post-synaptic elements in rodent brain. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate the functional expression of CB2-Rs in brain that may provide novel targets for the effects of cannabinoids in depression and substance abuse disorders beyond neuro-immunocannabinoid activity.

Cannabinoid Receptor Type 1 Expression in the Developing Avian Retina: Morphological and Functional Correlation With the Dopaminergic System

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Luzia da Silva Sampaio

2018-03-01

Full Text Available The avian retina has been used as a model to study signaling by different neuro- and gliotransmitters. It is unclear how dopaminergic and cannabinoid systems are related in the retina. Here we studied the expression of type 1 and 2 cannabinoid receptors (CB1 and CB2, as well as monoacylglycerol lipase (MAGL, the enzyme that degrades 2-arachidonoylglycerol (2-AG, during retina development. Our data show that CB1 receptor is highly expressed from embryonic day 5 (E5 until post hatched day 7 (PE7, decreasing its levels throughout development. CB1 is densely found in the ganglion cell layer (GCL and inner plexiform layer (IPL. CB2 receptor was also found from E5 until PE7 with a decrease in its contents from E9 afterwards. CB2 was mainly present in the lamination of the IPL at PE7. MAGL is expressed in all retinal layers, mainly in the IPL and OPL from E9 to PE7 retina. CB1 and CB2 were found both in neurons and glia cells, but MAGL was only expressed in Müller glia. Older retinas (PE7 show CB1 positive cells mainly in the INL and co-expression of CB1 and tyrosine hydroxylase (TH are shown in a few cells when both systems are mature. CB1 co-localized with TH and was heavily associated to D1 receptor labeling in primary cell cultures. Finally, cyclic AMP (cAMP was activated by the selective D1 agonist SKF38393, and inhibited when cultures were treated with WIN55, 212–2 (WIN in a CB1 dependent manner. The results suggest a correlation between the endocannabinoid and dopaminergic systems (DSs during the avian retina development. Activation of CB1 limits cAMP accumulation via D1 receptor activation and may influence embryological parameters during avian retina differentiation.

Maternal deprivation and adolescent cannabinoid exposure impact hippocampal astrocytes, CB1 receptors and brain-derived neurotrophic factor in a sexually dimorphic fashion.

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López-Gallardo, M; López-Rodríguez, A B; Llorente-Berzal, Á; Rotllant, D; Mackie, K; Armario, A; Nadal, R; Viveros, M-P

2012-03-01

We have recently reported that early maternal deprivation (MD) for 24 h [postnatal day (PND) 9-10] and/or an adolescent chronic treatment with the cannabinoid agonist CP-55,940 (CP) [0.4 mg/kg, PND 28-42] in Wistar rats induced, in adulthood, diverse sex-dependent long-term behavioral and physiological modifications. Here we show the results obtained from investigating the immunohistochemical analysis of CB1 cannabinoid receptors, glial fibrillary acidic protein (GFAP) positive (+) cells and brain-derived neurotrophic factor (BDNF) expression in the hippocampus of the same animals. MD induced, in males, a significant increase in the number of GFAP+ cells in CA1 and CA3 areas and in the polymorphic layer of the dentate gyrus (DG), an effect that was attenuated by CP in the two latter regions. Adolescent cannabinoid exposure induced, in control non-deprived males, a significant increase in the number of GFAP+ cells in the polymorphic layer of the DG. MD induced a decrease in CB1 expression in both sexes, and this effect was reversed in males by the cannabinoid treatment. In turn, the drug "per se" induced, in males, a general decrease in CB1 immunoreactivity, and the opposite effect was observed in females. Cannabinoid exposure tended to reduce BDNF expression in CA1 and CA3 of females, whereas MD counteracted this trend and induced an increase of BDNF in females. As a whole, the present results show sex-dependent long-term effects of both MD and juvenile cannabinoid exposure as well as functional interactions between the two treatments. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

MATERNAL DEPRIVATION AND ADOLESCENT CANNABINOID EXPOSURE IMPACT HIPPOCAMPAL ASTROCYTES, CB1 RECEPTORS AND BRAIN-DERIVED NEUROTROPHIC FACTOR IN A SEXUALLY DIMORPHIC FASHION

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LÓPEZ-GALLARDO, M.; LÓPEZ-RODRÍGUEZ, A. B.; LLORENTE-BERZAL, Á.; ROTLLANT, D.; MACKIE, K.; ARMARIO, A.; NADAL, R.; VIVEROS, M.-P.

2013-01-01

We have recently reported that early maternal deprivation (MD) for 24 h [postnatal day (PND) 9–10] and/or an adolescent chronic treatment with the cannabinoid agonist CP-55,940 (CP) [0.4 mg/kg, PND 28–42] in Wistar rats induced, in adulthood, diverse sex-dependent long-term behavioral and physiological modifications. Here we show the results obtained from investigating the immunohistochemical analysis of CB1 cannabinoid receptors, glial fibrillary acidic protein (GFAP) positive (+) cells and brain-derived neurotrophic factor (BDNF) expression in the hippocampus of the same animals. MD induced, in males, a significant increase in the number of GFAP+ cells in CA1 and CA3 areas and in the polymorphic layer of the dentate gyrus (DG), an effect that was attenuated by CP in the two latter regions. Adolescent cannabinoid exposure induced, in control non-deprived males, a significant increase in the number of GFAP+ cells in the polymorphic layer of the DG. MD induced a decrease in CB1 expression in both sexes, and this effect was reversed in males by the cannabinoid treatment. In turn, the drug “per se” induced, in males, a general decrease in CB1 immunoreactivity, and the opposite effect was observed in females. Cannabinoid exposure tended to reduce BDNF expression in CA1 and CA3 of females, whereas MD counteracted this trend and induced an increase of BDNF in females. As a whole, the present results show sex-dependent long-term effects of both MD and juvenile cannabinoid exposure as well as functional interactions between the two treatments. PMID:22001306

G-protein-coupled inward rectifier potassium channels involved in corticostriatal presynaptic modulation.

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Meneses, David; Mateos, Verónica; Islas, Gustavo; Barral, Jaime

2015-09-01

Presynaptic modulation has been associated mainly with calcium channels but recent data suggests that inward rectifier potassium channels (K(IR)) also play a role. In this work we set to characterize the role of presynaptic K(IR) channels in corticostriatal synaptic transmission. We elicited synaptic potentials in striatum by stimulating cortical areas and then determined the synaptic responses of corticostriatal synapsis by using paired pulse ratio (PPR) in the presence and absence of several potassium channel blockers. Unspecific potassium channels blockers Ba(2+) and Cs(+) reduced the PPR, suggesting that these channels are presynaptically located. Further pharmacological characterization showed that application of tertiapin-Q, a specific K(IR)3 channel family blocker, also induced a reduction of PPR, suggesting that K(IR)3 channels are present at corticostriatal terminals. In contrast, exposure to Lq2, a specific K(IR)1.1 inward rectifier potassium channel, did not induce any change in PPR suggesting the absence of these channels in the presynaptic corticostriatal terminals. Our results indicate that K(IR)3 channels are functionally expressed at the corticostriatal synapses, since blockage of these channels result in PPR decrease. Our results also help to explain how synaptic activity may become sensitive to extracellular signals mediated by G-protein coupled receptors. A vast repertoire of receptors may influence neurotransmitter release in an indirect manner through regulation of K(IR)3 channels. © 2015 Wiley Periodicals, Inc.

Beneficial metabolic effects of CB1R anti-sense oligonucleotide treatment in diet-induced obese AKR/J mice.

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Yuting Tang

Full Text Available An increasing amount of evidence supports pleiotropic metabolic roles of the cannibinoid-1 receptor (CB1R in peripheral tissues such as adipose, liver, skeletal muscle and pancreas. To further understand the metabolic consequences of specific blockade of CB1R function in peripheral tissues, we performed a 10-week-study with an anti-sense oligonucleotide directed against the CB1R in diet-induced obese (DIO AKR/J mice. DIO AKR/J mice were treated with CB1R ASO Isis-414930 (6.25, 12.5 and 25 mg/kg/week or control ASO Isis-141923 (25 mg/kg/week via intraperitoneal injection for 10 weeks. At the end of the treatment, CB1R mRNA from the 25 mg/kg/week CB1R ASO group in the epididymal fat and kidney was decreased by 81% and 63%, respectively. Body weight gain was decreased in a dose-dependent fashion, significantly different in the 25 mg/kg/week CB1R ASO group (46.1±1.0 g vs veh, 51.2±0.9 g, p<0.05. Body fat mass was reduced in parallel with attenuated body weight gain. CB1R ASO treatment led to decreased fed glucose level (at week 8, 25 mg/kg/week group, 145±4 mg/dL vs veh, 195±10 mg/dL, p<0.05. Moreover, CB1R ASO treatment dose-dependently improved glucose excursion during an oral glucose tolerance test, whereas control ASO exerted no effect. Liver steatosis was also decreased upon CB1R ASO treatment. At the end of the study, plasma insulin and leptin levels were significantly reduced by 25 mg/kg/week CB1R ASO treatment. SREBP1 mRNA expression was decreased in both epididymal fat and liver. G6PC and fatty acid translocase/CD36 mRNA levels were also reduced in the liver. In summary, CB1R ASO treatment in DIO AKR/J mice led to improved insulin sensitivity and glucose homeostasis. The beneficial effects of CB1R ASO treatment strongly support the notion that selective inhibition of the peripheral CB1R, without blockade of central CB1R, may serve as an effective approach for treating type II diabetes, obesity and the metabolic syndrome.

Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

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Dickenson Anthony H

2009-02-01

Full Text Available Abstract Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1 has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal

Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

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Nguyen, David; Deng, Ping; Matthews, Elizabeth A; Kim, Doo-Sik; Feng, Guoping; Dickenson, Anthony H; Xu, Zao C; Luo, Z David

2009-01-01

Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2δ1) has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia) similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR) neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cavα2δ1 transgenic mice. Our data indicated that overexpression of Cavα2δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal horn neurons to innocuous

Role of Cannabinoid CB2 Receptor Gene (CNR2) Polymorphism in Children with Immune Thrombocytopenic Purpura in Beni-Suef Governorate in Egypt.

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Ezzat, Dina A; Hammam, Amira A; El-Malah, Waleed M; Khattab, Rasha A; Mangoud, Eman M

2017-01-01

The cannabinoid system is involved in the immune regulation by modulation of Th cells type 1 and 2. It is composed of the CB2 receptor which is expressed at 10 to 100 folds greater levels on immune cells than the CB1 receptors. The CB2 is encoded by the cannabinoid CB receptor gene (CNR2) gene. This study aims to investigate the polymorphism in CNR2 gene variation rs 35761398 (Q63R) in Egyptian children with immune thrombocytopenic purpura and to investigate the relation between this gene polymorphism and either the susceptibility to or the chronicity of the disease. Forty children diagnosed as ITP were included in this study and 20 healthy children as normal control. CNR2 gene was investigated in those children by PCR RFLP technique (restriction fragment length polymorphism). CNR2 genotyping revealed that 45% of ITP patients had the QR heterotype, 50% had the RR homotype and 5% had QQ, the wild type with significantly higher frequency of homomutant genotype in comparison to controls. The relative odds ratio suggested a double risk for developing ITP in RR homotype (OR 2.152). A significant overpresentation of the RR genotype and of R allele was observed in the chronic patients (P=0.002 and 0.003, respectively). The associated risk to develop chronic ITP increased more than two folds for the RR homotype (OR=2.854). In conclusion, this study confirms the role of CNR2 Q63R polymorphism in the susceptibility to ITP in children and chronicity of the disease. Copyright© by the Egyptian Association of Immunologists.

The maintenance of cisplatin- and paclitaxel-induced mechanical and cold allodynia is suppressed by cannabinoid CB2 receptor activation and independent of CXCR4 signaling in models of chemotherapy-induced peripheral neuropathy

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Deng Liting

2012-09-01

Full Text Available Abstract Background Chemotherapeutic agents produce dose-limiting peripheral neuropathy through mechanisms that remain poorly understood. We previously showed that AM1710, a cannabilactone CB2 agonist, produces antinociception without producing central nervous system (CNS-associated side effects. The present study was conducted to examine the antinociceptive effect of AM1710 in rodent models of neuropathic pain evoked by diverse chemotherapeutic agents (cisplatin and paclitaxel. A secondary objective was to investigate the potential contribution of alpha-chemokine receptor (CXCR4 signaling to both chemotherapy-induced neuropathy and CB2 agonist efficacy. Results AM1710 (0.1, 1 or 5 mg/kg i.p. suppressed the maintenance of mechanical and cold allodynia in the cisplatin and paclitaxel models. Anti-allodynic effects of AM1710 were blocked by the CB2 antagonist AM630 (3 mg/kg i.p., but not the CB1 antagonist AM251 (3 mg/kg i.p., consistent with a CB2-mediated effect. By contrast, blockade of CXCR4 signaling with its receptor antagonist AMD3100 (10 mg/kg i.p. failed to attenuate mechanical or cold hypersensitivity induced by either cisplatin or paclitaxel. Moreover, blockade of CXCR4 signaling failed to alter the anti-allodynic effects of AM1710 in the paclitaxel model, further suggesting distinct mechanisms of action. Conclusions Our results indicate that activation of cannabinoid CB2 receptors by AM1710 suppresses both mechanical and cold allodynia in two distinct models of chemotherapy-induced neuropathic pain. By contrast, CXCR4 signaling does not contribute to the maintenance of chemotherapy-induced established neuropathy or efficacy of AM1710. Our studies suggest that CB2 receptors represent a promising therapeutic target for the treatment of toxic neuropathies produced by cisplatin and paclitaxel chemotherapeutic agents.

Phosphorylation of synaptotagmin-1 controls a post-priming step in PKC-dependent presynaptic plasticity

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de Jong, Arthur P H; Meijer, Marieke; Saarloos, Ingrid

2016-01-01

Presynaptic activation of the diacylglycerol (DAG)/protein kinase C (PKC) pathway is a central event in short-term synaptic plasticity. Two substrates, Munc13-1 and Munc18-1, are essential for DAG-induced potentiation of vesicle priming, but the role of most presynaptic PKC substrates is not unde......Presynaptic activation of the diacylglycerol (DAG)/protein kinase C (PKC) pathway is a central event in short-term synaptic plasticity. Two substrates, Munc13-1 and Munc18-1, are essential for DAG-induced potentiation of vesicle priming, but the role of most presynaptic PKC substrates...... is not understood. Here, we show that a mutation in synaptotagmin-1 (Syt1(T112A)), which prevents its PKC-dependent phosphorylation, abolishes DAG-induced potentiation of synaptic transmission in hippocampal neurons. This mutant also reduces potentiation of spontaneous release, but only if alternative Ca(2+)sensors...

Cannabinoid Regulation of Brain Reward Processing with an Emphasis on the Role of CB1 Receptors: A Step Back into the Future.

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Panagis, George; Mackey, Brian; Vlachou, Styliani

2014-01-01

Over the last decades, the endocannabinoid system has been implicated in a large variety of functions, including a crucial modulation of brain-reward circuits and the regulation of motivational processes. Importantly, behavioral studies have shown that cannabinoid compounds activate brain reward mechanisms and circuits in a similar manner to other drugs of abuse, such as nicotine, alcohol, cocaine, and heroin, although the conditions under which cannabinoids exert their rewarding effects may be more limited. Furthermore, there is evidence on the involvement of the endocannabinoid system in the regulation of cue- and drug-induced relapsing phenomena in animal models. The aim of this review is to briefly present the available data obtained using diverse behavioral experimental approaches in experimental animals, namely, the intracranial self-stimulation paradigm, the self-administration procedure, the conditioned place preference procedure, and the reinstatement of drug-seeking behavior procedure, to provide a comprehensive picture of the current status of what is known about the endocannabinoid system mechanisms that underlie modification of brain-reward processes. Emphasis is placed on the effects of cannabinoid 1 (CB1) receptor agonists, antagonists, and endocannabinoid modulators. Further, the role of CB1 receptors in reward processes is investigated through presentation of respective genetic ablation studies in mice. The vast majority of studies in the existing literature suggest that the endocannabinoid system plays a major role in modulating motivation and reward processes. However, much remains to be done before we fully understand these interactions. Further research in the future will shed more light on these processes and, thus, could lead to the development of potential pharmacotherapies designed to treat reward-dysfunction-related disorders.

Cannabinoid regulation of brain reward processing with an emphasis on the role of CB1 receptors: a step back into the future

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George ePanagis

2014-07-01

Full Text Available Over the last decades the endocannabinoid system has been implicated in a large variety of functions, including a crucial modulation of brain reward circuits and the regulation of motivational processes. Importantly, behavioural studies have shown that cannabinoid compounds activate brain reward mechanisms and circuits in a similar manner to other drugs of abuse, such as nicotine, alcohol, cocaine and heroin, although the conditions under which cannabinoids exert their rewarding effects may be more limited. Furthermore, there is evidence on the involvement of the endocannabinoid system in the regulation of cue- and drug-induced relapsing phenomena in animal models. The aim of this review is to briefly present the available data obtained using diverse behavioural experimental approaches in experimental animals, namely, the intracranial self-stimulation paradigm, the self-administration procedure, the conditioned place preference procedure and the reinstatement of drug-seeking behaviour procedure, to provide a comprehensive picture of the current status of what is known about the endocannabinoid system mechanisms that underlie modification of brain reward processes. Emphasis is placed on the effects of cannabinoid 1 (CB1 receptor agonists, antagonists and endocannabinoid modulators. Further, the role of CB1 receptors in reward processes is investigated through presentation of respective genetic ablation studies in mice. The vast majority of studies in the existing literature suggests that the endocannabinoid system plays a major role in modulating motivation and reward processes. However, much remains to be done before we fully understand these interactions. Further research in the future will shed more light on these processes and, thus, could lead to the development of potential pharmacotherapies designed to treat reward-dysfunction related disorders.

The Biogenic Amine Tyramine and its Receptor (AmTyr1 in Olfactory Neuropils in the Honey Bee (Apis mellifera Brain

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Irina T. Sinakevitch

2017-10-01

Full Text Available This article describes the cellular sources for tyramine and the cellular targets of tyramine via the Tyramine Receptor 1 (AmTyr1 in the olfactory learning and memory neuropils of the honey bee brain. Clusters of approximately 160 tyramine immunoreactive neurons are the source of tyraminergic fibers with small varicosities in the optic lobes, antennal lobes, lateral protocerebrum, mushroom body (calyces and gamma lobes, tritocerebrum and subesophageal ganglion (SEG. Our tyramine mapping study shows that the primary sources of tyramine in the antennal lobe and calyx of the mushroom body are from at least two Ventral Unpaired Median neurons (VUMmd and VUMmx with cell bodies in the SEG. To reveal AmTyr1 receptors in the brain, we used newly characterized anti-AmTyr1 antibodies. Immunolocalization studies in the antennal lobe with anti-AmTyr1 antibodies showed that the AmTyr1 expression pattern is mostly in the presynaptic sites of olfactory receptor neurons (ORNs. In the mushroom body calyx, anti-AmTyr1 mapped the presynaptic sites of uniglomerular Projection Neurons (PNs located primarily in the microglomeruli of the lip and basal ring calyx area. Release of tyramine/octopamine from VUM (md and mx neurons in the antennal lobe and mushroom body calyx would target AmTyr1 expressed on ORN and uniglomerular PN presynaptic terminals. The presynaptic location of AmTyr1, its structural similarity with vertebrate alpha-2 adrenergic receptors, and previous pharmacological evidence suggests that it has an important role in the presynaptic inhibitory control of neurotransmitter release.

Rational design, synthesis, and pharmacological properties of new 1,8-naphthyridin-2(1H)-on-3-carboxamide derivatives as highly selective cannabinoid-2 receptor agonists

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Manera, Clementina; Saccomanni, Giuseppe; Adinolfi, Barbara

2009-01-01

The CB(2) receptor activation can be exploited for the treatment of diseases such as chronic pain and tumors of immune origin, devoid of psychotropic activity. On the basis of our already reported 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives, new 1,8-naphthyridin-2(1H)-on-3-carboxamide......-dependent decrease of cell viability. The obtained results suggest that 1,8-naphthyridin-2(1H)-on-3-carboxamides represent a new scaffold very suitable for the development of new promising CB(2) agonists....... derivatives were designed, synthesized, and tested for their affinities toward the human CB(1) and CB(2) cannabinoid receptors. Some of the reported compounds showed a subnanomolar CB(2) affinity with a CB(1)/CB(2) selectivity ratio greater than 200 (compounds 6, 12, cis-12, 13, and cis-13). Further studies...

Optimization of cAMP fluorescence dataset from ACTOne cannabinoid receptor 1 cell line

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Chaela S. Presley

2016-06-01

Full Text Available The ACTOne cannabinoid receptor 1 functional system is comprised of transfected HEK cells with the parental cyclic nucleotide gated channel (CNG co-transfected with cannabinoid receptor 1 (CB1. The ACTOne CB1 cell line was evaluated for cAMP driven fluorescence by optimizing experimental conditions for sensitivity to forskolin and CP 55,940, reading time point, reliability of cell passage number, and pertussis inactivation of Gi/o.

Evidence for CB2 receptor involvement in LPS-induced reduction of cAMP intracellular levels in uterine explants from pregnant mice: pathophysiological implications.

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Salazar, Ana Inés; Carozzo, Alejandro; Correa, Fernando; Davio, Carlos; Franchi, Ana María

2017-07-01

What is the role of the endocannabinoid system (eCS) on the lipopolysaccharide (LPS) effects on uterine explants from 7-day pregnant mice in a murine model of endotoxin-induced miscarriage? We found evidence for cannabinoid receptor type2 (CB2) involvement in LPS-induced increased prostaglandin-F2α (PGF2α) synthesis and diminished cyclic adenosine monophosphate (cAMP) intracellular content in uterine explants from early pregnant mice. Genital tract infections by Gram-negative bacteria are a common complication of human pregnancy that results in an increased risk of pregnancy loss. LPS, the main component of the Gram-negative bacterial wall, elicits a strong maternal inflammatory response that results in embryotoxicity and embryo resorption in a murine model endotoxin-induced early pregnancy loss. We have previously shown that the eCS mediates the embryotoxic effects of LPS, mainly via CB1 receptor activation. An in vitro study of mice uterine explants was performed to investigate the eCS in mediating the effects of LPS on PGF2α production and cAMP intracellular content. Eight to 12-week-old virgin female BALB/c or CD1 (wild-type [WT] or CB1-knockout [CB1-KO]) mice were paired with 8- to 12-week-old BALB/c or CD1 (WT or CB1-KO) males, respectively. On day 7 of pregnancy, BALB/c, CD1 WT or CD1 CB1-KO mice were euthanized, the uteri were excised, implantation sites were removed and the uterine tissues were separated from decidual and embryo tissues. Uterine explants were cultured and exposed for an appropriate amount of time to different pharmacological treatments. The tissues were then collected for cAMP assay and PGF2α content determination by radioimmunoassay. In vitro treatment of uteri explants from 7-day pregnant BALB/c or CD1 (WT or CB1-KO) mice with LPS induced an increased production of PGF2α (P Investigaciones Científicas y Técnicas (PIP 2012/0061). Dr Carlos Davio was funded by Agencia Nacional para la Promoción Científica y Tecnológica (PICT 2013

Enhanced self-administration of the CB1 receptor agonist WIN55,212-2 in olfactory bulbectomized rats: evaluation of possible serotonergic and dopaminergic underlying mechanisms

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Petra eAmchova

2014-03-01

Full Text Available Depression has been associated with drug consumption, including heavy or problematic cannabis use. According to an animal model of depression and substance use disorder comorbidity, we combined the olfactory bulbectomy model of depression with intravenous drug self-administration procedure to verify whether depressive-like rats displayed higher voluntary intake of the CB1 receptor agonist WIN55,212-2 (WIN, 12.5 µg/kg/infusion. To this aim, olfactory-bulbectomized (OBX and sham-operated (SHAM Lister Hooded rats were allowed to self-administer WIN by lever-pressing under a continuous (FR-1 schedule of reinforcement in 2h daily sessions. Data showed that both OBX and SHAM rats developed stable WIN intake; yet, responses in OBX were constantly higher than in SHAM rats soon after the first week of training. In addition, OBX rats took significantly longer to extinguish the drug-seeking behaviour after vehicle substitution. Acute pre-treatment with serotonin 5HT1B receptor agonist, CGS-12066B (2.5-10 mg/kg, did not significantly modify WIN intake in OBX and SHAM Lister Hooded rats. Furthermore, acute pre-treatment with CGS-12066B (10 and 15 mg/kg did not alter responses in parallel groups of OBX and SHAM Sprague Dawley rats self-administering methamphetamine under higher (FR-2 reinforcement schedule with nose-poking as operandum. Finally, dopamine levels in the nucleus accumbens of OBX rats did not increase in response to a WIN challenge, as in SHAM rats, indicating a dopaminergic dysfunction in bulbectomized rats. Altogether, our findings suggest that a depressive state may alter cannabinoid CB1 receptor agonist-induced brain reward function and that a dopaminergic rather than a 5-HT1B mechanism is likely to underlie enhanced WIN self-administration in OBX rats.

Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10−/− mice by attenuating the activation of T cells and promoting their apoptosis

International Nuclear Information System (INIS)

Singh, Udai P.; Singh, Narendra P.; Singh, Balwan; Price, Robert L.; Nagarkatti, Mitzi; Nagarkatti, Prakash S.

2012-01-01

Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10 −/− mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10 −/− mice. After JWH-133 treatment, the percentage of CD4 + T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ► JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ► JWH-133 suppressed inflammation and toxicity to colon

Cannabinoid 1 receptor knockout mice display cold allodynia, but enhanced recovery from spared-nerve injury-induced mechanical hypersensitivity.

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Sideris, Alexandra; Piskoun, Boris; Russo, Lori; Norcini, Monica; Blanck, Thomas; Recio-Pinto, Esperanza

2016-01-01

The function of the Cannabinoid 1 receptor (CB1R) in the development of neuropathic pain is not clear. Mounting evidence suggest that CB1R expression and activation may contribute to pain. Cannabinoid 1 receptor knockout mice (CB1R-/-) generated on a C57Bl/6 background exhibit hypoalgesia in the hotplate assay and formalin test. These findings suggest that Cannabinoid 1 receptor expression mediates the responses to at least some types of painful stimuli. By using this mouse line, we sought to determine if the lack of Cannabinoid 1 receptor unveils a general hypoalgesic phenotype, including protection against the development of neuropathic pain. The acetone test was used to measure cold sensitivity, the electronic von Frey was used to measure mechanical thresholds before and after spared-nerve injury, and analysis of footprint patterns was conducted to determine if motor function is differentially affected after nerve-injury in mice with varying levels of Cannabinoid 1 receptor. At baseline, CB1R-/- mice were hypersensitive in the acetone test, and this phenotype was maintained after spared-nerve injury. Using calcium imaging of lumbar dorsal root ganglion (DRG) cultures, a higher percentage of neurons isolated from CB1R-/- mice were menthol sensitive relative to DRG isolated from wild-type (CB1R+/+) mice. Baseline mechanical thresholds did not differ among genotypes, and mechanical hypersensitivity developed similarly in the first two weeks following spared-nerve injury (SNI). At two weeks post-SNI, CB1R-/- mice recovered significantly from mechanical hypersensitivity, while the CB1R+/+ mice did not. Heterozygous knockouts (CB1R+/-) transiently developed cold allodynia only after injury, but recovered mechanical thresholds to a similar extent as the CB1R-/- mice. Sciatic functional indices, which reflect overall nerve health, and alternation coefficients, which indicate uniformity of strides, were not significantly different among genotypes. Cold allodynia and

Potential upstream regulators of cannabinoid receptor 1 signaling in prostate cancer: a Bayesian network analysis of data from a tissue microarray.

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Häggström, Jenny; Cipriano, Mariateresa; Forshell, Linus Plym; Persson, Emma; Hammarsten, Peter; Stella, Nephi; Fowler, Christopher J

2014-08-01

The endocannabinoid system regulates cancer cell proliferation, and in prostate cancer a high cannabinoid CB1 receptor expression is associated with a poor prognosis. Down-stream mediators of CB1 receptor signaling in prostate cancer are known, but information on potential upstream regulators is lacking. Data from a well-characterized tumor tissue microarray were used for a Bayesian network analysis using the max-min hill-climbing method. In non-malignant tissue samples, a directionality of pEGFR (the phosphorylated form of the epidermal growth factor receptor) → CB1 receptors were found regardless as to whether the endocannabinoid metabolizing enzyme fatty acid amide hydrolase (FAAH) was included as a parameter. A similar result was found in the tumor tissue, but only when FAAH was included in the analysis. A second regulatory pathway, from the growth factor receptor ErbB2 → FAAH was also identified in the tumor samples. Transfection of AT1 prostate cancer cells with CB1 receptors induced a sensitivity to the growth-inhibiting effects of the CB receptor agonist CP55,940. The sensitivity was not dependent upon the level of receptor expression. Thus a high CB1 receptor expression alone does not drive the cells towards a survival phenotype in the presence of a CB receptor agonist. The data identify two potential regulators of the endocannabinoid system in prostate cancer and allow the construction of a model of a dysregulated endocannabinoid signaling network in this tumor. Further studies should be designed to test the veracity of the predictions of the network analysis in prostate cancer and other solid tumors. © 2014 The Authors. The Prostate published by Wiley Periodicals, Inc.

Effects of a selective cannabinoid CB2 agonist and antagonist on intravenous nicotine self administration and reinstatement of nicotine seeking.

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Islam Gamaleddin

Full Text Available Over the last decade there have been significant advances in the discovery and understanding of the cannabinoid system along with the development of pharmacologic tools that modulate its function. Characterization of the crosstalk between nicotine addiction and the cannabinoid system may have significant implications on our understanding of the neurobiological mechanisms underlying nicotine dependence. Two types of cannabinoid receptors (CB1 and CB2 have been identified. CB1 receptors are expressed in the brain and modulate drug taking and drug seeking for various drugs of abuse, including nicotine. CB2 receptors have been recently identified in the brain and have been proposed to play a functional role in mental disorders and drug addiction. Our objective was to explore the role of CB2 receptors on intravenous nicotine self administration under two schedules of reinforcement (fixed and progressive ratio and on nicotine seeking induced by nicotine priming or by nicotine associated cues. For this, we evaluated the effects of various doses of the selective CB2 antagonist AM630 (1.25 to 5 mg/kg and CB2 agonist AM1241 (1 to 10 mg/kg on these behavioral responses in rats. Different groups of male Long Evans rats were trained to lever press for nicotine at a unit dose of 30 µg/kg/infusion. Subsequently, animals were randomized using a Latin-square design and injected with either AM1241 or AM630 using a counterbalanced within subject design. Administration of the CB2 ligands did not affect either nicotine-taking nicotine-seeking behavior. Our results do not support the involvement of CB2 receptors in nicotine-taking or nicotine-seeking behavior.

Polymorphisms in the endocannabinoid receptor 1 in relation to fat mass distribution

DEFF Research Database (Denmark)

Frost, M; Nielsen, T L; Wraae, K

2010-01-01

Both animal and human studies have associated the endocannabinoid system with obesity and markers of metabolic dysfunction. Blockade of the cannabinoid receptor 1 (CB1) caused weight loss and reduction in waist size in both obese and type II diabetics. Recent studies on common variants of the CB1...... receptor gene (CNR1) and the link to obesity have been conflicting. The aim of the present study was to evaluate whether selected common variants of the CNR1 are associated with measures of obesity and fat distribution....

Presynaptic excitability.

Science.gov (United States)

Jackson, M B

1995-01-01

+ channels. In four of the five preparations reviewed in this chapter--motor nerve, squid giant synapse, ciliary ganglion, and retina bipolar neurons--evidence was presented that supports a location for Ca2+ channels that is very close to active zones of secretion. All of these synapses secrete from clear vesicles, and the speed and specificity of transduction provided by proximity may be a common feature of these rapid synapses. In contrast, the posterior pituitary secretion apparatus may be triggered by higher-affinity Ca2+ receptors and lower concentrations of Ca2+ (Lindau et al., 1992). This would correspond with the slower performance of peptidergic secretion, but because of the large stimuli needed to evoke release from neurosecretosomes, the possibility remains that the threshold for secretion is higher than that reported. While the role of Ca2+ as a trigger of secretion dictates a requirement for voltage-activated Ca2+ channels as universal components of the presynaptic membrane, the presence of other channels is more difficult to predict. Depolarizations caused by voltage-activated Na+ channels activate the presynaptic Ca2+ channels, but whether this depolarization requires Na+ channels in the presynaptic membrane itself may depend on the electrotonic length of the nerve terminal. Variations in density between motor nerve terminals may reflect species differences in geometry. The high Na+ channel density in the posterior pituitary reflects the great electrotonic length of this terminal arbor. Whether Na+ channels are abundant or not in a presynaptic membrane, K+ channels provide the most robust mechanism for limiting depolarization-induced Ca2+ entry. K+ channel blockers enhance transmission at most synapses. In general, K+ channels are abundant in nerve terminals, although their apparent lower priority compared to Ca2+ channels in the eyes of many investigators leaves us with fewer detailed investigations in some preparations. Most nerve terminals have more than

Evidence for presynaptically silent synapses in the immature hippocampus

International Nuclear Information System (INIS)

Yoon, Jae Young; Choi, Sukwoo

2017-01-01

Silent synapses show NMDA receptor (NMDAR)-mediated synaptic responses, but not AMPAR-mediated synaptic responses. A prevailing hypothesis states that silent synapses contain NMDARs, but not AMPARs. However, alternative presynaptic hypotheses, according to which AMPARs are present at silent synapses, have been proposed; silent synapses show slow glutamate release via a fusion pore, and glutamate spillover from the neighboring synaptic terminals. Consistent with these presynaptic hypotheses, the peak glutamate concentrations at silent synapses have been estimated to be ≪170 μM, much lower than those seen at functional synapses. Glutamate transients predicted based on the two presynaptic mechanisms have been shown to activate only high-affinity NMDARs, but not low-affinity AMPARs. Interestingly, a previous study has developed a new approach to distinguish between the two presynaptic mechanisms using dextran, an inert macromolecule that reduces the diffusivity of released glutamate: postsynaptic responses through the fusion pore mechanism, but not through the spillover mechanism, are potentiated by reduced glutamate diffusivity. Therefore, we reasoned that if the fusion pore mechanism underlies silent synapses, dextran application would reveal AMPAR-mediated synaptic responses at silent synapses. In the present study, we recorded AMPAR-mediated synaptic responses at the CA3-CA1 synapses in neonatal rats in the presence of blockers for NMDARs and GABAARs. Bath application of dextran revealed synaptic responses at silent synapses. GYKI53655, a selective AMPAR-antagonist, completely inhibited the unsilenced synaptic responses, indicating that the unsilenced synaptic responses are mediated by AMPARs. The dextran-mediated reduction in glutamate diffusivity would also lead to the activation of metabotropic glutamate receptors (mGluRs), which might induce unsilencing via the activation of unknown intracellular signaling. Hence, we determined whether mGluR-blockers alter

Multiple sleep alterations in mice lacking cannabinoid type 1 receptors.

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Alessandro Silvani

Full Text Available Cannabinoid type 1 (CB1 receptors are highly expressed in the brain and play a role in behavior control. Endogenous cannabinoid signaling is modulated by high-fat diet (HFD. We investigated the consequences of congenital lack of CB1 receptors on sleep in mice fed standard diet (SD and HFD. CB1 cannabinoid receptor knock-out (KO and wild-type (WT mice were fed SD or HFD for 4 months (n = 9-10 per group. Mice were instrumented with electroencephalographic (EEG and electromyographic electrodes. Recordings were performed during baseline (48 hours, sleep deprivation (gentle handling, 6 hours, sleep recovery (18 hours, and after cage switch (insomnia model paradigm, 6 hours. We found multiple significant effects of genotype on sleep. In particular, KO spent more time awake and less time in non-rapid-eye-movement sleep (NREMS and rapid-eye-movement sleep (REMS than WT during the dark (active period but not during the light (rest period, enhancing the day-night variation of wake-sleep amounts. KO had slower EEG theta rhythm during REMS. REMS homeostasis after sleep deprivation was less effective in KO than in WT. Finally, KO habituated more rapidly to the arousing effect of the cage-switch test than WT. We did not find any significant effects of diet or of diet x genotype interaction on sleep. The occurrence of multiple sleep alterations in KO indicates important roles of CB1 cannabinoid receptors in limiting arousal during the active period of the day, in sleep regulation, and in sleep EEG in mice.

Impaired fear memory specificity associated with deficient endocannabinoid-dependent long-term plasticity.

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Lovelace, Jonathan W; Vieira, Philip A; Corches, Alex; Mackie, Ken; Korzus, Edward

2014-06-01

In addition to its central role in learning and memory, N-methyl D-aspartate receptor (NMDAR)-dependent signaling regulates central glutamatergic synapse maturation and has been implicated in schizophrenia. We have transiently induced NMDAR hypofunction in infant mice during postnatal days 7-11, followed by testing fear memory specificity and presynaptic plasticity in the prefrontal cortex (PFC) in adult mice. We show that transient NMDAR hypofunction during early brain development, coinciding with the maturation of cortical plasticity results in a loss of an endocannabinoid (eCB)-mediated form of long-term depression (eCB-LTD) at adult central glutamatergic synapses, while another form of presynaptic long-term depression mediated by the metabotropic glutamate receptor 2/3 (mGluR2/3-LTD) remains intact. Mice with this selective impairment of presynaptic plasticity also showed deficits in fear memory specificity. The observed deficit in cortical presynaptic plasticity may represent a neural maladaptation contributing to network instability and abnormal cognitive functioning.

Cannabinoid receptor-2 (CB2) agonist ameliorates colitis in IL-10{sup −/−} mice by attenuating the activation of T cells and promoting their apoptosis

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Singh, Udai P.; Singh, Narendra P. [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Singh, Balwan [National Primate Research Center, Emory University, Atlanta GA 30329 (United States); Price, Robert L. [Department of Cell and Developmental Biology, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Mitzi [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States); Nagarkatti, Prakash S., E-mail: Prakash.Nagarkatti@uscmed.sc.edu [Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC 29208 (United States)

2012-01-15

Inflammatory bowel disease (IBD) is a chronic intestinal inflammation caused by hyperactivated effector immune cells that produce pro-inflammatory cytokines. Recent studies have shown that the cannabinoid system may play a critical role in mediating protection against intestinal inflammation. However, the effect of cannabinoid receptor induction after chronic colitis progression has not been investigated. Here, we investigate the effect of cannabinoid receptor-2 (CB2) agonist, JWH-133, after chronic colitis in IL-10{sup −/−} mice. JWH-133 effectively attenuated the overall clinical score, and reversed colitis-associated pathogenesis and decrease in body weight in IL-10{sup −/−} mice. After JWH-133 treatment, the percentage of CD4{sup +} T cells, neutrophils, mast cells, natural killer (NK1.1) cells, and activated T cells declined in the intestinal lamina propria (LP) and mesenteric lymph nodes (MLN) of mice with chronic colitis. JWH-133 was also effective in ameliorating dextran sodium sulfate (DSS)-induced colitis. In this model, JWH-133 reduced the number and percentage of macrophages and IFN-γ expressing cells that were induced during colitis progression. Treatment with aminoalkylindole 6-iodo-pravadoline (AM630), a CB2 receptor antagonist, reversed the colitis protection provided by JWH-133 treatment. Also, activated T cells were found to undergo apoptosis following JWH-133 treatment both in-vivo and in-vitro. These findings suggest that JWH-133 mediates its effect through CB2 receptors, and ameliorates chronic colitis by inducing apoptosis in activated T cells, reducing the numbers of activated T cells, and suppressing induction of mast cells, NK cells, and neutrophils at sites of inflammation in the LP. These results support the idea that the CB2 receptor agonists may serve as a therapeutic modality against IBD. -- Highlights: ► JWH-133, a cannnabinoid receptor-2 agonist ameliorates experimental colitis. ► JWH-133 suppressed inflammation and

Evaluation of the In Vivo and Ex Vivo Binding of Novel BC1 Cannabinoid Receptor Radiotracers

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Miller, A.; Gatley, J.; Gifford, A.

2002-01-01

The primary active ingredient of marijuana, 9-tetrahydrocannabinol, exerts its psychoactive effects by binding to cannabinoid CB1 receptors. These receptors are found throughout the brain with high concentrations in the hippocampus and cerebellum. The current study was conducted to evaluate the binding of a newly developed putative cannabinoid antagonist, AM630, and a classical cannabinoid 8-tetrahydrocannabinol as potential PET and/or SPECT imaging agents for brain CB1 receptors. For both of these ligands in vivo and ex vivo studies in mice were conducted. AM630 showed good overall brain uptake (as measure by %IA/g) and a moderately rapid clearance from the brain with a half-clearance time of approximately 30 minutes. However, AM630 did not show selective binding to CB1 cannabinoid receptors. Ex vivo autoradiography supported the lack of selective binding seen in the in vivo study. Similar to AM630, 8-tetrahydrocanibol also failed to show selective binding to CB1 receptor rich brain areas. The 8-tetrahydrocanibol showed moderate overall brain uptake and relatively slow brain clearance as compared to AM630. Further studies were done with AM2233, a cannabinoid ligand with a similar structure as AM630. These studies were done to develop an ex vivo binding assay to quantify the displacement of [131I]AM2233 binding by other ligands in Swiss-Webster and CB1 receptor knockout mice. By developing this assay we hoped to determine the identity of an unknown binding site for AM2233 present in the hippocampus of CB1 knockout mice. Using an approach based on incubation of brain slices prepared from mice given intravenous [131I]AM2233 in either the presence or absence of AM2233 (unlabelled) it was possible to demonstrate a significant AM2233-displacable binding in the Swiss-Webster mice. Future studies will determine if this assay is appropriate for identifying the unknown binding site for AM2233 in the CB1 knockout mice.

Presynaptic inhibition of spontaneous acetylcholine release induced by adenosine at the mouse neuromuscular junction.

Science.gov (United States)

De Lorenzo, Silvana; Veggetti, Mariela; Muchnik, Salomón; Losavio, Adriana

2004-05-01

1. At the mouse neuromuscular junction, adenosine (AD) and the A(1) agonist 2-chloro-N(6)-cyclopentyl-adenosine (CCPA) induce presynaptic inhibition of spontaneous acetylcholine (ACh) release by activation of A(1) AD receptors through a mechanism that is still unknown. To evaluate whether the inhibition is mediated by modulation of the voltage-dependent calcium channels (VDCCs) associated with tonic secretion (L- and N-type VDCCs), we measured the miniature end-plate potential (mepp) frequency in mouse diaphragm muscles. 2. Blockade of VDCCs by Cd(2+) prevented the effect of the CCPA. Nitrendipine (an L-type VDCC antagonist) but not omega-conotoxin GVIA (an N-type VDCC antagonist) blocked the action of CCPA, suggesting that the decrease in spontaneous mepp frequency by CCPA is associated with an action on L-type VDCCs only. 3. As A(1) receptors are coupled to a G(i/o) protein, we investigated whether the inhibition of PKA or the activation of PKC is involved in the presynaptic inhibition mechanism. Neither N-(2[p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide (H-89, a PKA inhibitor), nor 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine (H-7, a PKC antagonist), nor phorbol 12-myristate 13-acetate (PHA, a PKC activator) modified CCPA-induced presynaptic inhibition, suggesting that these second messenger pathways are not involved. 4. The effect of CCPA was eliminated by the calmodulin antagonist N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) and by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-acetoxymethyl ester epsilon6TDelta-BM, which suggests that the action of CCPA to modulate L-type VDCCs may involve Ca(2+)-calmodulin. 5. To investigate the action of CCPA on diverse degrees of nerve terminal depolarization, we studied its effect at different external K(+) concentrations. The effect of CCPA on ACh secretion evoked by 10 mm K(+) was prevented by the P/Q-type VDCC antagonist omega-agatoxin IVA. 6. CCPA failed to

Ciproxifan, a histamine H{sub 3} receptor antagonist and inverse agonist, presynaptically inhibits glutamate release in rat hippocampus

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Lu, Cheng-Wei; Lin, Tzu-Yu [Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan (China); Department of Mechanical Engineering, Yuan Ze University, Taoyuan 320, Taiwan (China); Chang, Chia-Ying [Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan (China); Department of Chemistry, Fu Jen Catholic University, No. 510, Chung-Cheng Road, Hsin-Chuang District, New Taipei City 24205, Taiwan (China); Huang, Shu-Kuei [Department of Anesthesiology, Far-Eastern Memorial Hospital, Pan-Chiao District, New Taipei City 22060, Taiwan (China); Wang, Su-Jane, E-mail: med0003@mail.fju.edu.tw [School of Medicine, Fu Jen Catholic University, No. 510, Chung-Cheng Rd., Hsin-Chuang, New Taipei 24205, Taiwan (China); Research Center for Chinese Herbal Medicine, College of Human Ecology, Chang Gung University of Science and Technology, Taoyuan City, Taiwan (China)

2017-03-15

Ciproxifan is an H{sub 3} receptor antagonist and inverse agonist with antipsychotic effects in several preclinical models; its effect on glutamate release has been investigated in the rat hippocampus. In a synaptosomal preparation, ciproxifan reduced 4-aminopyridine (4-AP)-evoked Ca{sup 2+}-dependent glutamate release and cytosolic Ca{sup 2+} concentration elevation but did not affect the membrane potential. The inhibitory effect of ciproxifan on 4-AP-evoked glutamate release was prevented by the Gi/Go-protein inhibitor pertussis toxin and Ca{sub v}2.2 (N-type) and Ca{sub v}2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, but was not affected by the intracellular Ca{sup 2+}-release inhibitors dantrolene and CGP37157. Furthermore, the phospholipase A{sub 2} (PLA{sub 2}) inhibitor OBAA, prostaglandin E{sub 2} (PGE{sub 2}), PGE2 subtype 2 (EP{sub 2}) receptor antagonist PF04418948, and extracellular signal-regulated kinase (ERK) inhibitor FR180204 eliminated the inhibitory effect of ciproxifan on glutamate release. Ciproxifan reduced the 4-AP-evoked phosphorylation of ERK and synapsin I, a presynaptic target of ERK. The ciproxifan-mediated inhibition of glutamate release was prevented in synaptosomes from synapsin I-deficient mice. Moreover, ciproxifan reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude in hippocampal slices. Our data suggest that ciproxifan, acting through the blockade of Gi/Go protein-coupled H{sub 3} receptors present on hippocampal nerve terminals, reduces voltage-dependent Ca{sup 2+} entry by diminishing PLA{sub 2}/PGE{sub 2}/EP{sub 2} receptor pathway, which subsequently suppresses the ERK/synapsin I cascade to decrease the evoked glutamate release. - Highlights: • Ciproxifan presynaptically reduces glutamate release in the hippocampus in vitro. • Decrease in voltage-dependent Ca{sup 2+} influx is involved. • A role for the PLA{sub 2}/PGE{sub 2}/EP{sub 2} pathway in the action of

Small-animal PET imaging of the type 1 and type 2 cannabinoid receptors in a photothrombotic stroke model

International Nuclear Information System (INIS)

Vandeputte, Caroline; Casteels, Cindy; Koole, Michel; Gerits, Anneleen; Struys, Tom; Veghel, Daisy van; Evens, Nele; Bormans, Guy; Dresselaers, Tom; Himmelreich, Uwe; Lambrichts, Ivo; Laere, Koen van

2012-01-01

Recent ex vivo and pharmacological evidence suggests involvement of the endocannabinoid system in the pathophysiology of stroke, but conflicting roles for type 1 and 2 cannabinoid receptors (CB 1 and CB 2 ) have been suggested. The purpose of this study was to evaluate CB 1 and CB 2 receptor binding over time in vivo in a rat photothrombotic stroke model using PET. CB 1 and CB 2 microPET imaging was performed at regular time-points up to 2 weeks after stroke using [ 18 F]MK-9470 and [ 11 C]NE40. Stroke size was measured using MRI at 9.4 T. Ex vivo validation was performed via immunostaining for CB 1 and CB 2 . Immunofluorescent double stainings were also performed with markers for astrocytes (GFAP) and macrophages/microglia (CD68). [ 18 F]MK-9470 PET showed a strong increase in CB 1 binding 24 h and 72 h after stroke in the cortex surrounding the lesion, extending to the insular cortex 24 h after surgery. These alterations were consistently confirmed by CB 1 immunohistochemical staining. [ 11 C]NE40 did not show any significant differences between stroke and sham-operated animals, although staining for CB 2 revealed minor immunoreactivity at 1 and 2 weeks after stroke in this model. Both CB 1 + and CB 2 + cells showed minor immunoreactivity for CD68. Time-dependent and regionally strongly increased CB 1 , but not CB 2 , binding are early consequences of photothrombotic stroke. Pharmacological interventions should primarily aim at CB 1 signalling as the role of CB 2 seems minor in the acute and subacute phases of stroke. (orig.)

Role of hypothalamic cannabinoid receptors in post-stroke depression in rats.

Science.gov (United States)

Wang, Shanshan; Sun, Hong; Liu, Sainan; Wang, Ting; Guan, Jinqun; Jia, Jianjun

2016-03-01

One of the most common psychological consequences of stroke is post-stroke depression (PSD). While more than 30 percent of stroke patients eventually develop PSD, the neurobiological mechanisms underlying such a phenomenon have not been well investigated. Given the critical involvement of hypothalamic-pituitary-adrenal axis and endocannabinoid system in response to stressful stimuli, we evaluated the hypothesis that cannabinoid receptors in the hypothalamus are critical for modulation of post-stroke depression-like behaviors in rats. To this end, rats were treated with middle cerebral artery occlusion (MCAO) followed by chronic unpredictable mild stress (CUMS) treatment procedure. We then assessed the expression of CB1 and CB2 receptors in the hypothalamus, and evaluated the effects of pharmacological stimulations of CB1 or CB2 receptors on the expression and development of depression-like behaviors in PSD rats. We found that PSD rats exhibited decreased the expression of CB1 receptor, but not CB2 receptor, in the ventral medial hypothalamus (VMH). Such an effect was not observed in the dorsally adjacent brain regions. Furthermore, intra-VMH injections of CB2 receptor agonist, but not CB1 receptor agonist, attenuated the expression of depression-like behaviors in PSD rats. Finally, repeated intraperitoneal injections of CB1 or CB2 receptor agonists during CUMS treatment inhibited the development of depression-like behaviors in PSD rats. Taken together, these results suggest that decreased CB1 receptor expression is likely associated with the development of post-stroke depression, and CB2 receptor may be a potential therapeutic target for the treatment post-stroke depressive disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

Cannabinoid modulation of drug reward and the implications of marijuana legalization.

Science.gov (United States)

Covey, Dan P; Wenzel, Jennifer M; Cheer, Joseph F

2015-12-02

Marijuana is the most popular illegal drug worldwide. Recent trends indicate that this may soon change; not due to decreased marijuana use, but to an amendment in marijuana's illegal status. The cannabinoid type 1 (CB1) receptor mediates marijuana's psychoactive and reinforcing properties. CB1 receptors are also part of the brain endocannabinoid (eCB) system and support numerous forms of learning and memory, including the conditioned reinforcing properties of cues predicting reward or punishment. This is accomplished via eCB-dependent alterations in mesolimbic dopamine function, which plays an obligatory role in reward learning and motivation. Presynaptic CB1 receptors control midbrain dopamine neuron activity and thereby shape phasic dopamine release in target regions, particularly the nucleus accumbens (NAc). By also regulating synaptic input to the NAc, CB1 receptors modulate NAc output onto downstream neurons of the basal ganglia motor circuit, and thereby support goal-directed behaviors. Abused drugs promote short- and long-term adaptations in eCB-regulation of mesolimbic dopamine function, and thereby hijack neural systems related to the pursuit of rewards to promote drug abuse. By pharmacologically targeting the CB1 receptors, marijuana has preferential access to this neuronal system and can potently alter eCB-dependent processing of reward-related stimuli. As marijuana legalization progresses, greater access to this drug should increase the utility of marijuana as a research tool to better understand the eCB system, which has the potential to advance cannabinoid-based treatments for drug addiction. Copyright © 2014 Elsevier B.V. All rights reserved.

Small-animal PET imaging of the type 1 and type 2 cannabinoid receptors in a photothrombotic stroke model

Energy Technology Data Exchange (ETDEWEB)

Vandeputte, Caroline; Casteels, Cindy; Koole, Michel; Gerits, Anneleen [KU Leuven, Division of Nuclear Medicine, Leuven (Belgium); KU Leuven, Molecular Small Animal Imaging Center, MoSAIC, Leuven (Belgium); Struys, Tom [Hasselt University, Laboratory of Histology, Biomedical Research Institute, Hasselt (Belgium); KU Leuven, Biomedical NMR Unit, Leuven (Belgium); Veghel, Daisy van; Evens, Nele; Bormans, Guy [KU Leuven, Molecular Small Animal Imaging Center, MoSAIC, Leuven (Belgium); KU Leuven, Laboratory of Radiopharmacy, Leuven (Belgium); Dresselaers, Tom; Himmelreich, Uwe [KU Leuven, Molecular Small Animal Imaging Center, MoSAIC, Leuven (Belgium); KU Leuven, Biomedical NMR Unit, Leuven (Belgium); Lambrichts, Ivo [Hasselt University, Laboratory of Histology, Biomedical Research Institute, Hasselt (Belgium); Laere, Koen van [KU Leuven, Division of Nuclear Medicine, Leuven (Belgium); KU Leuven, Molecular Small Animal Imaging Center, MoSAIC, Leuven (Belgium); UZ Leuven, Division of Nuclear Medicine, Leuven (Belgium)

2012-11-15

Recent ex vivo and pharmacological evidence suggests involvement of the endocannabinoid system in the pathophysiology of stroke, but conflicting roles for type 1 and 2 cannabinoid receptors (CB{sub 1} and CB{sub 2}) have been suggested. The purpose of this study was to evaluate CB{sub 1} and CB{sub 2} receptor binding over time in vivo in a rat photothrombotic stroke model using PET. CB{sub 1} and CB{sub 2} microPET imaging was performed at regular time-points up to 2 weeks after stroke using [{sup 18}F]MK-9470 and [{sup 11}C]NE40. Stroke size was measured using MRI at 9.4 T. Ex vivo validation was performed via immunostaining for CB{sub 1} and CB{sub 2}. Immunofluorescent double stainings were also performed with markers for astrocytes (GFAP) and macrophages/microglia (CD68). [{sup 18}F]MK-9470 PET showed a strong increase in CB{sub 1} binding 24 h and 72 h after stroke in the cortex surrounding the lesion, extending to the insular cortex 24 h after surgery. These alterations were consistently confirmed by CB{sub 1} immunohistochemical staining. [{sup 11}C]NE40 did not show any significant differences between stroke and sham-operated animals, although staining for CB{sub 2} revealed minor immunoreactivity at 1 and 2 weeks after stroke in this model. Both CB{sub 1} {sup +} and CB{sub 2} {sup +} cells showed minor immunoreactivity for CD68. Time-dependent and regionally strongly increased CB{sub 1}, but not CB{sub 2}, binding are early consequences of photothrombotic stroke. Pharmacological interventions should primarily aim at CB{sub 1} signalling as the role of CB{sub 2} seems minor in the acute and subacute phases of stroke. (orig.)

A critical review of both the synthesis approach and the receptor profile of the 8-chloro-1-(2',4'-dichlorophenyl)-N-piperidin-1-yl-1,4,5,6-tetrahydrobenzo[6,7]cyclohepta[1,2-c]pyrazole-3-carboxamide and analogue derivatives.

Science.gov (United States)

Lazzari, Paolo; Distinto, Rita; Manca, Ilaria; Baillie, Gemma; Murineddu, Gabriele; Pira, Marilena; Falzoi, Matteo; Sani, Monica; Morales, Paula; Ross, Ruth; Zanda, Matteo; Jagerovic, Nadine; Pinna, Gérard Aimè

2016-10-04

8-Chloro-1-(2',4'-dichlorophenyl)-N-piperidin-1-yl-1,4,5,6-tetrahydrobenzo[6,7]cyclohepta[1,2-c]pyrazole-3-carboxamide 9a was discovered as potent and selective CB1 antagonist by part of our group few years ago. In particular it was reported to have an affinity towards the CB1 cannabinoid receptor (CB1R), expressed as Ki, of 0.00035 nM. Nevertheless significantly divergent data were reported for the same compound from other laboratories. To unequivocally define the receptor profile of 9a, we have critically reviewed both its synthesis approach and binding data. Here we report that, in contrast to our previously reported data, 9a showed a Ki value for CB1R in the order of nanomolar rather than of fentomolar range. The new determined receptor profile of 9a was also ascertained for analogue derivatives 9b-i, as well as for 12. Moreover, the structural features of the synthesized compounds necessary for CB1R were investigated. Amongst the novel series, effects on CB1R intrinsic activity was highlighted due to the substituents at the position 3 of the pyrazole ring of the 1,4,5,6-tetrahydrobenzo[6,7]cyclohepta[1,2-c]pyrazole scaffold. Although the cannabinoid receptor profile of 9a was reviewed in this work, the relevance of this compound in CB1R antagonist based drug discovery is confirmed. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Type 1 cannabinoid receptor mapping with [18F]MK-9470 PET in the rat brain after quinolinic acid lesion: a comparison to dopamine receptors and glucose metabolism

International Nuclear Information System (INIS)

Casteels, Cindy; Martinez, Emili; Camon, Lluisa; Vera, Nuria de; Planas, Anna M.; Bormans, Guy; Baekelandt, Veerle; Laere, Koen van

2010-01-01

Several lines of evidence imply early alterations in metabolic, dopaminergic and endocannabinoid neurotransmission in Huntington's disease (HD). Using [ 18 F]MK-9470 and small animal PET, we investigated cerebral changes in type 1 cannabinoid (CB 1 ) receptor binding in the quinolinic acid (QA) rat model of HD in relation to glucose metabolism, dopamine D 2 receptor availability and amphetamine-induced turning behaviour. Twenty-one Wistar rats (11 QA and 10 shams) were investigated. Small animal PET acquisitions were conducted on a Focus 220 with approximately 18 MBq of [ 18 F]MK-9470, [ 18 F]FDG and [ 11 C]raclopride. Relative glucose metabolism and parametric CB 1 receptor and D 2 binding images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping (SPM2). In the QA model, [ 18 F]MK-9470 uptake, glucose metabolism and D 2 receptor binding were reduced in the ipsilateral caudate-putamen by 7, 35 and 77%, respectively (all p -5 ), while an increase for these markers was observed on the contralateral side (>5%, all p -4 ). [ 18 F]MK-9470 binding was also increased in the cerebellum (p = 2.10 -5 ), where it was inversely correlated to the number of ipsiversive turnings (p = 7.10 -6 ), suggesting that CB 1 receptor upregulation in the cerebellum is related to a better functional outcome. Additionally, glucose metabolism was relatively increased in the contralateral hippocampus, thalamus and sensorimotor cortex (p = 1.10 -6 ). These data point to in vivo changes in endocannabinoid transmission, specifically for CB 1 receptors in the QA model, with involvement of the caudate-putamen, but also distant regions of the motor circuitry, including the cerebellum. These data also indicate the occurrence of functional plasticity on metabolism, D 2 and CB 1 neurotransmission in the contralateral hemisphere. (orig.)

Activation of presynaptic oxytocin receptors enhances glutamate release in the ventral hippocampus of prenatally restraint stressed rats.

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Mairesse, Jérôme; Gatta, Eleonora; Reynaert, Marie-Line; Marrocco, Jordan; Morley-Fletcher, Sara; Soichot, Marion; Deruyter, Lucie; Camp, Gilles Van; Bouwalerh, Hammou; Fagioli, Francesca; Pittaluga, Anna; Allorge, Delphine; Nicoletti, Ferdinando; Maccari, Stefania

2015-12-01

Oxytocin receptors are known to modulate synaptic transmission and network activity in the hippocampus, but their precise function has been only partially elucidated. Here, we have found that activation of presynaptic oxytocin receptor with the potent agonist, carbetocin, enhanced depolarization-evoked glutamate release in the ventral hippocampus with no effect on GABA release. This evidence paved the way for examining the effect of carbetocin treatment in "prenatally restraint stressed" (PRS) rats, i.e., the offspring of dams exposed to repeated episodes of restraint stress during pregnancy. Adult PRS rats exhibit an anxious/depressive-like phenotype associated with an abnormal glucocorticoid feedback regulation of the hypothalamus-pituitary-adrenal (HPA) axis, and, remarkably, with a reduced depolarization-evoked glutamate release in the ventral hippocampus. Chronic systemic treatment with carbetocin (1mg/kg, i.p., once a day for 2-3 weeks) in PRS rats corrected the defect in glutamate release, anxiety- and depressive-like behavior, and abnormalities in social behavior, in the HPA response to stress, and in the expression of stress-related genes in the hippocampus and amygdala. Of note, carbetocin treatment had no effect on these behavioral and neuroendocrine parameters in prenatally unstressed (control) rats, with the exception of a reduced expression of the oxytocin receptor gene in the amygdala. These findings disclose a novel function of oxytocin receptors in the hippocampus, and encourage the use of oxytocin receptor agonists in the treatment of stress-related psychiatric disorders in adult life. Copyright © 2015 Elsevier Ltd. All rights reserved.

Localización de los Receptores Cannabinoides 1 (CB1) en Glándulas Salivales Submandibulares y Sublinguales de Ratones Durante el Desarrollo Postnatal

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Hipkaeo, Wiphawi; Watanabe, Masahiko; Kondo, Hisatake

2015-01-01

In view of the fact that human marijuana users often show dry mouth symptom, the present study was attempted to examine the localization of CB1, which was originally identified in brain, in the submandibular and sublingual salivary glands of postnatal developing male mice by immunohistochemistry. In submandibular gland, CB1-immunoreactivity was positive in a majority of acinar cells in forms of granular appearance in their apical cytoplasm, while it was negative in the ducts at newborn stage....

Resistance to diet-induced adiposity in cannabinoid receptor-1 deficient mice is not due to impaired adipocyte function

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Oosterveer Maaike H

2011-12-01

Full Text Available Abstract Background Overactivity and/or dysregulation of the endocannabinoid system (ECS contribute to development of obesity. In vitro studies indicate a regulatory role for the cannabinoid receptor 1 (CB1 in adipocyte function and CB1-receptor deficient (CB1-/- mice are resistant to high fat diet-induced obesity. Whether this phenotype of CB1-/- mice is related to altered fat metabolism in adipose tissue is unknown. Methods We evaluated adipose tissue differentiation/proliferation markers and quantified lipogenic and lipolytic activities in fat tissues of CB1-/- and CB1+/+ mice fed a high-fat (HF or a high-fat/fish oil (HF/FO diet as compared to animals receiving a low-fat chow diet. Comparison between HF diet and HF/FO diet allowed to investigate the influence of dietary fat quality on adipose tissue biology in relation to CB1 functioning. Results The adiposity-resistant phenotype of the CB1-/- mice was characterized by reduced fat mass and adipocyte size in HF and HF/FO-fed CB1-/- mice in parallel to a significant increase in energy expenditure as compared to CB1+/+ mice. The expression levels of adipocyte differentiation and proliferation markers were however maintained in these animals. Consistent with unaltered lipogenic gene expression, the fatty acid synthesis rates in adipose tissues from CB1-/- and CB1+/+ mice were unchanged. Whole-body and adipose-specific lipoprotein lipase (LPL activities were also not altered in CB1-/- mice. Conclusions These findings indicate that protection against diet-induced adiposity in CB1-deficient mice is not related to changes in adipocyte function per se, but rather results from increased energy dissipation by oxidative and non-oxidative pathways.

Macroglia-derived thrombospondin 2 regulates alterations of presynaptic proteins of retinal neurons following elevated hydrostatic pressure.

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Wang, Shuchao; Hu, Tu; Wang, Zhen; Li, Na; Zhou, Lihong; Liao, Lvshuang; Wang, Mi; Liao, Libin; Wang, Hui; Zeng, Leping; Fan, Chunling; Zhou, Hongkang; Xiong, Kun; Huang, Jufang; Chen, Dan

2017-01-01

Many studies on retinal injury and repair following elevated intraocular pressure suggest that the survival ratio of retinal neurons has been improved by various measures. However, the visual function recovery is far lower than expected. The homeostasis of retinal synapses in the visual signal pathway is the key structural basis for the delivery of visual signals. Our previous studies found that complicated changes in the synaptic structure between retinal neurons occurred much earlier than obvious degeneration of retinal ganglion cells in rat retinae. The lack of consideration of these earlier retinal synaptic changes in the rescue strategy may be partly responsible for the limited visual function recovery with the types of protective methods for retinal neurons used following elevated intraocular pressure. Thus, research on the modulatory mechanisms of the synaptic changes after elevated intraocular pressure injury may give new light to visual function rescue. In this study, we found that thrombospondin 2, an important regulator of synaptogenesis in central nervous system development, was distributed in retinal macroglia cells, and its receptor α2δ-1 was in retinal neurons. Cell cultures including mixed retinal macroglia cells/neuron cultures and retinal neuron cultures were exposed to elevated hydrostatic pressure for 2 h. The expression levels of glial fibrillary acidic protein (the marker of activated macroglia cells), thrombospondin 2, α2δ-1 and presynaptic proteins were increased following elevated hydrostatic pressure in mixed cultures, but the expression levels of postsynaptic proteins were not changed. SiRNA targeting thrombospondin 2 could decrease the upregulation of presynaptic proteins induced by the elevated hydrostatic pressure. However, in retinal neuron cultures, elevated hydrostatic pressure did not affect the expression of presynaptic or postsynaptic proteins. Rather, the retinal neuron cultures with added recombinant thrombospondin 2

Pharmacological benefits of selective modulation of cannabinoid receptor type 2 (CB2) in experimental Alzheimer's disease.

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Jayant, Shalini; Sharma, Brij Mohan; Bansal, Rani; Sharma, Bhupesh

2016-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that pervasively affects the population across the world. Currently, there is no effective treatment available for this and existing drugs merely slow the progression of cognitive function decline. Thus, massive effort is required to find an intended therapeutic target to overcome this condition. The present study has been framed to investigate the ameliorative role of selective modulator of cannabinoid receptor type 2 (CB2), 1-phenylisatin in experimental AD condition. We have induced experimental AD in mice by using two induction models viz., intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose. Morris water maze (MWM) and attentional set shifting test (ASST) were used to assess learning and memory. Hematoxylin-eosin and Congo red staining were used to examine the structural variation in brain. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), nitric oxide levels (nitrites/nitrates), acetyl cholinesterase activity, myeloperoxidase and calcium levels were also estimated. i.c.v. STZ as well as AlCl3+d-galactose have impaired spatial and reversal learning with executive functioning, increased brain oxidative and nitrosative stress, cholinergic activity, inflammation and calcium levels. Furthermore, these agents have also enhanced the burden of Aβ plaque in the brain. Treatment with 1-phenylisatin and donepezil attenuated i.c.v. STZ as well as AlCl3+d-galactose induced impairment of learning-memory, brain biochemistry and brain damage. Hence, this study concludes that CB2 receptor modulation can be a potential therapeutic target for the management of AD. Copyright © 2015 Elsevier Inc. All rights reserved.

Proximal Tubular Cannabinoid-1 Receptor Regulates Obesity-Induced CKD.

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Udi, Shiran; Hinden, Liad; Earley, Brian; Drori, Adi; Reuveni, Noa; Hadar, Rivka; Cinar, Resat; Nemirovski, Alina; Tam, Joseph

2017-12-01

Obesity-related structural and functional changes in the kidney develop early in the course of obesity and occur independently of hypertension, diabetes, and dyslipidemia. Activating the renal cannabinoid-1 receptor (CB 1 R) induces nephropathy, whereas CB 1 R blockade improves kidney function. Whether these effects are mediated via a specific cell type within the kidney remains unknown. Here, we show that specific deletion of CB 1 R in the renal proximal tubule cells did not protect the mice from obesity, but markedly attenuated the obesity-induced lipid accumulation in the kidney and renal dysfunction, injury, inflammation, and fibrosis. These effects associated with increased activation of liver kinase B1 and the energy sensor AMP-activated protein kinase, as well as enhanced fatty acid β -oxidation. Collectively, these findings indicate that renal proximal tubule cell CB 1 R contributes to the pathogenesis of obesity-induced renal lipotoxicity and nephropathy by regulating the liver kinase B1/AMP-activated protein kinase signaling pathway. Copyright © 2017 by the American Society of Nephrology.

A Novel Selective Inverse Agonist of the CB2 Receptor as a Radiolabeled Tool Compound for Kinetic Binding Studies.

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Martella, Andrea; Sijben, Huub; Rufer, Arne C; Grether, Uwe; Fingerle, Juergen; Ullmer, Christoph; Hartung, Thomas; IJzerman, Adriaan P; van der Stelt, Mario; Heitman, Laura H

2017-10-01

The endocannabinoid system, and in particular the cannabinoid type 2 receptor (CB2R), raised the interest of many medicinal chemistry programs for its therapeutic relevance in several (patho)physiologic processes. However, the physico-chemical properties of tool compounds for CB2R (e.g., the radioligand [ 3 H]CP55,940) are not optimal, despite the research efforts in developing effective drugs to target this system. At the same time, the importance of drug-target binding kinetics is growing since the kinetic binding profile of a ligand may provide important insights for the resulting in vivo efficacy. In this context we synthesized and characterized [ 3 H]RO6957022, a highly selective CB2R inverse agonist, as a radiolabeled tool compound. In equilibrium and kinetic binding experiments [ 3 H]RO6957022 showed high affinity for human CB2R with fast association ( k on ) and moderate dissociation ( k off ) kinetics. To demonstrate the robustness of [ 3 H]RO6957022 binding, affinity studies were carried out for a wide range of CB2R reference ligands, spanning the range of full, partial, and inverse agonists. Finally, we used [ 3 H]RO6957022 to study the kinetic binding profiles (i.e., k on and k off values) of selected synthetic and endogenous (i.e., 2-arachidonoylglycerol, anandamide, and noladin ether) CB2R ligands by competition association experiments. All tested ligands, and in particular the endocannabinoids, displayed distinct kinetic profiles, shedding more light on their mechanism of action and the importance of association rates in the determination of CB2R affinity. Altogether, this study shows that the use of a novel tool compound, i.e., [ 3 H]RO6957022, can support the development of novel ligands with a repertoire of kinetic binding profiles for CB2R. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

Slit2 as a β-catenin/Ctnnb1-dependent retrograde signal for presynaptic differentiation

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Wu, Haitao; Barik, Arnab; Lu, Yisheng; Shen, Chengyong; Bowman, Andrew; Li, Lei; Sathyamurthy, Anupama; Lin, Thiri W; Xiong, Wen-Cheng; Mei, Lin

2015-01-01

Neuromuscular junction formation requires proper interaction between motoneurons and muscle cells. β-Catenin (Ctnnb1) in muscle is critical for motoneuron differentiation; however, little is known about the relevant retrograde signal. In this paper, we dissected which functions of muscle Ctnnb1 are critical by an in vivo transgenic approach. We show that Ctnnb1 mutant without the transactivation domain was unable to rescue presynaptic deficits of Ctnnb1 mutation, indicating the involvement of transcription regulation. On the other hand, the cell-adhesion function of Ctnnb1 is dispensable. We screened for proteins that may serve as a Ctnnb1-directed retrograde factor and identified Slit2. Transgenic expression of Slit2 specifically in the muscle was able to diminish presynaptic deficits by Ctnnb1 mutation in mice. Slit2 immobilized on beads was able to induce synaptophysin puncta in axons of spinal cord explants. Together, these observations suggest that Slit2 serves as a factor utilized by muscle Ctnnb1 to direct presynaptic differentiation. DOI: http://dx.doi.org/10.7554/eLife.07266.001 PMID:26159615

CA1 Pyramidal Cell Theta-Burst Firing Triggers Endocannabinoid-Mediated Long-Term Depression at Both Somatic and Dendritic Inhibitory Synapses

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Younts, Thomas J.; Chevaleyre, Vivien

2013-01-01

Endocannabinoids (eCBs) are retrograde lipid messengers that, by targeting presynaptic type 1 cannabinoid receptors (CB1Rs), mediate short- and long-term synaptic depression of neurotransmitter release throughout the brain. Short-term depression is typically triggered by postsynaptic, depolarization-induced calcium rises, whereas long-term depression is induced by synaptic activation of Gq/11 protein-coupled receptors. Here we report that a physiologically relevant pattern of postsynaptic activity, in the form of theta-burst firing (TBF) of hippocampal CA1 pyramidal neurons, can trigger long-term depression of inhibitory transmission (iLTD) in rat hippocampal slices. Paired recordings between CA1 interneurons and pyramidal cells, followed by post hoc morphological reconstructions of the interneurons' axon, revealed that somatic and dendritic inhibitory synaptic inputs equally expressed TBF-induced iLTD. Simultaneous recordings from neighboring pyramidal cells demonstrated that eCB signaling triggered by TBF was highly restricted to only a single, active cell. Furthermore, pairing submaximal endogenous activation of metabotropic glutamate or muscarinic acetylcholine receptors with submaximal TBF unmasked associative iLTD. Although CB1Rs are also expressed at Schaffer-collateral excitatory terminals, long-term plasticity under various recording conditions was spared at these synapses. Consistent with this observation, TBF also shifted the balance of excitation and inhibition in favor of excitatory throughput, thereby altering information flow through the CA1 circuit. Given the near ubiquity of burst-firing activity patterns and CB1R expression in the brain, the properties described here may be a general means by which neurons fine tune the strength of their inputs in a cell-wide and cell-specific manner. PMID:23966696

Dopamine synapse is a neuroligin-2–mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures

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Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

2016-01-01

Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

Brain-derived neurotrophic factor (BDNF)-induced mitochondrial motility arrest and presynaptic docking contribute to BDNF-enhanced synaptic transmission.

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Su, Bo; Ji, Yun-Song; Sun, Xu-lu; Liu, Xiang-Hua; Chen, Zhe-Yu

2014-01-17

Appropriate mitochondrial transport and distribution are essential for neurons because of the high energy and Ca(2+) buffering requirements at synapses. Brain-derived neurotrophic factor (BDNF) plays an essential role in regulating synaptic transmission and plasticity. However, whether and how BDNF can regulate mitochondrial transport and distribution are still unclear. Here, we find that in cultured hippocampal neurons, application of BDNF for 15 min decreased the percentage of moving mitochondria in axons, a process dependent on the activation of the TrkB receptor and its downstream PI3K and phospholipase-Cγ signaling pathways. Moreover, the BDNF-induced mitochondrial stopping requires the activation of transient receptor potential canonical 3 and 6 (TRPC3 and TRPC6) channels and elevated intracellular Ca(2+) levels. The Ca(2+) sensor Miro1 plays an important role in this process. Finally, the BDNF-induced mitochondrial stopping leads to the accumulation of more mitochondria at presynaptic sites. Mutant Miro1 lacking the ability to bind Ca(2+) prevents BDNF-induced mitochondrial presynaptic accumulation and synaptic transmission, suggesting that Miro1-mediated mitochondrial motility is involved in BDNF-induced mitochondrial presynaptic docking and neurotransmission. Together, these data suggest that mitochondrial transport and distribution play essential roles in BDNF-mediated synaptic transmission.

Control of the subthalamic innervation of substantia nigra pars reticulata by D1 and D2 dopamine receptors.

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Ibañez-Sandoval, Osvaldo; Hernández, Adán; Florán, Benjamin; Galarraga, Elvira; Tapia, Dagoberto; Valdiosera, Rene; Erlij, David; Aceves, Jorge; Bargas, José

2006-03-01

The effects of activating dopaminergic D1 and D2 class receptors of the subthalamic projections that innervate the pars reticulata of the subtantia nigra (SNr) were explored in slices of the rat brain using the whole cell patch-clamp technique. Excitatory postsynaptic currents (EPSCs) that could be blocked by 6-cyano-7-nitroquinoxalene-2,3-dione and D-(-)-2-amino-5-phosphonopentanoic acid were evoked onto reticulata GABAergic projection neurons by local field stimulation inside the subthalamic nucleus in the presence of bicuculline. Bath application of (RS)-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine hydrochloride (SKF-38393), a dopaminergic D1-class receptor agonist, increased evoked EPSCs by approximately 30% whereas the D2-class receptor agonist, trans-(-)-4aR-4,4a,5,6,7,8,8a,9-octahydro-5-propyl-1H-pyrazolo(3,4-g)quinoline (quinpirole), reduced EPSCs by approximately 25%. These apparently opposing actions were blocked by the specific D1- and D2-class receptor antagonists: R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetra-hydro-1H-3-benzazepinehydrochloride (SCH 23390) and S-(-)-5-amino-sulfonyl-N-[(1-ethyl-2-pyrrolidinyl)-methyl]-2-methoxybenzamide (sulpiride), respectively. Both effects were accompanied by changes in the paired-pulse ratio, indicative of a presynaptic site of action. The presynaptic location of dopamine receptors at the subthalamonigral projections was confirmed by mean-variance analysis. The effects of both SKF-38393 and quinpirole could be observed on terminals contacting the same postsynaptic neuron. Sulpiride and SCH 23390 enhanced and reduced the evoked EPSC, respectively, suggesting a constitutive receptor activation probably arising from endogenous dopamine. These data suggest that dopamine presynaptically modulates the subthalamic projection that targets GABAergic neurons of the SNr. Implications of this modulation for basal ganglia function are discussed.

The Role of Cannabinoid Receptors in the Descending Modulation of Pain

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Francesco Rossi

2010-08-01

Full Text Available The endogenous antinociceptive descending pathway represents a circuitry of the supraspinal central nervous system whose task is to counteract pain. It includes the periaqueductal grey (PAG-rostral ventromedial medulla (RVM-dorsal horn (DH axis, which is the best characterized pain modulation system through which pain is endogenously inhibited. Thus, an alternative rational strategy for silencing pain is the activation of this anatomical substrate. Evidence of the involvement of cannabinoid receptors (CB in the supraspinal modulation of pain can be found in several studies in which intra-cerebral microinjections of cannabinoid ligands or positive modulators have proved to be analgesic in different pain models, whereas cannabinoid receptor antagonists or antisense nucleotides towards CB1 receptors have facilitated pain. Like opioids, cannabinoids produce centrally-mediated analgesia by activating a descending pathway which includes PAG and its projection to downstream RVM neurons, which in turn send inhibitory projections to the dorsal horn of the spinal cord. Indeed, several studies underline a supraspinal regulation of cannabinoids on g-aminobutyric acid (GABA and glutamate release which inhibit and enhance the antinociceptive descending pathway, respectively. Cannabinoid receptor activation expressed on presynaptic GABAergic terminals reduces the probability of neurotransmitter release thus dis-inhibiting the PAG-RVM-dorsal horn antinociceptive pathway. Cannabinoids seem to increase glutamate release (maybe as consequence of GABA decrease and to require glutamate receptor activation to induce antinociception. The consequent outcome is behavioral analgesia, which is reproduced in several pain conditions, from acute to chronic pain models such as inflammatory and neuropathic pain. Taken together these findings would suggest that supraspinal cannabinoid receptors have broad applications, from pain control to closely related central nervous system

GABA(B) receptor modulation of feedforward inhibition through hippocampal neurogliaform cells.

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Price, Christopher J; Scott, Ricardo; Rusakov, Dmitri A; Capogna, Marco

2008-07-02

Feedforward inhibition of neurons is a fundamental component of information flow control in the brain. We studied the roles played by neurogliaform cells (NGFCs) of stratum lacunosum moleculare of the hippocampus in providing feedforward inhibition to CA1 pyramidal cells. We recorded from synaptically coupled pairs of anatomically identified NGFCs and CA1 pyramidal cells and found that, strikingly, a single presynaptic action potential evoked a biphasic unitary IPSC (uIPSC), consisting of two distinct components mediated by GABA(A) and GABA(B) receptors. A GABA(B) receptor-mediated unitary response has not previously been observed in hippocampal excitatory neurons. The decay of the GABA(A) receptor-mediated response was slow (time constant = 50 ms), and was tightly regulated by presynaptic GABA(B) receptors. Surprisingly, the GABA(B) receptor ligands baclofen and (2S)-3-{[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl}(phenylmethyl)phosphinic acid (CGP55845), while affecting the NGFC-mediated uIPSCs, had no effect on action potential-evoked presynaptic Ca2+ signals monitored in individual axonal boutons of NGFCs with two-photon microscopy. In contrast, baclofen clearly depressed presynaptic Ca2+ transients in non-NGF interneurons. Changes in extracellular Ca2+ concentration that mimicked the effects of baclofen or CGP55845 on uIPSCs significantly altered presynaptic Ca2+ transients. Electrophysiological data suggest that GABA(B) receptors expressed by NGFCs contribute to the dynamic control of the excitatory input to CA1 pyramidal neurons from the temporoammonic path. The NGFC-CA1 pyramidal cell connection therefore provides a unique and subtle mechanism to shape the integration time domain for signals arriving via a major excitatory input to CA1 pyramidal cells.

Pharmacodynamic and pharmacokinetic effects of the intravenous CB1 receptor agonist Org 26828 in healthy male volunteers.

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Zuurman, Lineke; Passier, Paul C C M; de Kam, Marieke L; Kleijn, Huub J; Cohen, Adam F; van Gerven, Joop M A

2010-11-01

An ideal drug for outpatient treatments under conscious sedation would have both sedative and analgesic properties. CB1/CB2 agonists are expected to have sedative, amnestic, analgesic and anti-emetic properties. The main objective of this first study in humans was to assess the sedative properties of intravenous Org 26828. In addition, pharmacokinetics, amnestic properties, postural stability, and behavioural and cardiovascular effects were studied. Midazolam intravenous 0.1 mg/kg and placebo were used as controls. The pharmacokinetic parameters (Cmax and AUC0-inf) of the main metabolite Org 26761 were proportional to dose. No effects were observed after doses up to 0.3 μg/kg of Org 26828. Dose-related effects were observed at higher doses. Although subjects reported subjective sedation after administration of Org 26828 at 3 and 6 μg/kg, the observed sedation was considerably less than after midazolam. Doses higher than the maximum tolerated dose of 1 μg/kg of Org 26828 caused unpleasant central nervous system effects (anxiety, paranoia, hallucinations). Therefore, Org 26828 is not suitable for providing sedation for outpatient surgical procedures.

CB1R-Mediated Activation of Caspase-3 Causes Epigenetic and Neurobehavioral Abnormalities in Postnatal Ethanol-Exposed Mice

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Shivakumar Subbanna

2018-02-01

Full Text Available Alcohol exposure can affect brain development, leading to long-lasting behavioral problems, including cognitive impairment, which together is defined as fetal alcohol spectrum disorder (FASD. However, the fundamental mechanisms through which this occurs are largely unknown. In this study, we report that the exposure of postnatal day 7 (P7 mice to ethanol activates caspase-3 via cannabinoid receptor type-1 (CB1R in neonatal mice and causes a reduction in methylated DNA binding protein (MeCP2 levels. The developmental expression of MeCP2 in mice is closely correlated with synaptogenesis and neuronal maturation. It was shown that ethanol treatment of P7 mice enhanced Mecp2 mRNA levels but reduced protein levels. The genetic deletion of CB1R prevented, and administration of a CB1R antagonist before ethanol treatment of P7 mice inhibited caspase-3 activation. Additionally, it reversed the loss of MeCP2 protein, cAMP response element binding protein (CREB activation, and activity-regulated cytoskeleton-associated protein (Arc expression. The inhibition of caspase-3 activity prior to ethanol administration prevented ethanol-induced loss of MeCP2, CREB activation, epigenetic regulation of Arc expression, long-term potentiation (LTP, spatial memory deficits and activity-dependent impairment of several signaling molecules, including MeCP2, in adult mice. Collectively, these results reveal that the ethanol-induced CB1R-mediated activation of caspase-3 degrades the MeCP2 protein in the P7 mouse brain and causes long-lasting neurobehavioral deficits in adult mice. This CB1R-mediated instability of MeCP2 during active synaptic maturation may disrupt synaptic circuit maturation and lead to neurobehavioral abnormalities, as observed in this animal model of FASD.

CB1-Dependent Long-Term Depression in Ventral Tegmental Area GABA Neurons: A Novel Target for Marijuana.

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Friend, Lindsey; Weed, Jared; Sandoval, Philip; Nufer, Teresa; Ostlund, Isaac; Edwards, Jeffrey G

2017-11-08

The VTA is necessary for reward behavior with dopamine cells critically involved in reward signaling. Dopamine cells in turn are innervated and regulated by neighboring inhibitory GABA cells. Using whole-cell electrophysiology in juvenile-adolescent GAD67-GFP male mice, we examined excitatory plasticity in fluorescent VTA GABA cells. A novel CB1-dependent LTD was induced in GABA cells that was dependent on metabotropic glutamate receptor 5, and cannabinoid receptor 1 (CB1). LTD was absent in CB1 knock-out mice but preserved in heterozygous littermates. Bath applied Δ 9 -tetrahydrocannabinol depressed GABA cell activity, therefore downstream dopamine cells will be disinhibited; and thus, this could potentially result in increased reward. Chronic injections of Δ 9 -tetrahydrocannabinol occluded LTD compared with vehicle injections; however, a single exposure was insufficient to do so. As synaptic modifications by drugs of abuse are often tied to addiction, these data suggest a possible mechanism for the addictive effects of Δ 9 -tetrahydrocannabinol in juvenile-adolescents, by potentially altering reward behavioral outcomes. SIGNIFICANCE STATEMENT The present study identifies a novel form of glutamatergic synaptic plasticity in VTA GABA neurons, a currently understudied cell type that is critical for the brain's reward circuit, and how Δ 9 -tetrahydrocannabinol occludes this plasticity. This study specifically addresses a potential unifying mechanism whereby marijuana could exert rewarding and addictive/withdrawal effects. Marijuana use and legalization are a pressing issue for many states in the United States. Although marijuana is the most commonly abused illicit drug, the implications of legalized, widespread, or continued usage are speculative. This study in juvenile-adolescent aged mice identifies a novel form of synaptic plasticity in VTA GABA cells, and the synaptic remodeling that can occur after Δ 9 -tetrahydrocannabinol use. Copyright © 2017 the

LKB1 Regulates Mitochondria-Dependent Presynaptic Calcium Clearance and Neurotransmitter Release Properties at Excitatory Synapses along Cortical Axons.

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Kwon, Seok-Kyu; Sando, Richard; Lewis, Tommy L; Hirabayashi, Yusuke; Maximov, Anton; Polleux, Franck

2016-07-01

Individual synapses vary significantly in their neurotransmitter release properties, which underlie complex information processing in neural circuits. Presynaptic Ca2+ homeostasis plays a critical role in specifying neurotransmitter release properties, but the mechanisms regulating synapse-specific Ca2+ homeostasis in the mammalian brain are still poorly understood. Using electrophysiology and genetically encoded Ca2+ sensors targeted to the mitochondrial matrix or to presynaptic boutons of cortical pyramidal neurons, we demonstrate that the presence or absence of mitochondria at presynaptic boutons dictates neurotransmitter release properties through Mitochondrial Calcium Uniporter (MCU)-dependent Ca2+ clearance. We demonstrate that the serine/threonine kinase LKB1 regulates MCU expression, mitochondria-dependent Ca2+ clearance, and thereby, presynaptic release properties. Re-establishment of MCU-dependent mitochondrial Ca2+ uptake at glutamatergic synapses rescues the altered neurotransmitter release properties characterizing LKB1-null cortical axons. Our results provide novel insights into the cellular and molecular mechanisms whereby mitochondria control neurotransmitter release properties in a bouton-specific way through presynaptic Ca2+ clearance.

The effect of leptin receptor deficiency and fasting on cannabinoid receptor 1 mRNA expression in the rat hypothalamus, brainstem and nodose ganglion.

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Jelsing, Jacob; Larsen, Philip Just; Vrang, Niels

2009-10-02

Despite ample evidence for the involvement of the endocannabinoid system in the control of appetite, food intake and energy balance, relatively little is known about the regulation of cannabinoid receptor 1 (CB(1)R) expression in respect to leptin signalling and fasting. In the present study, we examined CB(1)R mRNA levels in lean (Fa/?) and obese (fa/fa) male Zucker rats under basal and food-restricted conditions. Using stereological sampling principles coupled with semi-quantitative radioactive in situ hybridization we provide semi-quantitative estimates of CB(1)R mRNA expression in key appetite regulatory hypothalamic and brainstem areas, as well as in the nodose ganglia. Whereas no effect of fasting were determined on CB(1)R mRNA levels in the paraventricular (PVN) and ventromedial hypothalamic (VMH) nucleus, in the brainstem dorsal vagal complex or nodose ganglion of lean Zucker rats, CB(1)R mRNA levels were consistently elevated in obese Zucker rats pointing to a direct influence of disrupted leptin signalling on CB(1)R mRNA regulation.

The G protein Gi1 exhibits basal coupling but not preassembly with G protein-coupled receptors.

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Bondar, Alexey; Lazar, Josef

2017-06-09

The G i/o protein family transduces signals from a diverse group of G protein-coupled receptors (GPCRs). The observed specificity of G i/o -GPCR coupling and the high rate of G i/o signal transduction have been hypothesized to be enabled by the existence of stable associates between G i/o proteins and their cognate GPCRs in the inactive state (G i/o -GPCR preassembly). To test this hypothesis, we applied the recently developed technique of two-photon polarization microscopy (2PPM) to Gα i1 subunits labeled with fluorescent proteins and four GPCRs: the α 2A -adrenergic receptor, GABA B , cannabinoid receptor type 1 (CB 1 R), and dopamine receptor type 2. Our experiments with non-dissociating mutants of fluorescently labeled Gα i1 subunits (exhibiting impaired dissociation from activated GPCRs) showed that 2PPM is capable of detecting GPCR-G protein interactions. 2PPM experiments with non-mutated fluorescently labeled Gα i1 subunits and α 2A -adrenergic receptor, GABA B , or dopamine receptor type 2 receptors did not reveal any interaction between the G i1 protein and the non-stimulated GPCRs. In contrast, non-stimulated CB 1 R exhibited an interaction with the G i1 protein. Further experiments revealed that this interaction is caused solely by CB 1 R basal activity; no preassembly between CB 1 R and the G i1 protein could be observed. Our results demonstrate that four diverse GPCRs do not preassemble with non-active G i1 However, we also show that basal GPCR activity allows interactions between non-stimulated GPCRs and G i1 (basal coupling). These findings suggest that G i1 interacts only with active GPCRs and that the well known high speed of GPCR signal transduction does not require preassembly between G proteins and GPCRs. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB₁ receptor blockade.

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Bellocchio, Luigi; Soria-Gómez, Edgar; Quarta, Carmelo; Metna-Laurent, Mathilde; Cardinal, Pierre; Binder, Elke; Cannich, Astrid; Delamarre, Anna; Häring, Martin; Martín-Fontecha, Mar; Vega, David; Leste-Lasserre, Thierry; Bartsch, Dusan; Monory, Krisztina; Lutz, Beat; Chaouloff, Francis; Pagotto, Uberto; Guzman, Manuel; Cota, Daniela; Marsicano, Giovanni

2013-03-19

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.

Presynaptic Membrane Receptors Modulate ACh Release, Axonal Competition and Synapse Elimination during Neuromuscular Junction Development.

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Tomàs, Josep; Garcia, Neus; Lanuza, Maria A; Santafé, Manel M; Tomàs, Marta; Nadal, Laura; Hurtado, Erica; Simó, Anna; Cilleros, Víctor

2017-01-01

During the histogenesis of the nervous system a lush production of neurons, which establish an excessive number of synapses, is followed by a drop in both neurons and synaptic contacts as maturation proceeds. Hebbian competition between axons with different activities leads to the loss of roughly half of the neurons initially produced so connectivity is refined and specificity gained. The skeletal muscle fibers in the newborn neuromuscular junction (NMJ) are polyinnervated but by the end of the competition, 2 weeks later, the NMJ are innervated by only one axon. This peripheral synapse has long been used as a convenient model for synapse development. In the last few years, we have studied transmitter release and the local involvement of the presynaptic muscarinic acetylcholine autoreceptors (mAChR), adenosine autoreceptors (AR) and trophic factor receptors (TFR, for neurotrophins and trophic cytokines) during the development of NMJ and in the adult. This review article brings together previously published data and proposes a molecular background for developmental axonal competition and loss. At the end of the first week postnatal, these receptors modulate transmitter release in the various nerve terminals on polyinnervated NMJ and contribute to axonal competition and synapse elimination.

Presynaptic Membrane Receptors Modulate ACh Release, Axonal Competition and Synapse Elimination during Neuromuscular Junction Development

Directory of Open Access Journals (Sweden)

Josep Tomàs

2017-05-01

Full Text Available During the histogenesis of the nervous system a lush production of neurons, which establish an excessive number of synapses, is followed by a drop in both neurons and synaptic contacts as maturation proceeds. Hebbian competition between axons with different activities leads to the loss of roughly half of the neurons initially produced so connectivity is refined and specificity gained. The skeletal muscle fibers in the newborn neuromuscular junction (NMJ are polyinnervated but by the end of the competition, 2 weeks later, the NMJ are innervated by only one axon. This peripheral synapse has long been used as a convenient model for synapse development. In the last few years, we have studied transmitter release and the local involvement of the presynaptic muscarinic acetylcholine autoreceptors (mAChR, adenosine autoreceptors (AR and trophic factor receptors (TFR, for neurotrophins and trophic cytokines during the development of NMJ and in the adult. This review article brings together previously published data and proposes a molecular background for developmental axonal competition and loss. At the end of the first week postnatal, these receptors modulate transmitter release in the various nerve terminals on polyinnervated NMJ and contribute to axonal competition and synapse elimination.

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.

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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.

G-protein coupling of cannabinoid receptors

International Nuclear Information System (INIS)

Glass, M.

2001-01-01

Full text: Since the cloning of the cannabinoid CB1 and CB2 receptors in the early 1990's extensive research has focused on understanding their signal transduction pathways. While it has been known for sometime that both receptors can couple to intracellular signalling via pertussis toxin sensitive G-proteins (Gi/Go), the specificity and kinetics of these interactions have only recently been elucidated. We have developed an in situ reconstitution approach to investigating receptor-G-protein interactions. This approach involves chaotropic extraction of receptor containing membranes in order to inactivate or remove endogenous G-proteins. Recombinant or isolated brain G-proteins can then be added back to the receptors, and their activation monitored through the binding of [ 35 S]-GTPγS. This technique has been utilised for an extensive study of cannabinoid receptor mediated activation of G-proteins. In these studies we have established that CB1 couples with high affinity to both Gi and Go type G-proteins. In contrast, CB2 couples strongly to Gi, but has a very low affinity for Go. This finding correlated well with the previous findings that while CB1 and CB2 both couple to the inhibition of adenylate cyclase, CB1 but not CB2 could also inhibit calcium channels. We then examined the ability of a range of cannabinoid agonists to activate the Gi and Go via CB1. Conventional receptor theory suggests that a receptor is either active or inactive with regard to a G-protein and that the active receptor activates all relevant G-proteins equally. However, in this study we found that agonists could produce different degrees of activation, depending on which G-protein was present. Further studies have compared the ability of the two endocannabinoids to drive the activation of Gi or Go. These studies show that agonists can induce multiple forms of activated receptor that differ in their ability to catalyse the activation of Gi or Go. The ability of an agonist to drive a receptor

Scotopic vision in the monkey is modulated by the G protein-coupled receptor 55

DEFF Research Database (Denmark)

Bouskila, Joseph; Harrar, Vanessa; Javadi, Pasha

2016-01-01

The endogenous cannabinoid system plays important roles in the retina of mice and monkeys via their classic CB1 and CB2 receptors. We have previously reported that the G protein-coupled receptor 55 (GPR55), a putative cannabinoid receptor, is exclusively expressed in rod photoreceptors in the mon......The endogenous cannabinoid system plays important roles in the retina of mice and monkeys via their classic CB1 and CB2 receptors. We have previously reported that the G protein-coupled receptor 55 (GPR55), a putative cannabinoid receptor, is exclusively expressed in rod photoreceptors...

Expression of presynaptic markers in a neurodevelopmental animal model with relevance to schizophrenia

DEFF Research Database (Denmark)

Karlsen, Anna S; Kaalund, Sanne Simone; Møller, Morten

2013-01-01

Administration of N-methyl-D-aspartate receptor antagonist phencyclidine (PCP) to rat pups at postnatal day (PND) 7, 9, and 11 [neonatal PCP (neoPCP) model] induces cognitive deficits similar to those observed in schizophrenia. Expression of presynaptic SNARE protein, synaptosomal......-associated protein of 25 kDa (Snap25), has been shown to be downregulated in postmortem brains from patients with schizophrenia. The present study was designed to investigate the long-term effects of neoPCP administration on expression of presynaptic markers altered in schizophrenia. Using radioactive in...

Constitutive cannabinoid 1 and mu opioid receptor activity in the ventral tegmental area: occurrence, function and therapeutic relevance

NARCIS (Netherlands)

Meye, F.J.

2012-01-01

Cannabinoid 1 receptors (CB1Rs) play a crucial role in regulating systems dedicated to processing rewards and emotions. It was known that in artificial systems, CB1Rs can exhibit activity that is independent of the typical agonist-driven form. However, it remained largely unclear whether this

Does human presynaptic striatal dopamine function predict social conformity?

Science.gov (United States)

Stokes, Paul R A; Benecke, Aaf; Puraite, Julita; Bloomfield, Michael A P; Shotbolt, Paul; Reeves, Suzanne J; Lingford-Hughes, Anne R; Howes, Oliver; Egerton, Alice

2014-03-01

Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two. In this study, we used a [¹⁸F]-DOPA positron emission tomography (PET) image database to investigate whether SDR is associated with presynaptic dopamine function. Striatal [¹⁸F]-DOPA uptake, (k(i)(cer), min⁻¹), was determined in two independent healthy participant cohorts (n=27 and 19), by Patlak analysis using a cerebellar reference region. SDR was assessed using the revised Eysenck Personality Questionnaire (EPQ-R) Lie scale, and IM and SDE were measured using the Paulhus Deception Scales. No significant associations were detected between Lie, SDE or IM scores and striatal [¹⁸F]-DOPA k(i)(cer). These results indicate that presynaptic striatal dopamine function is not associated with social conformity and suggests that social conformity may be associated with striatal D₂/₃ receptor expression rather than with synaptic dopamine levels.

The cannabinoid quinol VCE-004.8 alleviates bleomycin-induced scleroderma and exerts potent antifibrotic effects through peroxisome proliferator-activated receptor-γ and CB2 pathways.

Science.gov (United States)

del Río, Carmen; Navarrete, Carmen; Collado, Juan A; Bellido, M Luz; Gómez-Cañas, María; Pazos, M Ruth; Fernández-Ruiz, Javier; Pollastro, Federica; Appendino, Giovanni; Calzado, Marco A; Cantarero, Irene; Muñoz, Eduardo

2016-02-18

Scleroderma is a group of rare diseases associated with early and transient inflammation and vascular injury, followed by fibrosis affecting the skin and multiple internal organs. Fibroblast activation is the hallmark of scleroderma, and disrupting the intracellular TGFβ signaling may provide a novel approach to controlling fibrosis. Because of its potential role in modulating inflammatory and fibrotic responses, both PPARγ and CB2 receptors represent attractive targets for the development of cannabinoid-based therapies. We have developed a non-thiophilic and chemically stable derivative of the CBD quinol (VCE-004.8) that behaves as a dual agonist of PPARγ and CB2 receptors, VCE-004.8 inhibited TGFβ-induced Col1A2 gene transcription and collagen synthesis. Moreover, VCE-004.8 inhibited TGFβ-mediated myofibroblast differentiation and impaired wound-healing activity. The anti-fibrotic efficacy in vivo was investigated in a murine model of dermal fibrosis induced by bleomycin. VCE-004.8 reduced dermal thickness, blood vessels collagen accumulation and prevented mast cell degranulation and macrophage infiltration in the skin. These effects were impaired by the PPARγ antagonist T0070907 and the CB2 antagonist AM630. In addition, VCE-004.8 downregulated the expression of several key genes associated with fibrosis, qualifying this semi-synthetic cannabinoid as a novel compound for the management of scleroderma and, potentially, other fibrotic diseases.

Palmitoylethanolamide Inhibits Glutamate Release in Rat Cerebrocortical Nerve Terminals

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Tzu-Yu Lin

2015-03-01

Full Text Available The effect of palmitoylethanolamide (PEA, an endogenous fatty acid amide displaying neuroprotective actions, on glutamate release from rat cerebrocortical nerve terminals (synaptosomes was investigated. PEA inhibited the Ca2+-dependent release of glutamate, which was triggered by exposing synaptosomes to the potassium channel blocker 4-aminopyridine. This release inhibition was concentration dependent, associated with a reduction in cytosolic Ca2+ concentration, and not due to a change in synaptosomal membrane potential. The glutamate release-inhibiting effect of PEA was prevented by the Cav2.1 (P/Q-type channel blocker ω-agatoxin IVA or the protein kinase A inhibitor H89, not affected by the intracellular Ca2+ release inhibitors dantrolene and CGP37157, and partially antagonized by the cannabinoid CB1 receptor antagonist AM281. Based on these results, we suggest that PEA exerts its presynaptic inhibition, likely through a reduction in the Ca2+ influx mediated by Cav2.1 (P/Q-type channels, thereby inhibiting the release of glutamate from rat cortical nerve terminals. This release inhibition might be linked to the activation of presynaptic cannabinoid CB1 receptors and the suppression of the protein kinase A pathway.

Effect of blockage of the endocannabinoid system by CB(1) antagonism on cardiovascular risk.

Science.gov (United States)

Mach, François; Montecucco, Fabrizio; Steffens, Sabine

2009-01-01

The endocannabinoid system is a crucial player in the inflammatory processes underlying atherosclerosis. Recently, basic research studies and animal models have strongly supported the role of the endocannabinoid system not only in the regulation of classical cardiovascular risk factors (including lipid profile and glucose homeostasis), but also in the activation of immune cells and inflammatory mediators. Clinical trials investigating treatment with rimonabant (a selective antagonist of the cannabinoid type 1 receptor) have suggested a beneficial effect of this drug in the management of obesity. Further studies are needed to explore a possible use for rimonabant in treating type 2 diabetes and acute and chronic cardiovascular disease. Despite the slight increase in adverse events (mainly psychiatric), which has led to the recent withdrawal of rimonabant from the market, CB(1) receptor antagonism might represent a very promising therapeutic strategy to reduce the cardiovascular risk. In the present review, we focused on the most important experimental investigations into the role of the endocannabinoid system in atherosclerosis and cardiovascular risk.

Exercise reduces adipose tissue via cannabinoid receptor type 1 which is regulated by peroxisome proliferator-activated receptor-delta

DEFF Research Database (Denmark)

Yan, Zhen Cheng; Liu, Dao Yan; Zhang, Li Li

2007-01-01

Obesity is one major cardiovascular risk factor. We tested effects of endurance exercise on cannabinoid receptor type 1 (CB1) and peroxisome proliferator-activated receptor-delta (PPAR-delta)-dependent pathways in adipose tissue. Male Wistar rats were randomly assigned to standard laboratory chow...... or a high-fat diet without and with regular endurance exercise. Exercise in rats on high-fat diet significantly reduced visceral fat mass, blood pressure, and adipocyte size (each p...

Localization of Presynaptic Plasticity Mechanisms Enables Functional Independence of Synaptic and Ectopic Transmission in the Cerebellum

Directory of Open Access Journals (Sweden)

Katharine L. Dobson

2015-01-01

Full Text Available In the cerebellar molecular layer parallel fibre terminals release glutamate from both the active zone and from extrasynaptic “ectopic” sites. Ectopic release mediates transmission to the Bergmann glia that ensheathe the synapse, activating Ca2+-permeable AMPA receptors and glutamate transporters. Parallel fibre terminals exhibit several forms of presynaptic plasticity, including cAMP-dependent long-term potentiation and endocannabinoid-dependent long-term depression, but it is not known whether these presynaptic forms of long-term plasticity also influence ectopic transmission to Bergmann glia. Stimulation of parallel fibre inputs at 16 Hz evoked LTP of synaptic transmission, but LTD of ectopic transmission. Pharmacological activation of adenylyl cyclase by forskolin caused LTP at Purkinje neurons, but only transient potentiation at Bergmann glia, reinforcing the concept that ectopic sites lack the capacity to express sustained cAMP-dependent potentiation. Activation of mGluR1 caused depression of synaptic transmission via retrograde endocannabinoid signalling but had no significant effect at ectopic sites. In contrast, activation of NMDA receptors suppressed both synaptic and ectopic transmission. The results suggest that the signalling mechanisms for presynaptic LTP and retrograde depression by endocannabinoids are restricted to the active zone at parallel fibre synapses, allowing independent modulation of synaptic transmission to Purkinje neurons and ectopic transmission to Bergmann glia.

Syntheses of 7-Substituted α-Cyperone Derivatives for Selective Sigma-1 Receptor over Cannabinoid-1 Receptor Binding Affinities

Energy Technology Data Exchange (ETDEWEB)

Park, Juyoung; Shin, Younggyun; Yoon, Sunghwa [Ajou Univ., Suwon (Korea, Republic of); Kim, Keewon; Kwon, Youngbae [ChonBuk National Univ., Jeonju (Korea, Republic of)

2013-11-15

We have successfully synthesized seven α-cyperone derivatives and found that the presence of a hydrogen bond donor/acceptor groups at the C7 position of α-cyperone significantly affects specificity and potency of CB{sub 1} receptor binding affinity over sigma-1 receptor binding affinity. In particular, the presence of the amino moiety at the C7 position of α-cyperone is beneficial for binding to sigmia-1 receptor. The molecular mechanism of compound 8 involved in the high binding affinity to sigma-1 receptor is under investigation. We first synthesized α-cyperone 1 by following the previously reported synthetic routes.15-19 In brief, azeotropic imination of (+)-dihydrocarvone and (R)-(+)-1-phenylethylamine followed by alkylation with a slight excess of ethyl vinyl ketone (EVK) in THF at 40 .deg. C produced the Micheal adduct. The resulting adduct was hydrolyzed and then treated with sodium methoxide at room temperature to give an easily separable mixture of α-cyperone 1 and its side product. Flash chromatography resulted in pure α-cyperone 1 in a 30% yield from (+)-dihydrocarvone.

The peripheral cannabinoid receptor Cb2, frequently expressed on AML blasts, either induces a neutrophilic differentiation block or confers abnormal migration properties in a ligand-dependent manner

NARCIS (Netherlands)

M. Alberich-Jorda (Meritxell); N. Rayman (Nazik); M. Tas (Marjolein); S.E. Verbakel (Sandra); N. Battista (Natalia); K. van Lom (Kirsten); B. Löwenberg (Bob); M. Maccarrone (Mauro); H.R. Delwel (Ruud)

2004-01-01

textabstractCb2, the gene encoding the peripheral cannabinoid receptor, is located in a common virus integration site and is overex-pressed in retrovirally induced murine myeloid leukemias. Here we show that this G protein-coupled receptor (GPCR) is also aberrantly expressed in a

Presynaptic (Type III) cells in mouse taste buds sense sour (acid) taste.

Science.gov (United States)

Huang, Yijen A; Maruyama, Yutaka; Stimac, Robert; Roper, Stephen D

2008-06-15

Taste buds contain two types of cells that directly participate in taste transduction - receptor (Type II) cells and presynaptic (Type III) cells. Receptor cells respond to sweet, bitter and umami taste stimulation but until recently the identity of cells that respond directly to sour (acid) tastants has only been inferred from recordings in situ, from behavioural studies, and from immunostaining for putative sour transduction molecules. Using calcium imaging on single isolated taste cells and with biosensor cells to identify neurotransmitter release, we show that presynaptic (Type III) cells specifically respond to acid taste stimulation and release serotonin. By recording responses in cells isolated from taste buds and in taste cells in lingual slices to acetic acid titrated to different acid levels (pH), we also show that the active stimulus for acid taste is the membrane-permeant, uncharged acetic acid moiety (CH(3)COOH), not free protons (H(+)). That observation is consistent with the proximate stimulus for acid taste being intracellular acidification, not extracellular protons per se. These findings may also have implications for other sensory receptors that respond to acids, such as nociceptors.

Data of evolutionary structure change: 1A5CB-2QUTC [Confc[Archive

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Polymorphisms in the endocannabinoid receptor 1 in relation to fat mass distribution

DEFF Research Database (Denmark)

Nielsen, Morten Frost; Nielsen, T L; Wraae, K

2010-01-01

OBJECTIVE: Both animal and human studies have associated the endocannabinoid system with obesity and markers of metabolic dysfunction. Blockade of the cannabinoid receptor 1 (CB1) caused weight loss and reduction in waist size in both obese and type II diabetics. Recent studies on common variants...... of the CB1 receptor gene (CNR1) and the link to obesity have been conflicting. The aim of the present study was to evaluate whether selected common variants of the CNR1 are associated with measures of obesity and fat distribution. DESIGN AND METHODS: The single nucleotide polymorphisms (SNPs) rs806381, rs......10485179 and rs1049353 were genotyped, and body fat and fat distribution were assessed by the use of dual-energy X-ray absorptiometry and magnetic resonance imaging in a population-based study comprising of 783 Danish men, aged 20-29 years. RESULTS: The rs806381 polymorphism was significantly associated...

G protein betagamma-subunits activated by serotonin mediate presynaptic inhibition by regulating vesicle fusion properties.

Science.gov (United States)

Photowala, Huzefa; Blackmer, Trillium; Schwartz, Eric; Hamm, Heidi E; Alford, Simon

2006-03-14

Neurotransmitters are thought to be released as quanta, where synaptic vesicles deliver packets of neurotransmitter to the synaptic cleft by fusion with the plasma membrane. However, synaptic vesicles may undergo incomplete fusion. We provide evidence that G protein-coupled receptors inhibit release by causing such incomplete fusion. 5-hydroxytryptamine (5-HT) receptor signaling potently inhibits excitatory postsynaptic currents (EPSCs) between lamprey reticulospinal axons and their postsynaptic targets by a direct action on the vesicle fusion machinery. We show that 5-HT receptor-mediated presynaptic inhibition, at this synapse, involves a reduction in EPSC quantal size. Quantal size was measured directly by comparing unitary quantal amplitudes of paired EPSCs before and during 5-HT application and indirectly by determining the effect of 5-HT on the relationship between mean-evoked EPSC amplitude and variance. Results from FM dye-labeling experiments indicate that 5-HT prevents full fusion of vesicles. 5-HT reduces FM1-43 staining of vesicles with a similar efficacy to its effect on the EPSC. However, destaining of FM1-43-labeled vesicles is abolished by lower concentrations of 5-HT that leave a substantial EPSC. The use of a water-soluble membrane impermeant quenching agent in the extracellular space reduced FM1-43 fluorescence during stimulation in 5-HT. Thus vesicles contact the extracellular space during inhibition of synaptic transmission by 5-HT. We conclude that 5-HT, via free Gbetagamma, prevents the collapse of synaptic vesicles into the presynaptic membrane.

Data of evolutionary structure change: 1A5CB-2QUUC [Confc[Archive

Lifescience Database Archive (English)

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Processing cardiovascular information in the vlPAG during electroacupuncture in rats: roles of endocannabinoids and GABA

Science.gov (United States)

Tjen-A-Looi, Stephanie C.; Li, Peng; Longhurst, John C.

2009-01-01

A long-loop pathway, involving the hypothalamic arcuate nucleus (ARC), ventrolateral periaqueductal gray (vlPAG), and the rostral ventrolateral medulla (rVLM), is essential in electroacupuncture (EA) attenuation of sympathoexcitatory cardiovascular reflex responses. The ARC provides excitatory input to the vlPAG, which, in turn, inhibits neuronal activity in the rVLM. Although previous studies have shown that endocannabinoid CB1 receptor activation modulates γ-aminobutyric acid (GABA)-ergic and glutamatergic neurotransmission in the dorsolateral PAG in stress-induced analgesia, an important role for endocannabinoids in the vlPAG has not yet been observed. We recently have shown (Fu LW, Longhurst JC. J Appl Physiol; doi:10.1152/japplphysiol.91648.2008) that EA reduces the local vlPAG concentration of GABA, but not glutamate, as measured with high-performance liquid chromatography from extracellular samples collected by microdialysis. We, therefore, hypothesized that, during EA, endocannabinoids, acting through CB1 receptors, presynaptically inhibit GABA release to disinhibit the vlPAG and ultimately modulate excitatory reflex blood pressure responses. Rats were anesthetized, ventilated, and instrumented to measure heart rate and blood pressure. Gastric distention-induced blood pressure responses of 18 ± 5 mmHg were reduced to 6 ± 1 mmHg by 30 min of low-current, low-frequency EA applied bilaterally at pericardial P 5–6 acupoints overlying the median nerves. Like EA, microinjection of the fatty acid amide hydrolase inhibitor URB597 (0.1 nmol, 50 nl) into the vlPAG to increase endocannabinoids locally reduced the gastric distention cardiovascular reflex response from 21 ± 5 to 3 ± 4 mmHg. This inhibition was reversed by pretreatment with the GABAA antagonist gabazine (27 mM, 50 nl), suggesting that endocannabinoids exert their action through a GABAergic receptor mechanism in the vlPAG. The EA-related inhibition from 18 ± 3 to 8 ± 2 mmHg was reversed to 14 �

Presynaptic mGlu1 and mGlu5 autoreceptors facilitate glutamate exocytosis from mouse cortical nerve endings.

Science.gov (United States)

Musante, Veronica; Neri, Elisa; Feligioni, Marco; Puliti, Aldamaria; Pedrazzi, Marco; Conti, Valerio; Usai, Cesare; Diaspro, Alberto; Ravazzolo, Roberto; Henley, Jeremy M; Battaglia, Giuseppe; Pittaluga, Anna

2008-09-01

The effects of mGlu1 and mGlu5 receptor activation on the depolarization-evoked release of [3H]d-aspartate ([3H]D-ASP) from mouse cortical synaptosomes were investigated. The mGlu1/5 receptor agonist 3,5-DHPG (0.1-100microM) potentiated the K+(12mM)-evoked [3H]D-ASP overflow. The potentiation occurred in a concentration-dependent manner showing a biphasic pattern. The agonist potentiated [3H]D-ASP exocytosis when applied at 0.3microM; the efficacy of 3,5-DHPG then rapidly declined and reappeared at 30-100microM. The fall of efficacy of agonist at intermediate concentration may be consistent with 3,5-DHPG-induced receptor desensitization. Facilitation of [3H]D-ASP exocytosis caused by 0.3microM 3,5-DHPG was prevented by the selective mGlu5 receptor antagonist MPEP, but was insensitive to the selective mGlu1 receptor antagonist CPCCOEt. In contrast, CPCCOEt prevented the potentiation by 50microM 3,5-DHPG, while MPEP had minimal effect. Unexpectedly, LY 367385 antagonized both the 3,5-DHPG-induced effects. A total of 0.3microM 3,5-DHPG failed to facilitate the K+-evoked [3H]D-ASP overflow from mGlu5 receptor knockout (mGlu5-/-) cortical synaptosomes, but not from nerve terminals prepared from the cortex of animals lacking the mGlu1 receptors, the crv4/crv4 mice. On the contrary, 50microM 3,5-DHPG failed to affect the [3H]D-ASP exocytosis from cortical synaptosomes obtained from crv4/crv4 and mGlu5-/-mice. Western blot analyses in subsynaptic fractions support the existence of both mGlu1 and mGlu5 autoreceptors located presynaptically, while immunocytochemistry revealed their presence at glutamatergic terminals. We propose that mGlu1 and mGlu5 autoreceptors exist on mouse glutamatergic cortical terminals; mGlu5 receptors may represent the "high affinity" binding sites for 3,5-DHPG, while mGlu1 autoreceptors represent the "low affinity" binding sites.

Modulation of cannabinoid receptor activation as a neuroprotective strategy for EAE and stroke.

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Zhang, Ming; Martin, Billy R; Adler, Martin W; Razdan, Raj J; Kong, Weimin; Ganea, Doina; Tuma, Ronald F

2009-06-01

Recognition of the importance of the endocannabinoid system in both homeostasis and pathologic responses raised interest recently in the development of therapeutic agents based on this system. The CB(2) receptor, a component of the endocannabinoid system, has significant influence on immune function and inflammatory responses. Inflammatory responses are major contributors to central nervous system (CNS) injury in a variety of diseases. In this report, we present evidence that activation of CB(2) receptors, by selective CB(2) agonists, reduces inflammatory responses that contribute to CNS injury. The studies demonstrate neuroprotective effects in experimental autoimmune encephalomyelitis, a model of multiple sclerosis, and in a murine model of cerebral ischemia/reperfusion injury. In both cases, CB(2) receptor activation results in reduced white cell rolling and adhesion to cerebral microvessels, a reduction in immune cell invasion, and improved neurologic function after insult. In addition, administration of the CB(1) antagonist SR141716A reduces infarct size following ischemia/reperfusion injury. Administration of both a selective CB(2) agonist and a CB(1) antagonist has the unique property of increasing blood flow to the brain during the occlusion period, suggesting an effect on collateral blood flow. In summary, selective CB(2) receptor agonists and CB(1) receptor antagonists have significant potential for neuroprotection in animal models of two devastating diseases that currently lack effective treatment options.

Muscle Contraction Regulates BDNF/TrkB Signaling to Modulate Synaptic Function through Presynaptic cPKCα and cPKCβI.

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Hurtado, Erica; Cilleros, Víctor; Nadal, Laura; Simó, Anna; Obis, Teresa; Garcia, Neus; Santafé, Manel M; Tomàs, Marta; Halievski, Katherine; Jordan, Cynthia L; Lanuza, Maria A; Tomàs, Josep

2017-01-01

The neurotrophin brain-derived neurotrophic factor (BDNF) acts via tropomyosin-related kinase B receptor (TrkB) to regulate synapse maintenance and function in the neuromuscular system. The potentiation of acetylcholine (ACh) release by BDNF requires TrkB phosphorylation and Protein Kinase C (PKC) activation. BDNF is secreted in an activity-dependent manner but it is not known if pre- and/or postsynaptic activities enhance BDNF expression in vivo at the neuromuscular junction (NMJ). Here, we investigated whether nerve and muscle cell activities regulate presynaptic conventional PKC (cPKCα and βI) via BDNF/TrkB signaling to modulate synaptic strength at the NMJ. To differentiate the effects of presynaptic activity from that of muscle contraction, we stimulated the phrenic nerve of rat diaphragms (1 Hz, 30 min) with or without contraction (abolished by μ-conotoxin GIIIB). Then, we performed ELISA, Western blotting, qRT-PCR, immunofluorescence and electrophysiological techniques. We found that nerve-induced muscle contraction: (1) increases the levels of mature BDNF protein without affecting pro-BDNF protein or BDNF mRNA levels; (2) downregulates TrkB.T1 without affecting TrkB.FL or p75 neurotrophin receptor (p75) levels; (3) increases presynaptic cPKCα and cPKCβI protein level through TrkB signaling; and (4) enhances phosphorylation of cPKCα and cPKCβI. Furthermore, we demonstrate that cPKCβI, which is exclusively located in the motor nerve terminals, increases activity-induced acetylcholine release. Together, these results show that nerve-induced muscle contraction is a key regulator of BDNF/TrkB signaling pathway, retrogradely activating presynaptic cPKC isoforms (in particular cPKCβI) to modulate synaptic function. These results indicate that a decrease in neuromuscular activity, as occurs in several neuromuscular disorders, could affect the BDNF/TrkB/PKC pathway that links pre- and postsynaptic activity to maintain neuromuscular function.

Muscle Contraction Regulates BDNF/TrkB Signaling to Modulate Synaptic Function through Presynaptic cPKCα and cPKCβI

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Erica Hurtado

2017-05-01

Full Text Available The neurotrophin brain-derived neurotrophic factor (BDNF acts via tropomyosin-related kinase B receptor (TrkB to regulate synapse maintenance and function in the neuromuscular system. The potentiation of acetylcholine (ACh release by BDNF requires TrkB phosphorylation and Protein Kinase C (PKC activation. BDNF is secreted in an activity-dependent manner but it is not known if pre- and/or postsynaptic activities enhance BDNF expression in vivo at the neuromuscular junction (NMJ. Here, we investigated whether nerve and muscle cell activities regulate presynaptic conventional PKC (cPKCα and βI via BDNF/TrkB signaling to modulate synaptic strength at the NMJ. To differentiate the effects of presynaptic activity from that of muscle contraction, we stimulated the phrenic nerve of rat diaphragms (1 Hz, 30 min with or without contraction (abolished by μ-conotoxin GIIIB. Then, we performed ELISA, Western blotting, qRT-PCR, immunofluorescence and electrophysiological techniques. We found that nerve-induced muscle contraction: (1 increases the levels of mature BDNF protein without affecting pro-BDNF protein or BDNF mRNA levels; (2 downregulates TrkB.T1 without affecting TrkB.FL or p75 neurotrophin receptor (p75 levels; (3 increases presynaptic cPKCα and cPKCβI protein level through TrkB signaling; and (4 enhances phosphorylation of cPKCα and cPKCβI. Furthermore, we demonstrate that cPKCβI, which is exclusively located in the motor nerve terminals, increases activity-induced acetylcholine release. Together, these results show that nerve-induced muscle contraction is a key regulator of BDNF/TrkB signaling pathway, retrogradely activating presynaptic cPKC isoforms (in particular cPKCβI to modulate synaptic function. These results indicate that a decrease in neuromuscular activity, as occurs in several neuromuscular disorders, could affect the BDNF/TrkB/PKC pathway that links pre- and postsynaptic activity to maintain neuromuscular function.

Targeting the Endocannabinoid/CB1 Receptor System For Treating Major Depression Through Antidepressant Activities of Curcumin and Dexanabinol-Loaded Solid Lipid Nanoparticles

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Xiaolie He

2017-08-01

Full Text Available Background/Aims: This study investigated the underlying mechanisms of the antidepressant effects of curcumin and dexanabinol-loaded solid lipid nanoparticles in corticosterone-induced cell and mice depression models. Methods: Curcumin and dexanabinol-loaded solid lipid nanoparticles (Cur/SLNs-HU-211 were synthesized via an emulsifcation and low-temperature solidification method. Antidepressant activities of nanoparticles in a corticosterone-induced major depression model were investigated by MTT assay, cellular uptake by flow cytometry, behaviour by Forced Swimming Test and rotarod test, neurotransmitters by High Performance Liquid Chromatography, Western blotting, qPCR and immunofluorescence. Results: Treatment with Cur/SLNs-HU-211 induced greater dopamine (DA/5-hydroxytryptamine (5-HT release with reduced corticosterone-induced apoptotic cell death in PC12 cells. Additionally, in vivo Cur/SLNs-HU-211 significantly induced recovery from depressive behaviour with increased DA/5-HT levels, CB1 mRNA levels and CB1, p-MEK1 and p-ERK1/2 protein expression levels in the hippocampus and striatum. Cur/SLNs-HU-211 improved CB1 expression and inspired the proliferation of astrocytes in the hippocampus and striatum, exerted neuroprotective effects by preventing corticosterone -induced BDNF/NeuN expression reduction. Conclusion: Our study implies that Cur/SLNs-HU-211 may be a useful approach for treatment of major depression.

Data of evolutionary structure change: 1A5CB-2QUTA [Confc[Archive

Lifescience Database Archive (English)

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Presynaptic DLG regulates synaptic function through the localization of voltage-activated Ca2+ Channels

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Astorga, César; Jorquera, Ramón A.; Ramírez, Mauricio; Kohler, Andrés; López, Estefanía; Delgado, Ricardo; Córdova, Alex; Olguín, Patricio; Sierralta, Jimena

2016-01-01

The DLG-MAGUK subfamily of proteins plays a role on the recycling and clustering of glutamate receptors (GLUR) at the postsynaptic density. discs-large1 (dlg) is the only DLG-MAGUK gene in Drosophila and originates two main products, DLGA and DLGS97 which differ by the presence of an L27 domain. Combining electrophysiology, immunostaining and genetic manipulation at the pre and postsynaptic compartments we study the DLG contribution to the basal synaptic-function at the Drosophila larval neuromuscular junction. Our results reveal a specific function of DLGS97 in the regulation of the size of GLUR fields and their subunit composition. Strikingly the absence of any of DLG proteins at the presynaptic terminal disrupts the clustering and localization of the calcium channel DmCa1A subunit (Cacophony), decreases the action potential-evoked release probability and alters short-term plasticity. Our results show for the first time a crucial role of DLG proteins in the presynaptic function in vivo. PMID:27573697

Presynaptic DLG regulates synaptic function through the localization of voltage-activated Ca(2+) Channels.

Science.gov (United States)

Astorga, César; Jorquera, Ramón A; Ramírez, Mauricio; Kohler, Andrés; López, Estefanía; Delgado, Ricardo; Córdova, Alex; Olguín, Patricio; Sierralta, Jimena

2016-08-30

The DLG-MAGUK subfamily of proteins plays a role on the recycling and clustering of glutamate receptors (GLUR) at the postsynaptic density. discs-large1 (dlg) is the only DLG-MAGUK gene in Drosophila and originates two main products, DLGA and DLGS97 which differ by the presence of an L27 domain. Combining electrophysiology, immunostaining and genetic manipulation at the pre and postsynaptic compartments we study the DLG contribution to the basal synaptic-function at the Drosophila larval neuromuscular junction. Our results reveal a specific function of DLGS97 in the regulation of the size of GLUR fields and their subunit composition. Strikingly the absence of any of DLG proteins at the presynaptic terminal disrupts the clustering and localization of the calcium channel DmCa1A subunit (Cacophony), decreases the action potential-evoked release probability and alters short-term plasticity. Our results show for the first time a crucial role of DLG proteins in the presynaptic function in vivo.

Presynaptic muscarinic acetylcholine autoreceptors (M1, M2 and M4 subtypes), adenosine receptors (A1 and A2A) and tropomyosin-related kinase B receptor (TrkB) modulate the developmental synapse elimination process at the neuromuscular junction.