Norepinephrine metabolism in neuronal cultures is increased by angiotensin II

International Nuclear Information System (INIS)

Sumners, C.; Shalit, S.L.; Kalberg, C.J.; Raizada, M.K.

1987-01-01

In this study the authors have examined the actions of angiotensin II (ANG II) on catecholamine metabolism in neuronal brain cell cultures prepared from the hypothalamus and brain stem. Neuronal cultures prepared from the brains of 1-day-old Sprague-Dawley rats exhibit specific neuronal uptake mechanisms for both norepinephrine (NE) and dopamine (DA), and also monoamine oxidase (MAO) and catechol O-methyltransferase (COMT) activity. Separate neuronal uptake sites for NE and DA were identified by using specific neuronal uptake inhibitors for each amine. In previous studies, they determined that ANG II (10 nM-1 μM) stimulates increased neuronal [ 3 H]NE uptake by acting as specific receptors. They have confirmed these results here and in addition have shown that ANG II has not significant effects on neuronal [ 3 H]DA uptake. These results suggest that the actions of ANG II are restricted to the NE transporter in neuronal cultures. It is possible that ANG II stimulates the intraneuronal metabolism of at least part of the NE that is taken up, because the peptide stimulates MAO activity, an effect mediated by specific ANG II receptors. ANG II had no effect on COMT activity in neuronal cultures. Therefore, the use of neuronal cultures of hypothalamus and brain stem they have determined that ANG II can specifically alter NE metabolism in these areas, while apparently not altering DA metabolism

Interferon-γ increases neuronal death in response to amyloid-β1-42

Directory of Open Access Journals (Sweden)

Williams Alun

2006-03-01

Full Text Available Abstract Background Alzheimer's disease is a neurodegenerative disorder characterized by a progressive cognitive impairment, the consequence of neuronal dysfunction and ultimately the death of neurons. The amyloid hypothesis proposes that neuronal damage results from the accumulation of insoluble, hydrophobic, fibrillar peptides such as amyloid-β1-42. These peptides activate enzymes resulting in a cascade of second messengers including prostaglandins and platelet-activating factor. Apoptosis of neurons is thought to follow as a consequence of the uncontrolled release of second messengers. Biochemical, histopathological and genetic studies suggest that pro-inflammatory cytokines play a role in neurodegeneration during Alzheimer's disease. In the current study we examined the effects of interferon (IFN-γ, tumour necrosis factor (TNFα, interleukin (IL-1β and IL-6 on neurons. Methods Primary murine cortical or cerebellar neurons, or human SH-SY5Y neuroblastoma cells, were grown in vitro. Neurons were treated with cytokines prior to incubation with different neuronal insults. Cell survival, caspase-3 activity (a measure of apoptosis and prostaglandin production were measured. Immunoblots were used to determine the effects of cytokines on the levels of cytoplasmic phospholipase A2 or phospholipase C γ-1. Results While none of the cytokines tested were directly neurotoxic, pre-treatment with IFN-γ sensitised neurons to the toxic effects of amyloid-β1-42 or HuPrP82-146 (a neurotoxic peptide found in prion diseases. The effects of IFN-γ were seen on cortical and cerebellar neurons, and on SH-SY5Y neuroblastoma cells. However, pre-treatment with IFN-γ did not affect the sensitivity to neurons treated with staurosporine or hydrogen peroxide. Pre-treatment with IFN-γ increased the levels of cytoplasmic phospholipase A2 in SH-SY5Y cells and increased prostaglandin E2 production in response to amyloid-β1-42. Conclusion Treatment of neuronal cells

Cellular Links Between Neuronal Activity and Energy Homeostasis

Directory of Open Access Journals (Sweden)

Pavan K Shetty

2012-03-01

Full Text Available Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function. Nervous system energy homeostasis also varies during long-term physiological conditions (ie, development and aging and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation which leads initially to substrate depletion, induction of a variety of signals for enhanced astrocytic function, and increased local blood flow and substrate delivery. Energy generation (particularly in mitochondria and use during ATP hydrolysis also lead to considerable heat generation. The local increases in blood flow noted following neuronal activation can both enhance local substrate delivery but also provides a heat sink to help cool the brain and removal of waste byproducts. In this review we highlight the interactions between short-term neuronal activity and energy metabolism with an emphasis on signals and factors regulating astrocyte function and substrate supply.

CRISPR Epigenome Editing of AKAP150 in DRG Neurons Abolishes Degenerative IVD-Induced Neuronal Activation.

Science.gov (United States)

Stover, Joshua D; Farhang, Niloofar; Berrett, Kristofer C; Gertz, Jason; Lawrence, Brandon; Bowles, Robby D

2017-09-06

Back pain is a major contributor to disability and has significant socioeconomic impacts worldwide. The degenerative intervertebral disc (IVD) has been hypothesized to contribute to back pain, but a better understanding of the interactions between the degenerative IVD and nociceptive neurons innervating the disc and treatment strategies that directly target these interactions is needed to improve our understanding and treatment of back pain. We investigated degenerative IVD-induced changes to dorsal root ganglion (DRG) neuron activity and utilized CRISPR epigenome editing as a neuromodulation strategy. By exposing DRG neurons to degenerative IVD-conditioned media under both normal and pathological IVD pH levels, we demonstrate that degenerative IVDs trigger interleukin (IL)-6-induced increases in neuron activity to thermal stimuli, which is directly mediated by AKAP and enhanced by acidic pH. Utilizing this novel information on AKAP-mediated increases in nociceptive neuron activity, we developed lentiviral CRISPR epigenome editing vectors that modulate endogenous expression of AKAP150 by targeted promoter histone methylation. When delivered to DRG neurons, these epigenome-modifying vectors abolished degenerative IVD-induced DRG-elevated neuron activity while preserving non-pathologic neuron activity. This work elucidates the potential for CRISPR epigenome editing as a targeted gene-based pain neuromodulation strategy. Copyright © 2017 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

Hyperactivity of newborn Pten knock-out neurons results from increased excitatory synaptic drive.

Science.gov (United States)

Williams, Michael R; DeSpenza, Tyrone; Li, Meijie; Gulledge, Allan T; Luikart, Bryan W

2015-01-21

Developing neurons must regulate morphology, intrinsic excitability, and synaptogenesis to form neural circuits. When these processes go awry, disorders, including autism spectrum disorder (ASD) or epilepsy, may result. The phosphatase Pten is mutated in some patients having ASD and seizures, suggesting that its mutation disrupts neurological function in part through increasing neuronal activity. Supporting this idea, neuronal knock-out of Pten in mice can cause macrocephaly, behavioral changes similar to ASD, and seizures. However, the mechanisms through which excitability is enhanced following Pten depletion are unclear. Previous studies have separately shown that Pten-depleted neurons can drive seizures, receive elevated excitatory synaptic input, and have abnormal dendrites. We therefore tested the hypothesis that developing Pten-depleted neurons are hyperactive due to increased excitatory synaptogenesis using electrophysiology, calcium imaging, morphological analyses, and modeling. This was accomplished by coinjecting retroviruses to either "birthdate" or birthdate and knock-out Pten in granule neurons of the murine neonatal dentate gyrus. We found that Pten knock-out neurons, despite a rapid onset of hypertrophy, were more active in vivo. Pten knock-out neurons fired at more hyperpolarized membrane potentials, displayed greater peak spike rates, and were more sensitive to depolarizing synaptic input. The increased sensitivity of Pten knock-out neurons was due, in part, to a higher density of synapses located more proximal to the soma. We determined that increased synaptic drive was sufficient to drive hypertrophic Pten knock-out neurons beyond their altered action potential threshold. Thus, our work contributes a developmental mechanism for the increased activity of Pten-depleted neurons. Copyright © 2015 the authors 0270-6474/15/350943-17$15.00/0.

Activity of Raphé Serotonergic Neurons Controls Emotional Behaviors.

Science.gov (United States)

Teissier, Anne; Chemiakine, Alexei; Inbar, Benjamin; Bagchi, Sneha; Ray, Russell S; Palmiter, Richard D; Dymecki, Susan M; Moore, Holly; Ansorge, Mark S

2015-12-01

Despite the well-established role of serotonin signaling in mood regulation, causal relationships between serotonergic neuronal activity and behavior remain poorly understood. Using a pharmacogenetic approach, we find that selectively increasing serotonergic neuronal activity in wild-type mice is anxiogenic and reduces floating in the forced-swim test, whereas inhibition has no effect on the same measures. In a developmental mouse model of altered emotional behavior, increased anxiety and depression-like behaviors correlate with reduced dorsal raphé and increased median raphé serotonergic activity. These mice display blunted responses to serotonergic stimulation and behavioral rescues through serotonergic inhibition. Furthermore, we identify opposing consequences of dorsal versus median raphé serotonergic neuron inhibition on floating behavior, together suggesting that median raphé hyperactivity increases anxiety, whereas a low dorsal/median raphé serotonergic activity ratio increases depression-like behavior. Thus, we find a critical role of serotonergic neuronal activity in emotional regulation and uncover opposing roles of median and dorsal raphé function. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Enhancing excitability of dopamine neurons promotes motivational behaviour through increased action initiation.

Science.gov (United States)

Boekhoudt, Linde; Wijbrans, Ellen C; Man, Jodie H K; Luijendijk, Mieneke C M; de Jong, Johannes W; van der Plasse, Geoffrey; Vanderschuren, Louk J M J; Adan, Roger A H

2018-01-01

Motivational deficits are a key symptom in multiple psychiatric disorders, including major depressive disorder, schizophrenia and addiction. A likely neural substrate for these motivational deficits is the brain dopamine (DA) system. In particular, DA signalling in the nucleus accumbens, which originates from DA neurons in the ventral tegmental area (VTA), has been identified as a crucial substrate for effort-related and activational aspects of motivation. Unravelling how VTA DA neuronal activity relates to motivational behaviours is required to understand how motivational deficits in psychiatry can be specifically targeted. In this study, we therefore used designer receptors exclusively activated by designer drugs (DREADD) in TH:Cre rats, in order to determine the effects of chemogenetic DA neuron activation on different aspects of motivational behaviour. We found that chemogenetic activation of DA neurons in the VTA, but not substantia nigra, significantly increased responding for sucrose under a progressive ratio schedule of reinforcement. More specifically, high effort exertion was characterized by increased initiations of reward-seeking actions. This effect was dependent on effort requirements and instrumental contingencies, but was not affected by sucrose pre-feeding. Together, these findings indicate that VTA DA neuronal activation drives motivational behaviour by facilitating action initiation. With this study, we show that enhancing excitability of VTA DA neurons is a viable strategy to improve motivational behaviour. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

Glutamate mediated astrocytic filtering of neuronal activity.

Directory of Open Access Journals (Sweden)

Gilad Wallach

2014-12-01

Full Text Available Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity.

Glutamate Mediated Astrocytic Filtering of Neuronal Activity

Science.gov (United States)

Herzog, Nitzan; De Pittà, Maurizio; Jacob, Eshel Ben; Berry, Hugues; Hanein, Yael

2014-01-01

Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity. PMID:25521344

Neurochemistry of neurons in the ventrolateral medulla activated by hypotension: Are the same neurons activated by glucoprivation?

Science.gov (United States)

Parker, Lindsay M; Le, Sheng; Wearne, Travis A; Hardwick, Kate; Kumar, Natasha N; Robinson, Katherine J; McMullan, Simon; Goodchild, Ann K

2017-06-15

Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed. © 2017 Wiley Periodicals, Inc.

Activation of CRH receptor type 1 expressed on glutamatergic neurons increases excitability of CA1 pyramidal neurons by the modulation of voltage-gated ion channels

Directory of Open Access Journals (Sweden)

Stephan eKratzer

2013-07-01

Full Text Available Corticotropin-releasing hormone (CRH plays an important role in a substantial number of patients with stress-related mental disorders, such as anxiety disorders and depression. CRH has been shown to increase neuronal excitability in the hippocampus, but the underlying mechanisms are poorly understood. The effects of CRH on neuronal excitability were investigated in acute hippocampal brain slices. Population spikes (PS and field excitatory postsynaptic potentials (fEPSP were evoked by stimulating Schaffer-collaterals and recorded simultaneously from the somatic and dendritic region of CA1 pyramidal neurons. CRH was found to increase PS amplitudes (mean  Standard error of the mean; 231.8  31.2% of control; n=10 while neither affecting fEPSPs (104.3 ± 4.2%; n=10 nor long-term potentiation (LTP. However, when Schaffer-collaterals were excited via action potentials (APs generated by stimulation of CA3 pyramidal neurons, CRH increased fEPSP amplitudes (119.8 ± 3.6%; n=8 and the magnitude of LTP in the CA1 region. Experiments in slices from transgenic mice revealed that the effect on PS amplitude is mediated exclusively by CRH receptor 1 (CRHR1 expressed on glutamatergic neurons. The effects of CRH on PS were dependent on phosphatase-2B, L- and T-type calcium channels and voltage-gated potassium channels but independent on intracellular Ca2+-elevation. In patch-clamp experiments, CRH increased the frequency and decay times of APs and decreased currents through A-type and delayed-rectifier potassium channels. These results suggest that CRH does not affect synaptic transmission per se, but modulates voltage-gated ion currents important for the generation of APs and hence elevates by this route overall neuronal activity.

Essential roles of mitochondrial depolarization in neuron loss through microglial activation and attraction toward neurons.

Science.gov (United States)

Nam, Min-Kyung; Shin, Hyun-Ah; Han, Ji-Hye; Park, Dae-Wook; Rhim, Hyangshuk

2013-04-10

As life spans increased, neurodegenerative disorders that affect aging populations have also increased. Progressive neuronal loss in specific brain regions is the most common cause of neurodegenerative disease; however, key determinants mediating neuron loss are not fully understood. Using a model of mitochondrial membrane potential (ΔΨm) loss, we found only 25% cell loss in SH-SY5Y (SH) neuronal mono-cultures, but interestingly, 85% neuronal loss occurred when neurons were co-cultured with BV2 microglia. SH neurons overexpressing uncoupling protein 2 exhibited an increase in neuron-microglia interactions, which represent an early step in microglial phagocytosis of neurons. This result indicates that ΔΨm loss in SH neurons is an important contributor to recruitment of BV2 microglia. Notably, we show that ΔΨm loss in BV2 microglia plays a crucial role in microglial activation and phagocytosis of damaged SH neurons. Thus, our study demonstrates that ΔΨm loss in both neurons and microglia is a critical determinant of neuron loss. These findings also offer new insights into neuroimmunological and bioenergetical aspects of neurodegenerative disease. Copyright © 2013 Elsevier B.V. All rights reserved.

Dehydration-induced modulation of κ-opioid inhibition of vasopressin neurone activity

Science.gov (United States)

Scott, Victoria; Bishop, Valerie R; Leng, Gareth; Brown, Colin H

2009-01-01

Dehydration increases vasopressin (antidiuretic hormone) secretion from the posterior pituitary gland to reduce water loss in the urine. Vasopressin secretion is determined by action potential firing in vasopressin neurones, which can exhibit continuous, phasic (alternating periods of activity and silence), or irregular activity. Autocrine κ-opioid inhibition contributes to the generation of activity patterning of vasopressin neurones under basal conditions and so we used in vivo extracellular single unit recording to test the hypothesis that changes in autocrine κ-opioid inhibition drive changes in activity patterning of vasopressin neurones during dehydration. Dehydration increased the firing rate of rat vasopressin neurones displaying continuous activity (from 7.1 ± 0.5 to 9.0 ± 0.6 spikes s−1) and phasic activity (from 4.2 ± 0.7 to 7.8 ± 0.9 spikes s−1), but not those displaying irregular activity. The dehydration-induced increase in phasic activity was via an increase in intraburst firing rate. The selective κ-opioid receptor antagonist nor-binaltorphimine increased the firing rate of phasic neurones in non-dehydrated rats (from 3.4 ± 0.8 to 5.3 ± 0.6 spikes s−1) and dehydrated rats (from 6.4 ± 0.5 to 9.1 ± 1.2 spikes s−1), indicating that κ-opioid feedback inhibition of phasic bursts is maintained during dehydration. In a separate series of experiments, prodynorphin mRNA expression was increased in vasopressin neurones of hyperosmotic rats, compared to hypo-osmotic rats. Hence, it appears that dynorphin expression in vasopressin neurones undergoes dynamic changes in proportion to the required secretion of vasopressin so that, even under stimulated conditions, autocrine feedback inhibition of vasopressin neurones prevents over-excitation. PMID:19822541

GABAergic inhibition through synergistic astrocytic neuronal interaction transiently decreases vasopressin neuronal activity during hypoosmotic challenge.

Science.gov (United States)

Wang, Yu-Feng; Sun, Min-Yu; Hou, Qiuling; Hamilton, Kathryn A

2013-04-01

The neuropeptide vasopressin is crucial to mammalian osmotic regulation. Local hypoosmotic challenge transiently decreases and then increases vasopressin secretion. To investigate mechanisms underlying this transient response, we examined the effects of hypoosmotic challenge on the electrical activity of rat hypothalamic supraoptic nucleus (SON) vasopressin neurons using patch-clamp recordings. We found that 5 min exposure of hypothalamic slices to hypoosmotic solution transiently increased inhibitory postsynaptic current (IPSC) frequency and reduced the firing rate of vasopressin neurons. Recovery occurred by 10 min of exposure, even though the osmolality remained low. The γ-aminobutyric acid (GABA)A receptor blocker, gabazine, blocked the IPSCs and the hypoosmotic suppression of firing. The gliotoxin l-aminoadipic acid blocked the increase in IPSC frequency at 5 min and the recovery of firing at 10 min, indicating astrocytic involvement in hypoosmotic modulation of vasopressin neuronal activity. Moreover, β-alanine, an osmolyte of astrocytes and GABA transporter (GAT) inhibitor, blocked the increase in IPSC frequency at 5 min of hypoosmotic challenge. Confocal microscopy of immunostained SON sections revealed that astrocytes and magnocellular neurons both showed positive staining of vesicular GATs (VGAT). Hypoosmotic stimulation in vivo reduced the number of VGAT-expressing neurons, and increased co-localisation and molecular association of VGAT with glial fibrillary acidic protein that increased significantly by 10 min. By 30 min, neuronal VGAT labelling was partially restored, and astrocytic VGAT was relocated to the ventral portion while it decreased in the somatic zone of the SON. Thus, synergistic astrocytic and neuronal GABAergic inhibition could ensure that vasopressin neuron firing is only transiently suppressed under hypoosmotic conditions. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Cellular Links between Neuronal Activity and Energy Homeostasis

OpenAIRE

Shetty, Pavan K.; Galeffi, Francesca; Turner, Dennis A.

2012-01-01

Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function). Nervous system energy homeostasis also varies during long-term physiological conditions (i.e., development and aging) and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation) which lea...

Intrinsically active and pacemaker neurons in pluripotent stem cell-derived neuronal populations.

Science.gov (United States)

Illes, Sebastian; Jakab, Martin; Beyer, Felix; Gelfert, Renate; Couillard-Despres, Sébastien; Schnitzler, Alfons; Ritter, Markus; Aigner, Ludwig

2014-03-11

Neurons generated from pluripotent stem cells (PSCs) self-organize into functional neuronal assemblies in vitro, generating synchronous network activities. Intriguingly, PSC-derived neuronal assemblies develop spontaneous activities that are independent of external stimulation, suggesting the presence of thus far undetected intrinsically active neurons (IANs). Here, by using mouse embryonic stem cells, we provide evidence for the existence of IANs in PSC-neuronal networks based on extracellular multielectrode array and intracellular patch-clamp recordings. IANs remain active after pharmacological inhibition of fast synaptic communication and possess intrinsic mechanisms required for autonomous neuronal activity. PSC-derived IANs are functionally integrated in PSC-neuronal populations, contribute to synchronous network bursting, and exhibit pacemaker properties. The intrinsic activity and pacemaker properties of the neuronal subpopulation identified herein may be particularly relevant for interventions involving transplantation of neural tissues. IANs may be a key element in the regulation of the functional activity of grafted as well as preexisting host neuronal networks.

Synaptic and intrinsic activation of GABAergic neurons in the cardiorespiratory brainstem network.

Science.gov (United States)

Frank, Julie G; Mendelowitz, David

2012-01-01

GABAergic pathways in the brainstem play an essential role in respiratory rhythmogenesis and interactions between the respiratory and cardiovascular neuronal control networks. However, little is known about the identity and function of these GABAergic inhibitory neurons and what determines their activity. In this study we have identified a population of GABAergic neurons in the ventrolateral medulla that receive increased excitatory post-synaptic potentials during inspiration, but also have spontaneous firing in the absence of synaptic input. Using transgenic mice that express GFP under the control of the Gad1 (GAD67) gene promoter, we determined that this population of GABAergic neurons is in close apposition to cardioinhibitory parasympathetic cardiac neurons in the nucleus ambiguus (NA). These neurons fire in synchronization with inspiratory activity. Although they receive excitatory glutamatergic synaptic inputs during inspiration, this excitatory neurotransmission was not altered by blocking nicotinic receptors, and many of these GABAergic neurons continue to fire after synaptic blockade. The spontaneous firing in these GABAergic neurons was not altered by the voltage-gated calcium channel blocker cadmium chloride that blocks both neurotransmission to these neurons and voltage-gated Ca(2+) currents, but spontaneous firing was diminished by riluzole, demonstrating a role of persistent sodium channels in the spontaneous firing in these cardiorespiratory GABAergic neurons that possess a pacemaker phenotype. The spontaneously firing GABAergic neurons identified in this study that increase their activity during inspiration would support respiratory rhythm generation if they acted primarily to inhibit post-inspiratory neurons and thereby release inspiration neurons to increase their activity. This population of inspiratory-modulated GABAergic neurons could also play a role in inhibiting neurons that are most active during expiration and provide a framework for

Synaptic and intrinsic activation of GABAergic neurons in the cardiorespiratory brainstem network.

Directory of Open Access Journals (Sweden)

Julie G Frank

Full Text Available GABAergic pathways in the brainstem play an essential role in respiratory rhythmogenesis and interactions between the respiratory and cardiovascular neuronal control networks. However, little is known about the identity and function of these GABAergic inhibitory neurons and what determines their activity. In this study we have identified a population of GABAergic neurons in the ventrolateral medulla that receive increased excitatory post-synaptic potentials during inspiration, but also have spontaneous firing in the absence of synaptic input. Using transgenic mice that express GFP under the control of the Gad1 (GAD67 gene promoter, we determined that this population of GABAergic neurons is in close apposition to cardioinhibitory parasympathetic cardiac neurons in the nucleus ambiguus (NA. These neurons fire in synchronization with inspiratory activity. Although they receive excitatory glutamatergic synaptic inputs during inspiration, this excitatory neurotransmission was not altered by blocking nicotinic receptors, and many of these GABAergic neurons continue to fire after synaptic blockade. The spontaneous firing in these GABAergic neurons was not altered by the voltage-gated calcium channel blocker cadmium chloride that blocks both neurotransmission to these neurons and voltage-gated Ca(2+ currents, but spontaneous firing was diminished by riluzole, demonstrating a role of persistent sodium channels in the spontaneous firing in these cardiorespiratory GABAergic neurons that possess a pacemaker phenotype. The spontaneously firing GABAergic neurons identified in this study that increase their activity during inspiration would support respiratory rhythm generation if they acted primarily to inhibit post-inspiratory neurons and thereby release inspiration neurons to increase their activity. This population of inspiratory-modulated GABAergic neurons could also play a role in inhibiting neurons that are most active during expiration and provide a

Rivastigmine lowers Aβ and increases sAPPα levels, which parallel elevated synaptic markers and metabolic activity in degenerating primary rat neurons.

Directory of Open Access Journals (Sweden)

Jason A Bailey

Full Text Available Overproduction of amyloid-β (Aβ protein in the brain has been hypothesized as the primary toxic insult that, via numerous mechanisms, produces cognitive deficits in Alzheimer's disease (AD. Cholinesterase inhibition is a primary strategy for treatment of AD, and specific compounds of this class have previously been demonstrated to influence Aβ precursor protein (APP processing and Aβ production. However, little information is available on the effects of rivastigmine, a dual acetylcholinesterase and butyrylcholinesterase inhibitor, on APP processing. As this drug is currently used to treat AD, characterization of its various activities is important to optimize its clinical utility. We have previously shown that rivastigmine can preserve or enhance neuronal and synaptic terminal markers in degenerating primary embryonic cerebrocortical cultures. Given previous reports on the effects of APP and Aβ on synapses, regulation of APP processing represents a plausible mechanism for the synaptic effects of rivastigmine. To test this hypothesis, we treated degenerating primary cultures with rivastigmine and measured secreted APP (sAPP and Aβ. Rivastigmine treatment increased metabolic activity in these cultured cells, and elevated APP secretion. Analysis of the two major forms of APP secreted by these cultures, attributed to neurons or glia based on molecular weight showed that rivastigmine treatment significantly increased neuronal relative to glial secreted APP. Furthermore, rivastigmine treatment increased α-secretase cleaved sAPPα and decreased Aβ secretion, suggesting a therapeutic mechanism wherein rivastigmine alters the relative activities of the secretase pathways. Assessment of sAPP levels in rodent CSF following once daily rivastigmine administration for 21 days confirmed that elevated levels of APP in cell culture translated in vivo. Taken together, rivastigmine treatment enhances neuronal sAPP and shifts APP processing toward the �

Energy Model of Neuron Activation.

Science.gov (United States)

Romanyshyn, Yuriy; Smerdov, Andriy; Petrytska, Svitlana

2017-02-01

On the basis of the neurophysiological strength-duration (amplitude-duration) curve of neuron activation (which relates the threshold amplitude of a rectangular current pulse of neuron activation to the pulse duration), as well as with the use of activation energy constraint (the threshold curve corresponds to the energy threshold of neuron activation by a rectangular current pulse), an energy model of neuron activation by a single current pulse has been constructed. The constructed model of activation, which determines its spectral properties, is a bandpass filter. Under the condition of minimum-phase feature of the neuron activation model, on the basis of Hilbert transform, the possibilities of phase-frequency response calculation from its amplitude-frequency response have been considered. Approximation to the amplitude-frequency response by the response of the Butterworth filter of the first order, as well as obtaining the pulse response corresponding to this approximation, give us the possibility of analyzing the efficiency of activating current pulses of various shapes, including analysis in accordance with the energy constraint.

Spiking Activity of a LIF Neuron in Distributed Delay Framework

Directory of Open Access Journals (Sweden)

Saket Kumar Choudhary

2016-06-01

Full Text Available Evolution of membrane potential and spiking activity for a single leaky integrate-and-fire (LIF neuron in distributed delay framework (DDF is investigated. DDF provides a mechanism to incorporate memory element in terms of delay (kernel function into a single neuron models. This investigation includes LIF neuron model with two different kinds of delay kernel functions, namely, gamma distributed delay kernel function and hypo-exponential distributed delay kernel function. Evolution of membrane potential for considered models is studied in terms of stationary state probability distribution (SPD. Stationary state probability distribution of membrane potential (SPDV for considered neuron models are found asymptotically similar which is Gaussian distributed. In order to investigate the effect of membrane potential delay, rate code scheme for neuronal information processing is applied. Firing rate and Fano-factor for considered neuron models are calculated and standard LIF model is used for comparative study. It is noticed that distributed delay increases the spiking activity of a neuron. Increase in spiking activity of neuron in DDF is larger for hypo-exponential distributed delay function than gamma distributed delay function. Moreover, in case of hypo-exponential delay function, a LIF neuron generates spikes with Fano-factor less than 1.

Direct evidence for activity-dependent glucose phosphorylation in neurons with implications for the astrocyte-to-neuron lactate shuttle.

Science.gov (United States)

Patel, Anant B; Lai, James C K; Chowdhury, Golam M I; Hyder, Fahmeed; Rothman, Douglas L; Shulman, Robert G; Behar, Kevin L

2014-04-08

Previous (13)C magnetic resonance spectroscopy experiments have shown that over a wide range of neuronal activity, approximately one molecule of glucose is oxidized for every molecule of glutamate released by neurons and recycled through astrocytic glutamine. The measured kinetics were shown to agree with the stoichiometry of a hypothetical astrocyte-to-neuron lactate shuttle model, which predicted negligible functional neuronal uptake of glucose. To test this model, we measured the uptake and phosphorylation of glucose in nerve terminals isolated from rats infused with the glucose analog, 2-fluoro-2-deoxy-D-glucose (FDG) in vivo. The concentrations of phosphorylated FDG (FDG6P), normalized with respect to known neuronal metabolites, were compared in nerve terminals, homogenate, and cortex of anesthetized rats with and without bicuculline-induced seizures. The increase in FDG6P in nerve terminals agreed well with the increase in cortical neuronal glucose oxidation measured previously under the same conditions in vivo, indicating that direct uptake and oxidation of glucose in nerve terminals is substantial under resting and activated conditions. These results suggest that neuronal glucose-derived pyruvate is the major oxidative fuel for activated neurons, not lactate-derived from astrocytes, contradicting predictions of the original astrocyte-to-neuron lactate shuttle model under the range of study conditions.

Does rapid and physiological astrocyte–neuron signalling amplify epileptic activity?

Science.gov (United States)

2016-01-01

Abstract The hippocampus is a key brain region in the pathophysiology of mesial temporal lobe epilepsy. Long‐term changes of its architecture and function on the network and cellular level are well documented in epilepsy. Astrocytes can control many aspects of neuronal function and their long‐term alterations over weeks, months and years play an important role in epilepsy. However, a pathophysiological transformation of astrocytes does not seem to be required for astrocytes to contribute to epileptic activity. Some of the properties of physiological astrocyte–neuron communication could allow these cells to exacerbate or synchronize neuronal firing on shorter time scales of milliseconds to minutes. Therefore, these astrocyte–neuron interactions are increasingly recognized as potential contributors to epileptic activity. Fast and reciprocal communication between astrocytes and neurons is enabled by a diverse set of mechanisms that could both amplify and counteract epileptic activity. They may thus promote or cause development of epileptic activity or inhibit it. Mechanisms of astrocyte–neuron interactions that can quickly increase network excitability involve, for example, astrocyte Ca2+ and Na+ signalling, K+ buffering, gap junction coupling and metabolism. However, rapid changes of astrocyte neurotransmitter uptake and morphology may also underlie or support development of network hyperexcitability. The temporal characteristics of these interactions, their ability to synchronize neuronal activity and their net effect on network activity will determine their contribution to the emergence or maintenance of epileptic activity. PMID:27106234

Does rapid and physiological astrocyte-neuron signalling amplify epileptic activity?

Science.gov (United States)

Henneberger, Christian

2017-03-15

The hippocampus is a key brain region in the pathophysiology of mesial temporal lobe epilepsy. Long-term changes of its architecture and function on the network and cellular level are well documented in epilepsy. Astrocytes can control many aspects of neuronal function and their long-term alterations over weeks, months and years play an important role in epilepsy. However, a pathophysiological transformation of astrocytes does not seem to be required for astrocytes to contribute to epileptic activity. Some of the properties of physiological astrocyte-neuron communication could allow these cells to exacerbate or synchronize neuronal firing on shorter time scales of milliseconds to minutes. Therefore, these astrocyte-neuron interactions are increasingly recognized as potential contributors to epileptic activity. Fast and reciprocal communication between astrocytes and neurons is enabled by a diverse set of mechanisms that could both amplify and counteract epileptic activity. They may thus promote or cause development of epileptic activity or inhibit it. Mechanisms of astrocyte-neuron interactions that can quickly increase network excitability involve, for example, astrocyte Ca 2+ and Na + signalling, K + buffering, gap junction coupling and metabolism. However, rapid changes of astrocyte neurotransmitter uptake and morphology may also underlie or support development of network hyperexcitability. The temporal characteristics of these interactions, their ability to synchronize neuronal activity and their net effect on network activity will determine their contribution to the emergence or maintenance of epileptic activity. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Glycogen synthase kinase-3beta and the p25 activator of cyclin dependent kinase 5 increase pausing of mitochondria in neurons.

Science.gov (United States)

Morel, M; Authelet, M; Dedecker, R; Brion, J P

2010-06-02

The complex bi-directional axoplasmic transport of mitochondria is essential for proper metabolic functioning of neurons and is controlled by phosphorylation. We have investigated by time-lapse imaging the effects of increased expression of glycogen synthase kinase-3beta (GSK-3beta) and of the p25 activator of cyclin dependent kinase 5 on mitochondria movements in mammalian cortical neurons and in PC12 cells. Both GSK-3beta and p25 increased the stationary behaviour of mitochondria in PC12 and in neurons, decreased their anterograde transport but did not affect the intrinsic velocities of mitochondria. The microtubule-associated tau proteins were more phosphorylated in GSK-3beta and p25 transfected neurons, but ultrastructural observation showed that these cells still contained microtubules and nocodazole treatment further reduced residual mitochondria movements in GSK-3beta or p25 transfected neurons, indicating that microtubule disruption was not the primary cause of increased mitochondrial stationary behaviour in GSK-3beta or p25 transfected neurons. Our results suggest that increased expression of GSK-3beta and p25 acted rather by decreasing the frequency of mitochondrial movements driven by molecular motors and that GSK-3beta and p25 might regulate these transports by controlling the time that mitochondria spend pausing, rather than their velocities. Copyright 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Cocaine- and amphetamine-regulated transcript peptide increases mitochondrial respiratory chain complex II activity and protects against oxygen-glucose deprivation in neurons.

Science.gov (United States)

Sha, Dujuan; Wang, Luna; Zhang, Jun; Qian, Lai; Li, Qiming; Li, Jin; Qian, Jian; Gu, Shuangshuang; Han, Ling; Xu, Peng; Xu, Yun

2014-09-25

The mechanisms of ischemic stroke, a main cause of disability and death, are complicated. Ischemic stroke results from the interaction of various factors including oxidative stress, a key pathological mechanism that plays an important role during the acute stage of ischemic brain injury. This study demonstrated that cocaine- and amphetamine-regulated transcript (CART) peptide, specifically CART55-102, increased the survival rate, but decreased the mortality of neurons exposed to oxygen-glucose deprivation (OGD), in a dose-dependent manner. The above-mentioned effects of CART55-102 were most significant at 0.4nM. These results indicated that CART55-102 suppressed neurotoxicity and enhanced neuronal survival after oxygen-glucose deprivation. CART55-102 (0.4nM) significantly diminished reactive oxygen species levels and markedly increased the activity of mitochondrial respiratory chain complex II in oxygen-glucose deprived neurons. In summary, CART55-102 suppressed oxidative stress in oxygen-glucose deprived neurons, possibly through elevating the activity of mitochondrial respiratory chain complex II. This result provides evidence for the development of CART55-102 as an antioxidant drug. Copyright © 2014 Elsevier B.V. All rights reserved.

Vasculo-Neuronal Coupling: Retrograde Vascular Communication to Brain Neurons.

Science.gov (United States)

Kim, Ki Jung; Ramiro Diaz, Juan; Iddings, Jennifer A; Filosa, Jessica A

2016-12-14

Continuous cerebral blood flow is essential for neuronal survival, but whether vascular tone influences resting neuronal function is not known. Using a multidisciplinary approach in both rat and mice brain slices, we determined whether flow/pressure-evoked increases or decreases in parenchymal arteriole vascular tone, which result in arteriole constriction and dilation, respectively, altered resting cortical pyramidal neuron activity. We present evidence for intercellular communication in the brain involving a flow of information from vessel to astrocyte to neuron, a direction opposite to that of classic neurovascular coupling and referred to here as vasculo-neuronal coupling (VNC). Flow/pressure increases within parenchymal arterioles increased vascular tone and simultaneously decreased resting pyramidal neuron firing activity. On the other hand, flow/pressure decreases evoke parenchymal arteriole dilation and increased resting pyramidal neuron firing activity. In GLAST-CreERT2; R26-lsl-GCaMP3 mice, we demonstrate that increased parenchymal arteriole tone significantly increased intracellular calcium in perivascular astrocyte processes, the onset of astrocyte calcium changes preceded the inhibition of cortical pyramidal neuronal firing activity. During increases in parenchymal arteriole tone, the pyramidal neuron response was unaffected by blockers of nitric oxide, GABA A , glutamate, or ecto-ATPase. However, VNC was abrogated by TRPV4 channel, GABA B , as well as an adenosine A 1 receptor blocker. Differently to pyramidal neuron responses, increases in flow/pressure within parenchymal arterioles increased the firing activity of a subtype of interneuron. Together, these data suggest that VNC is a complex constitutive active process that enables neurons to efficiently adjust their resting activity according to brain perfusion levels, thus safeguarding cellular homeostasis by preventing mismatches between energy supply and demand. We present evidence for vessel-to-neuron

Serotonin neurons in the dorsal raphe mediate the anticataplectic action of orexin neurons by reducing amygdala activity.

Science.gov (United States)

Hasegawa, Emi; Maejima, Takashi; Yoshida, Takayuki; Masseck, Olivia A; Herlitze, Stefan; Yoshioka, Mitsuhiro; Sakurai, Takeshi; Mieda, Michihiro

2017-04-25

Narcolepsy is a sleep disorder caused by the loss of orexin (hypocretin)-producing neurons and marked by excessive daytime sleepiness and a sudden weakening of muscle tone, or cataplexy, often triggered by strong emotions. In a mouse model for narcolepsy, we previously demonstrated that serotonin neurons of the dorsal raphe nucleus (DRN) mediate the suppression of cataplexy-like episodes (CLEs) by orexin neurons. Using an optogenetic tool, in this paper we show that the acute activation of DRN serotonin neuron terminals in the amygdala, but not in nuclei involved in regulating rapid eye-movement sleep and atonia, suppressed CLEs. Not only did stimulating serotonin nerve terminals reduce amygdala activity, but the chemogenetic inhibition of the amygdala using designer receptors exclusively activated by designer drugs also drastically decreased CLEs, whereas chemogenetic activation increased them. Moreover, the optogenetic inhibition of serotonin nerve terminals in the amygdala blocked the anticataplectic effects of orexin signaling in DRN serotonin neurons. Taken together, the results suggest that DRN serotonin neurons, as a downstream target of orexin neurons, inhibit cataplexy by reducing the activity of amygdala as a center for emotional processing.

Osmotic Edema Rapidly Increases Neuronal Excitability Through Activation of NMDA Receptor-Dependent Slow Inward Currents in Juvenile and Adult Hippocampus

Directory of Open Access Journals (Sweden)

Kelli Lauderdale

2015-09-01

Full Text Available Cellular edema (cell swelling is a principal component of numerous brain disorders including ischemia, cortical spreading depression, hyponatremia, and epilepsy. Cellular edema increases seizure-like activity in vitro and in vivo, largely through nonsynaptic mechanisms attributable to reduction of the extracellular space. However, the types of excitability changes occurring in individual neurons during the acute phase of cell volume increase remain unclear. Using whole-cell patch clamp techniques, we report that one of the first effects of osmotic edema on excitability of CA1 pyramidal cells is the generation of slow inward currents (SICs, which initiate after approximately 1 min. Frequency of SICs increased as osmolarity decreased in a dose-dependent manner. Imaging of real-time volume changes in astrocytes revealed that neuronal SICs occurred while astrocytes were still in the process of swelling. SICs evoked by cell swelling were mainly nonsynaptic in origin and NMDA receptor-dependent. To better understand the relationship between SICs and changes in neuronal excitability, recordings were performed in increasingly physiological conditions. In the absence of any added pharmacological reagents or imposed voltage clamp, osmotic edema induced excitatory postsynaptic potentials and burst firing over the same timecourse as SICs. Like SICs, action potentials were blocked by NMDAR antagonists. Effects were more pronounced in adult (8–20 weeks old compared with juvenile (P15–P21 mice. Together, our results indicate that cell swelling triggered by reduced osmolarity rapidly increases neuronal excitability through activation of NMDA receptors. Our findings have important implications for understanding nonsynaptic mechanisms of epilepsy in relation to cell swelling and reduction of the extracellular space.

MMPs and soluble ICAM-5 increase neuronal excitability within in vitro networks of hippocampal neurons.

Directory of Open Access Journals (Sweden)

Mark Niedringhaus

Full Text Available Matrix metalloproteinases (MMPs are zinc-dependent endopeptidases that are released from neurons in an activity dependent manner. Published studies suggest their activity is important to varied forms of learning and memory. At least one MMP can stimulate an increase in the size of dendritic spines, structures which represent the post synaptic component for a large number of glutamatergic synapses. This change may be associated with increased synaptic glutamate receptor incorporation, and an increased amplitude and/or frequency of α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA mini excitatory post-synaptic currents (EPSCs. An associated increase in the probability of action potential occurrence would be expected. While the mechanism(s by which MMPs may influence synaptic structure and function are not completely understood, MMP dependent shedding of specific cell adhesion molecules (CAMs could play an important role. CAMs are ideally positioned to be cleaved by synaptically released MMPs, and shed N terminal domains could potentially interact with previously unengaged integrins to stimulate dendritic actin polymerization with spine expansion. In the present study, we have used multielectrode arrays (MEAs to investigate MMP and soluble CAM dependent changes in neuronal activity recorded from hippocampal cultures. We have focused on intercellular adhesion molecule-5 (ICAM-5 in particular, as this CAM is expressed on glutamatergic dendrites and shed in an MMP dependent manner. We show that chemical long-term potentiation (cLTP evoked changes in recorded activity, and the dynamics of action potential bursts in particular, are altered by MMP inhibition. A blocking antibody to β(1 integrins has a similar effect. We also show that the ectodomain of ICAM-5 can stimulate β(1 integrin dependent increases in spike counts and burst number. These results support a growing body of literature suggesting that MMPs have important effects on neuronal

Neuronal Depolarization Drives Increased Dopamine Synaptic Vesicle Loading via VGLUT.

Science.gov (United States)

Aguilar, Jenny I; Dunn, Matthew; Mingote, Susana; Karam, Caline S; Farino, Zachary J; Sonders, Mark S; Choi, Se Joon; Grygoruk, Anna; Zhang, Yuchao; Cela, Carolina; Choi, Ben Jiwon; Flores, Jorge; Freyberg, Robin J; McCabe, Brian D; Mosharov, Eugene V; Krantz, David E; Javitch, Jonathan A; Sulzer, David; Sames, Dalibor; Rayport, Stephen; Freyberg, Zachary

2017-08-30

The ability of presynaptic dopamine terminals to tune neurotransmitter release to meet the demands of neuronal activity is critical to neurotransmission. Although vesicle content has been assumed to be static, in vitro data increasingly suggest that cell activity modulates vesicle content. Here, we use a coordinated genetic, pharmacological, and imaging approach in Drosophila to study the presynaptic machinery responsible for these vesicular processes in vivo. We show that cell depolarization increases synaptic vesicle dopamine content prior to release via vesicular hyperacidification. This depolarization-induced hyperacidification is mediated by the vesicular glutamate transporter (VGLUT). Remarkably, both depolarization-induced dopamine vesicle hyperacidification and its dependence on VGLUT2 are seen in ventral midbrain dopamine neurons in the mouse. Together, these data suggest that in response to depolarization, dopamine vesicles utilize a cascade of vesicular transporters to dynamically increase the vesicular pH gradient, thereby increasing dopamine vesicle content. Copyright © 2017 Elsevier Inc. All rights reserved.

Prenatal androgenization of female mice programs an increase in firing activity of gonadotropin-releasing hormone (GnRH) neurons that is reversed by metformin treatment in adulthood.

Science.gov (United States)

Roland, Alison V; Moenter, Suzanne M

2011-02-01

Prenatal androgenization (PNA) of female mice with dihydrotestosterone programs reproductive dysfunction in adulthood, characterized by elevated luteinizing hormone levels, irregular estrous cycles, and central abnormalities. Here, we evaluated activity of GnRH neurons from PNA mice and the effects of in vivo treatment with metformin, an activator of AMP-activated protein kinase (AMPK) that is commonly used to treat the fertility disorder polycystic ovary syndrome. Estrous cycles were monitored in PNA and control mice before and after metformin administration. Before metformin, cycles were longer in PNA mice and percent time in estrus lower; metformin normalized cycles in PNA mice. Extracellular recordings were used to monitor GnRH neuron firing activity in brain slices from diestrous mice. Firing rate was higher and quiescence lower in GnRH neurons from PNA mice, demonstrating increased GnRH neuron activity. Metformin treatment of PNA mice restored firing activity and LH to control levels. To assess whether AMPK activation contributed to the metformin-induced reduction in GnRH neuron activity, the AMPK antagonist compound C was acutely applied to cells. Compound C stimulated cells from metformin-treated, but not untreated, mice, suggesting that AMPK was activated in GnRH neurons, or afferent neurons, in the former group. GnRH neurons from metformin-treated mice also showed a reduced inhibitory response to low glucose. These studies indicate that PNA causes enhanced firing activity of GnRH neurons and elevated LH that are reversible by metformin, raising the possibility that central AMPK activation by metformin may play a role in its restoration of reproductive cycles in polycystic ovary syndrome.

Synaptic network activity induces neuronal differentiation of adult hippocampal precursor cells through BDNF signaling

Directory of Open Access Journals (Sweden)

Harish Babu

2009-09-01

Full Text Available Adult hippocampal neurogenesis is regulated by activity. But how do neural precursor cells in the hippocampus respond to surrounding network activity and translate increased neural activity into a developmental program? Here we show that long-term potential (LTP-like synaptic activity within a cellular network of mature hippocampal neurons promotes neuronal differentiation of newly generated cells. In co-cultures of precursor cells with primary hippocampal neurons, LTP-like synaptic plasticity induced by addition of glycine in Mg2+-free media for 5 min, produced synchronous network activity and subsequently increased synaptic strength between neurons. Furthermore, this synchronous network activity led to a significant increase in neuronal differentiation from the co-cultured neural precursor cells. When applied directly to precursor cells, glycine and Mg2+-free solution did not induce neuronal differentiation. Synaptic plasticity-induced neuronal differentiation of precursor cells was observed in the presence of GABAergic neurotransmission blockers but was dependent on NMDA-mediated Ca2+ influx. Most importantly, neuronal differentiation required the release of brain-derived neurotrophic factor (BDNF from the underlying substrate hippocampal neurons as well as TrkB receptor phosphorylation in precursor cells. This suggests that activity-dependent stem cell differentiation within the hippocampal network is mediated via synaptically evoked BDNF signaling.

Role of neuronal activity in regulating the structure and function of auditory neurons

International Nuclear Information System (INIS)

Born, D.E.

1986-01-01

The role of afferent activity in maintaining neuronal structure and function was investigated in second order auditory neurons in nucleus magnocellularis (NM) of the chicken. The cochlea provides the major excitatory input to NM neurons via the eighth nerve. Removal of the cochlea causes dramatic changes in NM neurons. To determine if the elimination of neuronal activity is responsible for the changes in NM seen after cochlea removal, tetrodotoxin was used block action potentials in the cochlear ganglion cells. Tetrodotoxin injections into the perilymph reliably blocked neuronal activity in the cochlear nerve and NM. Far field recordings of sound-evoked potentials revealed that responses returned within 6 hours. Changes in amino acid incorporation in NM neurons were measured by giving intracardiac injections of 3 H-leucine and preparing tissue for autoradiographic demonstration of incorporated amino acid. Grain counts over individual neurons revealed that a single injection of tetrodotoxin produced a 40% decrease in grain density in ipsilateral NM neurons. It is concluded that neuronal activity plays an important contribution to the maintenance of the normal properties of NM neurons

Activity of gypsy moth dorsolateral neurosecretory neurons under increased rearing density

Directory of Open Access Journals (Sweden)

Mrdaković Marija

2012-01-01

Full Text Available Lymantria dispar caterpillars were reared under two different rearing densities for the first three days of the 4th larval instar: 5 larvae that were kept in a Petri dish (V = 80 ml belonged to the intense stress (D1 group; 5 larvae that were kept in a plastic cup (V = 300ml belonged to the group exposed to less intense stress (D2 group. In the control group, single larvae were reared in a Petri dish. Morphometric changes in L1, L2 and L2’ dorsolateral neurosecretory neurons (nsn were analyzed. After keeping 5 larvae in a Petri dish, the size of L2 neurosecretory neurons (nsn significantly increased. Rearing 5 larvae in a plastic cup significantly increased the size of L1 nsn nuclei and the number of L2’nsn. A decrease in relative band densities in the region of molecular masses (11-15 kD that correspond to prothoracicotropic hormones in the gypsy moth was observed in the electrophoretic profiles that were obtained after both treatments in comparison to the control group. [Acknowledgments. This study was supported by the Serbian Ministry of Education and Science (Grant No. 173027.

Population activity structure of excitatory and inhibitory neurons.

Science.gov (United States)

Bittner, Sean R; Williamson, Ryan C; Snyder, Adam C; Litwin-Kumar, Ashok; Doiron, Brent; Chase, Steven M; Smith, Matthew A; Yu, Byron M

2017-01-01

Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

Population activity structure of excitatory and inhibitory neurons.

Directory of Open Access Journals (Sweden)

Sean R Bittner

Full Text Available Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

Population activity structure of excitatory and inhibitory neurons

Science.gov (United States)

Doiron, Brent

2017-01-01

Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure. PMID:28817581

ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

Science.gov (United States)

Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

2004-01-01

Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

Neuronal medium that supports basic synaptic functions and activity of human neurons in vitro.

Science.gov (United States)

Bardy, Cedric; van den Hurk, Mark; Eames, Tameji; Marchand, Cynthia; Hernandez, Ruben V; Kellogg, Mariko; Gorris, Mark; Galet, Ben; Palomares, Vanessa; Brown, Joshua; Bang, Anne G; Mertens, Jerome; Böhnke, Lena; Boyer, Leah; Simon, Suzanne; Gage, Fred H

2015-05-19

Human cell reprogramming technologies offer access to live human neurons from patients and provide a new alternative for modeling neurological disorders in vitro. Neural electrical activity is the essence of nervous system function in vivo. Therefore, we examined neuronal activity in media widely used to culture neurons. We found that classic basal media, as well as serum, impair action potential generation and synaptic communication. To overcome this problem, we designed a new neuronal medium (BrainPhys basal + serum-free supplements) in which we adjusted the concentrations of inorganic salts, neuroactive amino acids, and energetic substrates. We then tested that this medium adequately supports neuronal activity and survival of human neurons in culture. Long-term exposure to this physiological medium also improved the proportion of neurons that were synaptically active. The medium was designed to culture human neurons but also proved adequate for rodent neurons. The improvement in BrainPhys basal medium to support neurophysiological activity is an important step toward reducing the gap between brain physiological conditions in vivo and neuronal models in vitro.

Opening of pannexin and connexin based-channels increases the excitability of nodose ganglion sensory neurons.

Directory of Open Access Journals (Sweden)

Mauricio Antonio Retamal

2014-06-01

Full Text Available Satellite glial cells (SGCs are the main glia in sensory ganglia. They surround neuronal bodies and form a cap that prevents the formation of chemical or electrical synapses between neighboring neurons. SGCs have been suggested to establish bidirectional paracrine communication with sensory neurons. However, the molecular mechanism involved in this cellular communication is unknown. In the central nervous system, astrocytes present connexin43 (Cx43 hemichannels and pannexin1 (Panx1 channels, and their opening allows the release of signal molecules, such as ATP and glutamate. We propose that these channels could play a role in the glia-neuron communication in sensory ganglia. Therefore, we studied the expression and function of Cx43 and Panx1 in rat and mouse nodose-petrosal-jugular complex (NPJc by confocal immunofluorescence, molecular and electrophysiological techniques. Cx43 and Panx1 were detected in SGCs and sensory neurons, respectively. In the rat and mouse, the electrical activity of vagal nerve increased significantly after nodose neurons were exposed to Ca2+/ Mg2+-free solution, a condition that increases the open probability of Cx hemichannels. This response was partially mimicked by a cell-permeable peptide corresponding to the last 10 amino acids of Cx43 (TAT-Cx43CT. Enhanced neuronal activity was reduced by Cx hemichannel, Panx1 channel and P2X7 receptor blockers. Moreover, the role of Panx1 was confirmed in NPJc, because Panx1 knockout mouse showed a reduced increase of neuronal activity induced by Ca2+/Mg2+-free extracellular conditions. Data suggest that Cx hemichannels and Panx channels serve as paracrine communication pathways between SGCs and neurons by modulating the excitability of sensory neurons.

Sleep-Active Neurons: Conserved Motors of Sleep

Science.gov (United States)

Bringmann, Henrik

2018-01-01

Sleep is crucial for survival and well-being. This behavioral and physiological state has been studied in all major genetically accessible model animals, including rodents, fish, flies, and worms. Genetic and optogenetic studies have identified several neurons that control sleep, making it now possible to compare circuit mechanisms across species. The “motor” of sleep across animal species is formed by neurons that depolarize at the onset of sleep to actively induce this state by directly inhibiting wakefulness. These sleep-inducing neurons are themselves controlled by inhibitory or activating upstream pathways, which act as the “drivers” of the sleep motor: arousal inhibits “sleep-active” neurons whereas various sleep-promoting “tiredness” pathways converge onto sleep-active neurons to depolarize them. This review provides the first overview of sleep-active neurons across the major model animals. The occurrence of sleep-active neurons and their regulation by upstream pathways in both vertebrate and invertebrate species suggests that these neurons are general and ancient components that evolved early in the history of nervous systems. PMID:29618588

The chemokine CXCL1/growth related oncogene increases sodium currents and neuronal excitability in small diameter sensory neurons

Directory of Open Access Journals (Sweden)

Wick Dayna M

2008-09-01

Full Text Available Abstract Background Altered Na+ channel expression, enhanced excitability, and spontaneous activity occur in nerve-injury and inflammatory models of pathological pain, through poorly understood mechanisms. The cytokine GRO/KC (growth related oncogene; CXCL1 shows strong, rapid upregulation in dorsal root ganglion in both nerve injury and inflammatory models. Neurons and glia express its receptor (CXCR2. CXCL1 has well-known effects on immune cells, but little is known about its direct effects on neurons. Results We report that GRO/KC incubation (1.5 nM, overnight caused marked upregulation of Na+ currents in acutely isolated small diameter rat (adult sensory neurons in vitro. In both IB4-positive and IB4-negative sensory neurons, TTX-resistant and TTX-sensitive currents increased 2- to 4 fold, without altered voltage dependence or kinetic changes. These effects required long exposures, and were completely blocked by co-incubation with protein synthesis inhibitor cycloheximide. Amplification of cDNA from the neuronal cultures showed that 3 Na channel isoforms were predominant both before and after GRO/KC treatment (Nav 1.1, 1.7, and 1.8. TTX-sensitive isoforms 1.1 and 1.7 significantly increased 2 – 3 fold after GRO/KC incubation, while 1.8 showed a trend towards increased expression. Current clamp experiments showed that GRO/KC caused a marked increase in excitability, including resting potential depolarization, decreased rheobase, and lower action potential threshold. Neurons acquired a striking ability to fire repetitively; IB4-positive cells also showed marked broadening of action potentials. Immunohistochemical labelling confirmed that the CXCR2 receptor was present in most neurons both in dissociated cells and in DRG sections, as previously shown for neurons in the CNS. Conclusion Many studies on the role of chemokines in pain conditions have focused on their rapid and indirect effects on neurons, via release of inflammatory mediators

Brain innate immunity regulates hypothalamic arcuate neuronal activity and feeding behavior.

Science.gov (United States)

Reis, Wagner L; Yi, Chun-Xia; Gao, Yuanqing; Tschöp, Mathias H; Stern, Javier E

2015-04-01

Hypothalamic inflammation, involving microglia activation in the arcuate nucleus (ARC), is proposed as a novel underlying mechanism in obesity, insulin and leptin resistance. However, whether activated microglia affects ARC neuronal activity, and consequently basal and hormonal-induced food intake, is unknown. We show that lipopolysaccharide, an agonist of the toll-like receptor-4 (TLR4), which we found to be expressed in ARC microglia, inhibited the firing activity of the majority of orexigenic agouti gene-related protein/neuropeptide Y neurons, whereas it increased the activity of the majority of anorexigenic proopiomelanocortin neurons. Lipopolysaccharide effects in agouti gene-related protein/neuropeptide Y (but not in proopiomelanocortin) neurons were occluded by inhibiting microglia function or by blocking TLR4 receptors. Finally, we report that inhibition of hypothalamic microglia altered basal food intake, also preventing central orexigenic responses to ghrelin. Our studies support a major role for a TLR4-mediated microglia signaling pathway in the control of ARC neuronal activity and feeding behavior.

Optogenetic stimulation of locus ceruleus neurons augments inhibitory transmission to parasympathetic cardiac vagal neurons via activation of brainstem α1 and β1 receptors.

Science.gov (United States)

Wang, Xin; Piñol, Ramón A; Byrne, Peter; Mendelowitz, David

2014-04-30

Locus ceruleus (LC) noradrenergic neurons are critical in generating alertness. In addition to inducing cortical arousal, the LC also orchestrates changes in accompanying autonomic system function that compliments increased attention, such as during stress, excitation, and/or exposure to averse or novel stimuli. Although the association between arousal and increased heart rate is well accepted, the neurobiological link between the LC and parasympathetic neurons that control heart rate has not been identified. In this study, we test directly whether activation of noradrenergic neurons in the LC influences brainstem parasympathetic cardiac vagal neurons (CVNs). CVNs were identified in transgenic mice that express channel-rhodopsin-2 (ChR2) in LC tyrosine hydroxylase neurons. Photoactivation evoked a rapid depolarization, increased firing, and excitatory inward currents in ChR2-expressing neurons in the LC. Photostimulation of LC neurons did not alter excitatory currents, but increased inhibitory neurotransmission to CVNs. Optogenetic activation of LC neurons increased the frequency of isolated glycinergic IPSCs by 27 ± 8% (p = 0.003, n = 26) and augmented GABAergic IPSCs in CVNs by 21 ± 5% (p = 0.001, n = 26). Inhibiting α1, but not α2, receptors blocked the evoked responses. Inhibiting β1 receptors prevented the increase in glycinergic, but not GABAergic, IPSCs in CVNs. This study demonstrates LC noradrenergic neurons inhibit the brainstem CVNs that generate parasympathetic activity to the heart. This inhibition of CVNs would increase heart rate and risks associated with tachycardia. The receptors activated within this pathway, α1 and/or β1 receptors, are targets for clinically prescribed antagonists that promote slower, cardioprotective heart rates during heightened vigilant states.

Inhibiting cholesterol degradation induces neuronal sclerosis and epileptic activity in mouse hippocampus

Science.gov (United States)

Chali, Farah; Djelti, Fathia; Eugene, Emmanuel; Valderrama, Mario; Marquer, Catherine; Aubourg, Patrick; Duykaerts, Charles; Miles, Richard; Cartier, Nathalie; Navarro, Vincent

2015-01-01

Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing in surviving neurons are among the sequels of neuronal death in these diseases and also in some epileptic syndromes. Here, we attempted to increase neuronal cholesterol levels, using a short hairpin RNA (shRNA) to suppress expression of the enzyme CYP46A1. This protein hydroxylates cholesterol and so facilitates trans-membrane extrusion. A sh-RNA CYP46A1construction coupled to an adeno-associated virus (AAV5) was injected focally and unilaterally into mouse hippocampus. It was selectively expressed first in neurons of the CA3a region. Cytoplasmic and membrane cholesterol increased, neuronal soma volume increased and then decreased before pyramidal cells died. As CA3a pyramidal cells died, inter-ictal EEG events occurred during exploration and non-REM sleep. With time, neuronal death spread to involve pyramidal cells and interneurons of the CA1 region. CA1 neuronal death was correlated with a delayed local expression of phosphorylated tau. Astrocytes were activated throughout the hippocampus and microglial activation was specific to regions of neuronal death. CA1 neuronal death was correlated with distinct aberrant EEG activity. During exploratory behaviour and rapid eye movement sleep, EEG oscillations at 7-10 Hz (theta) could accelerate to 14-21 Hz (beta) waves. They were accompanied by low amplitude, high-frequency oscillations of peak power at ~300Hz and a range of 250-350 Hz. While episodes of EEG acceleration were not correlated with changes in exploratory behaviour, they were followed in some animals by structured seizure-like discharges. These data strengthen links between increased cholesterol, neuronal sclerosis and epileptic behavior PMID:25847620

Cdk5 Is Essential for Amphetamine to Increase Dendritic Spine Density in Hippocampal Pyramidal Neurons

Directory of Open Access Journals (Sweden)

Soledad Ferreras

2017-11-01

Full Text Available Psychostimulant drugs of abuse increase dendritic spine density in reward centers of the brain. However, little is known about their effects in the hippocampus, where activity-dependent changes in the density of dendritic spine are associated with learning and memory. Recent reports suggest that Cdk5 plays an important role in drug addiction, but its role in psychostimulant’s effects on dendritic spines in hippocampus remain unknown. We used in vivo and in vitro approaches to demonstrate that amphetamine increases dendritic spine density in pyramidal neurons of the hippocampus. Primary cultures and organotypic slice cultures were used for cellular, molecular, pharmacological and biochemical analyses of the role of Cdk5/p25 in amphetamine-induced dendritic spine formation. Amphetamine (two-injection protocol increased dendritic spine density in hippocampal neurons of thy1-green fluorescent protein (GFP mice, as well as in hippocampal cultured neurons and organotypic slice cultures. Either genetic or pharmacological inhibition of Cdk5 activity prevented the amphetamine–induced increase in dendritic spine density. Amphetamine also increased spine density in neurons overexpressing the strong Cdk5 activator p25. Finally, inhibition of calpain, the protease necessary for the conversion of p35 to p25, prevented amphetamine’s effect on dendritic spine density. We demonstrate, for the first time, that amphetamine increases the density of dendritic spine in hippocampal pyramidal neurons in vivo and in vitro. Moreover, we show that the Cdk5/p25 signaling and calpain activity are both necessary for the effect of amphetamine on dendritic spine density. The identification of molecular mechanisms underlying psychostimulant effects provides novel and promising therapeutic approaches for the treatment of drug addiction.

Npas4: Linking Neuronal Activity to Memory.

Science.gov (United States)

Sun, Xiaochen; Lin, Yingxi

2016-04-01

Immediate-early genes (IEGs) are rapidly activated after sensory and behavioral experience and are believed to be crucial for converting experience into long-term memory. Neuronal PAS domain protein 4 (Npas4), a recently discovered IEG, has several characteristics that make it likely to be a particularly important molecular link between neuronal activity and memory: it is among the most rapidly induced IEGs, is expressed only in neurons, and is selectively induced by neuronal activity. By orchestrating distinct activity-dependent gene programs in different neuronal populations, Npas4 affects synaptic connections in excitatory and inhibitory neurons, neural circuit plasticity, and memory formation. It may also be involved in circuit homeostasis through negative feedback and psychiatric disorders. We summarize these findings and discuss their implications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks

Science.gov (United States)

Amin, Hayder; Maccione, Alessandro; Nieus, Thierry

2017-01-01

Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs), interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities) that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity. PMID:28749937

Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks.

Directory of Open Access Journals (Sweden)

Davide Lonardoni

2017-07-01

Full Text Available Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs, interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity.

Are dragon-king neuronal avalanches dungeons for self-organized brain activity?

Science.gov (United States)

de Arcangelis, L.

2012-05-01

Recent experiments have detected a novel form of spontaneous neuronal activity both in vitro and in vivo: neuronal avalanches. The statistical properties of this activity are typical of critical phenomena, with power laws characterizing the distributions of avalanche size and duration. A critical behaviour for the spontaneous brain activity has important consequences on stimulated activity and learning. Very interestingly, these statistical properties can be altered in significant ways in epilepsy and by pharmacological manipulations. In particular, there can be an increase in the number of large events anticipated by the power law, referred to herein as dragon-king avalanches. This behaviour, as verified by numerical models, can originate from a number of different mechanisms. For instance, it is observed experimentally that the emergence of a critical behaviour depends on the subtle balance between excitatory and inhibitory mechanisms acting in the system. Perturbing this balance, by increasing either synaptic excitation or the incidence of depolarized neuronal up-states causes frequent dragon-king avalanches. Conversely, an unbalanced GABAergic inhibition or long periods of low activity in the network give rise to sub-critical behaviour. Moreover, the existence of power laws, common to other stochastic processes, like earthquakes or solar flares, suggests that correlations are relevant in these phenomena. The dragon-king avalanches may then also be the expression of pathological correlations leading to frequent avalanches encompassing all neurons. We will review the statistics of neuronal avalanches in experimental systems. We then present numerical simulations of a neuronal network model introducing within the self-organized criticality framework ingredients from the physiology of real neurons, as the refractory period, synaptic plasticity and inhibitory synapses. The avalanche critical behaviour and the role of dragon-king avalanches will be discussed in

Activity-based anorexia activates CRF immunoreactive neurons in female rats.

Science.gov (United States)

Scharner, Sophie; Friedrich, Tiemo; Goebel-Stengel, Miriam; Kobelt, Peter; Rose, Matthias; Stengel, Andreas

2018-05-01

Activity-based anorexia (ABA) is a well-established animal model mimicking the eating disorder anorexia nervosa (AN). Since the pathophysiology of AN is yet poorly understood and specific drug treatments are lacking so far, animal models might be useful to further understand this disease. ABA consists of time-restricted access to food for 1.5 h/day and the possibility to exercise in a running wheel for 24 h/day. This combination leads to robust body weight loss as observed in AN. Here, we investigated the activation of brain corticotropin-releasing factor (CRF) neurons, a transmitter involved in the response to stress, emotional processes and also food intake. After development of ABA, rat brains were processed for c-Fos and CRF double immunohistochemistry. ABA increased the number of c-Fos/CRF double labeled neurons in the paraventricular nucleus (PVN) and the dorsomedial hypothalamic nucleus (DMH) compared to the ad libitum (AL, ad libitum fed, no running wheel) and activity (AC, ad libitum fed, running wheel, p  0.05) group. Also the number of CRF neurons was increased in the DMH of ABA rats compared to AL and AC (p  0.05). Taken together, brain CRF activated under conditions of ABA might play a role in the development and maintenance of this animal model and possibly also in human AN. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced activation of RVLM-projecting PVN neurons in rats with chronic heart failure.

Science.gov (United States)

Xu, Bo; Zheng, Hong; Patel, Kaushik P

2012-04-15

Previous studies have indicated that there is increased activation of the paraventricular nucleus (PVN) in rats with chronic heart failure (CHF); however, it is not clear if the preautonomic neurons within the PVN are specifically overactive. Also, it is not known if these neurons have altered responses to baroreceptor or osmotic challenges. Experiments were conducted in rats with CHF (6-8 wk after coronary artery ligation). Spontaneously active neurons were recorded in the PVN, of which 36% were antidromically activated from the rostral ventrolateral medulla (RVLM). The baseline discharge rate in RVLM-projecting PVN (PVN-RVLM) neurons from CHF rats was significantly greater than in sham-operated (sham) rats (6.0 ± 0.6 vs. 2.6 ± 0.3 spikes/s, P neurons by 80% in CHF rats compared with 37% in sham rats. Fifty-two percent of spontaneously active PVN-RVLM neurons responded to changes in the mean arterial pressure (MAP). The changes in discharge rate in PVN-RVLM neurons after a reduction in MAP (+52 ± 7% vs. +184 ± 61%) or an increase in MAP (-42 ± 8% vs. -71 ± 6%) were significantly attenuated in rats with CHF compared with sham rats. Most PVN-RVLM neurons (63%), including all barosensitive PVN-RVLM neurons, were excited by an internal carotid artery injection of hypertonic NaCl (2.1 osmol/l), whereas a smaller number (7%) were inhibited. The increase in discharge rate in PVN-RVLM neurons to hypertonic stimulation was significantly enhanced in rats with CHF compared with sham rats (134 ± 15% vs. 92 ± 13%). Taken together, these data suggest that PVN-RVLM neurons are more active under basal conditions and this overactivation is mediated by an enhanced glutamatergic tone in rats with CHF. Furthermore, this enhanced activation of PVN-RVLM neurons may contribute to the altered responses to baroreceptor and osmotic challenges observed during CHF.

Neuronal MHC Class I Expression Is Regulated by Activity Driven Calcium Signaling.

Directory of Open Access Journals (Sweden)

Dan Lv

Full Text Available MHC class I (MHC-I molecules are important components of the immune system. Recently MHC-I have been reported to also play important roles in brain development and synaptic plasticity. In this study, we examine the molecular mechanism(s underlying activity-dependent MHC-I expression using hippocampal neurons. Here we report that neuronal expression level of MHC-I is dynamically regulated during hippocampal development after birth in vivo. Kainic acid (KA treatment significantly increases the expression of MHC-I in cultured hippocampal neurons in vitro, suggesting that MHC-I expression is regulated by neuronal activity. In addition, KA stimulation decreased the expression of pre- and post-synaptic proteins. This down-regulation is prevented by addition of an MHC-I antibody to KA treated neurons. Further studies demonstrate that calcium-dependent protein kinase C (PKC is important in relaying KA simulation activation signals to up-regulated MHC-I expression. This signaling cascade relies on activation of the MAPK pathway, which leads to increased phosphorylation of CREB and NF-κB p65 while also enhancing the expression of IRF-1. Together, these results suggest that expression of MHC-I in hippocampal neurons is driven by Ca2+ regulated activation of the MAPK signaling transduction cascade.

Roles of acid sphingomyelinase activation in neuronal cells apoptosis induced by microwave irradiation

International Nuclear Information System (INIS)

Zhang Lei; Xu Shangcheng; Zhang Guangbin; Yu Zhengping

2009-01-01

The present study is to examine the effect of microwave on acid sphingomyelinase (ASM) activity and expression, and to explore the role of ASM activation in neuronal cells apoptosis induced by microwave irradiation. Primary cultured hippocampal neurons were irradiated by 30 W/cm 2 microwave for 10 min, and ASM activity assay was used to investigate ASM activity alteration. RT-PCR and western blot were used to detect ASM mRNA and protein expression respectively. Apoptosis was observed by Hoechst 33342 fluorescence staining. ASM specific inhibitor imipramine was applied to inhibit ASM activation. It has been found that apoptosis rate of primary cultured hippocampal neurons increased significantly after microwave irradiation. ASM was activated while ASM mRNA and protein expression were upregulated in neurons after microwave irradiation. Pretreatment with imipramine could reverse neuronal apoptosis induced by microwave irradiation. Results show that microwave irradiation causes increment of ASM activation and expression and ASM activation is involved in microwave induced neuronal apoptosis. (authors)

elPBN neurons regulate rVLM activity through elPBN-rVLM projections during activation of cardiac sympathetic afferent nerves.

Science.gov (United States)

Guo, Zhi-Ling; Longhurst, John C; Tjen-A-Looi, Stephanie C; Fu, Liang-Wu

2016-08-01

The external lateral parabrachial nucleus (elPBN) within the pons and rostral ventrolateral medulla (rVLM) contributes to central processing of excitatory cardiovascular reflexes during stimulation of cardiac sympathetic afferent nerves (CSAN). However, the importance of elPBN cardiovascular neurons in regulation of rVLM activity during CSAN activation remains unclear. We hypothesized that CSAN stimulation excites the elPBN cardiovascular neurons and, in turn, increases rVLM activity through elPBN-rVLM projections. Compared with controls, in rats subjected to microinjection of retrograde tracer into the rVLM, the numbers of elPBN neurons double-labeled with c-Fos (an immediate early gene) and the tracer were increased after CSAN stimulation (P neurons contain vesicular glutamate transporter 3. In cats, epicardial bradykinin and electrical stimulation of CSAN increased the activity of elPBN cardiovascular neurons, which was attenuated (n = 6, P neurons in the elPBN and rVLM sequentially through a monosynaptic (glutamatergic) excitatory elPBN-rVLM pathway. Copyright © 2016 the American Physiological Society.

Activity deprivation induces neuronal cell death: mediation by tissue-type plasminogen activator.

Directory of Open Access Journals (Sweden)

Eldi Schonfeld-Dado

Full Text Available Spontaneous activity is an essential attribute of neuronal networks and plays a critical role in their development and maintenance. Upon blockade of activity with tetrodotoxin (TTX, neurons degenerate slowly and die in a manner resembling neurodegenerative diseases-induced neuronal cell death. The molecular cascade leading to this type of slow cell death is not entirely clear. Primary post-natal cortical neurons were exposed to TTX for up to two weeks, followed by molecular, biochemical and immunefluorescence analysis. The expression of the neuronal marker, neuron specific enolase (NSE, was down-regulated, as expected, but surprisingly, there was a concomitant and striking elevation in expression of tissue-type plasminogen activator (tPA. Immunofluorescence analysis indicated that tPA was highly elevated inside affected neurons. Transfection of an endogenous tPA inhibitor, plasminogen activator inhibitor-1 (PAI-1, protected the TTX-exposed neurons from dying. These results indicate that tPA is a pivotal player in slowly progressing activity deprivation-induced neurodegeneration.

Evidence that BDNF regulates heart rate by a mechanism involving increased brainstem parasympathetic neuron excitability

OpenAIRE

Wan, Ruiqian; Weigand, Letitia A.; Bateman, Ryan; Griffioen, Kathleen; Mendelowitz, David; Mattson, Mark P.

2014-01-01

Autonomic control of heart rate is mediated by cardioinhibitory parasympathetic cholinergic neurons located in the brainstem and stimulatory sympathetic noradrenergic neurons. During embryonic development the survival and cholinergic phenotype of brainstem autonomic neurons is promoted by brain-derived neurotrophic factor (BDNF). We now provide evidence that BDNF regulates heart rate by a mechanism involving increased brainstem cardioinhibitory parasympathetic activity. Mice with a BDNF haplo...

Inward rectifier potassium current IKir promotes intrinsic pacemaker activity of thalamocortical neurons.

Science.gov (United States)

Amarillo, Yimy; Tissone, Angela I; Mato, Germán; Nadal, Marcela S

2018-06-01

Slow repetitive burst firing by hyperpolarized thalamocortical (TC) neurons correlates with global slow rhythms (rectifier potassium current I Kir induces repetitive burst firing at slow and delta frequency bands. We demonstrate this in mouse TC neurons in brain slices by manipulating the Kir maximum conductance with dynamic clamp. We also performed a thorough theoretical analysis that explains how the unique properties of I Kir enable this current to induce slow periodic bursting in TC neurons. We describe a new ionic mechanism based on the voltage- and time-dependent interaction of I Kir and hyperpolarization-activated cationic current I h that endows TC neurons with the ability to oscillate spontaneously at very low frequencies, even below 0.5 Hz. Bifurcation analysis of conductance-based models of increasing complexity demonstrates that I Kir induces bistability of the membrane potential at the same time that it induces sustained oscillations in combination with I h and increases the robustness of low threshold-activated calcium current I T -mediated oscillations. NEW & NOTEWORTHY The strong inwardly rectifying potassium current I Kir of thalamocortical neurons displays a region of negative slope conductance in the current-voltage relationship that generates potassium currents activated by hyperpolarization. Bifurcation analysis shows that I Kir induces bistability of the membrane potential; generates sustained subthreshold oscillations by interacting with the hyperpolarization-activated cationic current I h ; and increases the robustness of oscillations mediated by the low threshold-activated calcium current I T . Upregulation of I Kir in thalamocortical neurons induces repetitive burst firing at slow and delta frequency bands (<4 Hz).

Inflammatory mediator bradykinin increases population of sensory neurons expressing functional T-type Ca(2+) channels.

Science.gov (United States)

Huang, Dongyang; Liang, Ce; Zhang, Fan; Men, Hongchao; Du, Xiaona; Gamper, Nikita; Zhang, Hailin

2016-04-29

T-type Ca(2+) channels are important regulators of peripheral sensory neuron excitability. Accordingly, T-type Ca(2+) currents are often increased in various pathological pain conditions, such as inflammation or nerve injury. Here we investigated effects of inflammation on functional expression of T-type Ca(2+) channels in small-diameter cultured dorsal root ganglion (DRG) neurons. We found that overnight treatment of DRG cultures with a cocktail of inflammatory mediators bradykinin (BK), adenosine triphosphate (ATP), norepinephrine (NE) and prostaglandin E2 (PGE2) strongly increased the population size of the small-diameter neurons displaying low-voltage activated (LVA, T-type) Ca(2+) currents while having no effect on the peak LVA current amplitude. When applied individually, BK and ATP also increased the population size of LVA-positive neurons while NE and PGE2 had no effect. The PLC inhibitor U-73122 and B2 receptor antagonist, Hoe-140, both abolished the increase of the population of LVA-positive DRG neurons. Inflammatory treatment did not affect CaV3.2 mRNA or protein levels in DRG cultures. Furthermore, an ubiquitination inhibitor, MG132, did not increase the population of LVA-positive neurons. Our data suggest that inflammatory mediators BK and ATP increase the abundance of LVA-positive DRG neurons in total neuronal population by stimulating the recruitment of a 'reserve pool' of CaV3.2 channels, particularly in neurons that do not display measurable LVA currents under control conditions. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Gs-coupled GPCR signalling in AgRP neurons triggers sustained increase in food intake.

Science.gov (United States)

Nakajima, Ken-ichiro; Cui, Zhenzhong; Li, Chia; Meister, Jaroslawna; Cui, Yinghong; Fu, Ou; Smith, Adam S; Jain, Shalini; Lowell, Bradford B; Krashes, Michael J; Wess, Jürgen

2016-01-08

Agouti-related peptide (AgRP) neurons of the hypothalamus play a key role in regulating food intake and body weight, by releasing three different orexigenic molecules: AgRP; GABA; and neuropeptide Y. AgRP neurons express various G protein-coupled receptors (GPCRs) with different coupling properties, including Gs-linked GPCRs. At present, the potential role of Gs-coupled GPCRs in regulating the activity of AgRP neurons remains unknown. Here we show that the activation of Gs-coupled receptors expressed by AgRP neurons leads to a robust and sustained increase in food intake. We also provide detailed mechanistic data linking the stimulation of this class of receptors to the observed feeding phenotype. Moreover, we show that this pathway is clearly distinct from other GPCR signalling cascades that are operative in AgRP neurons. Our data suggest that drugs able to inhibit this signalling pathway may become useful for the treatment of obesity.

Basal Forebrain Gating by Somatostatin Neurons Drives Prefrontal Cortical Activity.

Science.gov (United States)

Espinosa, Nelson; Alonso, Alejandra; Morales, Cristian; Espinosa, Pedro; Chávez, Andrés E; Fuentealba, Pablo

2017-11-17

The basal forebrain provides modulatory input to the cortex regulating brain states and cognitive processing. Somatostatin-expressing neurons constitute a heterogeneous GABAergic population known to functionally inhibit basal forebrain cortically projecting cells thus favoring sleep and cortical synchronization. However, it remains unclear if somatostatin cells can regulate population activity patterns in the basal forebrain and modulate cortical dynamics. Here, we demonstrate that somatostatin neurons regulate the corticopetal synaptic output of the basal forebrain impinging on cortical activity and behavior. Optogenetic inactivation of somatostatin neurons in vivo rapidly modified neural activity in the basal forebrain, with the consequent enhancement and desynchronization of activity in the prefrontal cortex, reflected in both neuronal spiking and network oscillations. Cortical activation was partially dependent on cholinergic transmission, suppressing slow waves and potentiating gamma oscillations. In addition, recruitment dynamics was cell type-specific, with interneurons showing similar temporal profiles, but stronger responses than pyramidal cells. Finally, optogenetic stimulation of quiescent animals during resting periods prompted locomotor activity, suggesting generalized cortical activation and increased arousal. Altogether, we provide physiological and behavioral evidence indicating that somatostatin neurons are pivotal in gating the synaptic output of the basal forebrain, thus indirectly controlling cortical operations via both cholinergic and non-cholinergic mechanisms. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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

Directory of Open Access Journals (Sweden)

Keith B Hengen

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

Ectopic Expression of α6 and δ GABAA Receptor Subunits in Hilar Somatostatin Neurons Increases Tonic Inhibition and Alters Network Activity in the Dentate Gyrus

Science.gov (United States)

Tong, Xiaoping; Peng, Zechun; Zhang, Nianhui; Cetina, Yliana; Huang, Christine S.; Wallner, Martin; Otis, Thomas S.

2015-01-01

The role of GABAA receptor (GABAAR)-mediated tonic inhibition in interneurons remains unclear and may vary among subgroups. Somatostatin (SOM) interneurons in the hilus of the dentate gyrus show negligible expression of nonsynaptic GABAAR subunits and very low tonic inhibition. To determine the effects of ectopic expression of tonic GABAAR subtypes in these neurons, Cre-dependent viral vectors were used to express GFP-tagged GABAAR subunits (α6 and δ) selectively in hilar SOM neurons in SOM-Cre mice. In single-transfected animals, immunohistochemistry demonstrated strong expression of either the α6 or δ subunit; in cotransfected animals, both subunits were consistently expressed in the same neurons. Electrophysiology revealed a robust increase of tonic current, with progressively larger increases following transfection of δ, α6, and α6/δ subunits, respectively, indicating formation of functional receptors in all conditions and likely coassembly of the subunits in the same receptor following cotransfection. An in vitro model of repetitive bursting was used to determine the effects of increased tonic inhibition in hilar SOM interneurons on circuit activity in the dentate gyrus. Upon cotransfection, the frequency of GABAAR-mediated bursting in granule cells was reduced, consistent with a reduction in synchronous firing among hilar SOM interneurons. Moreover, in vivo studies of Fos expression demonstrated reduced activation of α6/δ-cotransfected neurons following acute seizure induction by pentylenetetrazole. The findings demonstrate that increasing tonic inhibition in hilar SOM interneurons can alter dentate gyrus circuit activity during strong stimulation and suggest that tonic inhibition of interneurons could play a role in regulating excessive synchrony within the network. SIGNIFICANCE STATEMENT In contrast to many hippocampal interneurons, somatostatin (SOM) neurons in the hilus of the dentate gyrus have very low levels of nonsynaptic GABAARs and exhibit

Stress and Sucrose Intake Modulate Neuronal Activity in the Anterior Hypothalamic Area in Rats.

Science.gov (United States)

Mitra, Arojit; Guèvremont, Geneviève; Timofeeva, Elena

2016-01-01

The anterior hypothalamic area (AHA) is an important integrative relay structure for a variety of autonomic, endocrine, and behavioral responses including feeding behavior and response to stress. However, changes in the activity of the AHA neurons during stress and feeding in freely moving rats are not clear. The present study investigated the firing rate and burst activity of neurons in the central nucleus of the AHA (cAHA) during sucrose intake in non-stressful conditions and after acute stress in freely behaving rats. Rats were implanted with micro-electrodes into the cAHA, and extracellular multi-unit activity was recorded during 1-h access to 10% sucrose in non-stressful conditions or after acute foot shock stress. Acute stress significantly reduced sucrose intake, total sucrose lick number, and lick frequency in licking clusters, and increased inter-lick intervals. At the cluster start (CS) of sucrose licking, the cAHA neurons increased (CS-excited, 20% of the recorded neurons), decreased (CS-inhibited, 42% of the neurons) or did not change (CS-nonresponsive, 38% of the neurons) their firing rate. Stress resulted in a significant increase in the firing rate of the CS-inhibited neurons by decreasing inter-spike intervals within the burst firing of these neurons. This increase in the stress-induced firing rate of the CS-inhibited neurons was accompanied by a disruption of the correlation between the firing rate of CS-inhibited and CS-nonresponsive neurons that was observed in non-stressful conditions. Stress did not affect the firing rate of the CS-excited and CS-nonresponsive neurons. However, stress changed the pattern of burst firing of the CS-excited and CS-nonresponsive neurons by decreasing and increasing the burst number in the CS-excited and CS-nonresponsive neurons, respectively. These results suggest that the cAHA neurons integrate the signals related to stress and intake of palatable food and play a role in the stress- and eating-related circuitry.

Phospholipase D1 increases Bcl-2 expression during neuronal differentiation of rat neural stem cells.

Science.gov (United States)

Park, Shin-Young; Ma, Weina; Yoon, Sung Nyo; Kang, Min Jeong; Han, Joong-Soo

2015-01-01

We studied the possible role of phospholipase D1 (PLD1) in the neuronal differentiation, including neurite formation of neural stem cells. PLD1 protein and PLD activity increased during neuronal differentiation. Bcl-2 also increased. Downregulation of PLD1 by transfection with PLD1 siRNA or a dominant-negative form of PLD1 (DN-PLD1) inhibited both neurite outgrowth and Bcl-2 expression. PLD activity was dramatically reduced by a PLCγ (phospholipase Cγ) inhibitor (U73122), a Ca(2+)chelator (BAPTA-AM), and a PKCα (protein kinase Cα) inhibitor (RO320432). Furthermore, treatment with arachidonic acid (AA) which is generated by the action of PLA2 (phospholipase A2) on phosphatidic acid (a PLD1 product), increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, indicating that PLA2 is involved in the differentiation process resulting from PLD1 activation. PGE2 (prostaglandin E2), a cyclooxygenase product of AA, also increased during neuronal differentiation. Moreover, treatment with PGE2 increased the phosphorylation of p38 MAPK and CREB, as well as Bcl-2 expression, and this effect was inhibited by a PKA inhibitor (Rp-cAMP). As expected, inhibition of p38 MAPK resulted in loss of CREB activity, and when CREB activity was blocked with CREB siRNA, Bcl-2 production also decreased. We also showed that the EP4 receptor was required for the PKA/p38MAPK/CREB/Bcl-2 pathway. Taken together, these observations indicate that PLD1 is activated by PLCγ/PKCα signaling and stimulate Bcl-2 expression through PLA2/Cox2/EP4/PKA/p38MAPK/CREB during neuronal differentiation of rat neural stem cells.

The neurotoxicant PCB-95 by increasing the neuronal transcriptional repressor REST down-regulates caspase-8 and increases Ripk1, Ripk3 and MLKL expression determining necroptotic neuronal death.

Science.gov (United States)

Guida, Natascia; Laudati, Giusy; Serani, Angelo; Mascolo, Luigi; Molinaro, Pasquale; Montuori, Paolo; Di Renzo, Gianfranco; Canzoniero, Lorella M T; Formisano, Luigi

2017-10-15

Our previous study showed that the environmental neurotoxicant non-dioxin-like polychlorinated biphenyl (PCB)-95 increases RE1-silencing transcription factor (REST) expression, which is related to necrosis, but not apoptosis, of neurons. Meanwhile, necroptosis is a type of a programmed necrosis that is positively regulated by receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL) and negatively regulated by caspase-8. Here we evaluated whether necroptosis contributes to PCB-95-induced neuronal death through REST up-regulation. Our results demonstrated that in cortical neurons PCB-95 increased RIPK1, RIPK3, and MLKL expression and decreased caspase-8 at the gene and protein level. Furthermore, the RIPK1 inhibitor necrostatin-1 or siRNA-mediated RIPK1, RIPK3 and MLKL expression knockdown significantly reduced PCB-95-induced neuronal death. Intriguingly, PCB-95-induced increases in RIPK1, RIPK3, MLKL expression and decreases in caspase-8 expression were reversed by knockdown of REST expression with a REST-specific siRNA (siREST). Notably, in silico analysis of the rat genome identified a REST consensus sequence in the caspase-8 gene promoter (Casp8-RE1), but not the RIPK1, RIPK3 and MLKL promoters. Interestingly, in PCB-95-treated neurons, REST binding to the Casp8-RE1 sequence increased in parallel with a reduction in its promoter activity, whereas under the same experimental conditions, transfection of siREST or mutation of the Casp8-RE1 sequence blocked PCB-95-induced caspase-8 reduction. Since RIPK1, RIPK3 and MLKL rat genes showed no putative REST binding site, we assessed whether the transcription factor cAMP Responsive Element Binding Protein (CREB), which has a consensus sequence in all three genes, affected neuronal death. In neurons treated with PCB-95, CREB protein expression decreased in parallel with a reduction in binding to the RIPK1, RIPK3 and MLKL gene promoter sequence. Furthermore, CREB overexpression was

Activation of AMPK by OSU53 protects spinal cord neurons from oxidative stress.

Science.gov (United States)

Xu, Jun; Wu, Liang; Zhang, Yiming; Gu, Huijie; Huang, Zhongyue; Zhou, Kaifeng; Yin, Xiaofan

2017-12-22

The present study tested the potential effect of OSU53, a novel AMPK activator, against hydrogen peroxide (H2O2)-induced spinal cord neuron damages. Treatment with OSU53 attenuated H2O2-induced death and apoptosis of primary murine spinal cord neurons. OSU53 activated AMPK signaling, which is required for its actions in spinal cord neurons. The AMPK inhibitor Compound C or AMPKα1 siRNA almost abolished OSU53-mediated neuroprotection against H2O2. On the other hand, sustained-activation of AMPK by introducing the constitutive-active AMPKα1 mimicked OSU53's actions, and protected spinal cord neurons from oxidative stress. OSU53 significantly attenuated H2O2-induced reactive oxygen species production, lipid peroxidation and DNA damages in spinal cord neurons. Additionally, OSU53 increased NADPH content and heme oxygenase-1 mRNA expression in H2O2-treated spinal cord neurons. Together, we indicate that targeted-activation of AMPK by OSU53 protects spinal cord neurons from oxidative stress.

Increased neuronal firing in resting and sleep in areas of the macaque medial prefrontal cortex.

Science.gov (United States)

Gabbott, Paul L; Rolls, Edmund T

2013-06-01

The medial prefrontal cortex (mPFC) of humans and macaques is an integral part of the default mode network and is a brain region that shows increased activation in the resting state. A previous paper from our laboratory reported significantly increased firing rates of neurons in the macaque subgenual cingulate cortex, Brodmann area (BA) 25, during disengagement from a task and also during slow wave sleep [E.T. Rolls et al. (2003) J. Neurophysiology, 90, 134-142]. Here we report the finding that there are neurons in other areas of mPFC that also increase their firing rates during disengagement from a task, drowsiness and eye-closure. During the neurophysiological recording of single mPFC cells (n = 249) in BAs 9, 10, 13 m, 14c, 24b and especially pregenual area 32, populations of neurons were identified whose firing rates altered significantly with eye-closure compared with eye-opening. Three types of neuron were identified: Type 1 cells (28.1% of the total population) significantly increased (mean + 329%; P ≪ 0.01) their average firing rate with eye-closure, from 3.1 spikes/s when awake to 10.2 spikes/s when asleep; Type 2 cells (6.0%) significantly decreased (mean -68%; P areas of mPFC, implicated in the anterior default mode network, there is a substantial population of neurons that significantly increase their firing rates during periods of eye-closure. Such neurons may be part of an interconnected network of distributed brain regions that are more active during periods of relaxed wakefulness than during attention-demanding tasks. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

BAD and KATP channels regulate neuron excitability and epileptiform activity.

Science.gov (United States)

Martínez-François, Juan Ramón; Fernández-Agüera, María Carmen; Nathwani, Nidhi; Lahmann, Carolina; Burnham, Veronica L; Danial, Nika N; Yellen, Gary

2018-01-25

Brain metabolism can profoundly influence neuronal excitability. Mice with genetic deletion or alteration of Bad ( B CL-2 a gonist of cell d eath) exhibit altered brain-cell fuel metabolism, accompanied by resistance to acutely induced epileptic seizures; this seizure protection is mediated by ATP-sensitive potassium (K ATP ) channels. Here we investigated the effect of BAD manipulation on K ATP channel activity and excitability in acute brain slices. We found that BAD's influence on neuronal K ATP channels was cell-autonomous and directly affected dentate granule neuron (DGN) excitability. To investigate the role of neuronal K ATP channels in the anticonvulsant effects of BAD, we imaged calcium during picrotoxin-induced epileptiform activity in entorhinal-hippocampal slices. BAD knockout reduced epileptiform activity, and this effect was lost upon knockout or pharmacological inhibition of K ATP channels. Targeted BAD knockout in DGNs alone was sufficient for the antiseizure effect in slices, consistent with a 'dentate gate' function that is reinforced by increased K ATP channel activity. © 2018, Martínez-François et al.

Toxoplasma gondii Actively Inhibits Neuronal Function in Chronically Infected Mice

Science.gov (United States)

Haroon, Fahad; Händel, Ulrike; Angenstein, Frank; Goldschmidt, Jürgen; Kreutzmann, Peter; Lison, Holger; Fischer, Klaus-Dieter; Scheich, Henning; Wetzel, Wolfram; Schlüter, Dirk; Budinger, Eike

2012-01-01

Upon infection with the obligate intracellular parasite Toxoplasma gondii, fast replicating tachyzoites infect a broad spectrum of host cells including neurons. Under the pressure of the immune response, tachyzoites convert into slow-replicating bradyzoites, which persist as cysts in neurons. Currently, it is unclear whether T. gondii alters the functional activity of neurons, which may contribute to altered behaviour of T. gondii–infected mice and men. In the present study we demonstrate that upon oral infection with T. gondii cysts, chronically infected BALB/c mice lost over time their natural fear against cat urine which was paralleled by the persistence of the parasite in brain regions affecting behaviour and odor perception. Detailed immunohistochemistry showed that in infected neurons not only parasitic cysts but also the host cell cytoplasm and some axons stained positive for Toxoplasma antigen suggesting that parasitic proteins might directly interfere with neuronal function. In fact, in vitro live cell calcium (Ca2+) imaging studies revealed that tachyzoites actively manipulated Ca2+ signalling upon glutamate stimulation leading either to hyper- or hypo-responsive neurons. Experiments with the endoplasmatic reticulum Ca2+ uptake inhibitor thapsigargin indicate that tachyzoites deplete Ca2+ stores in the endoplasmatic reticulum. Furthermore in vivo studies revealed that the activity-dependent uptake of the potassium analogue thallium was reduced in cyst harbouring neurons indicating their functional impairment. The percentage of non-functional neurons increased over time In conclusion, both bradyzoites and tachyzoites functionally silence infected neurons, which may significantly contribute to the altered behaviour of the host. PMID:22530040

Toxoplasma gondii actively inhibits neuronal function in chronically infected mice.

Directory of Open Access Journals (Sweden)

Fahad Haroon

Full Text Available Upon infection with the obligate intracellular parasite Toxoplasma gondii, fast replicating tachyzoites infect a broad spectrum of host cells including neurons. Under the pressure of the immune response, tachyzoites convert into slow-replicating bradyzoites, which persist as cysts in neurons. Currently, it is unclear whether T. gondii alters the functional activity of neurons, which may contribute to altered behaviour of T. gondii-infected mice and men. In the present study we demonstrate that upon oral infection with T. gondii cysts, chronically infected BALB/c mice lost over time their natural fear against cat urine which was paralleled by the persistence of the parasite in brain regions affecting behaviour and odor perception. Detailed immunohistochemistry showed that in infected neurons not only parasitic cysts but also the host cell cytoplasm and some axons stained positive for Toxoplasma antigen suggesting that parasitic proteins might directly interfere with neuronal function. In fact, in vitro live cell calcium (Ca(2+ imaging studies revealed that tachyzoites actively manipulated Ca(2+ signalling upon glutamate stimulation leading either to hyper- or hypo-responsive neurons. Experiments with the endoplasmatic reticulum Ca(2+ uptake inhibitor thapsigargin indicate that tachyzoites deplete Ca(2+ stores in the endoplasmatic reticulum. Furthermore in vivo studies revealed that the activity-dependent uptake of the potassium analogue thallium was reduced in cyst harbouring neurons indicating their functional impairment. The percentage of non-functional neurons increased over time In conclusion, both bradyzoites and tachyzoites functionally silence infected neurons, which may significantly contribute to the altered behaviour of the host.

Inflammation-induced increase in nicotinic acetylcholine receptor current in cutaneous nociceptive DRG neurons from the adult rat.

Science.gov (United States)

Zhang, X-L; Albers, K M; Gold, M S

2015-01-22

The goals of the present study were to determine (1) the properties of the nicotinic acetylcholine receptor (nAChR) currents in rat cutaneous dorsal root ganglion (DRG) neurons; (2) the impact of nAChR activation on the excitability of cutaneous DRG neurons; and (3) the impact of inflammation on the density and distribution of nAChR currents among cutaneous DRG neurons. Whole-cell patch-clamp techniques were used to study retrogradely labeled DRG neurons from naïve and complete Freund's adjuvant inflamed rats. Nicotine-evoked currents were detectable in ∼70% of the cutaneous DRG neurons, where only one of two current types, fast or slow currents based on rates of activation and inactivation, was present in each neuron. The biophysical and pharmacological properties of the fast current were consistent with nAChRs containing an α7 subunit while those of the slow current were consistent with nAChRs containing α3/β4 subunits. The majority of small diameter neurons with fast current were IB4- while the majority of small diameter neurons with slow current were IB4+. Preincubation with nicotine (1 μM) produced a transient (1 min) depolarization and increase in the excitability of neurons with fast current and a decrease in the amplitude of capsaicin-evoked current in neurons with slow current. Inflammation increased the current density of both slow and fast currents in small diameter neurons and increased the percentage of neurons with the fast current. With the relatively selective distribution of nAChR currents in putative nociceptive cutaneous DRG neurons, our results suggest that the role of these receptors in inflammatory hyperalgesia is likely to be complex and dependent on the concentration and timing of acetylcholine release in the periphery. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

Carbon Monoxide Releasing Molecule-A1 (CORM-A1) Improves Neurogenesis: Increase of Neuronal Differentiation Yield by Preventing Cell Death.

Science.gov (United States)

Almeida, Ana S; Soares, Nuno L; Vieira, Melissa; Gramsbergen, Jan Bert; Vieira, Helena L A

2016-01-01

Cerebral ischemia and neurodegenerative diseases lead to impairment or death of neurons in the central nervous system. Stem cell based therapies are promising strategies currently under investigation. Carbon monoxide (CO) is an endogenous product of heme degradation by heme oxygenase (HO) activity. Administration of CO at low concentrations produces several beneficial effects in distinct tissues, namely anti-apoptotic and anti-inflammatory. Herein the CO role on modulation of neuronal differentiation was assessed. Three different models with increasing complexity were used: human neuroblastoma SH-S5Y5 cell line, human teratocarcinoma NT2 cell line and organotypic hippocampal slice cultures (OHSC). Cell lines were differentiated into post-mitotic neurons by treatment with retinoic acid (RA) supplemented with CO-releasing molecule A1 (CORM-A1). CORM-A1 positively modulated neuronal differentiation, since it increased final neuronal production and enhanced the expression of specific neuronal genes: Nestin, Tuj1 and MAP2. Furthermore, during neuronal differentiation process, there was an increase in proliferative cell number (ki67 mRNA expressing cells) and a decrease in cell death (lower propidium iodide (PI) uptake, limitation of caspase-3 activation and higher Bcl-2 expressing cells). CO supplementation did not increase the expression of RA receptors. In the case of SH-S5Y5 model, small amounts of reactive oxygen species (ROS) generation emerges as important signaling molecules during CO-promoted neuronal differentiation. CO's improvement of neuronal differentiation yield was validated using OHSC as ex vivo model. CORM-A1 treatment of OHSC promoted higher levels of cells expressing the neuronal marker Tuj1. Still, CORM-A1 increased cell proliferation assessed by ki67 expression and also prevented cell death, which was followed by increased Bcl-2 expression, decreased levels of active caspase-3 and PI uptake. Likewise, ROS signaling emerged as key factors in CO

Phosphoinositide-3-kinase activation controls synaptogenesis and spinogenesis in hippocampal neurons.

Science.gov (United States)

Cuesto, Germán; Enriquez-Barreto, Lilian; Caramés, Cristina; Cantarero, Marta; Gasull, Xavier; Sandi, Carmen; Ferrús, Alberto; Acebes, Ángel; Morales, Miguel

2011-02-23

The possibility of changing the number of synapses may be an important asset in the treatment of neurological diseases. In this context, the synaptogenic role of the phosphoinositide-3-kinase (PI3K) signaling cascade has been previously demonstrated in Drosophila. This study shows that treatment with a PI3K-activating transduction peptide is able to promote synaptogenesis and spinogenesis in primary cultures of rat hippocampal neurons, as well as in CA1 hippocampal neurons in vivo. In culture, the peptide increases synapse density independently of cell density, culture age, dendritic complexity, or synapse type. The induced synapses also increase neurotransmitter release from cultured neurons. The synaptogenic signaling pathway includes PI3K-Akt. Furthermore, the treatment is effective on adult neurons, where it induces spinogenesis and enhances the cognitive behavior of treated animals in a fear-conditioning assay. These findings demonstrate that functional synaptogenesis can be induced in mature mammalian brains through PI3K activation.

Conditional Deletion of PDK1 in the Forebrain Causes Neuron Loss and Increased Apoptosis during Cortical Development

Directory of Open Access Journals (Sweden)

Congyu Xu

2017-10-01

Full Text Available Decreased expression but increased activity of PDK1 has been observed in neurodegenerative disease. To study in vivo function of PDK1 in neuron survival during cortical development, we generate forebrain-specific PDK1 conditional knockout (cKO mice. We demonstrate that PDK1 cKO mice display striking neuron loss and increased apoptosis. We report that PDK1 cKO mice exhibit deficits on several behavioral tasks. Moreover, PDK1 cKO mice show decreased activities for Akt and mTOR. These results highlight an essential role of endogenous PDK1 in the maintenance of neuronal survival during cortical development.

The satiety signaling neuropeptide perisulfakinin inhibits the activity of central neurons promoting general activity

Directory of Open Access Journals (Sweden)

Dieter Wicher

2007-12-01

Full Text Available The metabolic state is one of the determinants of the general activity level. Satiety is related to resting or sleep whereas hunger correlates to wakefulness and activity. The counterpart to the mammalian satiety signal cholecystokinin (CCK in insects are the sulfakinins. The aim of this study was to resolve the mechanism by which the antifeedant activity of perisulfakinin (PSK in Periplaneta americana is mediated. We identified the sources of PSK which is used both as hormone and as paracrine messenger. PSK is found in the neurohemal organ of the brain and in nerve endings throughout the central nervous system. To correlate the distributions of PSK and its receptor (PSKR, we cloned the gene coding for PSKR and provide evidence for its expression within the nervous system. It occurs only in a few neurons, among them are the dorsal unpaired median (DUM neurons which release octopamine thereby regulating the general level of activity. Application of PSK to DUM neurons attenuated the spiking frequency (EC50=11pM due to reduction of a pacemaker Ca2+ current through cAMP-inhibited pTRPγ channels. PSK increased the intracellular cAMP level while decreasing the intracellular Ca2+ concentration in DUM neurons. Thus, the satiety signal conferred by PSK acts antagonistically to the hunger signal, provided by the adipokinetic hormone (AKH: PSK depresses the electrical activity of DUM neurons by inhibiting the pTRPγ channel that is activated by AKH under conditions of food shortage.

Cellular activation of hypothalamic hypocretin/orexin neurons facilitates short-term spatial memory in mice.

Science.gov (United States)

Aitta-Aho, Teemu; Pappa, Elpiniki; Burdakov, Denis; Apergis-Schoute, John

2016-12-01

The hypothalamic hypocretin/orexin (HO) system holds a central role in the regulation of several physiological functions critical for food-seeking behavior including mnemonic processes for effective foraging behavior. It is unclear however whether physiological increases in HO neuronal activity can support such processes. Using a designer rM3Ds receptor activation approach increasing HO neuronal activity resulted in improved short-term memory for novel locations. When tested on a non-spatial novelty object recognition task no significant difference was detected between groups indicating that hypothalamic HO neuronal activation can selectively facilitate short-term spatial memory for potentially supporting memory for locations during active exploration. Copyright © 2016 Elsevier Inc. All rights reserved.

Changes in prefrontal neuronal activity after learning to perform a spatial working memory task.

Science.gov (United States)

Qi, Xue-Lian; Meyer, Travis; Stanford, Terrence R; Constantinidis, Christos

2011-12-01

The prefrontal cortex is considered essential for learning to perform cognitive tasks though little is known about how the representation of stimulus properties is altered by learning. To address this issue, we recorded neuronal activity in monkeys before and after training on a task that required visual working memory. After the subjects learned to perform the task, we observed activation of more prefrontal neurons and increased activity during working memory maintenance. The working memory-related increase in firing rate was due mostly to regular-spiking putative pyramidal neurons. Unexpectedly, the selectivity of neurons for stimulus properties and the ability of neurons to discriminate between stimuli decreased as the information about stimulus properties was apparently present in neural firing prior to training and neuronal selectivity degraded after training in the task. The effect was robust and could not be accounted for by differences in sampling sites, selection of neurons, level of performance, or merely the elapse of time. The results indicate that, in contrast to the effects of perceptual learning, mastery of a cognitive task degrades the apparent stimulus selectivity as neurons represent more abstract information related to the task. This effect is countered by the recruitment of more neurons after training.

Human temporal cortical single neuron activity during working memory maintenance.

Science.gov (United States)

Zamora, Leona; Corina, David; Ojemann, George

2016-06-01

The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

Human Temporal Cortical Single Neuron Activity During Working Memory Maintenance

Science.gov (United States)

Zamora, Leona; Corina, David; Ojemann, George

2016-01-01

The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

Linking neuronal brain activity to the glucose metabolism.

Science.gov (United States)

Göbel, Britta; Oltmanns, Kerstin M; Chung, Matthias

2013-08-29

Energy homeostasis ensures the functionality of the entire organism. The human brain as a missing link in the global regulation of the complex whole body energy metabolism is subject to recent investigation. The goal of this study is to gain insight into the influence of neuronal brain activity on cerebral and peripheral energy metabolism. In particular, the tight link between brain energy supply and metabolic responses of the organism is of interest. We aim to identifying regulatory elements of the human brain in the whole body energy homeostasis. First, we introduce a general mathematical model describing the human whole body energy metabolism. It takes into account the two central roles of the brain in terms of energy metabolism. The brain is considered as energy consumer as well as regulatory instance. Secondly, we validate our mathematical model by experimental data. Cerebral high-energy phosphate content and peripheral glucose metabolism are measured in healthy men upon neuronal activation induced by transcranial direct current stimulation versus sham stimulation. By parameter estimation we identify model parameters that provide insight into underlying neurophysiological processes. Identified parameters reveal effects of neuronal activity on regulatory mechanisms of systemic glucose metabolism. Our examinations support the view that the brain increases its glucose supply upon neuronal activation. The results indicate that the brain supplies itself with energy according to its needs, and preeminence of cerebral energy supply is reflected. This mechanism ensures balanced cerebral energy homeostasis. The hypothesis of the central role of the brain in whole body energy homeostasis as active controller is supported.

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs.

Science.gov (United States)

Roberts, Brandon L; Zhu, Mingyan; Zhao, Huan; Dillon, Crystal; Appleyard, Suzanne M

2017-09-01

Glucose is a crucial substrate essential for cell survival and function. Changes in glucose levels impact neuronal activity and glucose deprivation increases feeding. Several brain regions have been shown to respond to glucoprivation, including the nucleus of the solitary tract (NTS) in the brain stem. The NTS is the primary site in the brain that receives visceral afferent information from the gastrointestinal tract. The catecholaminergic (CA) subpopulation within the NTS modulates many homeostatic functions including cardiovascular reflexes, respiration, food intake, arousal, and stress. However, it is not known if they respond to changes in glucose. Here we determined whether NTS-CA neurons respond to changes in glucose concentration and the mechanism involved. We found that decreasing glucose concentrations from 5 mM to 2 mM to 1 mM, significantly decreased action potential firing in a cell-attached preparation, whereas increasing it back to 5 mM increased the firing rate. This effect was dependent on glutamate release from afferent terminals and required presynaptic 5-HT 3 Rs. Decreasing the glucose concentration also decreased both basal and 5-HT 3 R agonist-induced increase in the frequency of spontaneous glutamate inputs onto NTS-CA neurons. Low glucose also blunted 5-HT-induced inward currents in nodose ganglia neurons, which are the cell bodies of vagal afferents. The effect of low glucose in both nodose ganglia cells and in NTS slices was mimicked by the glucokinase inhibitor glucosamine. This study suggests that NTS-CA neurons are glucosensing through a presynaptic mechanism that is dependent on vagal glutamate release, 5-HT 3 R activity, and glucokinase. Copyright © 2017 the American Physiological Society.

Multi-timescale Modeling of Activity-Dependent Metabolic Coupling in the Neuron-Glia-Vasculature Ensemble

KAUST Repository

Jolivet, Renaud

2015-02-26

Glucose is the main energy substrate in the adult brain under normal conditions. Accumulating evidence, however, indicates that lactate produced in astrocytes (a type of glial cell) can also fuel neuronal activity. The quantitative aspects of this so-called astrocyte-neuron lactate shuttle (ANLS) are still debated. To address this question, we developed a detailed biophysical model of the brain’s metabolic interactions. Our model integrates three modeling approaches, the Buxton-Wang model of vascular dynamics, the Hodgkin-Huxley formulation of neuronal membrane excitability and a biophysical model of metabolic pathways. This approach provides a template for large-scale simulations of the neuron-glia-vasculature (NGV) ensemble, and for the first time integrates the respective timescales at which energy metabolism and neuronal excitability occur. The model is constrained by relative neuronal and astrocytic oxygen and glucose utilization, by the concentration of metabolites at rest and by the temporal dynamics of NADH upon activation. These constraints produced four observations. First, a transfer of lactate from astrocytes to neurons emerged in response to activity. Second, constrained by activity-dependent NADH transients, neuronal oxidative metabolism increased first upon activation with a subsequent delayed astrocytic glycolysis increase. Third, the model correctly predicted the dynamics of extracellular lactate and oxygen as observed in vivo in rats. Fourth, the model correctly predicted the temporal dynamics of tissue lactate, of tissue glucose and oxygen consumption, and of the BOLD signal as reported in human studies. These findings not only support the ANLS hypothesis but also provide a quantitative mathematical description of the metabolic activation in neurons and glial cells, as well as of the macroscopic measurements obtained during brain imaging.

Multi-timescale Modeling of Activity-Dependent Metabolic Coupling in the Neuron-Glia-Vasculature Ensemble

Science.gov (United States)

Jolivet, Renaud; Coggan, Jay S.; Allaman, Igor; Magistretti, Pierre J.

2015-01-01

Glucose is the main energy substrate in the adult brain under normal conditions. Accumulating evidence, however, indicates that lactate produced in astrocytes (a type of glial cell) can also fuel neuronal activity. The quantitative aspects of this so-called astrocyte-neuron lactate shuttle (ANLS) are still debated. To address this question, we developed a detailed biophysical model of the brain’s metabolic interactions. Our model integrates three modeling approaches, the Buxton-Wang model of vascular dynamics, the Hodgkin-Huxley formulation of neuronal membrane excitability and a biophysical model of metabolic pathways. This approach provides a template for large-scale simulations of the neuron-glia-vasculature (NGV) ensemble, and for the first time integrates the respective timescales at which energy metabolism and neuronal excitability occur. The model is constrained by relative neuronal and astrocytic oxygen and glucose utilization, by the concentration of metabolites at rest and by the temporal dynamics of NADH upon activation. These constraints produced four observations. First, a transfer of lactate from astrocytes to neurons emerged in response to activity. Second, constrained by activity-dependent NADH transients, neuronal oxidative metabolism increased first upon activation with a subsequent delayed astrocytic glycolysis increase. Third, the model correctly predicted the dynamics of extracellular lactate and oxygen as observed in vivo in rats. Fourth, the model correctly predicted the temporal dynamics of tissue lactate, of tissue glucose and oxygen consumption, and of the BOLD signal as reported in human studies. These findings not only support the ANLS hypothesis but also provide a quantitative mathematical description of the metabolic activation in neurons and glial cells, as well as of the macroscopic measurements obtained during brain imaging. PMID:25719367

Multi-timescale modeling of activity-dependent metabolic coupling in the neuron-glia-vasculature ensemble.

Directory of Open Access Journals (Sweden)

Renaud Jolivet

2015-02-01

Full Text Available Glucose is the main energy substrate in the adult brain under normal conditions. Accumulating evidence, however, indicates that lactate produced in astrocytes (a type of glial cell can also fuel neuronal activity. The quantitative aspects of this so-called astrocyte-neuron lactate shuttle (ANLS are still debated. To address this question, we developed a detailed biophysical model of the brain's metabolic interactions. Our model integrates three modeling approaches, the Buxton-Wang model of vascular dynamics, the Hodgkin-Huxley formulation of neuronal membrane excitability and a biophysical model of metabolic pathways. This approach provides a template for large-scale simulations of the neuron-glia-vasculature (NGV ensemble, and for the first time integrates the respective timescales at which energy metabolism and neuronal excitability occur. The model is constrained by relative neuronal and astrocytic oxygen and glucose utilization, by the concentration of metabolites at rest and by the temporal dynamics of NADH upon activation. These constraints produced four observations. First, a transfer of lactate from astrocytes to neurons emerged in response to activity. Second, constrained by activity-dependent NADH transients, neuronal oxidative metabolism increased first upon activation with a subsequent delayed astrocytic glycolysis increase. Third, the model correctly predicted the dynamics of extracellular lactate and oxygen as observed in vivo in rats. Fourth, the model correctly predicted the temporal dynamics of tissue lactate, of tissue glucose and oxygen consumption, and of the BOLD signal as reported in human studies. These findings not only support the ANLS hypothesis but also provide a quantitative mathematical description of the metabolic activation in neurons and glial cells, as well as of the macroscopic measurements obtained during brain imaging.

Dopamine suppresses neuronal activity of Helisoma B5 neurons via a D2-like receptor, activating PLC and K channels.

Science.gov (United States)

Zhong, L R; Artinian, L; Rehder, V

2013-01-03

Dopamine (DA) plays fundamental roles as a neurotransmitter and neuromodulator in the central nervous system. How DA modulates the electrical excitability of individual neurons to elicit various behaviors is of great interest in many systems. The buccal ganglion of the freshwater pond snail Helisoma trivolvis contains the neuronal circuitry for feeding and DA is known to modulate the feeding motor program in Helisoma. The buccal neuron B5 participates in the control of gut contractile activity and is surrounded by dopaminergic processes, which are expected to release DA. In order to study whether DA modulates the electrical activity of individual B5 neurons, we performed experiments on physically isolated B5 neurons in culture and on B5 neurons within the buccal ganglion in situ. We report that DA application elicited a strong hyperpolarization in both conditions and turned the electrical activity from a spontaneously firing state to an electrically silent state. Using the cell culture system, we demonstrated that the strong hyperpolarization was inhibited by the D2 receptor antagonist sulpiride and the phospholipase C (PLC) inhibitor U73122, indicating that DA affected the membrane potential of B5 neurons through the activation of a D2-like receptor and PLC. Further studies revealed that the DA-induced hyperpolarization was inhibited by the K channel blockers 4-aminopyridine and tetraethylammonium, suggesting that K channels might serve as the ultimate target of DA signaling. Through its modulatory effect on the electrical activity of B5 neurons, the release of DA in vivo may contribute to a neuronal output that results in a variable feeding motor program. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

MicroRNA-9 promotes the neuronal differentiation of rat bone marrow mesenchymal stem cells by activating autophagy

Directory of Open Access Journals (Sweden)

Guang-yu Zhang

2015-01-01

Full Text Available MicroRNA-9 (miR-9 has been shown to promote the differentiation of bone marrow mesenchymal stem cells into neuronal cells, but the precise mechanism is unclear. Our previous study confirmed that increased autophagic activity improved the efficiency of neuronal differentiation in bone marrow mesenchymal stem cells. Accumulating evidence reveals that miRNAs adjust the autophagic pathways. This study used miR-9-1 lentiviral vector and miR-9-1 inhibitor to modulate the expression level of miR-9. Autophagic activity and neuronal differentiation were measured by the number of light chain-3 (LC3-positive dots, the ratio of LC3-II/LC3, and the expression levels of the neuronal markers enolase and microtubule-associated protein 2. Results showed that LC3-positive dots, the ratio of LC3-II/LC3, and expression of neuron specific enolase and microtubule-associated protein 2 increased in the miR-9 + group. The above results suggest that autophagic activity increased and bone marrow mesenchymal stem cells were prone to differentiate into neuronal cells when miR-9 was overexpressed, demonstrating that miR-9 can promote neuronal differentiation by increasing autophagic activity.

Activity-Dependent Neurorehabilitation Beyond Physical Trainings: "Mental Exercise" Through Mirror Neuron Activation.

Science.gov (United States)

Yuan, Ti-Fei; Chen, Wei; Shan, Chunlei; Rocha, Nuno; Arias-Carrión, Oscar; Paes, Flávia; de Sá, Alberto Souza; Machado, Sergio

2015-01-01

The activity dependent brain repair mechanism has been widely adopted in many types of neurorehabilitation. The activity leads to target specific and non-specific beneficial effects in different brain regions, such as the releasing of neurotrophic factors, modulation of the cytokines and generation of new neurons in adult hood. However physical exercise program clinically are limited to some of the patients with preserved motor functions; while many patients suffered from paralysis cannot make such efforts. Here the authors proposed the employment of mirror neurons system in promoting brain rehabilitation by "observation based stimulation". Mirror neuron system has been considered as an important basis for action understanding and learning by mimicking others. During the action observation, mirror neuron system mediated the direct activation of the same group of motor neurons that are responsible for the observed action. The effect is clear, direct, specific and evolutionarily conserved. Moreover, recent evidences hinted for the beneficial effects on stroke patients after mirror neuron system activation therapy. Finally some music-relevant therapies were proposed to be related with mirror neuron system.

elPBN neurons regulate rVLM activity through elPBN-rVLM projections during activation of cardiac sympathetic afferent nerves

Science.gov (United States)

Longhurst, John C.; Tjen-A-Looi, Stephanie C.; Fu, Liang-Wu

2016-01-01

The external lateral parabrachial nucleus (elPBN) within the pons and rostral ventrolateral medulla (rVLM) contributes to central processing of excitatory cardiovascular reflexes during stimulation of cardiac sympathetic afferent nerves (CSAN). However, the importance of elPBN cardiovascular neurons in regulation of rVLM activity during CSAN activation remains unclear. We hypothesized that CSAN stimulation excites the elPBN cardiovascular neurons and, in turn, increases rVLM activity through elPBN-rVLM projections. Compared with controls, in rats subjected to microinjection of retrograde tracer into the rVLM, the numbers of elPBN neurons double-labeled with c-Fos (an immediate early gene) and the tracer were increased after CSAN stimulation (P < 0.05). The majority of these elPBN neurons contain vesicular glutamate transporter 3. In cats, epicardial bradykinin and electrical stimulation of CSAN increased the activity of elPBN cardiovascular neurons, which was attenuated (n = 6, P < 0.05) after blockade of glutamate receptors with iontophoresis of kynurenic acid (Kyn, 25 mM). In separate cats, microinjection of Kyn (1.25 nmol/50 nl) into the elPBN reduced rVLM activity evoked by both bradykinin and electrical stimulation (n = 5, P < 0.05). Excitation of the elPBN with microinjection of dl-homocysteic acid (2 nmol/50 nl) significantly increased basal and CSAN-evoked rVLM activity. However, the enhanced rVLM activity induced by dl-homocysteic acid injected into the elPBN was reversed following iontophoresis of Kyn into the rVLM (n = 7, P < 0.05). These data suggest that cardiac sympathetic afferent stimulation activates cardiovascular neurons in the elPBN and rVLM sequentially through a monosynaptic (glutamatergic) excitatory elPBN-rVLM pathway. PMID:27225950

The Slow Dynamics of Intracellular Sodium Concentration Increase the Time Window of Neuronal Integration: A Simulation Study

Directory of Open Access Journals (Sweden)

Asaph Zylbertal

2017-09-01

Full Text Available Changes in intracellular Na+ concentration ([Na+]i are rarely taken into account when neuronal activity is examined. As opposed to Ca2+, [Na+]i dynamics are strongly affected by longitudinal diffusion, and therefore they are governed by the morphological structure of the neurons, in addition to the localization of influx and efflux mechanisms. Here, we examined [Na+]i dynamics and their effects on neuronal computation in three multi-compartmental neuronal models, representing three distinct cell types: accessory olfactory bulb (AOB mitral cells, cortical layer V pyramidal cells, and cerebellar Purkinje cells. We added [Na+]i as a state variable to these models, and allowed it to modulate the Na+ Nernst potential, the Na+-K+ pump current, and the Na+-Ca2+ exchanger rate. Our results indicate that in most cases [Na+]i dynamics are significantly slower than [Ca2+]i dynamics, and thus may exert a prolonged influence on neuronal computation in a neuronal type specific manner. We show that [Na+]i dynamics affect neuronal activity via three main processes: reduction of EPSP amplitude in repeatedly active synapses due to reduction of the Na+ Nernst potential; activity-dependent hyperpolarization due to increased activity of the Na+-K+ pump; specific tagging of active synapses by extended Ca2+ elevation, intensified by concurrent back-propagating action potentials or complex spikes. Thus, we conclude that [Na+]i dynamics should be considered whenever synaptic plasticity, extensive synaptic input, or bursting activity are examined.

ALTERED HIPPOCAMPAL NEUROGENESIS AND AMYGDALAR NEURONAL ACTIVITY IN ADULT MICE WITH REPEATED EXPERIENCE OF AGGRESSION

Directory of Open Access Journals (Sweden)

Dmitriy eSmagin

2015-12-01

Full Text Available The repeated experience of winning in a social conflict setting elevates levels of aggression and may lead to violent behavioral patterns. Here we use a paradigm of repeated aggression and fighting deprivation to examine changes in behavior, neurogenesis, and neuronal activity in mice with positive fighting experience. We show that for males, repeated positive fighting experience induces persistent demonstration of aggression and stereotypic behaviors in daily agonistic interactions, enhances aggressive motivation, and elevates levels of anxiety. When winning males are deprived of opportunities to engage in further fights, they demonstrate increased levels of aggressiveness. Positive fighting experience results in increased levels of progenitor cell proliferation and production of young neurons in the hippocampus. This increase is not diminished after a fighting deprivation period. Furthermore, repeated winning experience decreases the number of activated (c-fos positive cells in the basolateral amygdala and increases the number of activated cells in the hippocampus; a subsequent no-fight period restores the number of c-fos-positive cells. Our results indicate that extended positive fighting experience in a social conflict heightens aggression, increases proliferation of neuronal progenitors and production of young neurons in the hippocampus, and decreases neuronal activity in the amygdala; these changes can be modified by depriving the winners of the opportunity for further fights.

Prepubertal Development of Gonadotropin-Releasing Hormone Neuron Activity Is Altered by Sex, Age, and Prenatal Androgen Exposure.

Science.gov (United States)

Dulka, Eden A; Moenter, Suzanne M

2017-11-01

Gonadotropin-releasing hormone (GnRH) neurons regulate reproduction though pulsatile hormone release. Disruption of GnRH release as measured via luteinizing hormone (LH) pulses occurs in polycystic ovary syndrome (PCOS), and in young hyperandrogenemic girls. In adult prenatally androgenized (PNA) mice, which exhibit many aspects of PCOS, increased LH is associated with increased GnRH neuron action potential firing. How GnRH neuron activity develops over the prepubertal period and whether this is altered by sex or prenatal androgen treatment are unknown. We hypothesized GnRH neurons are active before puberty and that this activity is sexually differentiated and altered by PNA. Dams were injected with dihydrotestosterone (DHT) on days 16 to 18 post copulation to generate PNA mice. Action potential firing of GFP-identified GnRH neurons in brain slices from 1-, 2-, 3-, and 4-week-old and adult mice was monitored. GnRH neurons were active at all ages tested. In control females, activity increased with age through 3 weeks, then decreased to adult levels. In contrast, activity did not change in PNA females and was reduced at 3 weeks. Activity was higher in control females than males from 2 to 3 weeks. PNA did not affect GnRH neuron firing rate in males at any age. Short-term action potential patterns were also affected by age and PNA treatment. GnRH neurons are thus typically more active during the prepubertal period than adulthood, and PNA reduces prepubertal activity in females. Prepubertal activity may play a role in establishing sexually differentiated neuronal networks upstream of GnRH neurons; androgen-induced changes during this time may contribute to the adult PNA, and possibly PCOS, phenotype. Copyright © 2017 Endocrine Society.

Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability.

Science.gov (United States)

Merriam, Laura A; Baran, Caitlin N; Girard, Beatrice M; Hardwick, Jean C; May, Victor; Parsons, Rodney L

2013-03-06

After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyap1) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyap1r1). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PAC1R signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability.

Manganese nanoparticle activates mitochondrial dependent apoptotic signaling and autophagy in dopaminergic neuronal cells

International Nuclear Information System (INIS)

Afeseh Ngwa, Hilary; Kanthasamy, Arthi; Gu, Yan; Fang, Ning; Anantharam, Vellareddy; Kanthasamy, Anumantha G.

2011-01-01

The production of man-made nanoparticles for various modern applications has increased exponentially in recent years, but the potential health effects of most nanoparticles are not well characterized. Unfortunately, in vitro nanoparticle toxicity studies are extremely limited by yet unresolved problems relating to dosimetry. In the present study, we systematically characterized manganese (Mn) nanoparticle sizes and examined the nanoparticle-induced oxidative signaling in dopaminergic neuronal cells. Differential interference contrast (DIC) microscopy and transmission electron microscopy (TEM) studies revealed that Mn nanoparticles range in size from single nanoparticles (∼ 25 nM) to larger agglomerates when in treatment media. Manganese nanoparticles were effectively internalized in N27 dopaminergic neuronal cells, and they induced a time-dependent upregulation of the transporter protein transferrin. Exposure to 25–400 μg/mL Mn nanoparticles induced cell death in a time- and dose-dependent manner. Mn nanoparticles also significantly increased ROS, accompanied by a caspase-mediated proteolytic cleavage of proapoptotic protein kinase Cδ (PKCδ), as well as activation loop phosphorylation. Blocking Mn nanoparticle-induced ROS failed to protect against the neurotoxic effects, suggesting the involvement of other pathways. Further mechanistic studies revealed changes in Beclin 1 and LC3, indicating that Mn nanoparticles induce autophagy. Primary mesencephalic neuron exposure to Mn nanoparticles induced loss of TH positive dopaminergic neurons and neuronal processes. Collectively, our results suggest that Mn nanoparticles effectively enter dopaminergic neuronal cells and exert neurotoxic effects by activating an apoptotic signaling pathway and autophagy, emphasizing the need for assessing possible health risks associated with an increased use of Mn nanoparticles in modern applications. -- Highlights: ► Mn nanoparticles activate mitochondrial cell death signaling

Block of voltage-gated potassium channels by Pacific ciguatoxin-1 contributes to increased neuronal excitability in rat sensory neurons

International Nuclear Information System (INIS)

Birinyi-Strachan, Liesl C.; Gunning, Simon J.; Lewis, Richard J.; Nicholson, Graham M.

2005-01-01

The present study investigated the actions of the polyether marine toxin Pacific ciguatoxin-1 (P-CTX-1) on neuronal excitability in rat dorsal root ganglion (DRG) neurons using patch-clamp recording techniques. Under current-clamp conditions, bath application of 2-20 nM P-CTX-1 caused a rapid, concentration-dependent depolarization of the resting membrane potential in neurons expressing tetrodotoxin (TTX)-sensitive voltage-gated sodium (Na v ) channels. This action was completely suppressed by the addition of 200 nM TTX to the external solution, indicating that this effect was mediated through TTX-sensitive Na v channels. In addition, P-CTX-1 also prolonged action potential and afterhyperpolarization (AHP) duration. In a subpopulation of neurons, P-CTX-1 also produced tonic action potential firing, an effect that was not accompanied by significant oscillation of the resting membrane potential. Conversely, in neurons expressing TTX-resistant Na v currents, P-CTX-1 failed to alter any parameter of neuronal excitability examined in this study. Under voltage-clamp conditions in rat DRG neurons, P-CTX-1 inhibited both delayed-rectifier and 'A-type' potassium currents in a dose-dependent manner, actions that occurred in the absence of alterations to the voltage dependence of activation. These actions appear to underlie the prolongation of the action potential and AHP, and contribute to repetitive firing. These data indicate that a block of potassium channels contributes to the increase in neuronal excitability, associated with a modulation of Na v channel gating, observed clinically in response to ciguatera poisoning

Vasoactive intestinal peptide and electrical activity influence neuronal survival

International Nuclear Information System (INIS)

Brenneman, D.E.; Eiden, L.E.

1986-01-01

Blockage of electrical activity in dissociated spinal cord cultures results in a significant loss of neurons during a critical period in development. Decreases in neuronal cell numbers and 125 I-labeled tetanus toxin fixation produced by electrical blockage with tetrodotoxin (TTX) were prevented by addition of vasoactive intestinal peptide (VIP) to the nutrient medium. The most effective concentration of VIP was 0.1 nM. At higher concentrations, the survival-enhancing effect of VIP on TTX-treated cultures was attenuated. Addition of the peptide alone had no significant effect on neuronal cell counts or tetanus toxin fixation. With the same experimental conditions, two closely related peptides, PHI-27 (peptide, histidyl-isoleucine amide) and secretin, were found not to increase the number of neurons in TTX-treated cultures. Interference with VIP action by VIP antiserum resulted in neuronal losses that were not significantly different from those observed after TTX treatment. These data indicate that under conditions of electrical blockade a neurotrophic action of VIP on neuronal survival can be demonstrated

Transient increase in neuronal chloride concentration by neuroactive amino acids released from glioma cells

Directory of Open Access Journals (Sweden)

Cristina eBertollini

2012-11-01

Full Text Available Neuronal chloride concentration ([Cl-]i is known to be dynamically modulated and alterations in Cl- homeostasis may occur in the brain at physiological and pathological conditions, being also likely involved in glioma-related seizures. However, the mechanism leading to changes in neuronal [Cl-]i during glioma invasion are still unclear. To characterize the potential effect of glioma released soluble factors on neuronal [Cl-]i, we used genetically encoded CFP/YFP-based ratiometric Cl-Sensor transiently expressed in cultured hippocampal neurons. Exposition of neurons to glioma conditioned medium (GCM caused rapid and transient elevation of [Cl-]i, resulting in the increase of fluorescence ratio, which was strongly reduced by blockers of ionotropic glutamate receptors APV and NBQX. Furthermore, in HEK cells expressing GluR1-AMPA receptors, GCM activated ionic current with efficacy similar to those caused by glutamate, supporting the notion that GCM contains glutamate or glutamatergic agonists, which cause neuronal depolarization, activation of NMDA and AMPA/KA receptors leading to elevation of [Cl-]i. Chromatographic analysis of the GCM showed that it contained several aminoacids, including glutamate, whose release from glioma cells did not occur via the most common glial mechanisms of transport, or in response to hypoosmotic stress. GCM also contained glycine, whose action contrasted the glutamate effect. Indeed, strychnine application significantly increased GCM-induced depolarization and [Cl-]i rise. GCM-evoked [Cl-]i elevation was not inhibited by antagonists of Cl- transporters and significantly reduced in the presence of anion channels blocker NPPB, suggesting that Cl-selective channels are a major route for GCM-induced Cl- influx. Altogether, these data show that glioma released aminoacids may dynamically alter Cl- equilibrium in surrounding neurons, deeply interfering with their inhibitory balance, likely leading to physiological and

Neuron activity in rat hippocampus and motor cortex during discrimination reversal.

Science.gov (United States)

Disterhoft, J F; Segal, M

1978-01-01

Chronic unit activity and gross movement were recorded from rats during two discrimination reversals in a classical appetitive conditioning situation. The anticipatory movement decreased in response to the former CS+ tone and increased to the previous CS- tone after each reversal. Hippocampus and motor cortex were differently related to these two kinds of behavioral change. Response rates of hippocampal neurons were more closely related to the increased movement response to the former CS- which now signaled food. Motor cortex neuron responses were more closely correlated with the decrease in movement responses to the former CS+ which became neutral after the reversal. It appeared that hippocampal neurons could have been involved in one cognitive aspect of the situation, motor cortex neurons in another. The data were related to current functional concepts of these brain regions.

Response of Cultured Neuronal Network Activity After High-Intensity Power Frequency Magnetic Field Exposure

Directory of Open Access Journals (Sweden)

Atsushi Saito

2018-03-01

Full Text Available High-intensity and low frequency (1–100 kHz time-varying electromagnetic fields stimulate the human body through excitation of the nervous system. In power frequency range (50/60 Hz, a frequency-dependent threshold of the external electric field-induced neuronal modulation in cultured neuronal networks was used as one of the biological indicator in international guidelines; however, the threshold of the magnetic field-induced neuronal modulation has not been elucidated. In this study, we exposed rat brain-derived neuronal networks to a high-intensity power frequency magnetic field (hPF-MF, and evaluated the modulation of synchronized bursting activity using a multi-electrode array (MEA-based extracellular recording technique. As a result of short-term hPF-MF exposure (50–400 mT root-mean-square (rms, 50 Hz, sinusoidal wave, 6 s, the synchronized bursting activity was increased in the 400 mT-exposed group. On the other hand, no change was observed in the 50–200 mT-exposed groups. In order to clarify the mechanisms of the 400 mT hPF-MF exposure-induced neuronal response, we evaluated it after blocking inhibitory synapses using bicuculline methiodide (BMI; subsequently, increase in bursting activity was observed with BMI application, and the response of 400 mT hPF-MF exposure disappeared. Therefore, it was suggested that the response of hPF-MF exposure was involved in the inhibitory input. Next, we screened the inhibitory pacemaker-like neuronal activity which showed autonomous 4–10 Hz firing with CNQX and D-AP5 application, and it was confirmed that the activity was reduced after 400 mT hPF-MF exposure. Comparison of these experimental results with estimated values of the induced electric field (E-field in the culture medium revealed that the change in synchronized bursting activity occurred over 0.3 V/m, which was equivalent to the findings of a previous study that used the external electric fields. In addition, the results suggested that

Fatty Acid Biosynthesis Inhibition Increases Reduction Potential in Neuronal Cells under Hypoxia

Directory of Open Access Journals (Sweden)

Stephen A Brose

2016-11-01

Full Text Available Recently, we have reported a novel neuronal specific pathway for adaptation to hypoxia through increased fatty acid (FA biosynthesis (FAS followed by esterification into lipids. However, the biological role of this pathway under hypoxia remains to be elucidated. In the presented study, we have tested our hypothesis that activation of FAS maintains reduction potential and reduces lactoacidosis in neuronal cells under hypoxia. To address this hypothesis, we measured the effect of FAS inhibition on NADH2+/NAD+ and NADPH2+/NADP+ ratios, and lactic acid levels in neuronal SH-SY5Y cells exposed to normoxic and hypoxic conditions. FAS inhibitors, TOFA (inhibits Acetyl-CoA carboxylase and cerulenin (inhibits FA synthase, increased NADH2+/NAD+ and NADPH2+/NADP+ ratios under hypoxia. Further, FAS inhibition increased lactic acid under both normoxic and hypoxic conditions, and caused cytotoxicity under hypoxia but not normoxia. These results indicate that FA may serve as hydrogen acceptors under hypoxia, thus supporting oxidation reactions including anaerobic glycolysis. These findings may help to identify a radically different approach to attenuate hypoxia related pathophysiology in the nervous system including stroke.

Fatty Acid Biosynthesis Inhibition Increases Reduction Potential in Neuronal Cells under Hypoxia.

Science.gov (United States)

Brose, Stephen A; Golovko, Svetlana A; Golovko, Mikhail Y

2016-01-01

Recently, we have reported a novel neuronal specific pathway for adaptation to hypoxia through increased fatty acid (FA) biosynthesis followed by esterification into lipids. However, the biological role of this pathway under hypoxia remains to be elucidated. In the presented study, we have tested our hypothesis that activation of FA synthesis maintains reduction potential and reduces lactoacidosis in neuronal cells under hypoxia. To address this hypothesis, we measured the effect of FA synthesis inhibition on [Formula: see text]/NAD + and [Formula: see text]/NADP + ratios, and lactic acid levels in neuronal SH-SY5Y cells exposed to normoxic and hypoxic conditions. FA synthesis inhibitors, TOFA (inhibits Acetyl-CoA carboxylase) and cerulenin (inhibits FA synthase), increased [Formula: see text]/NAD + and [Formula: see text]/NADP + ratios under hypoxia. Further, FA synthesis inhibition increased lactic acid under both normoxic and hypoxic conditions, and caused cytotoxicity under hypoxia but not normoxia. These results indicate that FA may serve as hydrogen acceptors under hypoxia, thus supporting oxidation reactions including anaerobic glycolysis. These findings may help to identify a radically different approach to attenuate hypoxia related pathophysiology in the nervous system including stroke.

Stimulation of the ventral tegmental area increased nociceptive thresholds and decreased spinal dorsal horn neuronal activity in rat.

Science.gov (United States)

Li, Ai-Ling; Sibi, Jiny E; Yang, Xiaofei; Chiao, Jung-Chih; Peng, Yuan Bo

2016-06-01

Deep brain stimulation has been found to be effective in relieving intractable pain. The ventral tegmental area (VTA) plays a role not only in the reward process, but also in the modulation of nociception. Lesions of VTA result in increased pain thresholds and exacerbate pain in several pain models. It is hypothesized that direct activation of VTA will reduce pain experience. In this study, we investigated the effect of direct electrical stimulation of the VTA on mechanical, thermal and carrageenan-induced chemical nociceptive thresholds in Sprague-Dawley rats using our custom-designed wireless stimulator. We found that: (1) VTA stimulation itself did not show any change in mechanical or thermal threshold; and (2) the decreased mechanical and thermal thresholds induced by carrageenan injection in the hind paw contralateral to the stimulation site were significantly reversed by VTA stimulation. To further explore the underlying mechanism of VTA stimulation-induced analgesia, spinal cord dorsal horn neuronal responses to graded mechanical stimuli were recorded. VTA stimulation significantly inhibited dorsal horn neuronal activity in response to pressure and pinch from the paw, but not brush. This indicated that VTA stimulation may have exerted its analgesic effect via descending modulatory pain pathways, possibly through its connections with brain stem structures and cerebral cortex areas.

Circadian and dark-pulse activation of orexin/hypocretin neurons

Directory of Open Access Journals (Sweden)

Marston Oliver J

2008-12-01

Full Text Available Temporal control of brain and behavioral states emerges as a consequence of the interaction between circadian and homeostatic neural circuits. This interaction permits the daily rhythm of sleep and wake, regulated in parallel by circadian cues originating from the suprachiasmatic nuclei (SCN and arousal-promoting signals arising from the orexin-containing neurons in the tuberal hypothalamus (TH. Intriguingly, the SCN circadian clock can be reset by arousal-promoting stimuli while activation of orexin/hypocretin neurons is believed to be under circadian control, suggesting the existence of a reciprocal relationship. Unfortunately, since orexin neurons are themselves activated by locomotor promoting cues, it is unclear how these two systems interact to regulate behavioral rhythms. Here mice were placed in conditions of constant light, which suppressed locomotor activity, but also revealed a highly pronounced circadian pattern in orexin neuronal activation. Significantly, activation of orexin neurons in the medial and lateral TH occurred prior to the onset of sustained wheel-running activity. Moreover, exposure to a 6 h dark pulse during the subjective day, a stimulus that promotes arousal and phase advances behavioral rhythms, activated neurons in the medial and lateral TH including those containing orexin. Concurrently, this stimulus suppressed SCN activity while activating cells in the median raphe. In contrast, dark pulse exposure during the subjective night did not reset SCN-controlled behavioral rhythms and caused a transient suppression of neuronal activation in the TH. Collectively these results demonstrate, for the first time, pronounced circadian control of orexin neuron activation and implicate recruitment of orexin cells in dark pulse resetting of the SCN circadian clock.

Human neuromelanin: an endogenous microglial activator for dopaminergic neuron death

OpenAIRE

Zhang, Wei; Zecca, Luigi; Wilson, Belinda; Ren, RW; Wang, Yong-jun; Wang, Xiao-min; Hong, Jau-Shyong

2013-01-01

Substantial evidence indicates that neuroinflammation caused by over-activation of microglial in the substantia nigra is critical in the pathogenesis of dopaminergic neurodegeneration in Parkinson’s disease (PD). Increasing data demonstrates that environmental factors such as rotenone, paraquat play pivotal roles in the death of dopaminergic neurons. Here, potential role and mechanism of neuromelanin (NM), a major endogenous component in dopaminergic neurons of the substantia nigra, on microg...

Increasing inhibitory input increases neuronal firing rate: why and when? Diffusion process cases

Energy Technology Data Exchange (ETDEWEB)

Feng Jianfeng [COGS, Sussex University (United Kingdom)]. E-mail: jf218@cam.ac.uk; Wei Gang [Department of Mathematics, Hong Kong Baptist University, Hong Kong (China)]. E-mail gwei@math.hkbu.edu.hk

2001-09-21

Increasing inhibitory input to single neuronal models, such as the FitzHugh-Nagumo model and the Hodgkin-Huxley model, can sometimes increase their firing rates, a phenomenon which we term inhibition-boosted firing (IBF). Here we consider neuronal models with diffusion approximation inputs, i.e. they share the identical first- and second-order statistics of the corresponding Poisson process inputs. Using the integrate-and-fire model and the IF-FHN model, we explore theoretically how and when IBF can happen. For both models, it is shown that there is a critical input frequency at which the efferent firing rate is identical when the neuron receives purely excitatory inputs or exactly balanced inhibitory and excitatory inputs. When the input frequency is lower than the critical frequency, IBF occurs. (author)

Activation of afferent renal nerves modulates RVLM-projecting PVN neurons.

Science.gov (United States)

Xu, Bo; Zheng, Hong; Liu, Xuefei; Patel, Kaushik P

2015-05-01

Renal denervation for the treatment of hypertension has proven to be successful; however, the underlying mechanism/s are not entirely clear. To determine if preautonomic neurons in the paraventricular nucleus (PVN) respond to afferent renal nerve (ARN) stimulation, extracellular single-unit recording was used to investigate the contribution of the rostral ventrolateral medulla (RVLM)-projecting PVN (PVN-RVLM) neurons to the response elicited during stimulation of ARN. In 109 spontaneously active neurons recorded in the PVN of anesthetized rats, 25 units were antidromically activated from the RVLM. Among these PVN-RVLM neurons, 84% (21/25) were activated by ARN stimulation. The baseline discharge rate was significantly higher in these neurons than those PVN-RVLM neurons not activated by ARN stimulation (16%, 4/25). The responsiveness of these neurons to baroreflex activation induced by phenylephrine and activation of cardiac sympathetic afferent reflex (CSAR) was also examined. Almost all of the PVN neurons that responded to ARN stimulation were sensitive to baroreflex (95%) and CSAR (100%). The discharge characteristics for nonevoked neurons (not activated by RVLM antidromic stimulation) showed that 23% of these PVN neurons responded to ARN stimulation. All the PVN neurons that responded to ARN stimulation were activated by N-methyl-D-aspartate, and these responses were attenuated by the glutamate receptor blocker AP5. These experiments demonstrated that sensory information originating in the kidney is integrated at the level of preautonomic neurons within the PVN, providing a novel mechanistic insight for use of renal denervation in the modulation of sympathetic outflow in disease states such as hypertension and heart failure. Copyright © 2015 the American Physiological Society.

Carbon monoxide improves neuronal differentiation and yield by increasing the functioning and number of mitochondria.

Science.gov (United States)

Almeida, Ana S; Sonnewald, Ursula; Alves, Paula M; Vieira, Helena L A

2016-08-01

The process of cell differentiation goes hand-in-hand with metabolic adaptations, which are needed to provide energy and new metabolites. Carbon monoxide (CO) is an endogenous cytoprotective molecule able to inhibit cell death and improve mitochondrial metabolism. Neuronal differentiation processes were studied using the NT2 cell line, which is derived from human testicular embryonic teratocarcinoma and differentiates into post-mitotic neurons upon retinoic acid treatment. CO-releasing molecule A1 (CORM-A1) was used do deliver CO into cell culture. CO treatment improved NT2 neuronal differentiation and yield, since there were more neurons and the total cell number increased following the differentiation process. CO supplementation enhanced the mitochondrial population in post-mitotic neurons derived from NT2 cells, as indicated by an increase in mitochondrial DNA. CO treatment during neuronal differentiation increased the extent of the classical metabolic change that occurs during neuronal differentiation, from glycolytic to more oxidative metabolism, by decreasing the ratio of lactate production and glucose consumption. The expression of pyruvate and lactate dehydrogenases was higher, indicating an augmented oxidative metabolism. Moreover, these findings were corroborated by an increased percentage of (13) C incorporation from [U-(13) C]glucose into the tricarboxylic acid cycle metabolites malate and citrate, and also glutamate and aspartate in CO-treated cells. Finally, under low levels of oxygen (5%), which enhances glycolytic metabolism, some of the enhancing effects of CO on mitochondria were not observed. In conclusion, our data show that CO improves neuronal and mitochondrial yield by stimulation of tricarboxylic acid cycle activity, and thus oxidative metabolism of NT2 cells during the process of neuronal differentiation. The process of cell differentiation is coupled with metabolic adaptations. Carbon monoxide (CO) is an endogenous cytoprotective

Reliable activation of immature neurons in the adult hippocampus.

Directory of Open Access Journals (Sweden)

Lucas A Mongiat

Full Text Available Neurons born in the adult dentate gyrus develop, mature, and connect over a long interval that can last from six to eight weeks. It has been proposed that, during this period, developing neurons play a relevant role in hippocampal signal processing owing to their distinctive electrical properties. However, it has remained unknown whether immature neurons can be recruited into a network before synaptic and functional maturity have been achieved. To address this question, we used retroviral expression of green fluorescent protein to identify developing granule cells of the adult mouse hippocampus and investigate the balance of afferent excitation, intrinsic excitability, and firing behavior by patch clamp recordings in acute slices. We found that glutamatergic inputs onto young neurons are significantly weaker than those of mature cells, yet stimulation of cortical excitatory axons elicits a similar spiking probability in neurons at either developmental stage. Young neurons are highly efficient in transducing ionic currents into membrane depolarization due to their high input resistance, which decreases substantially in mature neurons as the inward rectifier potassium (Kir conductance increases. Pharmacological blockade of Kir channels in mature neurons mimics the high excitability characteristic of young neurons. Conversely, Kir overexpression induces mature-like firing properties in young neurons. Therefore, the differences in excitatory drive of young and mature neurons are compensated by changes in membrane excitability that render an equalized firing activity. These observations demonstrate that the adult hippocampus continuously generates a population of highly excitable young neurons capable of information processing.

Neuronal medium that supports basic synaptic functions and activity of human neurons in vitro

NARCIS (Netherlands)

Bardy, C.; Hurk, M. van den; Eames, T.; Marchand, C.; Hernandez, R.V.; Kellogg, M.; Gorris, M.A.J.; Galet, B.; Palomares, V.; Brown, J.; Bang, A.G.; Mertens, J.; Bohnke, L.; Boyer, L.; Simon, S.; Gage, F.H.

2015-01-01

Human cell reprogramming technologies offer access to live human neurons from patients and provide a new alternative for modeling neurological disorders in vitro. Neural electrical activity is the essence of nervous system function in vivo. Therefore, we examined neuronal activity in media widely

Activation of AMP-activated protein kinase by tributyltin induces neuronal cell death

International Nuclear Information System (INIS)

Nakatsu, Yusuke; Kotake, Yaichiro; Hino, Atsuko; Ohta, Shigeru

2008-01-01

AMP-activated protein kinase (AMPK), a member of the metabolite-sensing protein kinase family, is activated by energy deficiency and is abundantly expressed in neurons. The environmental pollutant, tributyltin chloride (TBT), is a neurotoxin, and has been reported to decrease cellular ATP in some types of cells. Therefore, we investigated whether TBT activates AMPK, and whether its activation contributes to neuronal cell death, using primary cultures of cortical neurons. Cellular ATP levels were decreased 0.5 h after exposure to 500 nM TBT, and the reduction was time-dependent. It was confirmed that most neurons in our culture system express AMPK, and that TBT induced phosphorylation of AMPK. Compound C, an AMPK inhibitor, reduced the neurotoxicity of TBT, suggesting that AMPK is involved in TBT-induced cell death. Next, the downstream target of AMPK activation was investigated. Nitric oxide synthase, p38 phosphorylation and Akt dephosphorylation were not downstream of TBT-induced AMPK activation because these factors were not affected by compound C, but glutamate release was suggested to be controlled by AMPK. Our results suggest that activation of AMPK by TBT causes neuronal death through mediating glutamate release

Activation of Brainstem Pro-opiomelanocortin Neurons Produces Opioidergic Analgesia, Bradycardia and Bradypnoea.

Science.gov (United States)

Cerritelli, Serena; Hirschberg, Stefan; Hill, Rob; Balthasar, Nina; Pickering, Anthony E

2016-01-01

Opioids are widely used medicinally as analgesics and abused for hedonic effects, actions that are each complicated by substantial risks such as cardiorespiratory depression. These drugs mimic peptides such as β-endorphin, which has a key role in endogenous analgesia. The β-endorphin in the central nervous system originates from pro-opiomelanocortin (POMC) neurons in the arcuate nucleus and nucleus of the solitary tract (NTS). Relatively little is known about the NTSPOMC neurons but their position within the sensory nucleus of the vagus led us to test the hypothesis that they play a role in modulation of cardiorespiratory and nociceptive control. The NTSPOMC neurons were targeted using viral vectors in a POMC-Cre mouse line to express either opto-genetic (channelrhodopsin-2) or chemo-genetic (Pharmacologically Selective Actuator Modules). Opto-genetic activation of the NTSPOMC neurons in the working heart brainstem preparation (n = 21) evoked a reliable, titratable and time-locked respiratory inhibition (120% increase in inter-breath interval) with a bradycardia (125±26 beats per minute) and augmented respiratory sinus arrhythmia (58% increase). Chemo-genetic activation of NTSPOMC neurons in vivo was anti-nociceptive in the tail flick assay (latency increased by 126±65%, pneurons were found to project to key brainstem structures involved in cardiorespiratory control (nucleus ambiguus and ventral respiratory group) and endogenous analgesia (periaqueductal gray and midline raphe). Thus the NTSPOMC neurons may be capable of tuning behaviour by an opioidergic modulation of nociceptive, respiratory and cardiac control.

Brucella abortus-activated microglia induce neuronal death through primary phagocytosis.

Science.gov (United States)

Rodríguez, Ana M; Delpino, M Victoria; Miraglia, M Cruz; Costa Franco, Miriam M; Barrionuevo, Paula; Dennis, Vida A; Oliveira, Sergio C; Giambartolomei, Guillermo H

2017-07-01

Inflammation has long been implicated as a contributor to pathogenesis in neurobrucellosis. Many of the associated neurocognitive symptoms of neurobrucellosis may be the result of neuronal dysfunction resulting from the inflammatory response induced by Brucella abortus infection in the central nervous system. In this manuscript, we describe an immune mechanism for inflammatory activation of microglia that leads to neuronal death upon B. abortus infection. B. abortus was unable to infect or harm primary cultures of mouse neurons. However, when neurons were co-cultured with microglia and infected with B. abortus significant neuronal loss occurred. This phenomenon was dependent on TLR2 activation by Brucella lipoproteins. Neuronal death was not due to apoptosis, but it was dependent on the microglial release of nitric oxide (NO). B. abortus infection stimulated microglial proliferation, phagocytic activity and engulfment of neurons. NO secreted by B. abortus-activated microglia induced neuronal exposure of the "eat-me" signal phosphatidylserine (PS). Blocking of PS-binding to protein milk fat globule epidermal growth factor-8 (MFG-E8) or microglial vitronectin receptor-MFG-E8 interaction was sufficient to prevent neuronal loss by inhibiting microglial phagocytosis without affecting their activation. Taken together, our results indicate that B. abortus is not directly toxic to neurons; rather, these cells become distressed and are killed by phagocytosis in the inflammatory surroundings generated by infected microglia. Neuronal loss induced by B. abortus-activated microglia may explain, in part, the neurological deficits observed during neurobrucellosis. © 2017 Wiley Periodicals, Inc.

Curtailing effect of awakening on visual responses of cortical neurons by cholinergic activation of inhibitory circuits.

Science.gov (United States)

Kimura, Rui; Safari, Mir-Shahram; Mirnajafi-Zadeh, Javad; Kimura, Rie; Ebina, Teppei; Yanagawa, Yuchio; Sohya, Kazuhiro; Tsumoto, Tadaharu

2014-07-23

Visual responsiveness of cortical neurons changes depending on the brain state. Neural circuit mechanism underlying this change is unclear. By applying the method of in vivo two-photon functional calcium imaging to transgenic rats in which GABAergic neurons express fluorescent protein, we analyzed changes in visual response properties of cortical neurons when animals became awakened from anesthesia. In the awake state, the magnitude and reliability of visual responses of GABAergic neurons increased whereas the decay of responses of excitatory neurons became faster. To test whether the basal forebrain (BF) cholinergic projection is involved in these changes, we analyzed effects of electrical and optogenetic activation of BF on visual responses of mouse cortical neurons with in vivo imaging and whole-cell recordings. Electrical BF stimulation in anesthetized animals induced the same direction of changes in visual responses of both groups of neurons as awakening. Optogenetic activation increased the frequency of visually evoked action potentials in GABAergic neurons but induced the delayed hyperpolarization that ceased the late generation of action potentials in excitatory neurons. Pharmacological analysis in slice preparations revealed that photoactivation-induced depolarization of layer 1 GABAergic neurons was blocked by a nicotinic receptor antagonist, whereas non-fast-spiking layer 2/3 GABAergic neurons was blocked only by the application of both nicotinic and muscarinic receptor antagonists. These results suggest that the effect of awakening is mediated mainly through nicotinic activation of layer 1 GABAergic neurons and mixed nicotinic/muscarinic activation of layer 2/3 non-fast-spiking GABAergic neurons, which together curtails the visual responses of excitatory neurons. Copyright © 2014 the authors 0270-6474/14/3410122-12$15.00/0.

Activation of hypothalamic RIP-Cre neurons promotes beiging of WAT via sympathetic nervous system.

Science.gov (United States)

Wang, Baile; Li, Ang; Li, Xiaomu; Ho, Philip Wl; Wu, Donghai; Wang, Xiaoqi; Liu, Zhuohao; Wu, Kelvin Kl; Yau, Sonata Sy; Xu, Aimin; Cheng, Kenneth Ky

2018-04-01

Activation of brown adipose tissue (BAT) and beige fat by cold increases energy expenditure. Although their activation is known to be differentially regulated in part by hypothalamus, the underlying neural pathways and populations remain poorly characterized. Here, we show that activation of rat-insulin-promoter-Cre (RIP-Cre) neurons in ventromedial hypothalamus (VMH) preferentially promotes recruitment of beige fat via a selective control of sympathetic nervous system (SNS) outflow to subcutaneous white adipose tissue (sWAT), but has no effect on BAT Genetic ablation of APPL2 in RIP-Cre neurons diminishes beiging in sWAT without affecting BAT, leading to cold intolerance and obesity in mice. Such defects are reversed by activation of RIP-Cre neurons, inactivation of VMH AMPK, or treatment with a β3-adrenergic receptor agonist. Hypothalamic APPL2 enhances neuronal activation in VMH RIP-Cre neurons and raphe pallidus, thereby eliciting SNS outflow to sWAT and subsequent beiging. These data suggest that beige fat can be selectively activated by VMH RIP-Cre neurons, in which the APPL2-AMPK signaling axis is crucial for this defending mechanism to cold and obesity. © 2018 The Authors.

Deficient Rab11 activity underlies glucose hypometabolism in primary neurons of Huntington’s disease mice

International Nuclear Information System (INIS)

Li, Xueyi; Valencia, Antonio; McClory, Hollis; Sapp, Ellen; Kegel, Kimberly B.; DiFiglia, Marian

2012-01-01

Highlights: ► Primary Huntington’s disease neurons are impaired in taking up glucose. ► Rab11 modulates glucose uptake in neurons. ► Increasing Rab11 activity attenuates the glucose uptake defect in disease neurons. ► We provide a novel mechanism for glucose hypometabolism in Huntington’s disease. -- Abstract: Huntington’s disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Positron emission tomography studies have revealed a decline in glucose metabolism in the brain of patients with HD by a mechanism that has not been established. We examined glucose utilization in embryonic primary cortical neurons of wild-type (WT) and HD knock-in mice, which have 140 CAG repeats inserted in the endogenous mouse huntingtin gene (HD 140Q/140Q ). Primary HD 140Q/140Q cortical neurons took up significantly less glucose than did WT neurons. Expression of permanently inactive and permanently active forms of Rab11 correspondingly altered glucose uptake in WT neurons, suggesting that normal activity of Rab11 is needed for neuronal uptake of glucose. It is known that Rab11 activity is diminished in HD 140Q/140Q neurons. Expression of dominant active Rab11 to enhance the activity of Rab11 normalized glucose uptake in HD 140Q/140Q neurons. These results suggest that deficient activity of Rab11 is a novel mechanism for glucose hypometabolism in HD.

Spatio-temporal specialization of GABAergic septo-hippocampal neurons for rhythmic network activity.

Science.gov (United States)

Unal, Gunes; Crump, Michael G; Viney, Tim J; Éltes, Tímea; Katona, Linda; Klausberger, Thomas; Somogyi, Peter

2018-03-03

Medial septal GABAergic neurons of the basal forebrain innervate the hippocampus and related cortical areas, contributing to the coordination of network activity, such as theta oscillations and sharp wave-ripple events, via a preferential innervation of GABAergic interneurons. Individual medial septal neurons display diverse activity patterns, which may be related to their termination in different cortical areas and/or to the different types of innervated interneurons. To test these hypotheses, we extracellularly recorded and juxtacellularly labeled single medial septal neurons in anesthetized rats in vivo during hippocampal theta and ripple oscillations, traced their axons to distant cortical target areas, and analyzed their postsynaptic interneurons. Medial septal GABAergic neurons exhibiting different hippocampal theta phase preferences and/or sharp wave-ripple related activity terminated in restricted hippocampal regions, and selectively targeted a limited number of interneuron types, as established on the basis of molecular markers. We demonstrate the preferential innervation of bistratified cells in CA1 and of basket cells in CA3 by individual axons. One group of septal neurons was suppressed during sharp wave-ripples, maintained their firing rate across theta and non-theta network states and mainly fired along the descending phase of CA1 theta oscillations. In contrast, neurons that were active during sharp wave-ripples increased their firing significantly during "theta" compared to "non-theta" states, with most firing during the ascending phase of theta oscillations. These results demonstrate that specialized septal GABAergic neurons contribute to the coordination of network activity through parallel, target area- and cell type-selective projections to the hippocampus.

PERSPECTIVE: Electrical activity enhances neuronal survival and regeneration

Science.gov (United States)

Corredor, Raul G.; Goldberg, Jeffrey L.

2009-10-01

The failure of regeneration in the central nervous system (CNS) remains an enormous scientific and clinical challenge. After injury or in degenerative diseases, neurons in the adult mammalian CNS fail to regrow their axons and reconnect with their normal targets, and furthermore the neurons frequently die and are not normally replaced. While significant progress has been made in understanding the molecular basis for this lack of regenerative ability, a second approach has gained momentum: replacing lost neurons or lost connections with artificial electrical circuits that interface with the nervous system. In the visual system, gene therapy-based 'optogenetics' prostheses represent a competing technology. Now, the two approaches are converging, as recent data suggest that electrical activity itself, via the molecular signaling pathways such activity stimulates, is sufficient to induce neuronal survival and regeneration, particularly in retinal ganglion cells. Here, we review these data, discuss the effects of electrical activity on neurons' molecular signaling pathways and propose specific mechanisms by which exogenous electrical activity may be acting to enhance survival and regeneration.

Increased actin polymerization and stabilization interferes with neuronal function and survival in the AMPKγ mutant Loechrig.

Directory of Open Access Journals (Sweden)

Mandy Cook

Full Text Available loechrig (loe mutant flies are characterized by progressive neuronal degeneration, behavioral deficits, and early death. The mutation is due to a P-element insertion in the gene for the γ-subunit of the trimeric AMP-activated protein kinase (AMPK complex, whereby the insertion affects only one of several alternative transcripts encoding a unique neuronal isoform. AMPK is a cellular energy sensor that regulates a plethora of signaling pathways, including cholesterol and isoprenoid synthesis via its downstream target hydroxy-methylglutaryl (HMG-CoA reductase. We recently showed that loe interferes with isoprenoid synthesis and increases the prenylation and thereby activation of RhoA. During development, RhoA plays an important role in neuronal outgrowth by activating a signaling cascade that regulates actin dynamics. Here we show that the effect of loe/AMPKγ on RhoA prenylation leads to a hyperactivation of this signaling pathway, causing increased phosphorylation of the actin depolymerizating factor cofilin and accumulation of filamentous actin. Furthermore, our results show that the resulting cytoskeletal changes in loe interfere with neuronal growth and disrupt axonal integrity. Surprisingly, these phenotypes were enhanced by expressing the Slingshot (SSH phosphatase, which during development promotes actin depolymerization by dephosphorylating cofilin. However, our studies suggest that in the adult SSH promotes actin polymerization, supporting in vitro studies using human SSH1 that suggested that SSH can also stabilize and bundle filamentous actin. Together with the observed increase in SSH levels in the loe mutant, our experiments suggest that in mature neurons SSH may function as a stabilization factor for filamentous actin instead of promoting actin depolymerization.

Pseudorabies virus infection alters neuronal activity and connectivity in vitro.

Directory of Open Access Journals (Sweden)

Kelly M McCarthy

2009-10-01

Full Text Available Alpha-herpesviruses, including human herpes simplex virus 1 & 2, varicella zoster virus and the swine pseudorabies virus (PRV, infect the peripheral nervous system of their hosts. Symptoms of infection often include itching, numbness, or pain indicative of altered neurological function. To determine if there is an in vitro electrophysiological correlate to these characteristic in vivo symptoms, we infected cultured rat sympathetic neurons with well-characterized strains of PRV known to produce virulent or attenuated symptoms in animals. Whole-cell patch clamp recordings were made at various times after infection. By 8 hours of infection with virulent PRV, action potential (AP firing rates increased substantially and were accompanied by hyperpolarized resting membrane potentials and spikelet-like events. Coincident with the increase in AP firing rate, adjacent neurons exhibited coupled firing events, first with AP-spikelets and later with near identical resting membrane potentials and AP firing. Small fusion pores between adjacent cell bodies formed early after infection as demonstrated by transfer of the low molecular weight dye, Lucifer Yellow. Later, larger pores formed as demonstrated by transfer of high molecular weight Texas red-dextran conjugates between infected cells. Further evidence for viral-induced fusion pores was obtained by infecting neurons with a viral mutant defective for glycoprotein B, a component of the viral membrane fusion complex. These infected neurons were essentially identical to mock infected neurons: no increased AP firing, no spikelet-like events, and no electrical or dye transfer. Infection with PRV Bartha, an attenuated circuit-tracing strain delayed, but did not eliminate the increased neuronal activity and coupling events. We suggest that formation of fusion pores between infected neurons results in electrical coupling and elevated firing rates, and that these processes may contribute to the altered neural

Why Does Sleep Slow-Wave Activity Increase After Extended Wake? Assessing the Effects of Increased Cortical Firing During Wake and Sleep.

Science.gov (United States)

Rodriguez, Alexander V; Funk, Chadd M; Vyazovskiy, Vladyslav V; Nir, Yuval; Tononi, Giulio; Cirelli, Chiara

2016-12-07

During non-rapid eye movement (NREM) sleep, cortical neurons alternate between ON periods of firing and OFF periods of silence. This bi-stability, which is largely synchronous across neurons, is reflected in the EEG as slow waves. Slow-wave activity (SWA) increases with wake duration and declines homeostatically during sleep, but the underlying mechanisms remain unclear. One possibility is neuronal "fatigue": high, sustained firing in wake would force neurons to recover with more frequent and longer OFF periods during sleep. Another possibility is net synaptic potentiation during wake: stronger coupling among neurons would lead to greater synchrony and therefore higher SWA. Here, we obtained a comparable increase in sustained firing (6 h) in cortex by: (1) keeping mice awake by exposure to novel objects to promote plasticity and (2) optogenetically activating a local population of cortical neurons at wake-like levels during sleep. Sleep after extended wake led to increased SWA, higher synchrony, and more time spent OFF, with a positive correlation between SWA, synchrony, and OFF periods. Moreover, time spent OFF was correlated with cortical firing during prior wake. After local optogenetic stimulation, SWA and cortical synchrony decreased locally, time spent OFF did not change, and local SWA was not correlated with either measure. Moreover, laser-induced cortical firing was not correlated with time spent OFF afterward. Overall, these results suggest that high sustained firing per se may not be the primary determinant of SWA increases observed after extended wake. A long-standing hypothesis is that neurons fire less during slow-wave sleep to recover from the "fatigue" accrued during wake, when overall synaptic activity is higher than in sleep. This idea, however, has rarely been tested and other factors, namely increased cortical synchrony, could explain why sleep slow-wave activity (SWA) is higher after extended wake. We forced neurons in the mouse cortex to fire

Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Hippocampal Neurons from PrP(-/-) Mice.

Science.gov (United States)

Fan, Jing; Stemkowski, Patrick L; Gandini, Maria A; Black, Stefanie A; Zhang, Zizhen; Souza, Ivana A; Chen, Lina; Zamponi, Gerald W

2016-01-01

Genetic ablation of cellular prion protein (PrP(C)) has been linked to increased neuronal excitability and synaptic activity in the hippocampus. We have previously shown that synaptic activity in hippocampi of PrP-null mice is increased due to enhanced N-methyl-D-aspartate receptor (NMDAR) function. Here, we focused on the effect of PRNP gene knock-out (KO) on intrinsic neuronal excitability, and in particular, the underlying ionic mechanism in hippocampal neurons cultured from P0 mouse pups. We found that the absence of PrP(C) profoundly affected the firing properties of cultured hippocampal neurons in the presence of synaptic blockers. The membrane impedance was greater in PrP-null neurons, and this difference was abolished by the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker ZD7288 (100 μM). HCN channel activity appeared to be functionally regulated by PrP(C). The amplitude of voltage sag, a characteristic of activating HCN channel current (I h), was decreased in null mice. Moreover, I h peak current was reduced, along with a hyperpolarizing shift in activation gating and slower kinetics. However, neither HCN1 nor HCN2 formed a biochemical complex with PrP(C). These results suggest that the absence of PrP downregulates the activity of HCN channels through activation of a cell signaling pathway rather than through direct interactions. This in turn contributes to an increase in membrane impedance to potentiate neuronal excitability.

Palmitoylethanolamide Blunts Amyloid-β42-Induced Astrocyte Activation and Improves Neuronal Survival in Primary Mouse Cortical Astrocyte-Neuron Co-Cultures.

Science.gov (United States)

Beggiato, Sarah; Borelli, Andrea Celeste; Ferraro, Luca; Tanganelli, Sergio; Antonelli, Tiziana; Tomasini, Maria Cristina

2018-01-01

Based on the pivotal role of astrocytes in brain homeostasis and the strong metabolic cooperation existing between neurons and astrocytes, it has been suggested that astrocytic dysfunctions might cause and/or contribute to neuroinflammation and neurodegenerative processes. Therapeutic approaches aimed at both neuroprotection and neuroinflammation reduction may prove particularly effective in slowing the progression of these diseases. The endogenous lipid mediator palmitoylethanolamide (PEA) displayed neuroprotective and anti(neuro)inflammatory properties, and demonstrated interesting potential as a novel treatment for Alzheimer's disease. We firstly evaluated whether astrocytes could participate in regulating the Aβ42-induced neuronal damage, by using primary mouse astrocytes cell cultures and mixed astrocytes-neurons cultures. Furthermore, the possible protective effects of PEA against Aβ42-induced neuronal toxicity have also been investigated by evaluating neuronal viability, apoptosis, and morphometric parameters. The presence of astrocytes pre-exposed to Aβ42 (0.5μM; 24 h) induced a reduction of neuronal viability in primary mouse astrocytes-neurons co-cultures. Furthermore, under these experimental conditions, an increase in the number of neuronal apoptotic nuclei and a decrease in the number of MAP-2 positive neurons were observed. Finally, astrocytic Aβ42 pre-exposure induced an increase in the number of neurite aggregations/100μm as compared to control (i.e., untreated) astrocytes-neurons co-cultures. These effects were not observed in neurons cultured in the presence of astrocytes pre-exposed to PEA (0.1μM), applied 1 h before and maintained during Aβ42 treatment. Astrocytes contribute to Aβ42-induced neurotoxicity and PEA, by blunting Aβ42-induced astrocyte activation, improved neuronal survival in mouse astrocyte-neuron co-cultures.

Bi-directional astrocytic regulation of neuronal activity within a network

Directory of Open Access Journals (Sweden)

Susan Yu Gordleeva

2012-11-01

Full Text Available The concept of a tripartite synapse holds that astrocytes can affect both the pre- and postsynaptic compartments through the Ca2+-dependent release of gliotransmitters. Because astrocytic Ca2+ transients usually last for a few seconds, we assumed that astrocytic regulation of synaptic transmission may also occur on the scale of seconds. Here, we considered the basic physiological functions of tripartite synapses and investigated astrocytic regulation at the level of neural network activity. The firing dynamics of individual neurons in a spontaneous firing network was described by the Hodgkin-Huxley model. The neurons received excitatory synaptic input driven by the Poisson spike train with variable frequency. The mean field concentration of the released neurotransmitter was used to describe the presynaptic dynamics. The amplitudes of the excitatory postsynaptic currents (PSCs obeyed the gamma distribution law. In our model, astrocytes depressed the presynaptic release and enhanced the postsynaptic currents. As a result, low frequency synaptic input was suppressed while high frequency input was amplified. The analysis of the neuron spiking frequency as an indicator of network activity revealed that tripartite synaptic transmission dramatically changed the local network operation compared to bipartite synapses. Specifically, the astrocytes supported homeostatic regulation of the network activity by increasing or decreasing firing of the neurons. Thus, the astrocyte activation may modulate a transition of neural network into bistable regime of activity with two stable firing levels and spontaneous transitions between them.

Bone conducted vibration selectively activates irregular primary otolithic vestibular neurons in the guinea pig.

Science.gov (United States)

Curthoys, Ian S; Kim, Juno; McPhedran, Samara K; Camp, Aaron J

2006-11-01

The main objective of this study was to determine whether bone-conducted vibration (BCV) is equally effective in activating both semicircular canal and otolith afferents in the guinea pig or whether there is preferential activation of one of these classes of vestibular afferents. To answer this question a large number (346) of single primary vestibular neurons were recorded extracellularly in anesthetized guinea pigs and were identified by their location in the vestibular nerve and classed as regular or irregular on the basis of the variability of their spontaneous discharge. If a neuron responded to angular acceleration it was classed as a semicircular canal neuron, if it responded to maintained roll or pitch tilts it was classified as an otolith neuron. Each neuron was then tested by BCV stimuli-either clicks, continuous pure tones (200-1,500 Hz) or short tone bursts (500 Hz lasting 7 ms)-delivered by a B-71 clinical bone-conduction oscillator cemented to the guinea pig's skull. All stimulus intensities were referred to that animal's own auditory brainstem response (ABR) threshold to BCV clicks, and the maximum intensity used was within the animal's physiological range and was usually around 70 dB above BCV threshold. In addition two sensitive single axis linear accelerometers cemented to the skull gave absolute values of the stimulus acceleration in the rostro-caudal direction. The criterion for a neuron being classed as activated was an audible, stimulus-locked increase in firing rate (a 10% change was easily detectable) in response to the BCV stimulus. At the stimulus levels used in this study, semicircular canal neurons, both regular and irregular, were insensitive to BCV stimuli and very few responded: only nine of 189 semicircular canal neurons tested (4.7%) showed a detectable increase in firing in response to BCV stimuli up to the maximum 2 V peak-to-peak level we delivered to the B-71 oscillator (which produced a peak-to-peak skull acceleration of around

A computational paradigm for dynamic logic-gates in neuronal activity

Directory of Open Access Journals (Sweden)

Amir eGoldental

2014-04-01

Full Text Available In 1943 McCulloch and Pitts suggested that the brain is composed of reliable logic-gates similar to the logic at the core of today's computers. This framework had a limited impact on neuroscience, since neurons exhibit far richer dynamics. Here we propose a new experimentally corroborated paradigm in which the truth tables of the brain's logic-gates are time dependent, i.e. dynamic logic-gates (DLGs. The truth tables of the DLGs depend on the history of their activity and the stimulation frequencies of their input neurons. Our experimental results are based on a procedure where conditioned stimulations were enforced on circuits of neurons embedded within a large-scale network of cortical cells in-vitro. We demonstrate that the underlying biological mechanism is the unavoidable increase of neuronal response latencies to ongoing stimulations, which imposes a non-uniform gradual stretching of network delays. The limited experimental results are confirmed and extended by simulations and theoretical arguments based on identical neurons with a fixed increase of the neuronal response latency per evoked spike. We anticipate our results to lead to better understanding of the suitability of this computational paradigm to account for the brain's functionalities and will require the development of new systematic mathematical methods beyond the methods developed for traditional Boolean algebra.

Phenobarbital and midazolam increase neonatal seizure-associated neuronal injury.

Science.gov (United States)

Torolira, Daniel; Suchomelova, Lucie; Wasterlain, Claude G; Niquet, Jerome

2017-07-01

Status epilepticus is common in neonates and infants, and is associated with neuronal injury and adverse developmental outcomes. γ-Aminobutyric acidergic (GABAergic) drugs, the standard treatment for neonatal seizures, can have excitatory effects in the neonatal brain, which may worsen the seizures and their effects. Using a recently developed model of status epilepticus in postnatal day 7 rat pups that results in widespread neuronal injury, we found that the GABA A agonists phenobarbital and midazolam significantly increased status epilepticus-associated neuronal injury in various brain regions. Our results suggest that more research is needed into the possible deleterious effects of GABAergic drugs on neonatal seizures and on excitotoxic neuronal injury in the immature brain. Ann Neurol 2017;82:115-120. © 2017 American Neurological Association.

Increased histone H3 phosphorylation in neurons in specific brain structures after induction of status epilepticus in mice.

Directory of Open Access Journals (Sweden)

Tetsuji Mori

Full Text Available Status epilepticus (SE induces pathological and morphological changes in the brain. Recently, it has become clear that excessive neuronal excitation, stress and drug abuse induce chromatin remodeling in neurons, thereby altering gene expression. Chromatin remodeling is a key mechanism of epigenetic gene regulation. Histone H3 phosphorylation is frequently used as a marker of chromatin remodeling and is closely related to the upregulation of mRNA transcription. In the present study, we analyzed H3 phosphorylation levels in vivo using immunohistochemistry in the brains of mice with pilocarpine-induced SE. A substantial increase in H3 phosphorylation was detected in neurons in specific brain structures. Increased H3 phosphorylation was dependent on neuronal excitation. In particular, a robust upregulation of H3 phosphorylation was detected in the caudate putamen, and there was a gradient of phosphorylated H3(+ (PH3(+ neurons along the medio-lateral axis. After unilateral ablation of dopaminergic neurons in the substantia nigra by injection of 6-hydroxydopamine, the distribution of PH3(+ neurons changed in the caudate putamen. Moreover, our histological analysis suggested that, in addition to the well-known MSK1 (mitogen and stress-activated kinase/H3 phosphorylation/c-fos pathway, other signaling pathways were also activated. Together, our findings suggest that a number of genes involved in the pathology of epileptogenesis are upregulated in PH3(+ brain regions, and that H3 phosphorylation is a suitable indicator of strong neuronal excitation.

Neurons derived from sporadic Alzheimer's disease iPSCs reveal elevated TAU hyperphosphorylation, increased amyloid levels, and GSK3B activation

DEFF Research Database (Denmark)

Ochalek, Anna; Mihalik, Balázs; Avci, Hasan X.

2017-01-01

, our aim was to establish an in vitro cell model based on patient-specific human neurons to study the pathomechanism of sporadic AD. Methods: We compared neurons derived from induced pluripotent stem cell (iPSC) lines of patients with early-onset familial Alzheimer's disease (fAD), all caused...... blotting methods. Results: Neurons from patients with fAD and patients with sAD showed increased phosphorylation of TAU protein at all investigated phosphorylation sites. Relative to the control neurons, neurons derived from patients with fAD and patients with sAD exhibited higher levels of extracellular......, a physiological kinase of TAU, in neurons derived from AD iPSCs, as well as significant upregulation of amyloid precursor protein (APP) synthesis and APP carboxy-terminal fragment cleavage. Moreover, elevated sensitivity to oxidative stress, as induced by amyloid oligomers or peroxide, was detected in both f...

Three-dimensional distribution of sensory stimulation-evoked neuronal activity of spinal dorsal horn neurons analyzed by in vivo calcium imaging.

Science.gov (United States)

Nishida, Kazuhiko; Matsumura, Shinji; Taniguchi, Wataru; Uta, Daisuke; Furue, Hidemasa; Ito, Seiji

2014-01-01

The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET)-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn.

Three-dimensional distribution of sensory stimulation-evoked neuronal activity of spinal dorsal horn neurons analyzed by in vivo calcium imaging.

Directory of Open Access Journals (Sweden)

Kazuhiko Nishida

Full Text Available The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn.

Increased Nerve Growth Factor Signaling in Sensory Neurons of Early Diabetic Rats Is Corrected by Electroacupuncture

Directory of Open Access Journals (Sweden)

Stefania Lucia Nori

2013-01-01

Full Text Available Diabetic polyneuropathy (DPN, characterized by early hyperalgesia and increased nerve growth factor (NGF, evolves in late irreversible neuropathic symptoms with reduced NGF support to sensory neurons. Electroacupuncture (EA modulates NGF in the peripheral nervous system, being effective for the treatment of DPN symptoms. We hypothesize that NGF plays an important pathogenic role in DPN development, while EA could be useful in the therapy of DPN by modulating NGF expression/activity. Diabetes was induced in rats by streptozotocin (STZ injection. One week after STZ, EA was started and continued for three weeks. NGF system and hyperalgesia-related mediators were analyzed in the dorsal root ganglia (DRG and in their spinal cord and skin innervation territories. Our results show that four weeks long diabetes increased NGF and NGF receptors and deregulated intracellular signaling mediators of DRG neurons hypersensitization; EA in diabetic rats decreased NGF and NGF receptors, normalized c-Jun N-terminal and p38 kinases activation, decreased transient receptor potential vanilloid-1 ion channel, and possibly activated the nuclear factor kappa-light-chain-enhancer of activated B cells (Nf-κB. In conclusion, NGF signaling deregulation might play an important role in the development of DPN. EA represents a supportive tool to control DPN development by modulating NGF signaling in diabetes-targeted neurons.

The Limited Utility of Multiunit Data in Differentiating Neuronal Population Activity.

Directory of Open Access Journals (Sweden)

Corey J Keller

Full Text Available To date, single neuron recordings remain the gold standard for monitoring the activity of neuronal populations. Since obtaining single neuron recordings is not always possible, high frequency or 'multiunit activity' (MUA is often used as a surrogate. Although MUA recordings allow one to monitor the activity of a large number of neurons, they do not allow identification of specific neuronal subtypes, the knowledge of which is often critical for understanding electrophysiological processes. Here, we explored whether prior knowledge of the single unit waveform of specific neuron types is sufficient to permit the use of MUA to monitor and distinguish differential activity of individual neuron types. We used an experimental and modeling approach to determine if components of the MUA can monitor medium spiny neurons (MSNs and fast-spiking interneurons (FSIs in the mouse dorsal striatum. We demonstrate that when well-isolated spikes are recorded, the MUA at frequencies greater than 100Hz is correlated with single unit spiking, highly dependent on the waveform of each neuron type, and accurately reflects the timing and spectral signature of each neuron. However, in the absence of well-isolated spikes (the norm in most MUA recordings, the MUA did not typically contain sufficient information to permit accurate prediction of the respective population activity of MSNs and FSIs. Thus, even under ideal conditions for the MUA to reliably predict the moment-to-moment activity of specific local neuronal ensembles, knowledge of the spike waveform of the underlying neuronal populations is necessary, but not sufficient.

Gc-protein-derived macrophage activating factor counteracts the neuronal damage induced by oxaliplatin.

Science.gov (United States)

Morucci, Gabriele; Branca, Jacopo J V; Gulisano, Massimo; Ruggiero, Marco; Paternostro, Ferdinando; Pacini, Alessandra; Di Cesare Mannelli, Lorenzo; Pacini, Stefania

2015-02-01

Oxaliplatin-based regimens are effective in metastasized advanced cancers. However, a major limitation to their widespread use is represented by neurotoxicity that leads to peripheral neuropathy. In this study we evaluated the roles of a proven immunotherapeutic agent [Gc-protein-derived macrophage activating factor (GcMAF)] in preventing or decreasing oxaliplatin-induced neuronal damage and in modulating microglia activation following oxaliplatin-induced damage. The effects of oxaliplatin and of a commercially available formula of GcMAF [oleic acid-GcMAF (OA-GcMAF)] were studied in human neurons (SH-SY5Y cells) and in human microglial cells (C13NJ). Cell density, morphology and viability, as well as production of cAMP and expression of vascular endothelial growth factor (VEGF), markers of neuron regeneration [neuromodulin or growth associated protein-43 (Gap-43)] and markers of microglia activation [ionized calcium binding adaptor molecule 1 (Iba1) and B7-2], were determined. OA-GcMAF reverted the damage inflicted by oxaliplatin on human neurons and preserved their viability. The neuroprotective effect was accompanied by increased intracellular cAMP production, as well as by increased expression of VEGF and neuromodulin. OA-GcMAF did not revert the effects of oxaliplatin on microglial cell viability. However, it increased microglial activation following oxaliplatin-induced damage, resulting in an increased expression of the markers Iba1 and B7-2 without any concomitant increase in cell number. When neurons and microglial cells were co-cultured, the presence of OA-GcMAF significantly counteracted the toxic effects of oxaliplatin. Our results demonstrate that OA-GcMAF, already used in the immunotherapy of advanced cancers, may significantly contribute to neutralizing the neurotoxicity induced by oxaliplatin, at the same time possibly concurring to an integrated anticancer effect. The association between these two powerful anticancer molecules would probably produce

CaMKII Regulates Synaptic NMDA Receptor Activity of Hypothalamic Presympathetic Neurons and Sympathetic Outflow in Hypertension.

Science.gov (United States)

Li, De-Pei; Zhou, Jing-Jing; Zhang, Jixiang; Pan, Hui-Lin

2017-11-01

NMDAR activity in the hypothalamic paraventricular nucleus (PVN) is increased and critically involved in heightened sympathetic vasomotor tone in hypertension. Calcium/calmodulin-dependent protein kinase II (CaMKII) binds to and modulates NMDAR activity. In this study, we determined the role of CaMKII in regulating NMDAR activity of PVN presympathetic neurons in male spontaneously hypertensive rats (SHRs). NMDAR-mediated EPSCs and puff NMDA-elicited currents were recorded in spinally projecting PVN neurons in SHRs and male Wistar-Kyoto (WKY) rats. The basal amplitude of evoked NMDAR-EPSCs and puff NMDA currents in retrogradely labeled PVN neurons were significantly higher in SHRs than in WKY rats. The CaMKII inhibitor autocamtide-2-related inhibitory peptide (AIP) normalized the increased amplitude of NMDAR-EPSCs and puff NMDA currents in labeled PVN neurons in SHRs but had no effect in WKY rats. Treatment with AIP also normalized the higher frequency of NMDAR-mediated miniature EPSCs of PVN neurons in SHRs. CaMKII-mediated phosphorylation level of GluN2B serine 1303 (S1303) in the PVN, but not in the hippocampus and frontal cortex, was significantly higher in SHRs than in WKY rats. Lowering blood pressure with celiac ganglionectomy in SHRs did not alter the increased level of phosphorylated GluN2B S1303 in the PVN. In addition, microinjection of AIP into the PVN significantly reduced arterial blood pressure and lumbar sympathetic nerve discharges in SHRs. Our findings suggest that CaMKII activity is increased in the PVN and contributes to potentiated presynaptic and postsynaptic NMDAR activity to elevate sympathetic vasomotor tone in hypertension. SIGNIFICANCE STATEMENT Heightened sympathetic vasomotor tone is a major contributor to the development of hypertension. Although glutamate NMDA receptor (NMDAR)-mediated excitatory drive in the hypothalamus plays a critical role in increased sympathetic output in hypertension, the molecular mechanism involved in

Concentration-dependent activation of dopamine receptors differentially modulates GABA release onto orexin neurons.

Science.gov (United States)

Linehan, Victoria; Trask, Robert B; Briggs, Chantalle; Rowe, Todd M; Hirasawa, Michiru

2015-08-01

Dopamine (DA) and orexin neurons play important roles in reward and food intake. There are anatomical and functional connections between these two cell groups: orexin peptides stimulate DA neurons in the ventral tegmental area and DA inhibits orexin neurons in the hypothalamus. However, the cellular mechanisms underlying the action of DA on orexin neurons remain incompletely understood. Therefore, the effect of DA on inhibitory transmission to orexin neurons was investigated in rat brain slices using the whole-cell patch-clamp technique. We found that DA modulated the frequency of spontaneous and miniature IPSCs (mIPSCs) in a concentration-dependent bidirectional manner. Low (1 μM) and high (100 μM) concentrations of DA decreased and increased IPSC frequency, respectively. These effects did not accompany a change in mIPSC amplitude and persisted in the presence of G-protein signaling inhibitor GDPβS in the pipette, suggesting that DA acts presynaptically. The decrease in mIPSC frequency was mediated by D2 receptors whereas the increase required co-activation of D1 and D2 receptors and subsequent activation of phospholipase C. In summary, our results suggest that DA has complex effects on GABAergic transmission to orexin neurons, involving cooperation of multiple receptor subtypes. The direction of dopaminergic influence on orexin neurons is dependent on the level of DA in the hypothalamus. At low levels DA disinhibits orexin neurons whereas at high levels it facilitates GABA release, which may act as negative feedback to curb the excitatory orexinergic output to DA neurons. These mechanisms may have implications for consummatory and motivated behaviours. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

ASIC-like, proton-activated currents in rat hippocampal neurons.

Science.gov (United States)

Baron, Anne; Waldmann, Rainer; Lazdunski, Michel

2002-03-01

The expression of mRNA for acid sensing ion channels (ASIC) subunits ASIC1a, ASIC2a and ASIC2b has been reported in hippocampal neurons, but the presence of functional hippocampal ASIC channels was never assessed. We report here the first characterization of ASIC-like currents in rat hippocampal neurons in primary culture. An extracellular pH drop induces a transient Na(+) current followed by a sustained non-selective cation current. This current is highly sensitive to pH with an activation threshold around pH 6.9 and a pH(0.5) of 6.2. About half of the total peak current is inhibited by the spider toxin PcTX1, which is specific for homomeric ASIC1a channels. The remaining PcTX1-resistant ASIC-like current is increased by 300 microM Zn(2+) and, whereas not fully activated at pH 5, it shows a pH(0.5) of 6.0 between pH 7.4 and 5. We have previously shown that Zn(2+) is a co-activator of ASIC2a-containing channels. Thus, the hippocampal transient ASIC-like current appears to be generated by a mixture of homomeric ASIC1a channels and ASIC2a-containing channels, probably heteromeric ASIC1a+2a channels. The sustained non-selective current suggests the involvement of ASIC2b-containing heteromeric channels. Activation of the hippocampal ASIC-like current by a pH drop to 6.9 or 6.6 induces a transient depolarization which itself triggers an initial action potential (AP) followed by a sustained depolarization and trains of APs. Zn(2+) increases the acid sensitivity of ASIC channels, and consequently neuronal excitability. It is probably an important co-activator of ASIC channels in the central nervous system.

Global ablation of the mitochondrial calcium uniporter increases glycolysis in cortical neurons subjected to energetic stressors.

Science.gov (United States)

Nichols, Matthew; Elustondo, Pia A; Warford, Jordan; Thirumaran, Aruloli; Pavlov, Evgeny V; Robertson, George S

2017-08-01

The effects of global mitochondrial calcium (Ca 2+ ) uniporter (MCU) deficiency on hypoxic-ischemic (HI) brain injury, neuronal Ca 2+ handling, bioenergetics and hypoxic preconditioning (HPC) were examined. Forebrain mitochondria isolated from global MCU nulls displayed markedly reduced Ca 2+ uptake and Ca 2+ -induced opening of the membrane permeability transition pore. Despite evidence that these effects should be neuroprotective, global MCU nulls and wild-type (WT) mice suffered comparable HI brain damage. Energetic stress enhanced glycolysis and depressed Complex I activity in global MCU null, relative to WT, cortical neurons. HI reduced forebrain NADH levels more in global MCU nulls than WT mice suggesting that increased glycolytic consumption of NADH suppressed Complex I activity. Compared to WT neurons, pyruvate dehydrogenase (PDH) was hyper-phosphorylated in MCU nulls at several sites that lower the supply of substrates for the tricarboxylic acid cycle. Elevation of cytosolic Ca 2+ with glutamate or ionomycin decreased PDH phosphorylation in MCU null neurons suggesting the use of alternative mitochondrial Ca 2+ transport. Under basal conditions, global MCU nulls showed similar increases of Ca 2+ handling genes in the hippocampus as WT mice subjected to HPC. We propose that long-term adaptations, common to HPC, in global MCU nulls compromise resistance to HI brain injury and disrupt HPC.

Network feedback regulates motor output across a range of modulatory neuron activity.

Science.gov (United States)

Spencer, Robert M; Blitz, Dawn M

2016-06-01

Modulatory projection neurons alter network neuron synaptic and intrinsic properties to elicit multiple different outputs. Sensory and other inputs elicit a range of modulatory neuron activity that is further shaped by network feedback, yet little is known regarding how the impact of network feedback on modulatory neurons regulates network output across a physiological range of modulatory neuron activity. Identified network neurons, a fully described connectome, and a well-characterized, identified modulatory projection neuron enabled us to address this issue in the crab (Cancer borealis) stomatogastric nervous system. The modulatory neuron modulatory commissural neuron 1 (MCN1) activates and modulates two networks that generate rhythms via different cellular mechanisms and at distinct frequencies. MCN1 is activated at rates of 5-35 Hz in vivo and in vitro. Additionally, network feedback elicits MCN1 activity time-locked to motor activity. We asked how network activation, rhythm speed, and neuron activity levels are regulated by the presence or absence of network feedback across a physiological range of MCN1 activity rates. There were both similarities and differences in responses of the two networks to MCN1 activity. Many parameters in both networks were sensitive to network feedback effects on MCN1 activity. However, for most parameters, MCN1 activity rate did not determine the extent to which network output was altered by the addition of network feedback. These data demonstrate that the influence of network feedback on modulatory neuron activity is an important determinant of network output and feedback can be effective in shaping network output regardless of the extent of network modulation. Copyright © 2016 the American Physiological Society.

Deficient Rab11 activity underlies glucose hypometabolism in primary neurons of Huntington's disease mice

Energy Technology Data Exchange (ETDEWEB)

Li, Xueyi, E-mail: xli12@partners.org [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States); Valencia, Antonio; McClory, Hollis; Sapp, Ellen; Kegel, Kimberly B. [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States); DiFiglia, Marian, E-mail: difiglia@helix.mgh.harvard.edu [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States)

2012-05-18

Highlights: Black-Right-Pointing-Pointer Primary Huntington's disease neurons are impaired in taking up glucose. Black-Right-Pointing-Pointer Rab11 modulates glucose uptake in neurons. Black-Right-Pointing-Pointer Increasing Rab11 activity attenuates the glucose uptake defect in disease neurons. Black-Right-Pointing-Pointer We provide a novel mechanism for glucose hypometabolism in Huntington's disease. -- Abstract: Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Positron emission tomography studies have revealed a decline in glucose metabolism in the brain of patients with HD by a mechanism that has not been established. We examined glucose utilization in embryonic primary cortical neurons of wild-type (WT) and HD knock-in mice, which have 140 CAG repeats inserted in the endogenous mouse huntingtin gene (HD{sup 140Q/140Q}). Primary HD{sup 140Q/140Q} cortical neurons took up significantly less glucose than did WT neurons. Expression of permanently inactive and permanently active forms of Rab11 correspondingly altered glucose uptake in WT neurons, suggesting that normal activity of Rab11 is needed for neuronal uptake of glucose. It is known that Rab11 activity is diminished in HD{sup 140Q/140Q} neurons. Expression of dominant active Rab11 to enhance the activity of Rab11 normalized glucose uptake in HD{sup 140Q/140Q} neurons. These results suggest that deficient activity of Rab11 is a novel mechanism for glucose hypometabolism in HD.

INCREASE IN DOPAMINE RELEASE FROM THE NUCLEUS-ACCUMBENS IN RESPONSE TO FEEDING - A MODEL TO STUDY INTERACTIONS BETWEEN DRUGS AND NATURALLY ACTIVATED DOPAMINERGIC-NEURONS IN THE RAT-BRAIN

NARCIS (Netherlands)

WESTERINK, BHC; TEISMAN, A; DEVRIES, JB

The aim of the present study was to investigate the interactions between the in vivo release of dopamine and certain drugs, during conditions of increased dopaminergic activity. Dopaminergic neurons in the nucleus accumbens were activated by feeding hungry rats. 48-96 h after implantation of a

TRPA1 activation by lidocaine in nerve terminals results in glutamate release increase

International Nuclear Information System (INIS)

Piao, L.-H.; Fujita, Tsugumi; Jiang, C.-Y.; Liu Tao; Yue, H.-Y.; Nakatsuka, Terumasa; Kumamoto, Eiichi

2009-01-01

We examined the effects of local anesthetics lidocaine and procaine on glutamatergic spontaneous excitatory transmission in substantia gelatinosa (SG) neurons in adult rat spinal cord slices with whole-cell patch-clamp techniques. Bath-applied lidocaine (1-5 mM) dose-dependently and reversibly increased the frequency but not the amplitude of spontaneous excitatory postsynaptic current (sEPSC) in SG neurons. Lidocaine activity was unaffected by the Na + -channel blocker, tetrodotoxin, and the TRPV1 antagonist, capsazepine, but was inhibited by the TRP antagonist, ruthenium red. In the same neuron, the TRPA1 agonist, allyl isothiocyanate, and lidocaine both increased sEPSC frequency. In contrast, procaine did not produce presynaptic enhancement. These results indicate that lidocaine activates TRPA1 in nerve terminals presynaptic to SG neurons to increase the spontaneous release of L-glutamate.

Presynaptic Glycine Receptors Increase GABAergic Neurotransmission in Rat Periaqueductal Gray Neurons

Directory of Open Access Journals (Sweden)

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.

Dual-energy precursor and nuclear erythroid-related factor 2 activator treatment additively improve redox glutathione levels and neuron survival in aging and Alzheimer mouse neurons upstream of reactive oxygen species.

Science.gov (United States)

Ghosh, Debolina; LeVault, Kelsey R; Brewer, Gregory J

2014-01-01

To determine whether glutathione (GSH) loss or increased reactive oxygen species (ROS) are more important to neuron loss, aging, and Alzheimer's disease (AD), we stressed or boosted GSH levels in neurons isolated from aging 3xTg-AD neurons compared with those from age-matched nontransgenic (non-Tg) neurons. Here, using titrating with buthionine sulfoximine, an inhibitor of γ-glutamyl cysteine synthetase (GCL), we observed that GSH depletion increased neuronal death of 3xTg-AD cultured neurons at increasing rates across the age span, whereas non-Tg neurons were resistant to GSH depletion until old age. Remarkably, the rate of neuron loss with ROS did not increase in old age and was the same for both genotypes, which indicates that cognitive deficits in the AD model were not caused by ROS. Therefore, we targeted for neuroprotection activation of the redox sensitive transcription factor, nuclear erythroid-related factor 2 (Nrf2) by 18 alpha glycyrrhetinic acid to stimulate GSH synthesis through GCL. This balanced stimulation of a number of redox enzymes restored the lower levels of Nrf2 and GCL seen in 3xTg-AD neurons compared with those of non-Tg neurons and promoted translocation of Nrf2 to the nucleus. By combining the Nrf2 activator together with the NADH precursor, nicotinamide, we increased neuron survival against amyloid beta stress in an additive manner. These stress tests and neuroprotective treatments suggest that the redox environment is more important for neuron survival than ROS. The dual neuroprotective treatment with nicotinamide and an Nrf2 inducer indicates that these age-related and AD-related changes are reversible. Copyright © 2014 Elsevier Inc. All rights reserved.

Beyond Neuronal Activity Markers: Select Immediate Early Genes in Striatal Neuron Subtypes Functionally Mediate Psychostimulant Addiction

Directory of Open Access Journals (Sweden)

Ramesh Chandra

2017-06-01

Full Text Available Immediate early genes (IEGs were traditionally used as markers of neuronal activity in striatum in response to stimuli including drugs of abuse such as psychostimulants. Early studies using these neuronal activity markers led to important insights in striatal neuron subtype responsiveness to psychostimulants. Such studies have helped identify striatum as a critical brain center for motivational, reinforcement and habitual behaviors in psychostimulant addiction. While the use of IEGs as neuronal activity markers in response to psychostimulants and other stimuli persists today, the functional role and implications of these IEGs has often been neglected. Nonetheless, there is a subset of research that investigates the functional role of IEGs in molecular, cellular and behavioral alterations by psychostimulants through striatal medium spiny neuron (MSN subtypes, the two projection neuron subtypes in striatum. This review article will address and highlight the studies that provide a functional mechanism by which IEGs mediate psychostimulant molecular, cellular and behavioral plasticity through MSN subtypes. Insight into the functional role of IEGs in striatal MSN subtypes could provide improved understanding into addiction and neuropsychiatric diseases affecting striatum, such as affective disorders and compulsive disorders characterized by dysfunctional motivation and habitual behavior.

Effect of agmatine on locus coeruleus neuron activity: possible involvement of nitric oxide

Science.gov (United States)

Ruiz-Durántez, Eduardo; Ruiz-Ortega, José A; Pineda, Joseba; Ugedo, Luisa

2002-01-01

To investigate whether agmatine (the proposed endogenous ligand for imidazoline receptors) controls locus coeruleus neuron activity and to elucidate its mechanism of action, we used single-unit extracellular recording techniques in anaesthetized rats. Agmatine (10, 20 and 40 μg, i.c.v.) increased in a dose-related manner the firing rate of locus coeruleus neurons (maximal increase: 95±13% at 40 μg). I1-imidazoline receptor ligands stimulate locus coeruleus neuron activity through an indirect mechanism originated in the paragigantocellularis nucleus via excitatory amino acids. However, neither electrolytic lesions of the paragigantocellularis nucleus nor pretreatment with the excitatory amino acid antagonist kynurenic acid (1 μmol, i.c.v.) modified agmatine effect (10 μg, i.c.v.). After agmatine administration (20 μg, i.c.v.), dose-response curves for the effect of clonidine (0.625 – 10 μg kg−1 i.v.) or morphine (0.3 – 4.8 mg kg−1 i.v.) on locus coeruleus neurons were not different from those obtained in the control groups. Pretreatment with the nitric oxide synthase inhibitors Nω-nitro-L-arginine (10 μg, i.c.v.) or Nω-nitro-L-arginine methyl ester (100 μg, i.c.v.) but not with the less active stereoisomer Nω-nitro-D-arginine methyl ester (100 μg, i.c.v.) completely blocked agmatine effect (10 and 40 μg, i.c.v.). Similarly, when agmatine (20 pmoles) was applied into the locus coeruleus there was an increase that was blocked by Nω-nitro-L-arginine methyl ester (100 μg, i.c.v.) in the firing rate of the locus coeruleus neurons (maximal increase 53±11% and 14±10% before and after nitric oxide synthase inhibition, respectively). This study demonstrates that agmatine stimulates the firing rate of locus coeruleus neurons via a nitric oxide synthase-dependent mechanism located in this nucleus. PMID:11877321

Operant conditioning of synaptic and spiking activity patterns in single hippocampal neurons.

Science.gov (United States)

Ishikawa, Daisuke; Matsumoto, Nobuyoshi; Sakaguchi, Tetsuya; Matsuki, Norio; Ikegaya, Yuji

2014-04-02

Learning is a process of plastic adaptation through which a neural circuit generates a more preferable outcome; however, at a microscopic level, little is known about how synaptic activity is patterned into a desired configuration. Here, we report that animals can generate a specific form of synaptic activity in a given neuron in the hippocampus. In awake, head-restricted mice, we applied electrical stimulation to the lateral hypothalamus, a reward-associated brain region, when whole-cell patch-clamped CA1 neurons exhibited spontaneous synaptic activity that met preset criteria. Within 15 min, the mice learned to generate frequently the excitatory synaptic input pattern that satisfied the criteria. This reinforcement learning of synaptic activity was not observed for inhibitory input patterns. When a burst unit activity pattern was conditioned in paired and nonpaired paradigms, the frequency of burst-spiking events increased and decreased, respectively. The burst reinforcement occurred in the conditioned neuron but not in other adjacent neurons; however, ripple field oscillations were concomitantly reinforced. Neural conditioning depended on activation of NMDA receptors and dopamine D1 receptors. Acutely stressed mice and depression model mice that were subjected to forced swimming failed to exhibit the neural conditioning. This learning deficit was rescued by repetitive treatment with fluoxetine, an antidepressant. Therefore, internally motivated animals are capable of routing an ongoing action potential series into a specific neural pathway of the hippocampal network.

Altered Chloride Homeostasis Decreases the Action Potential Threshold and Increases Hyperexcitability in Hippocampal Neurons

DEFF Research Database (Denmark)

Sørensen, Andreas T; Ledri, Marco; Melis, Miriam

2017-01-01

Chloride ions play an important role in controlling excitability of principal neurons in the central nervous system. When neurotransmitter GABA is released from inhibitory interneurons, activated GABA type A (GABAA) receptors on principal neurons become permeable to chloride. Typically, chloride...... neurons, and promote AP generation. It is generally recognized that altered chloride homeostasis per se has no effect on the AP threshold. Here, we demonstrate that chloride overload of mouse principal CA3 pyramidal neurons not only makes these cells more excitable through GABAA receptor activation...

Electrophysiological characterization of harmane-induced activation of mesolimbic dopamine neurons.

Science.gov (United States)

Arib, Ouafa; Rat, Pascal; Molimard, Robert; Chait, Abderrahman; Faure, Philippe; de Beaurepaire, Renaud

2010-03-10

It has been suggested that the beta-carbolines harmane and norharmane may be involved in the pathophysiology of Parkinson's disease, psychosis and addiction, but the mechanisms of these possible effects remain to be elucidated. In the present study, the effects of the two compounds were examined by using in vivo extracellular recordings of ventral tegmental dopamine neurons. The effects of harmane (2mg/kg) and norharmane (2mg/kg), were compared to those of nicotine (11microg/kg), of cotinine (0.5mg/kg), of the monoamine-oxidase-A inhibitor befloxatone (0.12mg/kg), and of the monoamine-oxidase-B inhibitor selegiline (0.5mg/kg). The effects of harmane were also tested after pre-treatment with the nicotine receptor antagonist mecamylamine. The results show that all substances, except befloxatone, activate the firing and/or burst activity of dopamine neurons. The increase in firing rate produced by harmane was approximately 18 times greater than that produced by nicotine. Such powerful excitation of dopamine neurons by harmane may in part explain its involvement in neurotoxicity, psychosis and addiction. The absence of effect of befloxatone supports the hypothesis that the effect of harmane is not related to its monoamine-oxidase-A inhibitory properties. Mecamylamine inhibited by approximately 80% the activity of harmane, indicating that the activating effect of harmane on dopamine neurons involves several mechanisms, among which activation of nicotinic receptors likely has a prominent importance. The results of the present study support the hypothesis that harmane could be a tobacco (or smoke) component other than nicotine involved in tobacco dependence. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Shaping of neuronal activity through a Brain Computer Interface

OpenAIRE

Valero-Aguayo, Luis; Silva-Sauer, Leandro; Velasco-Alvarez, Ricardo; Ron-Angevin, Ricardo

2014-01-01

Neuronal responses are human actions which can be measured by an EEG, and which imply changes in waves when neurons are synchronized. This activity could be changed by principles of behaviour analysis. This research tests the efficacy of the behaviour shaping procedure to progressively change neuronal activity, so that those brain responses are adapted according to the differential reinforcement of visual feedback. The Brain Computer Interface (BCI) enables us to record the EEG in real ti...

Prolonged seizure activity leads to increased Protein Kinase A activation in the rat pilocarpine model of status epilepticus.

Science.gov (United States)

Bracey, James M; Kurz, Jonathan E; Low, Brian; Churn, Severn B

2009-08-04

Status epilepticus is a life-threatening form of seizure activity that represents a major medical emergency associated with significant morbidity and mortality. Protein Kinase A is an important regulator of synaptic strength that may play an important role in the development of status epilepticus-induced neuronal pathology. This study demonstrated an increase in PKA activity against exogenous and endogenous substrates during later stages of SE. As SE progressed, a significant increase in PKA-mediated phosphorylation of an exogenous peptide substrate was demonstrated in cortical structures. The increased activity was not due to altered expression of either regulatory or catalytic subunits of the enzyme. Through the use of phospho-specific antibodies, this study also investigated the effects of SE on the phosphorylation of the GluR1 subunit of the AMPA subtype of glutamate receptor. After the onset of continuous seizure activity, an increase in phosphorylation of the PKA site on the GluR1 subunit of the AMPA receptor was observed. These data suggest a potential mechanism by which SE may increase neuronal excitability in the cortex, potentially leading to maintenance of seizure activity or long-term neuronal pathology.

The mast cell degranulator compound 48/80 directly activates neurons.

Directory of Open Access Journals (Sweden)

Michael Schemann

Full Text Available BACKGROUND: Compound 48/80 is widely used in animal and tissue models as a "selective" mast cell activator. With this study we demonstrate that compound 48/80 also directly activates enteric neurons and visceral afferents. METHODOLOGY/PRINCIPAL FINDINGS: We used in vivo recordings from extrinsic intestinal afferents together with Ca(++ imaging from primary cultures of DRG and nodose neurons. Enteric neuronal activation was examined by Ca(++ and voltage sensitive dye imaging in isolated gut preparations and primary cultures of enteric neurons. Intraluminal application of compound 48/80 evoked marked afferent firing which desensitized on subsequent administration. In egg albumen-sensitized animals, intraluminal antigen evoked a similar pattern of afferent activation which also desensitized on subsequent exposure to antigen. In cross-desensitization experiments prior administration of compound 48/80 failed to influence the mast cell mediated response. Application of 1 and 10 µg/ml compound 48/80 evoked spike discharge and Ca(++ transients in enteric neurons. The same nerve activating effect was observed in primary cultures of DRG and nodose ganglion cells. Enteric neuron cultures were devoid of mast cells confirmed by negative staining for c-kit or toluidine blue. In addition, in cultured enteric neurons the excitatory action of compound 48/80 was preserved in the presence of histamine H(1 and H(2 antagonists. The mast cell stabilizer cromolyn attenuated compound 48/80 and nicotine evoked Ca(++ transients in mast cell-free enteric neuron cultures. CONCLUSIONS/SIGNIFICANCE: The results showed direct excitatory action of compound 48/80 on enteric neurons and visceral afferents. Therefore, functional changes measured in tissue or animal models may involve a mast cell independent effect of compound 48/80 and cromolyn.

Differential regulation of the Rac1 GTPase-activating protein (GAP) BCR during oxygen/glucose deprivation in hippocampal and cortical neurons.

Science.gov (United States)

Smith, Katharine R; Rajgor, Dipen; Hanley, Jonathan G

2017-12-08

Brain ischemia causes oxygen and glucose deprivation (OGD) in neurons, triggering a cascade of events leading to synaptic accumulation of glutamate. Excessive activation of glutamate receptors causes excitotoxicity and delayed cell death in vulnerable neurons. Following global cerebral ischemia, hippocampal CA1 pyramidal neurons are more vulnerable to injury than their cortical counterparts, but the mechanisms that underlie this difference are unclear. Signaling via Rho-family small GTPases, their upstream guanine nucleotide exchange factors, and GTPase-activating proteins (GAPs) is differentially dysregulated in response to OGD/ischemia in hippocampal and cortical neurons. Increased Rac1 activity caused by OGD/ischemia contributes to neuronal death in hippocampal neurons via diverse effects on NADPH oxidase activity and dendritic spine morphology. The Rac1 guanine nucleotide exchange factor Tiam1 mediates an OGD-induced increase in Rac1 activity in hippocampal neurons; however, the identity of an antagonistic GAP remains elusive. Here we show that the Rac1 GAP breakpoint cluster region (BCR) associates with NMDA receptors (NMDARs) along with Tiam1 and that this protein complex is more abundant in hippocampal compared with cortical neurons. Although total BCR is similar in the two neuronal types, BCR is more active in hippocampal compared with cortical neurons. OGD causes an NMDAR- and Ca 2+ -permeable AMPAR-dependent deactivation of BCR in hippocampal but not cortical neurons. BCR knockdown occludes OGD-induced Rac1 activation in hippocampal neurons. Furthermore, disrupting the Tiam1-NMDAR interaction with a fragment of Tiam1 blocks OGD-induced Tiam1 activation but has no effect on the deactivation of BCR. This work identifies BCR as a critical player in Rac1 regulation during OGD in hippocampal neurons. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Telomerase activity-independent function of telomerase reverse transcriptase is involved in acrylamide-induced neuron damage.

Science.gov (United States)

Zhang, P; Pan, H; Wang, J; Liu, X; Hu, X

2014-07-01

Polyacrylamide is used widely in industry, and its decomposition product, acrylamide (ACR), readily finds its way into commonly consumed cosmetics and baked and fried foods. ACR exerts potent neurotoxic effects in human and animal models. Telomerase reverse transcriptase (TERT), the catalytic subunit of telomerase, traditionally has been considered to play an important role in maintaining telomere length. Emerging evidence has shown, however, that TERT plays an important role in neuroprotection by inhibiting apoptosis and excitotoxicity, and by promoting angiogenesis, neuronal survival and neurogenesis, which are closely related to the telomere-independent functions of TERT. We investigated whether and how the TERT pathway is involved in ACR induced neurotoxicity in rat cortical neurons. We found that ACR 1) significantly reduced the viability of cortical neurons as measured by MTT assay, 2) induced neuron apoptosis as revealed by FITC-conjugated Annexin V/PI double staining and flow cytometry (FACS) analysis, 3) elevated expression of cleaved caspase-3, and 4) decreased bcl-2 expression of cortical neurons. ACR also increased intracellular ROS levels in cortical neurons, increased MDA levels and reduced GSH, SOD and GSH-Px levels in mitochondria in a dose-dependent manner. We found that TERT expression in mitochondria was increased by ACR at concentrations of 2.5 and 5.0 mM, but TERT expression was decreased by 10 mM ACR. Telomerase activity, however, was undetectable in rat cortical neurons. Our results suggest that the TERT pathway is involved in ACR induced apoptosis of cortical neurons. TERT also may exert its neuroprotective role in a telomerase activity-independent way, especially in mitochondria.

Enhancement of synchronized activity between hippocampal CA1 neurons during initial storage of associative fear memory.

Science.gov (United States)

Liu, Yu-Zhang; Wang, Yao; Shen, Weida; Wang, Zhiru

2017-08-01

Learning and memory storage requires neuronal plasticity induced in the hippocampus and other related brain areas, and this process is thought to rely on synchronized activity in neural networks. We used paired whole-cell recording in vivo to examine the synchronized activity that was induced in hippocampal CA1 neurons by associative fear learning. We found that both membrane potential synchronization and spike synchronization of CA1 neurons could be transiently enhanced after task learning, as observed on day 1 but not day 5. On day 1 after learning, CA1 neurons showed a decrease in firing threshold and rise times of suprathreshold membrane potential changes as well as an increase in spontaneous firing rates, possibly contributing to the enhancement of spike synchronization. The transient enhancement of CA1 neuronal synchronization may play important roles in the induction of neuronal plasticity for initial storage and consolidation of associative memory. The hippocampus is critical for memory acquisition and consolidation. This function requires activity- and experience-induced neuronal plasticity. It is known that neuronal plasticity is largely dependent on synchronized activity. As has been well characterized, repetitive correlated activity of presynaptic and postsynaptic neurons can lead to long-term modifications at their synapses. Studies on network activity have also suggested that memory processing in the hippocampus may involve learning-induced changes of neuronal synchronization, as observed in vivo between hippocampal CA3 and CA1 networks as well as between the rhinal cortex and the hippocampus. However, further investigation of learning-induced synchronized activity in the hippocampus is needed for a full understanding of hippocampal memory processing. In this study, by performing paired whole-cell recording in vivo on CA1 pyramidal cells (PCs) in anaesthetized adult rats, we examined CA1 neuronal synchronization before and after associative fear

Acute activation of GLP-1-expressing neurons promotes glucose homeostasis and insulin sensitivity.

Science.gov (United States)

Shi, Xuemei; Chacko, Shaji; Li, Feng; Li, Depei; Burrin, Douglas; Chan, Lawrence; Guan, Xinfu

2017-11-01

Glucagon-like peptides are co-released from enteroendocrine L cells in the gut and preproglucagon (PPG) neurons in the brainstem. PPG-derived GLP-1/2 are probably key neuroendocrine signals for the control of energy balance and glucose homeostasis. The objective of this study was to determine whether activation of PPG neurons per se modulates glucose homeostasis and insulin sensitivity in vivo. We generated glucagon (Gcg) promoter-driven Cre transgenic mice and injected excitatory hM3Dq-mCherry AAV into their brainstem NTS. We characterized the metabolic impact of PPG neuron activation on glucose homeostasis and insulin sensitivity using stable isotopic tracers coupled with hyperinsulinemic euglycemic clamp. We showed that after ip injection of clozapine N-oxide, Gcg-Cre lean mice transduced with hM3Dq in the brainstem NTS downregulated basal endogenous glucose production and enhanced glucose tolerance following ip glucose tolerance test. Moreover, acute activation of PPG neurons NTS enhanced whole-body insulin sensitivity as indicated by increased glucose infusion rate as well as augmented insulin-suppression of endogenous glucose production and gluconeogenesis. In contrast, insulin-stimulation of glucose disposal was not altered significantly. We conclude that acute activation of PPG neurons in the brainstem reduces basal glucose production, enhances intraperitoneal glucose tolerance, and augments hepatic insulin sensitivity, suggesting an important physiological role of PPG neurons-mediated circuitry in promoting glycemic control and insulin sensitivity. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

C75, a fatty acid synthase inhibitor, modulates AMP-activated protein kinase to alter neuronal energy metabolism.

Science.gov (United States)

Landree, Leslie E; Hanlon, Andrea L; Strong, David W; Rumbaugh, Gavin; Miller, Ian M; Thupari, Jagan N; Connolly, Erin C; Huganir, Richard L; Richardson, Christine; Witters, Lee A; Kuhajda, Francis P; Ronnett, Gabriele V

2004-01-30

C75, a synthetic inhibitor of fatty acid synthase (FAS), is hypothesized to alter the metabolism of neurons in the hypothalamus that regulate feeding behavior to contribute to the decreased food intake and profound weight loss seen with C75 treatment. In the present study, we characterize the suitability of primary cultures of cortical neurons for studies designed to investigate the consequences of C75 treatment and the alteration of fatty acid metabolism in neurons. We demonstrate that in primary cortical neurons, C75 inhibits FAS activity and stimulates carnitine palmitoyltransferase-1 (CPT-1), consistent with its effects in peripheral tissues. C75 alters neuronal ATP levels and AMP-activated protein kinase (AMPK) activity. Neuronal ATP levels are affected in a biphasic manner with C75 treatment, decreasing initially, followed by a prolonged increase above control levels. Cerulenin, a FAS inhibitor, causes a similar biphasic change in ATP levels, although levels do not exceed control. C75 and cerulenin modulate AMPK phosphorylation and activity. TOFA, an inhibitor of acetyl-CoA carboxylase, increases ATP levels, but does not affect AMPK activity. Several downstream pathways are affected by C75 treatment, including glucose metabolism and acetyl-CoA carboxylase (ACC) phosphorylation. These data demonstrate that C75 modulates the levels of energy intermediates, thus, affecting the energy sensor AMPK. Similar effects in hypothalamic neurons could form the basis for the effects of C75 on feeding behavior.

Cell-Type Specific Development of the Hyperpolarization-Activated Current, Ih, in Prefrontal Cortical Neurons

Directory of Open Access Journals (Sweden)

Sha-Sha Yang

2018-05-01

Full Text Available H-current, also known as hyperpolarization-activated current (Ih, is an inward current generated by the hyperpolarization-activated cyclic nucleotide-gated (HCN cation channels. Ih plays an essential role in regulating neuronal properties, synaptic integration and plasticity, and synchronous activity in the brain. As these biological factors change across development, the brain undergoes varying levels of vulnerability to disorders like schizophrenia that disrupt prefrontal cortex (PFC-dependent function. However, developmental changes in Ih in PFC neurons remains untested. Here, we examine Ih in pyramidal neurons vs. gamma-aminobutyric acid (GABAergic parvalbumin-expressing (PV+ interneurons in developing mouse PFC. Our findings show that the amplitudes of Ih in these cell types are identical during the juvenile period but differ at later time points. In pyramidal neurons, Ih amplitude significantly increases from juvenile to adolescence and follows a similar trend into adulthood. In contrast, the amplitude of Ih in PV+ interneurons decreases from juvenile to adolescence, and does not change from adolescence to adulthood. Moreover, the kinetics of HCN channels in pyramidal neurons is significantly slower than in PV+ interneurons, with a gradual decrease in pyramidal neurons and a gradual increase in PV+ cells across development. Our study reveals distinct developmental trajectories of Ih in pyramidal neurons and PV+ interneurons. The cell-type specific alteration of Ih during the critical period from juvenile to adolescence reflects the contribution of Ih to the maturation of the PFC and PFC-dependent function. These findings are essential for a better understanding of normal PFC function, and for elucidating Ih’s crucial role in the pathophysiology of neurodevelopmental disorders.

Estradiol-Dependent Stimulation and Suppression of Gonadotropin-Releasing Hormone Neuron Firing Activity by Corticotropin-Releasing Hormone in Female Mice.

Science.gov (United States)

Phumsatitpong, Chayarndorn; Moenter, Suzanne M

2018-01-01

Gonadotropin-releasing hormone (GnRH) neurons are the final central regulators of reproduction, integrating various inputs that modulate fertility. Stress typically inhibits reproduction but can be stimulatory; stress effects can also be modulated by steroid milieu. Corticotropin-releasing hormone (CRH) released during the stress response may suppress reproduction independent of downstream glucocorticoids. We hypothesized CRH suppresses fertility by decreasing GnRH neuron firing activity. To test this, mice were ovariectomized (OVX) and either implanted with an estradiol capsule (OVX+E) or not treated further to examine the influence of estradiol on GnRH neuron response to CRH. Targeted extracellular recordings were used to record firing activity from green fluorescent protein-identified GnRH neurons in brain slices before and during CRH treatment; recordings were done in the afternoon when estradiol has a positive feedback effect to increase GnRH neuron firing. In OVX mice, CRH did not affect the firing rate of GnRH neurons. In contrast, CRH exhibited dose-dependent stimulatory (30 nM) or inhibitory (100 nM) effects on GnRH neuron firing activity in OVX+E mice; both effects were reversible. The dose-dependent effects of CRH appear to result from activation of different receptor populations; a CRH receptor type-1 agonist increased firing activity in GnRH neurons, whereas a CRH receptor type-2 agonist decreased firing activity. CRH and specific agonists also differentially regulated short-term burst frequency and burst properties, including burst duration, spikes/burst, and/or intraburst interval. These results indicate that CRH alters GnRH neuron activity and that estradiol is required for CRH to exert both stimulatory and inhibitory effects on GnRH neurons. Copyright © 2018 Endocrine Society.

[Protective effects of luteolin on neurons against oxygen-glucose deprivation/reperfusion injury via improving Na+/K+ -ATPase activity].

Science.gov (United States)

Fang, Lumei; Zhang, Mingming; Ding, Yuemin; Fang, Yuting; Yao, Chunlei; Zhang, Xiong

2010-04-01

Luteolin, a flavone, has considerable neuroprotective effects by its anti-oxidative mechanism. However, it is still unclear whether luteolin can protect neurons against oxygen-glucose deprivation/reperfusion (OGD/R) induced injury. After 2 hours oxygen-glucose deprivation and 24 hours reperfusion treatment in primary cultured hippocampal neurons, the neuron viability, survival rate and apoptosis rate were evaluated by MTT assay, lactate dehydrogenase (LDH) leakage assay and Hoechst staining, respectively. The activity of Na+/K+ -ATPase was examined in cultured neurons or in the hippocampus of SD rats treated by 10 minutes global cerebral ischemia and followed 24 hours reperfusion. Treatment by OGD/R markedly reduced neuronal viability, increased LDH leakage rate and increased apoptosis rate. Application of luteolin (10-100 micromol x L(-1)) during OGD inhibited OGD/R induced neuron injury and apoptosis in a dose-dependent manner. Compared to the control group or OGP/R-treated neurons, the activity of Na+/K+ -ATPase was significantly suppressed in global ischemia/reperfusion group or OGD/R-treated neurons. Application of luteolin during ischemia or OGD preserved the Na+/K+ -ATPase activity. Furthermore, inhibition of Na+/K+ -ATPase with ouabain attenuated the protective effect afforded by luteolin. The data provide the evidence that luteolin has neuroprotective effect against OGD/R induced injury and the protective effect may be associated with its ability to improve Na+/K+ -ATPase activity after OGD/R.

Permanent genetic access to transiently active neurons via TRAP: targeted recombination in active populations.

Science.gov (United States)

Guenthner, Casey J; Miyamichi, Kazunari; Yang, Helen H; Heller, H Craig; Luo, Liqun

2013-06-05

Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed an approach, targeted recombination in active populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreER(T2) is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that express CreER(T2) can only undergo recombination when tamoxifen is present, allowing genetic access to neurons that are active during a time window of less than 12 hr. We show that TRAP can provide selective access to neurons activated by specific somatosensory, visual, and auditory stimuli and by experience in a novel environment. When combined with tools for labeling, tracing, recording, and manipulating neurons, TRAP offers a powerful approach for understanding how the brain processes information and generates behavior. Copyright © 2013 Elsevier Inc. All rights reserved.

Synaptic synthesis, dephosphorylation, and degradation: a novel paradigm for an activity-dependent neuronal control of CDKL5.

Science.gov (United States)

La Montanara, Paolo; Rusconi, Laura; Locarno, Albina; Forti, Lia; Barbiero, Isabella; Tramarin, Marco; Chandola, Chetan; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

2015-02-13

Mutations in the X-linked CDKL5 (cyclin-dependent kinase-like 5) gene have been associated with several forms of neurodevelopmental disorders, including atypical Rett syndrome, autism spectrum disorders, and early infantile epileptic encephalopathy. Accordingly, loss of CDKL5 in mice results in autistic-like features and impaired neuronal communication. Although the biological functions of CDKL5 remain largely unknown, recent pieces of evidence suggest that CDKL5 is involved in neuronal plasticity. Herein, we show that, at all stages of development, neuronal depolarization induces a rapid increase in CDKL5 levels, mostly mediated by extrasomatic synthesis. In young neurons, this induction is prolonged, whereas in more mature neurons, NMDA receptor stimulation induces a protein phosphatase 1-dependent dephosphorylation of CDKL5 that is mandatory for its proteasome-dependent degradation. As a corollary, neuronal activity leads to a prolonged induction of CDKL5 levels in immature neurons but to a short lasting increase of the kinase in mature neurons. Recent results demonstrate that many genes associated with autism spectrum disorders are crucial components of the activity-dependent signaling networks regulating the composition, shape, and strength of the synapse. Thus, we speculate that CDKL5 deficiency disrupts activity-dependent signaling and the consequent synapse development, maturation, and refinement. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A New Population of Parvocellular Oxytocin Neurons Controlling Magnocellular Neuron Activity and Inflammatory Pain Processing.

Science.gov (United States)

Eliava, Marina; Melchior, Meggane; Knobloch-Bollmann, H Sophie; Wahis, Jérôme; da Silva Gouveia, Miriam; Tang, Yan; Ciobanu, Alexandru Cristian; Triana Del Rio, Rodrigo; Roth, Lena C; Althammer, Ferdinand; Chavant, Virginie; Goumon, Yannick; Gruber, Tim; Petit-Demoulière, Nathalie; Busnelli, Marta; Chini, Bice; Tan, Linette L; Mitre, Mariela; Froemke, Robert C; Chao, Moses V; Giese, Günter; Sprengel, Rolf; Kuner, Rohini; Poisbeau, Pierrick; Seeburg, Peter H; Stoop, Ron; Charlet, Alexandre; Grinevich, Valery

2016-03-16

Oxytocin (OT) is a neuropeptide elaborated by the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Magnocellular OT neurons of these nuclei innervate numerous forebrain regions and release OT into the blood from the posterior pituitary. The PVN also harbors parvocellular OT cells that project to the brainstem and spinal cord, but their function has not been directly assessed. Here, we identified a subset of approximately 30 parvocellular OT neurons, with collateral projections onto magnocellular OT neurons and neurons of deep layers of the spinal cord. Evoked OT release from these OT neurons suppresses nociception and promotes analgesia in an animal model of inflammatory pain. Our findings identify a new population of OT neurons that modulates nociception in a two tier process: (1) directly by release of OT from axons onto sensory spinal cord neurons and inhibiting their activity and (2) indirectly by stimulating OT release from SON neurons into the periphery. Copyright © 2016 Elsevier Inc. All rights reserved.

Measure of synchrony in the activity of intrinsic cardiac neurons

International Nuclear Information System (INIS)

Longpré, Jean-Philippe; Salavatian, Siamak; Jacquemet, Vincent; Beaumont, Eric; Armour, J Andrew; Ardell, Jeffrey L

2014-01-01

Recent multielectrode array recordings in ganglionated plexi of canine atria have opened the way to the study of population dynamics of intrinsic cardiac neurons. These data provide critical insights into the role of local processing that these ganglia play in the regulation of cardiac function. Low firing rates, marked non-stationarity, interplay with the cardiovascular and pulmonary systems and artifacts generated by myocardial activity create new constraints not present in brain recordings for which almost all neuronal analysis techniques have been developed. We adapted and extended the jitter-based synchrony index (SI) to (1) provide a robust and computationally efficient tool for assessing the level and statistical significance of SI between cardiac neurons, (2) estimate the bias on SI resulting from neuronal activity possibly hidden in myocardial artifacts, (3) quantify the synchrony or anti-synchrony between neuronal activity and the phase in the cardiac and respiratory cycles. The method was validated on firing time series from a total of 98 individual neurons identified in 8 dog experiments. SI ranged from −0.14 to 0.66, with 23 pairs of neurons with SI > 0.1. The estimated bias due to artifacts was typically <1%. Strongly cardiovascular- and pulmonary-related neurons (SI > 0.5) were found. Results support the use of jitter-based SI in the context of intrinsic cardiac neurons. (paper)

Insulin receptors mediate growth effects in cultured fetal neurons. II. Activation of a protein kinase that phosphorylates ribosomal protein S6

International Nuclear Information System (INIS)

Heidenreich, K.A.; Toledo, S.P.

1989-01-01

As an initial attempt to identify early steps in insulin action that may be involved in the growth responses of neurons to insulin, we investigated whether insulin receptor activation increases the phosphorylation of ribosomal protein S6 in cultured fetal neurons and whether activation of a protein kinase is involved in this process. When neurons were incubated for 2 h with 32Pi, the addition of insulin (100 ng/ml) for the final 30 min increased the incorporation of 32Pi into a 32K microsomal protein. The incorporation of 32Pi into the majority of other neuronal proteins was unaltered by the 30-min exposure to insulin. Cytosolic extracts from insulin-treated neurons incubated in the presence of exogenous rat liver 40S ribosomes and [gamma-32P]ATP displayed a 3- to 8-fold increase in the phosphorylation of ribosomal protein S6 compared to extracts from untreated cells. Inclusion of cycloheximide during exposure of the neurons to insulin did not inhibit the increased cytosolic kinase activity. Activation of S6 kinase activity by insulin was dose dependent (seen at insulin concentration as low as 0.1 ng/ml) and reached a maximum after 20 min of incubation. Addition of phosphatidylserine, diolein, and Ca2+ to the in vitro kinase reaction had no effect on the phosphorylation of ribosomal protein S6. Likewise, treatment of neurons with (Bu)2cAMP did not alter the phosphorylation of ribosomal protein S6 by neuronal cytosolic extracts. We conclude that insulin activates a cytosolic protein kinase that phosphorylates ribosomal S6 in neurons and is distinct from protein kinase-C and cAMP-dependent protein kinase. Stimulation of this kinase may play a role in insulin signal transduction in neurons

Tissue Plasminogen Activator Induction in Purkinje Neurons After Cerebellar Motor Learning

Science.gov (United States)

Seeds, Nicholas W.; Williams, Brian L.; Bickford, Paula C.

1995-12-01

The cerebellar cortex is implicated in the learning of complex motor skills. This learning may require synaptic remodeling of Purkinje cell inputs. An extracellular serine protease, tissue plasminogen activator (tPA), is involved in remodeling various nonneural tissues and is associated with developing and regenerating neurons. In situ hybridization showed that expression of tPA messenger RNA was increased in the Purkinje neurons of rats within an hour of their being trained for a complex motor task. Antibody to tPA also showed the induction of tPA protein associated with cerebellar Purkinje cells. Thus, the induction of tPA during motor learning may play a role in activity-dependent synaptic plasticity.

Mutant HFE H63D Protein Is Associated with Prolonged Endoplasmic Reticulum Stress and Increased Neuronal Vulnerability*

Science.gov (United States)

Liu, Yiting; Lee, Sang Y.; Neely, Elizabeth; Nandar, Wint; Moyo, Mthabisi; Simmons, Zachary; Connor, James R.

2011-01-01

A specific polymorphism in the hemochromatosis (HFE) gene, H63D, is over-represented in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer disease. Mutations of HFE are best known as being associated with cellular iron overload, but the mechanism by which HFE H63D might increase the risk of neuron degeneration is unclear. Here, using an inducible expression cell model developed from a human neuronal cell line SH-SY5Y, we reported that the presence of the HFE H63D protein activated the unfolded protein response (UPR). This response was followed by a persistent endoplasmic reticulum (ER) stress, as the signals of UPR sensors attenuated and followed by up-regulation of caspase-3 cleavage and activity. Our in vitro findings were recapitulated in a transgenic mouse model carrying Hfe H67D, the mouse equivalent of the human H63D mutation. In this model, UPR activation was detected in the lumbar spinal cord at 6 months then declined at 12 months in association with increased caspase-3 cleavage. Moreover, upon the prolonged ER stress, the number of cells expressing HFE H63D in early apoptosis was increased moderately. Cell proliferation was decreased without increased cell death. Additionally, despite increased iron level in cells carrying HFE H63D, it appeared that ER stress was not responsive to the change of cellular iron status. Overall, our studies indicate that the HFE H63D mutant protein is associated with prolonged ER stress and chronically increased neuronal vulnerability. PMID:21349849

Neuron-specific deletion of peroxisome proliferator-activated receptor delta (PPARδ in mice leads to increased susceptibility to diet-induced obesity.

Directory of Open Access Journals (Sweden)

Heidi E Kocalis

Full Text Available Central nervous system (CNS lipid accumulation, inflammation and resistance to adipo-regulatory hormones, such as insulin and leptin, are implicated in the pathogenesis of diet-induced obesity (DIO. Peroxisome proliferator-activated receptors (PPAR α, δ, γ are nuclear transcription factors that act as environmental fatty acid sensors and regulate genes involved in lipid metabolism and inflammation in response to dietary and endogenous fatty acid ligands. All three PPAR isoforms are expressed in the CNS at different levels. Recent evidence suggests that activation of CNS PPARα and/or PPARγ may contribute to weight gain and obesity. PPARδ is the most abundant isoform in the CNS and is enriched in the hypothalamus, a region of the brain involved in energy homeostasis regulation. Because in peripheral tissues, expression of PPARδ increases lipid oxidative genes and opposes inflammation, we hypothesized that CNS PPARδ protects against the development of DIO. Indeed, genetic neuronal deletion using Nes-Cre loxP technology led to elevated fat mass and decreased lean mass on low-fat diet (LFD, accompanied by leptin resistance and hypothalamic inflammation. Impaired regulation of neuropeptide expression, as well as uncoupling protein 2, and abnormal responses to a metabolic challenge, such as fasting, also occur in the absence of neuronal PPARδ. Consistent with our hypothesis, KO mice gain significantly more fat mass on a high-fat diet (HFD, yet are surprisingly resistant to diet-induced elevations in CNS inflammation and lipid accumulation. We detected evidence of upregulation of PPARγ and target genes of both PPARα and PPARγ, as well as genes of fatty acid oxidation. Thus, our data reveal a previously underappreciated role for neuronal PPARδ in the regulation of body composition, feeding responses, and in the regulation of hypothalamic gene expression.

Mechanisms for multiple activity modes of VTA dopamine neurons

Directory of Open Access Journals (Sweden)

Andrew eOster

2015-07-01

Full Text Available Midbrain ventral segmental area (VTA dopaminergic neurons send numerous projections to cortical and sub-cortical areas, and diffusely release dopamine (DA to their targets. DA neurons display a range of activity modes that vary in frequency and degree of burst firing. Importantly, DA neuronal bursting is associated with a significantly greater degree of DA release than an equivalent tonic activity pattern. Here, we introduce a single compartmental, conductance-based computational model for DA cell activity that captures the behavior of DA neuronal dynamics and examine the multiple factors that underlie DA firing modes: the strength of the SK conductance, the amount of drive, and GABA inhibition. Our results suggest that neurons with low SK conductance fire in a fast firing mode, are correlated with burst firing, and require higher levels of applied current before undergoing depolarization block. We go on to consider the role of GABAergic inhibition on an ensemble of dynamical classes of DA neurons and find that strong GABA inhibition suppresses burst firing. Our studies suggest differences in the distribution of the SK conductance and GABA inhibition levels may indicate subclasses of DA neurons within the VTA. We further identify, that by considering alternate potassium dynamics, the dynamics display burst patterns that terminate via depolarization block, akin to those observed in vivo in VTA DA neurons and in substantia nigra pars compacta DA cell preparations under apamin application. In addition, we consider the generation of transient burst firing events that are NMDA-initiated or elicited by a sudden decrease of GABA inhibition, that is, disinhibition.

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro

Institute of Scientific and Technical Information of China (English)

Fang Su; An-Chen Guo; Wei-Wei Li; Yi-Long Zhao; Zheng-Yi Qu; Yong-Jun Wang; Qun Wang; Yu-Lan Zhu

2017-01-01

Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion;however,the underlying mechanism has not been elucidated.In the present study,we showed that expression of the neuronal large-conductance,Ca2+-activated K+ channel (BKCa) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivatior/reoxygenation (OGD/R) compared with controls.Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R,attenuated the OGD/R-induced elevation of cytosolic Ca2+ levels,and reduced the number of apoptotic neurons.Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax.The protective effect of ethanol preconditioning was antagonized by a BKCa channel inhibitor,paxilline.Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol.The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca2+ and preventing neuronal apoptosis,and this is mediated by BKCa channel activation.

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca2+-Activated K+ Channels In Vitro.

Science.gov (United States)

Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

2017-02-01

Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca 2+ -activated K + channel (BK Ca ) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca 2+ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BK Ca channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BK Ca channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca 2+ and preventing neuronal apoptosis, and this is mediated by BK Ca channel activation.

Reversed synaptic effects of hypocretin and NPY mediated by excitatory GABA-dependent synaptic activity in developing MCH neurons.

Science.gov (United States)

Li, Ying; Xu, Youfen; van den Pol, Anthony N

2013-03-01

In mature neurons, GABA is the primary inhibitory neurotransmitter. In contrast, in developing neurons, GABA exerts excitatory actions, and in some neurons GABA-mediated excitatory synaptic activity is more prevalent than glutamate-mediated excitation. Hypothalamic neuropeptides that modulate cognitive arousal and energy homeostasis, hypocretin/orexin and neuropeptide Y (NPY), evoked reversed effects on synaptic actions that were dependent on presynaptic GABA release onto melanin-concentrating hormone (MCH) neurons. MCH neurons were identified by selective green fluorescent protein (GFP) expression in transgenic mice. In adults, hypocretin increased GABA release leading to reduced excitation. In contrast, in the developing brain as studied here with analysis of miniature excitatory postsynaptic currents, paired-pulse ratios, and evoked potentials, hypocretin acted presynaptically to enhance the excitatory actions of GABA. The ability of hypocretin to enhance GABA release increases inhibition in adult neurons but paradoxically enhances excitation in developing MCH neurons. In contrast, NPY attenuation of GABA release reduced inhibition in mature neurons but enhanced inhibition during development by attenuating GABA excitation. Both hypocretin and NPY also evoked direct actions on developing MCH neurons. Hypocretin excited MCH cells by activating a sodium-calcium exchanger and by reducing potassium currents; NPY reduced activity by increasing an inwardly rectifying potassium current. These data for the first time show that both hypocretin and NPY receptors are functional presynaptically during early postnatal hypothalamic development and that both neuropeptides modulate GABA actions during development with a valence of enhanced excitation or inhibition opposite to that of the adult state, potentially allowing neuropeptide modulation of use-dependent synapse stabilization.

Safrole oxide induces neuronal apoptosis through inhibition of integrin beta4/SOD activity and elevation of ROS/NADPH oxidase activity.

Science.gov (United States)

Su, Le; Zhao, BaoXiang; Lv, Xin; Wang, Nan; Zhao, Jing; Zhang, ShangLi; Miao, JunYing

2007-02-20

Neuronal apoptosis is a very important event in the development of the central nervous system (CNS), but the underlying mechanisms remain to be elucidated. We have previously shown that safrole oxide, a small molecule, induces integrin beta4 expression and promotes apoptosis in vascular endothelial cells. In this study, the effects of safrole oxide on cell growth and apoptosis have been examined in primary cultures of mouse neurons. Safrole oxide was found to significantly inhibit neuronal cell growth and to induce apoptosis. The inhibitory and apoptotic activities of safrole oxide followed a dose- and time-dependent manner. Interestingly, the expression of integrin beta4 was significantly inhibited with safrole oxide treatment. Furthermore, safrole oxide dramatically increases the level of intracellular reactive oxygen species (ROS) and the activity of NADPH oxidase. Moreover, manganese-dependent superoxide dismutase (MnSOD) activity was decreased significantly with safrole oxide treatment. Our study thus demonstrates that safrole oxide induces neuronal apoptosis through integrin beta4, ROS, NADPH, and MnSOD.

Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

Science.gov (United States)

Magou, George C; Pfister, Bryan J; Berlin, Joshua R

2015-10-22

The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

Phrenic long-term facilitation requires PKCθ activity within phrenic motor neurons.

Science.gov (United States)

Devinney, Michael J; Fields, Daryl P; Huxtable, Adrianne G; Peterson, Timothy J; Dale, Erica A; Mitchell, Gordon S

2015-05-27

Acute intermittent hypoxia (AIH) induces a form of spinal motor plasticity known as phrenic long-term facilitation (pLTF); pLTF is a prolonged increase in phrenic motor output after AIH has ended. In anesthetized rats, we demonstrate that pLTF requires activity of the novel PKC isoform, PKCθ, and that the relevant PKCθ is within phrenic motor neurons. Whereas spinal PKCθ inhibitors block pLTF, inhibitors targeting other PKC isoforms do not. PKCθ is highly expressed in phrenic motor neurons, and PKCθ knockdown with intrapleural siRNAs abolishes pLTF. Intrapleural siRNAs targeting PKCζ, an atypical PKC isoform expressed in phrenic motor neurons that underlies a distinct form of phrenic motor plasticity, does not affect pLTF. Thus, PKCθ plays a critical role in spinal AIH-induced respiratory motor plasticity, and the relevant PKCθ is localized within phrenic motor neurons. Intrapleural siRNA delivery has considerable potential as a therapeutic tool to selectively manipulate plasticity in vital respiratory motor neurons. Copyright © 2015 the authors 0270-6474/15/358107-11$15.00/0.

Visualization of odor-induced neuronal activity by immediate early gene expression

Directory of Open Access Journals (Sweden)

Bepari Asim K

2012-11-01

Full Text Available Abstract Background Sensitive detection of sensory-evoked neuronal activation is a key to mechanistic understanding of brain functions. Since immediate early genes (IEGs are readily induced in the brain by environmental changes, tracing IEG expression provides a convenient tool to identify brain activity. In this study we used in situ hybridization to detect odor-evoked induction of ten IEGs in the mouse olfactory system. We then analyzed IEG induction in the cyclic nucleotide-gated channel subunit A2 (Cnga2-null mice to visualize residual neuronal activity following odorant exposure since CNGA2 is a key component of the olfactory signal transduction pathway in the main olfactory system. Results We observed rapid induction of as many as ten IEGs in the mouse olfactory bulb (OB after olfactory stimulation by a non-biological odorant amyl acetate. A robust increase in expression of several IEGs like c-fos and Egr1 was evident in the glomerular layer, the mitral/tufted cell layer and the granule cell layer. Additionally, the neuronal IEG Npas4 showed steep induction from a very low basal expression level predominantly in the granule cell layer. In Cnga2-null mice, which are usually anosmic and sexually unresponsive, glomerular activation was insignificant in response to either ambient odorants or female stimuli. However, a subtle induction of c-fos took place in the OB of a few Cnga2-mutants which exhibited sexual arousal. Interestingly, very strong glomerular activation was observed in the OB of Cnga2-null male mice after stimulation with either the neutral odor amyl acetate or the predator odor 2, 3, 5-trimethyl-3-thiazoline (TMT. Conclusions This study shows for the first time that in vivo olfactory stimulation can robustly induce the neuronal IEG Npas4 in the mouse OB and confirms the odor-evoked induction of a number of IEGs. As shown in previous studies, our results indicate that a CNGA2-independent signaling pathway(s may activate the

Endoplasmic reticulum stress in wake-active neurons progresses with aging.

Science.gov (United States)

Naidoo, Nirinjini; Zhu, Jingxu; Zhu, Yan; Fenik, Polina; Lian, Jie; Galante, Ray; Veasey, Sigrid

2011-08-01

Fragmentation of wakefulness and sleep are expected outcomes of advanced aging. We hypothesize that wake neurons develop endoplasmic reticulum dyshomeostasis with aging, in parallel with impaired wakefulness. In this series of experiments, we sought to more fully characterize age-related changes in wakefulness and then, in relevant wake neuronal populations, explore functionality and endoplasmic reticulum homeostasis. We report that old mice show greater sleep/wake transitions in the active period with markedly shortened wake periods, shortened latencies to sleep, and less wake time in the subjective day in response to a novel social encounter. Consistent with sleep/wake instability and reduced social encounter wakefulness, orexinergic and noradrenergic wake neurons in aged mice show reduced c-fos response to wakefulness and endoplasmic reticulum dyshomeostasis with increased nuclear translocation of CHOP and GADD34. We have identified an age-related unfolded protein response injury to and dysfunction of wake neurons. It is anticipated that these changes contribute to sleep/wake fragmentation and cognitive impairment in aging. © 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

The contribution of ketone bodies to basal and activity-dependent neuronal oxidation in vivo.

Science.gov (United States)

Chowdhury, Golam M I; Jiang, Lihong; Rothman, Douglas L; Behar, Kevin L

2014-07-01

The capacity of ketone bodies to replace glucose in support of neuronal function is unresolved. Here, we determined the contributions of glucose and ketone bodies to neocortical oxidative metabolism over a large range of brain activity in rats fasted 36 hours and infused intravenously with [2,4-(13)C₂]-D-β-hydroxybutyrate (BHB). Three animal groups and conditions were studied: awake ex vivo, pentobarbital-induced isoelectricity ex vivo, and halothane-anesthetized in vivo, the latter data reanalyzed from a recent study. Rates of neuronal acetyl-CoA oxidation from ketone bodies (V(acCoA-kbN)) and pyruvate (V(pdhN)), and the glutamate-glutamine cycle (V(cyc)) were determined by metabolic modeling of (13)C label trapped in major brain amino acid pools. V(acCoA-kbN) increased gradually with increasing activity, as compared with the steeper change in tricarboxylic acid (TCA) cycle rate (V(tcaN)), supporting a decreasing percentage of neuronal ketone oxidation: ∼100% (isoelectricity), 56% (halothane anesthesia), 36% (awake) with the BHB plasma levels achieved in our experiments (6 to 13 mM). In awake animals ketone oxidation reached saturation for blood levels >17 mM, accounting for 62% of neuronal substrate oxidation, the remainder (38%) provided by glucose. We conclude that ketone bodies present at sufficient concentration to saturate metabolism provides full support of basal (housekeeping) energy needs and up to approximately half of the activity-dependent oxidative needs of neurons.

Spontaneous neuronal activity as a self-organized critical phenomenon

Science.gov (United States)

de Arcangelis, L.; Herrmann, H. J.

2013-01-01

Neuronal avalanches are a novel mode of activity in neuronal networks, experimentally found in vitro and in vivo, and exhibit a robust critical behaviour. Avalanche activity can be modelled within the self-organized criticality framework, including threshold firing, refractory period and activity-dependent synaptic plasticity. The size and duration distributions confirm that the system acts in a critical state, whose scaling behaviour is very robust. Next, we discuss the temporal organization of neuronal avalanches. This is given by the alternation between states of high and low activity, named up and down states, leading to a balance between excitation and inhibition controlled by a single parameter. During these periods both the single neuron state and the network excitability level, keeping memory of past activity, are tuned by homeostatic mechanisms. Finally, we verify if a system with no characteristic response can ever learn in a controlled and reproducible way. Learning in the model occurs via plastic adaptation of synaptic strengths by a non-uniform negative feedback mechanism. Learning is a truly collective process and the learning dynamics exhibits universal features. Even complex rules can be learned provided that the plastic adaptation is sufficiently slow.

Superficial dorsal horn neurons with double spike activity in the rat.

Science.gov (United States)

Rojas-Piloni, Gerardo; Dickenson, Anthony H; Condés-Lara, Miguel

2007-05-29

Superficial dorsal horn neurons promote the transfer of nociceptive information from the periphery to supraspinal structures. The membrane and discharge properties of spinal cord neurons can alter the reliability of peripheral signals. In this paper, we analyze the location and response properties of a particular class of dorsal horn neurons that exhibits double spike discharge with a very short interspike interval (2.01+/-0.11 ms). These neurons receive nociceptive C-fiber input and are located in laminae I-II. Double spikes are generated spontaneously or by depolarizing current injection (interval of 2.37+/-0.22). Cells presenting double spike (interval 2.28+/-0.11) increased the firing rate by electrical noxious stimulation, as well as, in the first minutes after carrageenan injection into their receptive field. Carrageenan is a polysaccharide soluble in water and it is used for producing an experimental model of semi-chronic pain. In the present study carrageenan also produces an increase in the interval between double spikes and then, reduced their occurrence after 5-10 min. The results suggest that double spikes are due to intrinsic membrane properties and that their frequency is related to C-fiber nociceptive activity. The present work shows evidence that double spikes in superficial spinal cord neurones are related to the nociceptive stimulation, and they are possibly part of an acute pain-control mechanism.

Distinct Roles for JNK and IKK Activation in Agouti-Related Peptide Neurons in the Development of Obesity and Insulin Resistance

Directory of Open Access Journals (Sweden)

Eva Tsaousidou

2014-11-01

Full Text Available Activation of c-Jun N-terminal kinase 1 (JNK1- and inhibitor of nuclear factor kappa-B kinase 2 (IKK2-dependent signaling plays a crucial role in the development of obesity-associated insulin and leptin resistance not only in peripheral tissues but also in the CNS. Here, we demonstrate that constitutive JNK activation in agouti-related peptide (AgRP-expressing neurons of the hypothalamus is sufficient to induce weight gain and adiposity in mice as a consequence of hyperphagia. JNK activation increases spontaneous action potential firing of AgRP cells and causes both neuronal and systemic leptin resistance. Similarly, activation of IKK2 signaling in AgRP neurons also increases firing of these cells but fails to cause obesity and leptin resistance. In contrast to JNK activation, IKK2 activation blunts insulin signaling in AgRP neurons and impairs systemic glucose homeostasis. Collectively, these experiments reveal both overlapping and nonredundant effects of JNK- and IKK-dependent signaling in AgRP neurons, which cooperate in the manifestation of the metabolic syndrome.

GHRELIN ACTIVATES HYPOPHYSIOTROPIC CORTICOTROPIN-RELEASING FACTOR NEURONS INDEPENDENTLY OF THE ARCUATE NUCLEUS

Science.gov (United States)

Cabral, Agustina; Portiansky, Enrique; Sánchez-Jaramillo, Edith; Zigman, Jeffrey M.; Perello, Mario

2016-01-01

Previous work has established that the hormone ghrelin engages the hypothalamic-pituitary-adrenal neuroendocrine axis via activation of corticotropin-releasing factor (CRF) neurons of the hypothalamic paraventricular nucleus (PVN). The neuronal circuitry that mediates this effect of ghrelin is currently unknown. Here, we show that ghrelin-induced activation of PVN CRF neurons involved inhibition of γ-aminobutyric acid (GABA) inputs, likely via ghrelin binding sites that were localized at GABAergic terminals within the PVN. While ghrelin activated PVN CRF neurons in the presence of neuropeptide Y (NPY) receptor antagonists or in arcuate nucleus (ARC)-ablated mice, it failed to do it so in mice with ghrelin receptor expression limited to ARC agouti gene related protein (AgRP)/NPY neurons. These data support the notion that ghrelin activates PVN CRF neurons via inhibition of local GABAergic tone, in an ARC-independent manner. Furthermore, these data suggest that the neuronal circuits mediating ghrelin’s orexigenic action vs. its role as a stress signal are anatomically dissociated. PMID:26874559

Intratelencephalic corticostriatal neurons equally excite striatonigral and striatopallidal neurons and their discharge activity is selectively reduced in experimental parkinsonism

OpenAIRE

Ballion, B. (B.); Mallet, N. (Nicolas); Bezard, E. (E.); Lanciego, J.L. (José Luis); Gonon, F. (Francois)

2008-01-01

Striatonigral and striatopallidal neurons form distinct populations of striatal projection neurons. Their discharge activity is imbalanced after dopaminergic degeneration in Parkinson's disease. Striatal projection neurons receive massive cortical excitatory inputs from bilateral intratelencephalic (IT) neurons projecting to both the ipsilateral and contralateral striatum and from collateral axons of ipsilateral neurons that send their main axon through the pyramidal tract (PT). Previous anat...

Neuronal activity rapidly induces transcription of the CREB-regulated microRNA-132, in vivo

DEFF Research Database (Denmark)

Nudelman, Aaron Samuel; DiRocco, Derek P; Lambert, Talley J

2010-01-01

Activity-dependent changes in gene-expression are believed to underlie the molecular representation of memory. In this study, we report that in vivo activation of neurons rapidly induces the CREB-regulated microRNA miR-132. To determine if production of miR-132 is regulated by neuronal activity its......, olfactory bulb, and striatum by contextual fear conditioning, odor-exposure, and cocaine-injection, respectively, also increased pri-miR-132. Induction kinetics of pri-miR-132 were monitored and found to parallel those of immediate early genes, peaking at 45 min and returning to basal levels within 2 h...

Intracortical Microstimulation (ICMS) Activates Motor Cortex Layer 5 Pyramidal Neurons Mainly Transsynaptically.

Science.gov (United States)

Hussin, Ahmed T; Boychuk, Jeffery A; Brown, Andrew R; Pittman, Quentin J; Teskey, G Campbell

2015-01-01

Intracortical microstimulation (ICMS) is a technique used for a number of purposes including the derivation of cortical movement representations (motor maps). Its application can activate the output layer 5 of motor cortex and can result in the elicitation of body movements depending upon the stimulus parameters used. The extent to which pyramidal tract projection neurons of the motor cortex are activated transsynaptically or directly by ICMS remains an open question. Given this uncertainty in the mode of activation, we used a preparation that combined patch clamp whole-cell recordings from single layer 5 pyramidal neurons and extracellular ICMS in slices of motor cortex as well as a standard in vivo mapping technique to ask how ICMS activated motor cortex pyramidal neurons. We measured changes in synaptic spike threshold and spiking rate to ICMS in vitro and movement threshold in vivo in the presence or absence of specific pharmacological blockers of glutamatergic (AMPA, NMDA and Kainate) receptors and GABAA receptors. With major excitatory and inhibitory synaptic transmission blocked (with DNQX, APV and bicuculline methiodide), we observed a significant increase in the ICMS current intensity required to elicit a movement in vivo as well as to the first spike and an 85% reduction in spiking responses in vitro. Subsets of neurons were still responsive after the synaptic block, especially at higher current intensities, suggesting a modest direct activation. Taken together our data indicate a mainly synaptic mode of activation to ICMS in layer 5 of rat motor cortex. Copyright © 2015 Elsevier Inc. All rights reserved.

An electronic implementation for Liao's chaotic delayed neuron model with non-monotonous activation function

International Nuclear Information System (INIS)

Duan Shukai; Liao Xiaofeng

2007-01-01

A new chaotic delayed neuron model with non-monotonously increasing transfer function, called as chaotic Liao's delayed neuron model, was recently reported and analyzed. An electronic implementation of this model is described in detail. At the same time, some methods in circuit design, especially for circuit with time delayed unit and non-monotonously increasing activation unit, are also considered carefully. We find that the dynamical behaviors of the designed circuits are closely similar to the results predicted by numerical experiments

Neuronal activity in the hub of extrasynaptic Schwann cell-axon interactions

Directory of Open Access Journals (Sweden)

Chrysanthi eSamara

2013-11-01

Full Text Available The integrity and function of neurons depend on their continuous interactions with glial cells. In the peripheral nervous system glial functions are exerted by Schwann cells (SCs. SCs sense synaptic and extrasynaptic manifestations of action potential propagation and adapt their physiology to support neuronal activity. We review here existing literature data on extrasynaptic bidirectional axon-SC communication, focusing particularly on neuronal activity implications. To shed light on underlying mechanisms, we conduct a thorough analysis of microarray data from SC-rich mouse sciatic nerve at different developmental stages and in neuropathic models. We identify molecules that are potentially involved in SC detection of neuronal activity signals inducing subsequent glial responses. We further suggest that alterations in the activity-dependent axon-SC crosstalk impact on peripheral neuropathies. Together with previously reported data, these observations open new perspectives for deciphering glial mechanisms of neuronal function support.

Nutritive, Post-ingestive Signals Are the Primary Regulators of AgRP Neuron Activity

Directory of Open Access Journals (Sweden)

Zhenwei Su

2017-12-01

Full Text Available Summary: The brain regulates food intake by processing sensory cues and peripheral physiological signals, but the neural basis of this integration remains unclear. Hypothalamic, agouti-related protein (AgRP-expressing neurons are critical regulators of food intake. AgRP neuron activity is high during hunger and is rapidly reduced by the sight and smell of food. Here, we reveal two distinct components of AgRP neuron activity regulation: a rapid but transient sensory-driven signal and a slower, sustained calorie-dependent signal. We discovered that nutrients are necessary and sufficient for sustained reductions in AgRP neuron activity and that activity reductions are proportional to the calories obtained. This change in activity is recapitulated by exogenous administration of gut-derived satiation signals. Furthermore, we showed that the nutritive value of food trains sensory systems—in a single trial—to drive rapid, anticipatory AgRP neuron activity inhibition. Together, these data demonstrate that nutrients are the primary regulators of AgRP neuron activity. : Su et al. demonstrate that nutrient content in the GI tract is rapidly signaled to hypothalamic neurons activated by hunger. This rapid effect is mediated by three satiation signals that synergistically reduce the activity of AgRP neurons. These findings uncover how hunger circuits in the brain are regulated and raise the possibility that hunger can be pharmacologically controlled. Keywords: calcium imaging, AgRP neurons, calories, satiation signals, sensory regulation, single trial learning, cholecystokinin, CCK, peptide tyrosine tyrosine, PYY, amylin, homeostasis

Time-course of changes in neuronal activity markers following iTBS-TMS of the rat neocortex.

Science.gov (United States)

Hoppenrath, Kathrin; Funke, Klaus

2013-03-01

In a rat model of transcranial magnetic stimulation we could recently show that intermittent theta-burst stimulation (iTBS) affects the neocortical expression of the immediate early gene products c-Fos and zif268 as well as that of the two glutamic acid decarboxylase isoforms GAD65 and GAD67 and that of the calcium-binding proteins calbindin (CB) and parvalbumin (PV), known as markers of excitatory and inhibitory activity. We now analyzed in more detail the time course of changes in the expression of these proteins at 10, 20, 40, 80 and 160min following a single block of iTBS consisting of 600 stimuli. Initial increase in c-Fos, zif268 and GAD65 (20min) signals transient activation of excitatory and inhibitory neurons, thereafter first followed by a decrease in markers of activity of inhibitory neurons (GAD67, PV, CB: 20-80min) and then by a late decrease in c-Fos and GAD65 expression (160min). The results demonstrate that one iTBS block may have an after-effect of at least two different phases, an early phase with increased neuronal activity (c-Fos, zif268) but also the likelihood of increased GABA-release (GAD65), followed by a late phase (>40min) of reduced neuronal activity in excitatory and inhibitory systems which may indicate a state of reduced excitability. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

From Structure to Activity: Using Centrality Measures to Predict Neuronal Activity.

Science.gov (United States)

Fletcher, Jack McKay; Wennekers, Thomas

2018-03-01

It is clear that the topological structure of a neural network somehow determines the activity of the neurons within it. In the present work, we ask to what extent it is possible to examine the structural features of a network and learn something about its activity? Specifically, we consider how the centrality (the importance of a node in a network) of a neuron correlates with its firing rate. To investigate, we apply an array of centrality measures, including In-Degree, Closeness, Betweenness, Eigenvector, Katz, PageRank, Hyperlink-Induced Topic Search (HITS) and NeuronRank to Leaky-Integrate and Fire neural networks with different connectivity schemes. We find that Katz centrality is the best predictor of firing rate given the network structure, with almost perfect correlation in all cases studied, which include purely excitatory and excitatory-inhibitory networks, with either homogeneous connections or a small-world structure. We identify the properties of a network which will cause this correlation to hold. We argue that the reason Katz centrality correlates so highly with neuronal activity compared to other centrality measures is because it nicely captures disinhibition in neural networks. In addition, we argue that these theoretical findings are applicable to neuroscientists who apply centrality measures to functional brain networks, as well as offer a neurophysiological justification to high level cognitive models which use certain centrality measures.

Sex differences in feeding behavior in rats: the relationship with neuronal activation in the hypothalamus

Directory of Open Access Journals (Sweden)

Atsushi eFukushima

2015-03-01

Full Text Available There is general agreement that the central nervous system in rodents differs between sexes due to the presence of gonadal steroid hormone during differentiation. Sex differences in feeding seem to occur among species, and responses to fasting (i.e., starvation, gonadal steroids (i.e., testosterone and estradiol, and diet (i.e., western-style diet vary significantly between sexes. The hypothalamus is the center for controlling feeding behavior. We examined the activation of feeding-related peptides in neurons in the hypothalamus. Phosphorylation of cyclic AMP response element-binding protein (CREB is a good marker for neural activation, as is the Fos antigen. Therefore, we predicted that sex differences in the activity of melanin-concentrating hormone (MCH neurons would be associated with feeding behavior. We determined the response of MCH neurons to glucose in the lateral hypothalamic area (LHA and our results suggested MCH neurons play an important role in sex differences in feeding behavior. In addition, fasting increased the number of orexin neurons harboring phosphorylated CREB in female rats (regardless of the estrous day, but not male rats. Glucose injection decreased the number of these neurons with phosphorylated CREB in fasted female rats. Finally, under normal spontaneous food intake, MCH neurons, but not orexin neurons, expressed phosphorylated CREB. These sex differences in response to fasting and glucose, as well as under normal conditions, suggest a vulnerability to metabolic challenges in females.

Fast and direct detection of neuronal activation with diffusion MRI

Energy Technology Data Exchange (ETDEWEB)

Le Bihan, D. [Service Hospitalier Frederic Joliot (CEA/DSV/DRM), Lab. Anatomical and Functional Neuroimaging, 91 - Orsay (France); Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H. [Kyoto Univ. Graduate School of Medicine, Human Brain Research Center, Kyoto (Japan)

2006-07-01

Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H{sub 2}O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some

Fast and direct detection of neuronal activation with diffusion MRI

International Nuclear Information System (INIS)

Le Bihan, D.; Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H.

2006-01-01

Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H 2 O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some pathological

Relationships between selective neuronal loss and microglial activation after ischaemic stroke in man.

Science.gov (United States)

Morris, Rhiannon S; Simon Jones, P; Alawneh, Josef A; Hong, Young T; Fryer, Tim D; Aigbirhio, Franklin I; Warburton, Elizabeth A; Baron, Jean-Claude

2018-05-09

Modern ischaemic stroke management involves intravenous thrombolysis followed by mechanical thrombectomy, which allows markedly higher rates of recanalization and penumbral salvage than thrombolysis alone. However, <50% of treated patients eventually enjoy independent life. It is therefore important to identify complementary therapeutic targets. In rodent models, the salvaged penumbra is consistently affected by selective neuronal loss, which may hinder recovery by interfering with plastic processes, as well as by microglial activation, which may exacerbate neuronal death. However, whether the salvaged penumbra in man is similarly affected is still unclear. Here we determined whether these two processes affect the non-infarcted penumbra in man and, if so, whether they are inter-related. We prospectively recruited patients with (i) acute middle-cerebral artery stroke; (ii) penumbra present on CT perfusion obtained <4.5 h of stroke onset; and (iii) early neurological recovery as a marker of penumbral salvage. PET with 11C-flumazenil and 11C-PK11195, as well as MRI to map the final infarct, were obtained at predefined follow-up times. The presence of selective neuronal loss and microglial activation was determined voxel-wise within the MRI normal-appearing ipsilateral non-infarcted zone and surviving penumbra masks, and their inter-relationship was assessed both across and within patients. Dilated infarct contours were consistently excluded to control for partial volume effects. Across the 16 recruited patients, there was reduced 11C-flumazenil and increased 11C-PK11195 binding in the whole ipsilateral non-infarcted zone (P = 0.04 and 0.02, respectively). Within the non-infarcted penumbra, 11C-flumazenil was also reduced (P = 0.001), but without clear increase in 11C-PK11195 (P = 0.18). There was no significant correlation between 11C-flumazenil and 11C-PK11195 in either compartment. This mechanistic study provides direct evidence for the presence of both neuronal

Mechanosensing in hypothalamic osmosensory neurons.

Science.gov (United States)

Prager-Khoutorsky, Masha

2017-11-01

Osmosensory neurons are specialized cells activated by increases in blood osmolality to trigger thirst, secretion of the antidiuretic hormone vasopressin, and elevated sympathetic tone during dehydration. In addition to multiple extrinsic factors modulating their activity, osmosensory neurons are intrinsically osmosensitive, as they are activated by increased osmolality in the absence of neighboring cells or synaptic contacts. This intrinsic osmosensitivity is a mechanical process associated with osmolality-induced changes in cell volume. This review summarises recent findings revealing molecular mechanisms underlying the mechanical activation of osmosensory neurons and highlighting important roles of microtubules, actin, and mechanosensitive ion channels in this process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intermittent but not sustained hypoxia activates orexin-containing neurons in mice.

Science.gov (United States)

Yamaguchi, Keiji; Futatsuki, Takahiro; Ushikai, Jumpei; Kuroki, Chiharu; Minami, Toshiaki; Kakihana, Yasuyuki; Kuwaki, Tomoyuki

2015-01-15

Hypothalamic orexin-containing neurons are activated by CO2 and contribute to hypercapnic ventilatory activation. However, their role in oxygen-related regulation of breathing is not well defined. In this study, we examined whether an experimental model mimicking apnea-induced repetitive hypoxemia (intermittent hypoxia [IH]) activates orexin-containing neurons. Mice were exposed to IH (5×5min at 10% O2), intermittent hyperoxia (IO; 5×5min at 50% O2), sustained hypoxia (SH; 25min at 10% O2), or sham stimulation. Their brains were examined using double immunohistochemical staining for orexin and c-Fos. The results indicated that IH (25.8±3.0%), but not SH (9.0±1.5%) activated orexin-containing neurons when compared to IO (5.5±0.6%) and sham stimulation (5.9±1.4%). These results correlate with those of our previous work showing that IH-induced respiratory long-term facilitation is dependent on orexin-containing neurons. Taken together, orexin contributes to repetitive hypoxia-induced respiratory activation and the hypoxic activation of orexin-containing neurons is pattern dependent. Copyright © 2014 Elsevier B.V. All rights reserved.

Activity of D1/2 Receptor Expressing Neurons in the Nucleus Accumbens Regulates Running, Locomotion, and Food Intake

Directory of Open Access Journals (Sweden)

Xianglong eZhu

2016-04-01

Full Text Available While weight gain is clearly promoted by excessive energy intake and reduced expenditure, the underlying neural mechanisms of energy balance remain unclear. The NAc is one brain region that has received attention for its role in the regulation of energy balance; its D1 and D2 receptor containing neurons have distinct functions in regulating reward behavior and require further examination. The goal of the present study is to investigate how activation and inhibition of D1 and D2 neurons in the NAc influences behaviors related to energy intake and expenditure. Specific manipulation of D1 vs D2 neurons was done in both low expenditure and high expenditure (wheel running conditions to assess behavioral effects in these different states. Direct control of neural activity was achieved using a DREADD (Designer Receptors Exclusively Activated by Designer Drugs strategy. Activation of NAc D1 neurons increased food intake, wheel running and locomotor activity. In contrast, activation of D2 neurons in the NAc reduced running and locomotion while D2 neuron inhibition had opposite effects. These results highlight the importance of considering both intake and expenditure in the analysis of D1 and D2 neuronal manipulations. Moreover, the behavioral outcomes from D1 NAc neuronal manipulations depend upon the activity state of the animals (wheel running vs non-running. The data support and complement the hypothesis of specific NAc dopamine pathways facilitating energy expenditure and suggest a potential strategy for human weight control.

Contribution of synchronized GABAergic neurons to dopaminergic neuron firing and bursting.

Science.gov (United States)

Morozova, Ekaterina O; Myroshnychenko, Maxym; Zakharov, Denis; di Volo, Matteo; Gutkin, Boris; Lapish, Christopher C; Kuznetsov, Alexey

2016-10-01

In the ventral tegmental area (VTA), interactions between dopamine (DA) and γ-aminobutyric acid (GABA) neurons are critical for regulating DA neuron activity and thus DA efflux. To provide a mechanistic explanation of how GABA neurons influence DA neuron firing, we developed a circuit model of the VTA. The model is based on feed-forward inhibition and recreates canonical features of the VTA neurons. Simulations revealed that γ-aminobutyric acid (GABA) receptor (GABAR) stimulation can differentially influence the firing pattern of the DA neuron, depending on the level of synchronization among GABA neurons. Asynchronous activity of GABA neurons provides a constant level of inhibition to the DA neuron and, when removed, produces a classical disinhibition burst. In contrast, when GABA neurons are synchronized by common synaptic input, their influence evokes additional spikes in the DA neuron, resulting in increased measures of firing and bursting. Distinct from previous mechanisms, the increases were not based on lowered firing rate of the GABA neurons or weaker hyperpolarization by the GABAR synaptic current. This phenomenon was induced by GABA-mediated hyperpolarization of the DA neuron that leads to decreases in intracellular calcium (Ca 2+ ) concentration, thus reducing the Ca 2+ -dependent potassium (K + ) current. In this way, the GABA-mediated hyperpolarization replaces Ca 2+ -dependent K + current; however, this inhibition is pulsatile, which allows the DA neuron to fire during the rhythmic pauses in inhibition. Our results emphasize the importance of inhibition in the VTA, which has been discussed in many studies, and suggest a novel mechanism whereby computations can occur locally. Copyright © 2016 the American Physiological Society.

Nav 1.8-null mice show stimulus-dependent deficits in spinal neuronal activity

Directory of Open Access Journals (Sweden)

Wood John N

2006-02-01

Full Text Available Abstract Background The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord. Results Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field. Conclusion This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.

[Local GABA-ergic modulation of serotonergic neuron activity in the nucleus raphe magnus].

Science.gov (United States)

Iniushkin, A N; Merkulova, N A; Orlova, A O; Iniushkina, E M

2009-07-01

In voltage-clamp experimental on slices of the rat brainstem the effects of 5-HT and GABA on serotonergic neurons of nucleus raphe magnus were investigated. Local applications of 5-HT induced an increase in IPCSs frequency and amplitude in 45% of serotonergic cells. The effect suppressed by the blocker of fast sodium channels tetradotoxin. Antagonist of GABA receptor gabazine blocked IPSCs in neurons both sensitive and non-sensitive to 5-HT action. Applications of GABA induced a membrane current (I(GABA)), which was completely blocked by gabazine. The data suggest self-control of the activity of serotonergic neurons in nucleus raphe magnus by negative feedback loop via local GABAergic interneurons.

Molecular and functional differences in voltage-activated sodium currents between GABA projection neurons and dopamine neurons in the substantia nigra

OpenAIRE

Ding, Shengyuan; Wei, Wei; Zhou, Fu-Ming

2011-01-01

GABA projection neurons (GABA neurons) in the substantia nigra pars reticulata (SNr) and dopamine projection neurons (DA neurons) in substantia nigra pars compacta (SNc) have strikingly different firing properties. SNc DA neurons fire low-frequency, long-duration spikes, whereas SNr GABA neurons fire high-frequency, short-duration spikes. Since voltage-activated sodium (NaV) channels are critical to spike generation, the different firing properties raise the possibility that, compared with DA...

Increased intrinsic excitability of muscle vasoconstrictor preganglionic neurons may contribute to the elevated sympathetic activity in hypertensive rats.

Science.gov (United States)

Briant, Linford J B; Stalbovskiy, Alexey O; Nolan, Matthew F; Champneys, Alan R; Pickering, Anthony E

2014-12-01

Hypertension is associated with pathologically increased sympathetic drive to the vasculature. This has been attributed to increased excitatory drive to sympathetic preganglionic neurons (SPN) from brainstem cardiovascular control centers. However, there is also evidence supporting increased intrinsic excitability of SPN. To test this hypothesis, we made whole cell recordings of muscle vasoconstrictor-like (MVClike) SPN in the working-heart brainstem preparation of spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats. The MVClike SPN have a higher spontaneous firing frequency in the SH rat (3.85 ± 0.4 vs. 2.44 ± 0.4 Hz in WKY; P = 0.011) with greater respiratory modulation of their activity. The action potentials of SH SPN had smaller, shorter afterhyperpolarizations (AHPs) and showed diminished transient rectification indicating suppression of an A-type potassium conductance (IA). We developed mathematical models of the SPN to establish if changes in their intrinsic properties in SH rats could account for their altered firing. Reduction of the maximal conductance density of IA by 15-30% changed the excitability and output of the model from the WKY to a SH profile, with increased firing frequency, amplified respiratory modulation, and smaller AHPs. This change in output is predominantly a consequence of altered synaptic integration. Consistent with these in silico predictions, we found that intrathecal 4-aminopyridine (4-AP) increased sympathetic nerve activity, elevated perfusion pressure, and augmented Traube-Hering waves. Our findings indicate that IA acts as a powerful filter on incoming synaptic drive to SPN and that its diminution in the SH rat is potentially sufficient to account for the increased sympathetic output underlying hypertension. Copyright © 2014 the American Physiological Society.

Ejaculation Induced by the Activation of Crz Neurons Is Rewarding to Drosophila Males.

Science.gov (United States)

Zer-Krispil, Shir; Zak, Hila; Shao, Lisha; Ben-Shaanan, Shir; Tordjman, Lea; Bentzur, Assa; Shmueli, Anat; Shohat-Ophir, Galit

2018-05-07

The reward system is a collection of circuits that reinforce behaviors necessary for survival [1, 2]. Given the importance of reproduction for survival, actions that promote successful mating induce pleasurable feeling and are positively reinforced [3, 4]. This principle is conserved in Drosophila, where successful copulation is naturally rewarding to male flies, induces long-term appetitive memories [5], increases brain levels of neuropeptide F (NPF, the fly homolog of neuropeptide Y), and prevents ethanol, known otherwise as rewarding to flies [6, 7], from being rewarding [5]. It is not clear which of the multiple sensory and motor responses performed during mating induces perception of reward. Sexual interactions with female flies that do not reach copulation are not sufficient to reduce ethanol consumption [5], suggesting that only successful mating encounters are rewarding. Here, we uncoupled the initial steps of mating from its final steps and tested the ability of ejaculation to mimic the rewarding value of full copulation. We induced ejaculation by activating neurons that express the neuropeptide corazonin (CRZ) [8] and subsequently measured different aspects of reward. We show that activating Crz-expressing neurons is rewarding to male flies, as they choose to reside in a zone that triggers optogenetic stimulation of Crz neurons and display conditioned preference for an odor paired with the activation. Reminiscent of successful mating, repeated activation of Crz neurons increases npf levels and reduces ethanol consumption. Our results demonstrate that ejaculation stimulated by Crz/Crz-receptor signaling serves as an essential part of the mating reward mechanism in Drosophila. VIDEO ABSTRACT. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

GABAB-receptor activation alters the firing pattern of dopamine neurons in the rat substantia nigra.

Science.gov (United States)

Engberg, G; Kling-Petersen, T; Nissbrandt, H

1993-11-01

Previous electrophysiological experiments have emphasized the importance of the firing pattern for the functioning of midbrain dopamine (DA) neurons. In this regard, excitatory amino acid receptors appear to constitute an important modulatory control mechanism. In the present study, extracellular recording techniques were used to investigate the significance of GABAB-receptor activation for the firing properties of DA neurons in the substantia nigra (SN) in the rat. Intravenous administration of the GABAB-receptor agonist baclofen (1-16 mg/kg) was associated with a dose-dependent regularization of the firing pattern, concomitant with a reduction in burst firing. At higher doses (16-32 mg/kg), the firing rate of the DA neurons was dose-dependently decreased. Also, microiontophoretic application of baclofen regularized the firing pattern of nigral DA neurons, including a reduction of burst firing. Both the regularization of the firing pattern and inhibition of firing rate produced by systemic baclofen administration was antagonized by the GABAB-receptor antagonist CGP 35348 (200 mg/kg, i.v.). The GABAA-receptor agonist muscimol produced effects on the firing properties of DA neurons that were opposite to those observed following baclofen, i.e., an increase in firing rate accompanied by a decreased regularity. The NMDA receptor antagonist MK 801 (0.4-3.2 mg/kg, i.v.) produced a moderate, dose-dependent increase in the firing rate of the nigral DA neurons as well as a slightly regularized firing pattern. Pretreatment with MK 801 (3.2 mg/kg, i.v., 3-10 min) did neither promote nor prevent the regularization of the firing pattern or inhibition of firing rate on the nigral DA neurons produced by baclofen. The present results clearly show that GABAB-receptors can alter the firing pattern of nigral DA neurons, hereby counterbalancing the previously described ability of glutamate to induce burst firing activity on these neurons.

Increasing brain angiotensin converting enzyme 2 activity decreases anxiety-like behavior in male mice by activating central Mas receptors.

Science.gov (United States)

Wang, Lei; de Kloet, Annette D; Pati, Dipanwita; Hiller, Helmut; Smith, Justin A; Pioquinto, David J; Ludin, Jacob A; Oh, S Paul; Katovich, Michael J; Frazier, Charles J; Raizada, Mohan K; Krause, Eric G

2016-06-01

Over-activation of the brain renin-angiotensin system (RAS) has been implicated in the etiology of anxiety disorders. Angiotensin converting enzyme 2 (ACE2) inhibits RAS activity by converting angiotensin-II, the effector peptide of RAS, to angiotensin-(1-7), which activates the Mas receptor (MasR). Whether increasing brain ACE2 activity reduces anxiety by stimulating central MasR is unknown. To test the hypothesis that increasing brain ACE2 activity reduces anxiety-like behavior via central MasR stimulation, we generated male mice overexpressing ACE2 (ACE2 KI mice) and wild type littermate controls (WT). ACE2 KI mice explored the open arms of the elevated plus maze (EPM) significantly more than WT, suggesting increasing ACE2 activity is anxiolytic. Central delivery of diminazene aceturate, an ACE2 activator, to C57BL/6 mice also reduced anxiety-like behavior in the EPM, but centrally administering ACE2 KI mice A-779, a MasR antagonist, abolished their anxiolytic phenotype, suggesting that ACE2 reduces anxiety-like behavior by activating central MasR. To identify the brain circuits mediating these effects, we measured Fos, a marker of neuronal activation, subsequent to EPM exposure and found that ACE2 KI mice had decreased Fos in the bed nucleus of stria terminalis but had increased Fos in the basolateral amygdala (BLA). Within the BLA, we determined that ∼62% of GABAergic neurons contained MasR mRNA and expression of MasR mRNA was upregulated by ACE2 overexpression, suggesting that ACE2 may influence GABA neurotransmission within the BLA via MasR activation. Indeed, ACE2 overexpression was associated with increased frequency of spontaneous inhibitory postsynaptic currents (indicative of presynaptic release of GABA) onto BLA pyramidal neurons and central infusion of A-779 eliminated this effect. Collectively, these results suggest that ACE2 may reduce anxiety-like behavior by activating central MasR that facilitate GABA release onto pyramidal neurons within the

Exposure to an open-field arena increases c-Fos expression in a subpopulation of neurons in the dorsal raphe nucleus, including neurons projecting to the basolateral amygdaloid complex

DEFF Research Database (Denmark)

Hale, M.W.; Hay-Schmidt, A.; Mikkelsen, J.D.

2008-01-01

Serotonergic systems in the dorsal raphe nucleus are thought to play an important role in the regulation of anxiety states. To investigate responses of neurons in the dorsal raphe nucleus to a mild anxiety-related stimulus, we exposed rats to an open-field, under low-light or high-light conditions....... Treatment effects on c-Fos expression in serotonergic and non-serotonergic cells in the midbrain raphe nuclei were determined 2 h following open-field exposure or home cage control (CO) conditions. Rats tested under both light conditions responded with increases in c-Fos expression in serotonergic neurons...... within subdivisions of the midbrain raphe nuclei compared with CO rats. However, the total numbers of serotonergic neurons involved were small suggesting that exposure to the open-field may affect a subpopulation of serotonergic neurons. To determine if exposure to the open-field activates a subset...

Vulnerability to glutamate toxicity of dopaminergic neurons is dependent on endogenous dopamine and MAPK activation.

Science.gov (United States)

Izumi, Yasuhiko; Yamamoto, Noriyuki; Matsuo, Takaaki; Wakita, Seiko; Takeuchi, Hiroki; Kume, Toshiaki; Katsuki, Hiroshi; Sawada, Hideyuki; Akaike, Akinori

2009-07-01

Dopaminergic neurons are more vulnerable than other types of neurons in cases of Parkinson disease and ischemic brain disease. An increasing amount of evidence suggests that endogenous dopamine plays a role in the vulnerability of dopaminergic neurons. Although glutamate toxicity contributes to the pathogenesis of these disorders, the sensitivity of dopaminergic neurons to glutamate toxicity has not been clarified. In this study, we demonstrated that dopaminergic neurons were preferentially affected by glutamate toxicity in rat mesencephalic cultures. Glutamate toxicity in dopaminergic neurons was blocked by inhibiting extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase, and p38 MAPK. Furthermore, depletion of dopamine by alpha-methyl-dl-p-tyrosine methyl ester (alpha-MT), an inhibitor of tyrosine hydroxylase (TH), protected dopaminergic neurons from the neurotoxicity. Exposure to glutamate facilitated phosphoryration of TH at Ser31 by ERK, which contributes to the increased TH activity. Inhibition of ERK had no additive effect on the protection offered by alpha-MT, whereas alpha-MT and c-jun N-terminal kinase or p38 MAPK inhibitors had additive effects and yielded full protection. These data suggest that endogenous dopamine is responsible for the vulnerability to glutamate toxicity of dopaminergic neurons and one of the mechanisms may be an enhancement of dopamine synthesis mediated by ERK.

Cholesterol up-regulates neuronal G protein-gated inwardly rectifying potassium (GIRK) channel activity in the hippocampus.

Science.gov (United States)

Bukiya, Anna N; Durdagi, Serdar; Noskov, Sergei; Rosenhouse-Dantsker, Avia

2017-04-14

Hypercholesterolemia is a well known risk factor for the development of neurodegenerative disease. However, the underlying mechanisms are mostly unknown. In recent years, it has become increasingly evident that cholesterol-driven effects on physiology and pathophysiology derive from its ability to alter the function of a variety of membrane proteins including ion channels. Yet, the effect of cholesterol on G protein-gated inwardly rectifying potassium (GIRK) channels expressed in the brain is unknown. GIRK channels mediate the actions of inhibitory brain neurotransmitters. As a result, loss of GIRK function can enhance neuron excitability, whereas gain of GIRK function can reduce neuronal activity. Here we show that in rats on a high-cholesterol diet, cholesterol levels in hippocampal neurons are increased. We also demonstrate that cholesterol plays a critical role in modulating neuronal GIRK currents. Specifically, cholesterol enrichment of rat hippocampal neurons resulted in enhanced channel activity. In accordance, elevated currents upon cholesterol enrichment were also observed in Xenopus oocytes expressing GIRK2 channels, the primary GIRK subunit expressed in the brain. Furthermore, using planar lipid bilayers, we show that although cholesterol did not affect the unitary conductance of GIRK2, it significantly enhanced the frequency of channel openings. Last, combining computational and functional approaches, we identified two putative cholesterol-binding sites in the transmembrane domain of GIRK2. These findings establish that cholesterol plays a critical role in modulating GIRK activity in the brain. Because up-regulation of GIRK function can reduce neuronal activity, our findings may lead to novel approaches for prevention and therapy of cholesterol-driven neurodegenerative disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Alterations in Neuronal Activity in Basal Ganglia-Thalamocortical Circuits in the Parkinsonian State

Directory of Open Access Journals (Sweden)

Adriana eGalvan

2015-02-01

Full Text Available In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials, electroencephalograms or electrocorticograms. Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation therapy.

Alterations in neuronal activity in basal ganglia-thalamocortical circuits in the parkinsonian state

Science.gov (United States)

Galvan, Adriana; Devergnas, Annaelle; Wichmann, Thomas

2015-01-01

In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials (LFPs), electroencephalograms (EEGs) or electrocorticograms (ECoGs). Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation (DBS) therapy. PMID:25698937

Neuron-glial communication mediated by TNF-α and glial activation in dorsal root ganglia in visceral inflammatory hypersensitivity.

Science.gov (United States)

Song, Dan-dan; Li, Yong; Tang, Dong; Huang, Li-ya; Yuan, Yao-zong

2014-05-01

Communication between neurons and glia in the dorsal root ganglia (DRG) and the central nervous system is critical for nociception. Both glial activation and proinflammatory cytokine induction underlie this communication. We investigated whether satellite glial cell (SGC) and tumor necrosis factor-α (TNF-α) activation in DRG participates in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rat model of visceral hyperalgesia. In TNBS-treated rats, TNF-α expression increased in DRG and was colocalized to SGCs enveloping a given neuron. These SGCs were activated as visualized under electron microscopy: they had more elongated processes projecting into the connective tissue space and more gap junctions. When nerves attached to DRG (L6-S1) were stimulated with a series of electrical stimulations, TNF-α were released from DRG in TNBS-treated animals compared with controls. Using a current clamp, we noted that exogenous TNF-α (2.5 ng/ml) increased DRG neuron activity, and visceral pain behavioral responses were reversed by intrathecal administration of anti-TNF-α (10 μg·kg(-1)·day(-1)). Based on our findings, TNF-α and SGC activation in neuron-glial communication are critical in inflammatory visceral hyperalgesia.

Peroxisome proliferator-activated receptor γ is expressed in hippocampal neurons and its activation prevents β-amyloid neurodegeneration: role of Wnt signaling

International Nuclear Information System (INIS)

Inestrosa, Nibaldo C.; Godoy, Juan A.; Quintanilla, Rodrigo A.; Koenig, Cecilia S.; Bronfman, Miguel

2005-01-01

The molecular pathogenesis of Alzheimer's disease (AD) involves the participation of the amyloid-β-peptide (Aβ), which plays a critical role in the neurodegeneration that triggers the disease. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors, which are members of the nuclear receptor family. We report here that (1) PPARγ is present in rat hippocampal neurons in culture. (2) Activation of PPARγ by troglitazone and rosiglitazone protects rat hippocampal neurons against Aβ-induced neurodegeneration, as shown by the 3-[4,5 -2yl]-2,5-diphenyltetrazolium bromide (MTT) reduction assay, immunofluorescence using an anti-heavy neurofilament antibody, and quantitative electron microscopy. (3) Hippocampal neurons treated with several PPARγ agonists, including troglitazone, rosiglitazone, and ciglitazone, prevent the excitotoxic Aβ-induced rise in bulk-free Ca 2+ . (4) PPARγ activation results in the modulation of Wnt signaling components, including the inhibition of glycogen synthase kinase-3β (GSK-3β) and an increase of the cytoplasmic and nuclear β-catenin levels. We conclude that the activation of PPARγ prevents Aβ-induced neurodegeneration by a mechanism that may involve a cross talk between neuronal PPARγ and the Wnt signaling pathway. More important, the fact that the activation of PPARγ attenuated Aβ-dependent neurodegeneration opens the possibility to fight AD from a new therapeutic perspective

Male mice ultrasonic vocalizations enhance female sexual approach and hypothalamic kisspeptin neuron activity.

Science.gov (United States)

Asaba, Akari; Osakada, Takuya; Touhara, Kazushige; Kato, Masahiro; Mogi, Kazutaka; Kikusui, Takefumi

2017-08-01

Vocal communication in animals is important for ensuring reproductive success. Male mice emit song-like "ultrasonic vocalizations (USVs)" when they encounter female mice, and females show approach to the USVs. However, it is unclear whether USVs of male mice trigger female behavioral and endocrine responses in reproduction. In this study, we first investigated the relationship between the number of deliveries in breeding pairs for 4months and USVs syllables emitted from those paired males during 3min of sexual encounter with unfamiliar female mice. There was a positive correlation between these two indices, which suggests that breeding pairs in which males could emit USVs more frequently had more offspring. Further, we examined the effect of USVs of male mice on female sexual behavior. Female mice showed more approach behavior towards vocalizing males than devocalized males. Finally, to determine whether USVs of male mice could activate the neural system governing reproductive function in female mice, the activation of kisspeptin neurons, key neurons to drive gonadotropin-releasing hormone neurons in the hypothalamus, was examined using dual-label immunocytochemistry with cAMP response element-binding protein phosphorylation (pCREB). In the arcuate nucleus (Arc), the number of kisspeptin neurons expressing pCREB significantly increased after exposure to USVs of male as compared with noise exposure group. In conclusion, our results suggest that USVs of male mice promote fertility in female mice by activating both their approaching behavior and central kisspeptin neurons. Copyright © 2017 Elsevier Inc. All rights reserved.

FlyMAD: rapid thermogenetic control of neuronal activity in freely walking Drosophila.

Science.gov (United States)

Bath, Daniel E; Stowers, John R; Hörmann, Dorothea; Poehlmann, Andreas; Dickson, Barry J; Straw, Andrew D

2014-07-01

Rapidly and selectively modulating the activity of defined neurons in unrestrained animals is a powerful approach in investigating the circuit mechanisms that shape behavior. In Drosophila melanogaster, temperature-sensitive silencers and activators are widely used to control the activities of genetically defined neuronal cell types. A limitation of these thermogenetic approaches, however, has been their poor temporal resolution. Here we introduce FlyMAD (the fly mind-altering device), which allows thermogenetic silencing or activation within seconds or even fractions of a second. Using computer vision, FlyMAD targets an infrared laser to freely walking flies. As a proof of principle, we demonstrated the rapid silencing and activation of neurons involved in locomotion, vision and courtship. The spatial resolution of the focused beam enabled preferential targeting of neurons in the brain or ventral nerve cord. Moreover, the high temporal resolution of FlyMAD allowed us to discover distinct timing relationships for two neuronal cell types previously linked to courtship song.

Electrical Activity in a Time-Delay Four-Variable Neuron Model under Electromagnetic Induction

Directory of Open Access Journals (Sweden)

Keming Tang

2017-11-01

Full Text Available To investigate the effect of electromagnetic induction on the electrical activity of neuron, the variable for magnetic flow is used to improve Hindmarsh–Rose neuron model. Simultaneously, due to the existence of time-delay when signals are propagated between neurons or even in one neuron, it is important to study the role of time-delay in regulating the electrical activity of the neuron. For this end, a four-variable neuron model is proposed to investigate the effects of electromagnetic induction and time-delay. Simulation results suggest that the proposed neuron model can show multiple modes of electrical activity, which is dependent on the time-delay and external forcing current. It means that suitable discharge mode can be obtained by selecting the time-delay or external forcing current, which could be helpful for further investigation of electromagnetic radiation on biological neuronal system.

Pharmacological activation/inhibition of the cannabinoid system affects alcohol withdrawal-induced neuronal hypersensitivity to excitotoxic insults.

Directory of Open Access Journals (Sweden)

Marina Rubio

Full Text Available Cessation of chronic ethanol consumption can increase the sensitivity of the brain to excitotoxic damages. Cannabinoids have been proposed as neuroprotectants in different models of neuronal injury, but their effect have never been investigated in a context of excitotoxicity after alcohol cessation. Here we examined the effects of the pharmacological activation/inhibition of the endocannabinoid system in an in vitro model of chronic ethanol exposure and withdrawal followed by an excitotoxic challenge. Ethanol withdrawal increased N-methyl-D-aspartate (NMDA-evoked neuronal death, probably by altering the ratio between GluN2A and GluN2B NMDA receptor subunits. The stimulation of the endocannabinoid system with the cannabinoid agonist HU-210 decreased NMDA-induced neuronal death exclusively in ethanol-withdrawn neurons. This neuroprotection could be explained by a decrease in NMDA-stimulated calcium influx after the administration of HU-210, found exclusively in ethanol-withdrawn neurons. By contrast, the inhibition of the cannabinoid system with the CB1 receptor antagonist rimonabant (SR141716 during ethanol withdrawal increased death of ethanol-withdrawn neurons without any modification of NMDA-stimulated calcium influx. Moreover, chronic administration of rimonabant increased NMDA-stimulated toxicity not only in withdrawn neurons, but also in control neurons. In summary, we show for the first time that the stimulation of the endocannabinoid system is protective against the hyperexcitability developed during alcohol withdrawal. By contrast, the blockade of the endocannabinoid system is highly counterproductive during alcohol withdrawal.

MDMA Decreases Gluatamic Acid Decarboxylase (GAD) 67-Immunoreactive Neurons in the Hippocampus and Increases Seizure Susceptibility: Role for Glutamate

Science.gov (United States)

Huff, Courtney L.; Morano, Rachel L.; Herman, James P.; Yamamoto, Bryan K.; Gudelsky, Gary A.

2016-01-01

3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37–58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30 days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures. PMID:27773601

MDMA decreases glutamic acid decarboxylase (GAD) 67-immunoreactive neurons in the hippocampus and increases seizure susceptibility: Role for glutamate.

Science.gov (United States)

Huff, Courtney L; Morano, Rachel L; Herman, James P; Yamamoto, Bryan K; Gudelsky, Gary A

2016-12-01

3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37-58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures. Copyright © 2016 Elsevier B.V. All rights reserved.

Urethane anesthesia depresses activities of thalamocortical neurons and alters its response to nociception in terms of dual firing modes

Directory of Open Access Journals (Sweden)

Yeowool eHuh

2013-10-01

Full Text Available Anesthetics are often used to characterize the activity of single neurons in-vivo for its advantages such as reduced noise level and convenience in noxious stimulations. Of the anesthetics, urethane had been widely used in some thalamic studies under the assumption that sensory signals are still relayed to the thalamus under urethane anesthesia and that thalamic response would therefore reflect the response of the awake state. We tested whether this assumption stands by comparing thalamic activity in terms of tonic and burst firing modes during ‘the awake state’ or under ‘urethane anesthesia’ utilizing the extracellular single unit recording technique. First we have tested how thalamic relay neurons respond to the introduction of urethane and then tested how urethane influences thalamic discharges under formalin-induced nociception. Urethane significantly depressed overall firing rates of thalamic relay neurons, which was sustained despite the delayed increase of burst activity over the 4 hour recording period. Thalamic response to nociception under anesthesia was also similar overall except for the slight and transient increase of burst activity. Overall, results demonstrated that urethane suppresses the activity of thalamic relay neurons and that, despite the slight fluctuation of burst firing, formalin-induced nociception cannot significantly change the firing pattern of thalamic relay neurons that was caused by urethane.

Stimulation of renal afferent fibers leads to activation of catecholaminergic and non-catecholaminergic neurons in the medulla oblongata.

Science.gov (United States)

Nishi, Erika E; Martins, Beatriz S; Milanez, Maycon I O; Lopes, Nathalia R; de Melo, Jose F; Pontes, Roberto B; Girardi, Adriana C; Campos, Ruy R; Bergamaschi, Cássia T

2017-05-01

Presympathetic neurons in the rostral ventrolateral medulla (RVLM) including the adrenergic cell groups play a major role in the modulation of several reflexes required for the control of sympathetic vasomotor tone and blood pressure (BP). Moreover, sympathetic vasomotor drive to the kidneys influence natriuresis and diuresis by inhibiting the cAMP/PKA pathway and redistributing the Na + /H + exchanger isoform 3 (NHE3) to the body of the microvilli in the proximal tubules. In this study we aimed to evaluate the effects of renal afferents stimulation on (1) the neurochemical phenotype of Fos expressing neurons in the medulla oblongata and (2) the level of abundance and phosphorylation of NHE3 in the renal cortex. We found that electrical stimulation of renal afferents increased heart rate and BP transiently and caused activation of tyrosine hydroxylase (TH)-containing neurons in the RVLM and non-TH neurons in the NTS. Additionally, activation of the inhibitory renorenal reflex over a 30-min period resulted in increased natriuresis and diuresis associated with increased phosphorylation of NHE3 at serine 552, a surrogate for reduced activity of this exchanger, in the contralateral kidney. This effect was not dependent of BP changes considering that no effects on natriuresis or diuresis were found in the ipsilateral-stimulated kidney. Therefore, our data show that renal afferents leads to activation of catecholaminergic and non-catecholaminergic neurons in the medulla oblongata. When renorenal reflex is induced, NHE3 exchanger activity appears to be decreased, resulting in decreased sodium and water reabsorption in the contralateral kidney. Copyright © 2017 Elsevier B.V. All rights reserved.

Manipulating neuronal activity with low frequency transcranial ultrasound

Science.gov (United States)

Moore, Michele Elizabeth

Stimulation of the rodent cerebral cortex is used to investigate the underlying biological basis for the restorative effects of slow wave sleep. Neuronal activation by optogenetic and ultrasound stimulation elicits changes in action potentials across the cerebral cortex that are recorded as electroencephalograms. Optogenetic stimulation requires an invasive implantation procedure limiting its application in human studies. We sought to determine whether ultrasound stimulation could be as effective as optogenetic techniques currently used, in an effort to further understand the physiological and metabolic requirements of sleep. We successfully recorded electroencephalograms in response to transcranial ultrasound stimulation of the barrel cortex at 1 and 7 Hz frequencies, comparing them to those recorded in response to optogenetic stimuli applied at the same frequencies. Our results showed application of a 473 nm blue LED positioned 6 cm above the skull and ultrasound stimulation at an output voltage of 1000 mVpp produced electroencephalograms with physiological responses of similar amplitude. We concluded that there exists an intensity-proportionate response in the optogenetic stimulation, but not with ultrasound stimulation at the frequencies we surveyed. Activation of neuronal cells in response to optogenetic stimulation in a Thy1-ChR2 transgenic mouse line is specifically targeted to pyramidal cells in the cerebral cortex. ChR2 responses to optogenetic stimulation are mediated by a focal activation of neuronal ion channels. We measured electrophysiological responses to ultrasound stimulation, comparing them to those recorded from optogenetic stimuli. Our results show striking similarities between ultrasound-induced responses and optogenetically-induced responses, which may indicate that transcranial ultrasound stimulation is also mediated by ion channel dependent processes in cerebral cortical neurons. The biophysical substrates for electrical excitability of

CALHM1 deficiency impairs cerebral neuron activity and memory flexibility in mice.

Science.gov (United States)

Vingtdeux, Valérie; Chang, Eric H; Frattini, Stephen A; Zhao, Haitian; Chandakkar, Pallavi; Adrien, Leslie; Strohl, Joshua J; Gibson, Elizabeth L; Ohmoto, Makoto; Matsumoto, Ichiro; Huerta, Patricio T; Marambaud, Philippe

2016-04-12

CALHM1 is a cell surface calcium channel expressed in cerebral neurons. CALHM1 function in the brain remains unknown, but recent results showed that neuronal CALHM1 controls intracellular calcium signaling and cell excitability, two mechanisms required for synaptic function. Here, we describe the generation of Calhm1 knockout (Calhm1(-/-)) mice and investigate CALHM1 role in neuronal and cognitive functions. Structural analysis revealed that Calhm1(-/-) brains had normal regional and cellular architecture, and showed no evidence of neuronal or synaptic loss, indicating that CALHM1 deficiency does not affect brain development or brain integrity in adulthood. However, Calhm1(-/-) mice showed a severe impairment in memory flexibility, assessed in the Morris water maze, and a significant disruption of long-term potentiation without alteration of long-term depression, measured in ex vivo hippocampal slices. Importantly, in primary neurons and hippocampal slices, CALHM1 activation facilitated the phosphorylation of NMDA and AMPA receptors by protein kinase A. Furthermore, neuronal CALHM1 activation potentiated the effect of glutamate on the expression of c-Fos and C/EBPβ, two immediate-early gene markers of neuronal activity. Thus, CALHM1 controls synaptic activity in cerebral neurons and is required for the flexible processing of memory in mice. These results shed light on CALHM1 physiology in the mammalian brain.

Possible involvement of 12-lipoxygenase activation in glucose-deprivation/reload-treated neurons.

Science.gov (United States)

Nagasawa, Kazuki; Kakuda, Taichi; Higashi, Youichirou; Fujimoto, Sadaki

2007-12-18

The aim of this study was to clarify whether 12-lipoxygenase (12-LOX) activation was involved in reactive oxygen species (ROS) generation, extensive poly(ADP-ribose) polymerase (PARP) activation and neuronal death induced by glucose-deprivation, followed by glucose-reload (GD/R). The decrease of neuronal viability and accumulation of poly(ADP-ribose) induced by GD/R were prevented 3-aminobenzamide, a representative PARP inhibitor, demonstrating this treatment protocol caused the same oxidative stress with the previously reported one. The PARP activation, ROS generation and decrease of neuron viability induced by GD/R treatment were almost completely abolished by an extracellular zinc chelator, CaEDTA. p47(phox), a cytosolic component of NADPH oxidase was translocated the membrane fraction by GD/R, indicating its activation, but it did not generate detectable ROS. Surprisingly, pharmacological inhibition of NADPH oxidase with apocynin and AEBSF further decreased the decreased neuron viability induced by GD/R. On the other hand, AA861, a 12-LOX inhibitor, prevented ROS generation and decrease of neuron viability caused by GD/R. Interestingly, an antioxidant, N-acetyl-l-cysteine rescued the neurons from GD/R-induced oxidative stress, implying effectiveness of antioxidant administration. These findings suggested that activation of 12-LOX, but not NADPH oxidase, following to zinc release might play an important role in ROS generation and decrease of viability in GD/R-treated neurons.

CRF1 receptor activation increases the response of neurons in the basolateral nucleus of the amygdala to afferent stimulation

Directory of Open Access Journals (Sweden)

2008-07-01

Full Text Available The basolateral nucleus (BLA of the amygdala contributes to the consolidation of memories for emotional or stressful events. The nucleus contains a high density of CRF1 receptors that are activated by corticotropin-releasing factor (CRF. Modulation of the excitability of neurons in the BLA by CRF may regulate the immediate response to stressful events and the formation of associated memories. In the present study, CRF was found to increase the amplitude of field potentials recorded in the BLA following excitatory afferent stimulation, in vitro. The increase was mediated by CRF1 receptors, since it could be blocked by the selective, non-peptide antagonists, NBI30775 and NBI35583, but not by the CRF2-selective antagonist, astressin 2B. Furthermore, the CRF2-selective agonist, urocortin II had no effect on field potential amplitude. The increase induced by CRF was long-lasting, could not be reversed by subsequent administration of NBI35583, and required the activation of protein kinase C. This effect of CRF in the BLA may be important for increasing the salience of aversive stimuli under stressful conditions, and for enhancing the consolidation of associated memories. The results provide further justification for studying the efficacy of selective antagonists of the CRF1 receptor to reduce memory formation linked to emotional or traumatic events, and suggest that these compounds might be useful as prophylactic treatment for stress-related illness such as post-traumatic stress disorder.

Mitogen-activated protein kinase phosphatase (MKP)-1 as a neuroprotective agent: promotion of the morphological development of midbrain dopaminergic neurons.

Science.gov (United States)

Collins, Louise M; O'Keeffe, Gerard W; Long-Smith, Caitriona M; Wyatt, Sean L; Sullivan, Aideen M; Toulouse, André; Nolan, Yvonne M

2013-06-01

A greater understanding of the mechanisms that promote the survival and growth of dopaminergic neurons is essential for the advancement of cell replacement therapies for Parkinson's disease (PD). Evidence supports a role for the mitogen-activated protein kinase p38 in the demise of dopaminergic neurons, while mitogen-activated protein kinase phosphatase-1 (MKP-1), which negatively regulates p38 activity, has not yet been investigated in this context. Here, we show that MKP-1 is expressed in dopaminergic neurons cultured from E14 rat ventral mesencephalon (VM). When dopaminergic neurons were transfected to overexpress MKP-1, they displayed a more complex morphology than their control counterparts in vitro. Specifically, MKP-1-transfection induced significant increases in neurite length and branching with a maximum increase observed in primary branches. We demonstrate that inhibition of dopaminergic neurite growth induced by treatment of rat VM neurons with the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA) in vitro is mediated by p38 and is concomitant with a significant and selective decrease in MKP-1 expression in these neurons. We further show that overexpression of MKP-1 in dopaminergic neurons contributes to neuroprotection against the effects of 6-OHDA. Collectively, we report that MKP-1 can promote the growth and elaboration of dopaminergic neuronal processes and can help protect them from the neurotoxic effects of 6-OHDA. Thus, we propose that strategies aimed at augmenting MKP-1 expression or activity may be beneficial in protecting dopaminergic neurons and may provide potential therapeutic approaches for PD.

P21-activated kinase 2 (PAK2) regulates glucose uptake and insulin sensitivity in neuronal cells.

Science.gov (United States)

Varshney, Pallavi; Dey, Chinmoy Sankar

2016-07-05

P21-activated kinases (PAKs) are recently reported as important players of insulin signaling and glucose homeostasis in tissues like muscle, pancreas and liver. However, their role in neuronal insulin signaling is still unknown. Present study reports the involvement of PAK2 in neuronal insulin signaling, glucose uptake and insulin resistance. Irrespective of insulin sensitivity, insulin stimulation decreased PAK2 activity. PAK2 downregulation displayed marked enhancement of GLUT4 translocation with increase in glucose uptake whereas PAK2 over-expression showed its reduction. Treatment with Akti-1/2 and wortmannin suggested that Akt and PI3K are mediators of insulin effect on PAK2 and glucose uptake. Rac1 inhibition demonstrated decreased PAK2 activity while inhibition of PP2A resulted in increased PAK2 activity, with corresponding changes in glucose uptake. Taken together, present study demonstrates an inhibitory role of insulin signaling (via PI3K-Akt) and PP2A on PAK2 activity and establishes PAK2 as a Rac1-dependent negative regulator of neuronal glucose uptake and insulin sensitivity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Aldosterone-Sensing Neurons in the NTS Exhibit State-Dependent Pacemaker Activity and Drive Sodium Appetite via Synergy with Angiotensin II Signaling.

Science.gov (United States)

Resch, Jon M; Fenselau, Henning; Madara, Joseph C; Wu, Chen; Campbell, John N; Lyubetskaya, Anna; Dawes, Brian A; Tsai, Linus T; Li, Monica M; Livneh, Yoav; Ke, Qingen; Kang, Peter M; Fejes-Tóth, Géza; Náray-Fejes-Tóth, Anikó; Geerling, Joel C; Lowell, Bradford B

2017-09-27

Sodium deficiency increases angiotensin II (ATII) and aldosterone, which synergistically stimulate sodium retention and consumption. Recently, ATII-responsive neurons in the subfornical organ (SFO) and aldosterone-sensitive neurons in the nucleus of the solitary tract (NTS HSD2 neurons) were shown to drive sodium appetite. Here we investigate the basis for NTS HSD2 neuron activation, identify the circuit by which NTS HSD2 neurons drive appetite, and uncover an interaction between the NTS HSD2 circuit and ATII signaling. NTS HSD2 neurons respond to sodium deficiency with spontaneous pacemaker-like activity-the consequence of "cardiac" HCN and Na v 1.5 channels. Remarkably, NTS HSD2 neurons are necessary for sodium appetite, and with concurrent ATII signaling their activity is sufficient to produce rapid consumption. Importantly, NTS HSD2 neurons stimulate appetite via projections to the vlBNST, which is also the effector site for ATII-responsive SFO neurons. The interaction between angiotensin signaling and NTS HSD2 neurons provides a neuronal context for the long-standing "synergy hypothesis" of sodium appetite regulation. Copyright © 2017 Elsevier Inc. All rights reserved.

Activation of Wnt Signaling in Cortical Neurons Enhances Glucose Utilization through Glycolysis.

Science.gov (United States)

Cisternas, Pedro; Salazar, Paulina; Silva-Álvarez, Carmen; Barros, L Felipe; Inestrosa, Nibaldo C

2016-12-09

The Wnt signaling pathway is critical for a number of functions in the central nervous system, including regulation of the synaptic cleft structure and neuroprotection against injury. Deregulation of Wnt signaling has been associated with several brain pathologies, including Alzheimer's disease. In recent years, it has been suggested that the Wnt pathway might act as a central integrator of metabolic signals from peripheral organs to the brain, which would represent a new role for Wnt signaling in cell metabolism. Energy metabolism is critical for normal neuronal function, which mainly depends on glucose utilization. Brain energy metabolism is important in almost all neurological disorders, to which a decrease in the capacity of the brain to utilize glucose has been linked. However, little is known about the relationship between Wnt signaling and neuronal glucose metabolism in the cellular context. In the present study, we found that acute treatment with the Wnt3a ligand induced a large increase in glucose uptake, without changes in the expression or localization of glucose transporter type 3. In addition, we observed that Wnt3a treatment increased the activation of the metabolic sensor Akt. Moreover, we observed an increase in the activity of hexokinase and in the glycolytic rate, and both processes were dependent on activation of the Akt pathway. Furthermore, we did not observe changes in the activity of glucose-6-phosphate dehydrogenase or in the pentose phosphate pathway. The effect of Wnt3a was independent of both the transcription of Wnt target genes and synaptic effects of Wnt3a. Together, our results suggest that Wnt signaling stimulates glucose utilization in cortical neurons through glycolysis to satisfy the high energy demand of these cells. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Acquisition, extinction, and recall of opiate reward memory are signaled by dynamic neuronal activity patterns in the prefrontal cortex.

Science.gov (United States)

Sun, Ninglei; Chi, Ning; Lauzon, Nicole; Bishop, Stephanie; Tan, Huibing; Laviolette, Steven R

2011-12-01

The medial prefrontal cortex (mPFC) comprises an important component in the neural circuitry underlying drug-related associative learning and memory processing. Neuronal activation within mPFC circuits is correlated with the recall of opiate-related drug-taking experiences in both humans and other animals. Using an unbiased associative place conditioning procedure, we recorded mPFC neuronal populations during the acquisition, recall, and extinction phases of morphine-related associative learning and memory. Our analyses revealed that mPFC neurons show increased activity both in terms of tonic and phasic activity patterns during the acquisition phase of opiate reward-related memory and demonstrate stimulus-locked associative activity changes in real time, during the recall of opiate reward memories. Interestingly, mPFC neuronal populations demonstrated divergent patterns of bursting activity during the acquisition versus recall phases of newly acquired opiate reward memory, versus the extinction of these memories, with strongly increased bursting during the recall of an extinction memory and no associative bursting during the recall of a newly acquired opiate reward memory. Our results demonstrate that neurons within the mPFC are involved in both the acquisition, recall, and extinction of opiate-related reward memories, showing unique patterns of tonic and phasic activity patterns during these separate components of the opiate-related reward learning and memory recall.

Regulation of Energy Stores and Feeding by Neuronal and Peripheral CREB Activity in Drosophila

Science.gov (United States)

Iijima, Koichi; Zhao, LiJuan; Shenton, Christopher; Iijima-Ando, Kanae

2009-01-01

The cAMP-responsive transcription factor CREB functions in adipose tissue and liver to regulate glycogen and lipid metabolism in mammals. While Drosophila has a homolog of mammalian CREB, dCREB2, its role in energy metabolism is not fully understood. Using tissue-specific expression of a dominant-negative form of CREB (DN-CREB), we have examined the effect of blocking CREB activity in neurons and in the fat body, the primary energy storage depot with functions of adipose tissue and the liver in flies, on energy balance, stress resistance and feeding behavior. We found that disruption of CREB function in neurons reduced glycogen and lipid stores and increased sensitivity to starvation. Expression of DN-CREB in the fat body also reduced glycogen levels, while it did not affect starvation sensitivity, presumably due to increased lipid levels in these flies. Interestingly, blocking CREB activity in the fat body increased food intake. These flies did not show a significant change in overall body size, suggesting that disruption of CREB activity in the fat body caused an obese-like phenotype. Using a transgenic CRE-luciferase reporter, we further demonstrated that disruption of the adipokinetic hormone receptor, which is functionally related to mammalian glucagon and β-adrenergic signaling, in the fat body reduced CRE-mediated transcription in flies. This study demonstrates that CREB activity in either neuronal or peripheral tissues regulates energy balance in Drosophila, and that the key signaling pathway regulating CREB activity in peripheral tissue is evolutionarily conserved. PMID:20041126

Regulation of autophagy by AMP-activated protein kinase/sirtuin 1 pathway reduces spinal cord neurons damage.

Science.gov (United States)

Yan, Peng; Bai, Liangjie; Lu, Wei; Gao, Yuzhong; Bi, Yunlong; Lv, Gang

2017-09-01

AMP-activated protein kinase/sirtuin 1 (AMPK/SIRT1) signaling pathway has been proved to be involved in the regulation of autophagy in various models. The aim of this study was to evaluate the effect of AMPK/SIRT1 pathway on autophagy after spinal cord injury (SCI). The SCI model was established in rats in vivo and the primary spinal cord neurons were subjected to mechanical injury (MI) in vitro . The apoptosis in spinal cord tissue and neurons was assessed by TUNEL staining and Hoechst 33342 staining, respectively. The autophagy-related proteins levels were detected by Western blot. The activation of AMPK/SIRT1 pathway was determined by Western blot and immunohistochemical staining. We found that the apoptosis of spinal cord tissue and cell damage of spinal cord neurons was obvious after the trauma. The ratio of LC3II/LC3I and level of p62 were first increased significantly and then decreased after the trauma in vivo and in vitro , indicating the defect in autophagy. The levels of p-AMPK and SIRT1 were increased obviously after the trauma in vivo and in vitro . Further activation of the AMPK/SIRT1 pathway by pretreatment with resveratrol, a confirmed activator of the AMPK/SIRT1 pathway, alleviated the cell damage and promoted the autophagy flux via downregulation of p62 in spinal cord neurons at 24 hr after MI. Our results demonstrate that regulation of autophagy by AMPK/SIRT1 pathway can restrain spinal cord neurons damage, which may be a potential intervention of SCI.

A natural form of learning can increase and decrease the survival of new neurons in the dentate gyrus.

Science.gov (United States)

Olariu, Ana; Cleaver, Kathryn M; Shore, Lauren E; Brewer, Michelle D; Cameron, Heather A

2005-01-01

Granule cells born in the adult dentate gyrus undergo a 4-week developmental period characterized by high susceptibility to cell death. Two forms of hippocampus-dependent learning have been shown to rescue many of the new neurons during this critical period. Here, we show that a natural form of associative learning, social transmission of food preference (STFP), can either increase or decrease the survival of young granule cells in adult rats. Increased numbers of pyknotic as well as phospho-Akt-expressing BrdU-labeled cells were seen 1 day after STFP training, indicating that training rapidly induces both cell death and active suppression of cell death in different subsets. A single day of training for STFP increased the survival of 8-day-old BrdU-labeled cells when examined 1 week later. In contrast, 2 days of training decreased the survival of BrdU-labeled cells and the density of immature neurons, identified with crmp-4. This change from increased to decreased survival could not be accounted for by the ages of the cells. Instead, we propose that training may initially increase young granule cell survival, then, if continued, cause them to die. This complex regulation of cell death could potentially serve to maintain granule cells that are actively involved in memory consolidation, while rapidly using and discarding young granule cells whose training is complete to make space for new naïve neurons. Published 2005 Wiley-Liss, Inc.

Cholinergic activation of neurons in the medulla oblongata changes urinary bladder activity by plasma vasopressin release in female rats.

Science.gov (United States)

Cafarchio, Eduardo M; da Silva, Luiz A; Auresco, Luciana C; Ogihara, Cristiana A; Almeida, Roberto L; Giannocco, Gisele; Luz, Maria C B; Fonseca, Fernando L A; Sato, Monica A

2016-04-05

The central control of the micturition is dependent on cortical areas and other ascending and descending pathways in the brain stem. The descendent pathways from the pons to the urinary bladder (UB) can be direct or indirect through medullary neurons (MN). Chemical stimulation with l-glutamate of MN known for their involvement in cardiovascular regulation evokes changes in pelvic nerves activities, which innervate the urinary bladder. Different neurotransmitters have been found in medullary areas; nevertheless, their involvement in UB control is few understood. We focused to investigate if cholinergic activation of neurons in the medulla oblongata changes the urinary bladder activity. Carbachol (cholinergic agonist) or atropine (cholinergic antagonist) was injected into the 4thV in anesthetized female Wistar rats and the intravesical pressure (IP), mean arterial pressure (MAP), heart rate (HR) and renal conductance (RC) were recorded for 30 min. Carbachol injection into the 4thV increased IP with peak response at 30 min after carbachol and yielded no changes in MAP, HR and RC. Atropine injection into the 4thV decreased IP and elicited no changes in MAP, HR and RC. Plasma vasopressin levels evaluated by ELISA kit assay increased after carbachol into the 4th V. Intravenous blockade of V1 receptors prior to carbachol into the 4thV abolished the increase in IP evoked by carbachol. Therefore, our findings suggest that cholinergic activation of neurons in the medulla oblongata by carbachol injections into the 4thV increases IP due to plasma vasopressin release, which acts in V1 receptors in the UB. Copyright © 2016 Elsevier B.V. All rights reserved.

Cross-interval histogram analysis of neuronal activity on multi-electrode arrays

NARCIS (Netherlands)

Castellone, P.; Rutten, Wim; Marani, Enrico

2003-01-01

Cross-neuron-interval histogram (CNIH) analysis has been performed in order to study correlated activity and connectivity between pairs of neurons in a spontaneously active developing cultured network of rat cortical cells. Thirty-eight histograms could be analyzed using two parameters, one for the

Neuronal Activation After Prolonged Immobilization: Do the Same or Different Neurons Respond to a Novel Stressor?

Science.gov (United States)

Marín-Blasco, Ignacio; Muñoz-Abellán, Cristina; Andero, Raül; Nadal, Roser; Armario, Antonio

2018-04-01

Despite extensive research on the impact of emotional stressors on brain function using immediate-early genes (e.g., c-fos), there are still important questions that remain unanswered such as the reason for the progressive decline of c-fos expression in response to prolonged stress and the neuronal populations activated by different stressors. This study tackles these 2 questions by evaluating c-fos expression in response to 2 different emotional stressors applied sequentially, and performing a fluorescent double labeling of c-Fos protein and c-fos mRNA on stress-related brain areas. Results were complemented with the assessment of the hypothalamic-pituitary-adrenal axis activation. We showed that the progressive decline of c-fos expression could be related to 2 differing mechanisms involving either transcriptional repression or changes in stimulatory inputs. Moreover, the neuronal populations that respond to the different stressors appear to be predominantly separated in high-level processing areas (e.g., medial prefrontal cortex). However, in low-hierarchy areas (e.g., paraventricular nucleus of the hypothalamus) neuronal populations appear to respond unspecifically. The data suggest that the distinct physiological and behavioral consequences of emotional stressors, and their implication in the development of psychopathologies, are likely to be closely associated with neuronal populations specifically activated by each stressor.

Nutrient-dependent increased dendritic arborization of somatosensory neurons.

Science.gov (United States)

Watanabe, Kaori; Furumizo, Yuki; Usui, Tadao; Hattori, Yukako; Uemura, Tadashi

2017-01-01

Suboptimal nutrition imposes developmental constraints on infant animals, which marshal adaptive responses to eventually become mature adults. Such responses are mounted at multiple levels from systemic to cellular. At the cellular level, the underlying mechanisms of cell proliferation control have been intensively studied. However, less is known about how growth of postmitotic and morphologically complex cells, such as neurons, is controlled by nutritional status. We address this question using Class I and Class IV dendritic arborization neurons in Drosophila larvae. Class IV neurons have been shown to sense nociceptive thermal, mechanical and light stimuli, whereas Class I neurons are proprioceptors. We reared larvae on diets with different protein and carbohydrate content throughout larval stages and examined how morphologies of Class I or Class IV neurons were affected. Dendritic arbors of Class IV neurons became more complex when larvae were reared on a low-yeast diet, which contains lower amounts of amino acids and other ingredients, compared to a high-yeast diet. In contrast, such low-yeast-dependent hyperarborization was not seen in Class I neurons. The physiological and metabolic implications of the hyperarborization phenotype are discussed in relation to a recent hypothesis that Class IV neurons sense protein-deficient stress and to our characterization of how the dietary yeast contents impacted larval metabolism. © 2016 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

Task-dependent changes in cross-level coupling between single neurons and oscillatory activity in multiscale networks.

Directory of Open Access Journals (Sweden)

Ryan T Canolty

Full Text Available Understanding the principles governing the dynamic coordination of functional brain networks remains an important unmet goal within neuroscience. How do distributed ensembles of neurons transiently coordinate their activity across a variety of spatial and temporal scales? While a complete mechanistic account of this process remains elusive, evidence suggests that neuronal oscillations may play a key role in this process, with different rhythms influencing both local computation and long-range communication. To investigate this question, we recorded multiple single unit and local field potential (LFP activity from microelectrode arrays implanted bilaterally in macaque motor areas. Monkeys performed a delayed center-out reach task either manually using their natural arm (Manual Control, MC or under direct neural control through a brain-machine interface (Brain Control, BC. In accord with prior work, we found that the spiking activity of individual neurons is coupled to multiple aspects of the ongoing motor beta rhythm (10-45 Hz during both MC and BC, with neurons exhibiting a diversity of coupling preferences. However, here we show that for identified single neurons, this beta-to-rate mapping can change in a reversible and task-dependent way. For example, as beta power increases, a given neuron may increase spiking during MC but decrease spiking during BC, or exhibit a reversible shift in the preferred phase of firing. The within-task stability of coupling, combined with the reversible cross-task changes in coupling, suggest that task-dependent changes in the beta-to-rate mapping play a role in the transient functional reorganization of neural ensembles. We characterize the range of task-dependent changes in the mapping from beta amplitude, phase, and inter-hemispheric phase differences to the spike rates of an ensemble of simultaneously-recorded neurons, and discuss the potential implications that dynamic remapping from oscillatory activity to

Neuron-derived IgG protects neurons from complement-dependent cytotoxicity.

Science.gov (United States)

Zhang, Jie; Niu, Na; Li, Bingjie; McNutt, Michael A

2013-12-01

Passive immunity of the nervous system has traditionally been thought to be predominantly due to the blood-brain barrier. This concept must now be revisited based on the existence of neuron-derived IgG. The conventional concept is that IgG is produced solely by mature B lymphocytes, but it has now been found to be synthesized by murine and human neurons. However, the function of this endogenous IgG is poorly understood. In this study, we confirm IgG production by rat cortical neurons at the protein and mRNA levels, with 69.0 ± 5.8% of cortical neurons IgG-positive. Injury to primary-culture neurons was induced by complement leading to increases in IgG production. Blockage of neuron-derived IgG resulted in more neuronal death and early apoptosis in the presence of complement. In addition, FcγRI was found in microglia and astrocytes. Expression of FcγR I in microglia was increased by exposure to neuron-derived IgG. Release of NO from microglia triggered by complement was attenuated by neuron-derived IgG, and this attenuation could be reversed by IgG neutralization. These data demonstrate that neuron-derived IgG is protective of neurons against injury induced by complement and microglial activation. IgG appears to play an important role in maintaining the stability of the nervous system.

Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

Directory of Open Access Journals (Sweden)

Patricia J Ward

Full Text Available Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2, we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2 to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555 was greater in mice that received optical treatment. Thus, the acute (1 hour, one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-. We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons.

Activation of extrasynaptic, but not synaptic, NMDA receptors modifies amyloid precursor protein expression pattern and increases amyloid-ß production.

Science.gov (United States)

Bordji, Karim; Becerril-Ortega, Javier; Nicole, Olivier; Buisson, Alain

2010-11-24

Calcium is a key mediator controlling essential neuronal functions depending on electrical activity. Altered neuronal calcium homeostasis affects metabolism of amyloid precursor protein (APP), leading to increased production of β-amyloid (Aβ), and contributing to the initiation of Alzheimer's disease (AD). A linkage between excessive glutamate receptor activation and neuronal Aβ release was established, and recent reports suggest that synaptic and extrasynaptic NMDA receptor (NMDAR) activation may have distinct consequences in plasticity, gene regulation, and neuronal death. Here, we report for the first time that prolonged activation of extrasynaptic NMDAR, but not synaptic NMDAR, dramatically increased the neuronal production of Aβ. This effect was preceded by a shift from APP695 to Kunitz protease inhibitory domain (KPI) containing APPs (KPI-APPs), isoforms exhibiting an important amyloidogenic potential. Conversely, after synaptic NMDAR activation, we failed to detect any KPI-APP expression and neuronal Aβ production was not modified. Calcium imaging data showed that intracellular calcium concentration after extrasynaptic NMDAR stimulation was lower than after synaptic activation. This suggests distinct signaling pathways for each pool of receptors. We found that modification of neuronal APP expression pattern triggered by extrasynaptic NMDAR activation was regulated at an alternative splicing level involving calcium-/calmodulin-dependent protein kinase IV, but overall APP expression remained identical. Finally, memantine dose-dependently inhibited extrasynaptic NMDAR-induced KPI-APPs expression as well as neuronal Aβ release. Altogether, these data suggest that a chronic activation of extrasynaptic NMDAR promotes amyloidogenic KPI-APP expression leading to neuronal Aβ release, representing a causal risk factor for developing AD.

Nesfatin-1 activates cardiac vagal neurons of nucleus ambiguus and elicits bradycardia in conscious rats.

Science.gov (United States)

Brailoiu, G Cristina; Deliu, Elena; Tica, Andrei A; Rabinowitz, Joseph E; Tilley, Douglas G; Benamar, Khalid; Koch, Walter J; Brailoiu, Eugen

2013-09-01

Nesfatin-1, a peptide whose receptor is yet to be identified, has been involved in the modulation of feeding, stress, and metabolic responses. More recently, increasing evidence supports a modulatory role for nesfatin-1 in autonomic and cardiovascular activity. This study was undertaken to test if the expression of nesfatin-1 in the nucleus ambiguus, a key site for parasympathetic cardiac control, may be correlated with a functional role. As we have previously demonstrated that nesfatin-1 elicits Ca²⁺ signaling in hypothalamic neurons, we first assessed the effect of this peptide on cytosolic Ca²⁺ in cardiac pre-ganglionic neurons of nucleus ambiguus. We provide evidence that nesfatin-1 increases cytosolic Ca²⁺ concentration via a Gi/o-coupled mechanism. The nesfatin-1-induced Ca²⁺ rise is critically dependent on Ca²⁺ influx via P/Q-type voltage-activated Ca²⁺ channels. Repeated administration of nesfatin-1 leads to tachyphylaxis. Furthermore, nesfatin-1 produces a dose-dependent depolarization of cardiac vagal neurons via a Gi/o-coupled mechanism. In vivo studies, using telemetric and tail-cuff monitoring of heart rate and blood pressure, indicate that microinjection of nesfatin-1 into the nucleus ambiguus produces bradycardia not accompanied by a change in blood pressure in conscious rats. Taken together, our results identify for the first time that nesfatin-1 decreases heart rate by activating cardiac vagal neurons of nucleus ambiguus. Our results indicate that nesfatin-1, one of the most potent feeding peptides, increases cytosolic Ca²⁺ by promoting Ca²⁺ influx via P/Q channels and depolarizes nucleus ambiguus neurons; both effects are Gi/o-mediated. In vivo studies indicate that microinjection of nesfatin-1 into nucleus ambiguus produces bradycardia in conscious rats. This is the first report that nesfatin-1 increases the parasympathetic cardiac tone. © 2013 International Society for Neurochemistry.

Acupuncture attenuates cognitive deficits and increases pyramidal neuron number in hippocampal CA1 area of vascular dementia rats.

Science.gov (United States)

Li, Fang; Yan, Chao-Qun; Lin, Li-Ting; Li, Hui; Zeng, Xiang-Hong; Liu, Yi; Du, Si-Qi; Zhu, Wen; Liu, Cun-Zhi

2015-04-28

Decreased cognition is recognized as one of the most severe and consistent behavioral impairments in dementia. Experimental studies have reported that acupuncture may improve cognitive deficits, relieve vascular dementia (VD) symptoms, and increase cerebral perfusion and electrical activity. Multi-infarction dementia was modeled in rats with 3% microemboli saline suspension. Two weeks after acupuncture at Zusanli (ST36), all rats were subjected to a hidden platform trial to test their 3-day spatial memory using the Morris water maze test. To estimate the numbers of pyramidal neuron, astrocytes, and synaptic boutons in hippocampal CA1 area, we adopted an unbiased stereology method to accurately sample and measure the size of cells. We found that acupuncture at ST36 significantly decreased the escape latency of VD rats. In addition, acupuncture significantly increased the pyramidal neuron number in hippocampal CA1 area (P area in any of the groups (P > 0.05). These findings suggest that acupuncture may improve cognitive deficits and increase pyramidal neuron number of hippocampal CA1 area in VD rats.

An electronic implementation for Liao's chaotic delayed neuron model with non-monotonous activation function

Energy Technology Data Exchange (ETDEWEB)

Duan Shukai [Department of Computer Science and Engineering, Chongqing University, Chongqing 400044 (China); School of Electronic and Information Engineering, Southwest University, Chongqing 400715 (China)], E-mail: duansk@swu.edu.cn; Liao Xiaofeng [Department of Computer Science and Engineering, Chongqing University, Chongqing 400044 (China)], E-mail: xfliao@cqu.edu.cn

2007-09-10

A new chaotic delayed neuron model with non-monotonously increasing transfer function, called as chaotic Liao's delayed neuron model, was recently reported and analyzed. An electronic implementation of this model is described in detail. At the same time, some methods in circuit design, especially for circuit with time delayed unit and non-monotonously increasing activation unit, are also considered carefully. We find that the dynamical behaviors of the designed circuits are closely similar to the results predicted by numerical experiments.

Preictal activity of subicular, CA1, and dentate gyrus principal neurons in the dorsal hippocampus before spontaneous seizures in a rat model of temporal lobe epilepsy.

Science.gov (United States)

Fujita, Satoshi; Toyoda, Izumi; Thamattoor, Ajoy K; Buckmaster, Paul S

2014-12-10

Previous studies suggest that spontaneous seizures in patients with temporal lobe epilepsy might be preceded by increased action potential firing of hippocampal neurons. Preictal activity is potentially important because it might provide new opportunities for predicting when a seizure is about to occur and insight into how spontaneous seizures are generated. We evaluated local field potentials and unit activity of single, putative excitatory neurons in the subiculum, CA1, CA3, and dentate gyrus of the dorsal hippocampus in epileptic pilocarpine-treated rats as they experienced spontaneous seizures. Average action potential firing rates of neurons in the subiculum, CA1, and dentate gyrus, but not CA3, increased significantly and progressively beginning 2-4 min before locally recorded spontaneous seizures. In the subiculum, CA1, and dentate gyrus, but not CA3, 41-57% of neurons displayed increased preictal activity with significant consistency across multiple seizures. Much of the increased preictal firing of neurons in the subiculum and CA1 correlated with preictal theta activity, whereas preictal firing of neurons in the dentate gyrus was independent of theta. In addition, some CA1 and dentate gyrus neurons displayed reduced firing rates preictally. These results reveal that different hippocampal subregions exhibit differences in the extent and potential underlying mechanisms of preictal activity. The finding of robust and significantly consistent preictal activity of subicular, CA1, and dentate neurons in the dorsal hippocampus, despite the likelihood that many seizures initiated in other brain regions, suggests the existence of a broader neuronal network whose activity changes minutes before spontaneous seizures initiate. Copyright © 2014 the authors 0270-6474/14/3416671-17$15.00/0.

Adenosine A2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats

Directory of Open Access Journals (Sweden)

Hui-Ling Diao

2017-11-01

Full Text Available The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

Models of the stochastic activity of neurones

CERN Document Server

Holden, Arun Vivian

1976-01-01

These notes have grown from a series of seminars given at Leeds between 1972 and 1975. They represent an attempt to gather together the different kinds of model which have been proposed to account for the stochastic activity of neurones, and to provide an introduction to this area of mathematical biology. A striking feature of the electrical activity of the nervous system is that it appears stochastic: this is apparent at all levels of recording, ranging from intracellular recordings to the electroencephalogram. The chapters start with fluctuations in membrane potential, proceed through single unit and synaptic activity and end with the behaviour of large aggregates of neurones: L have chgaen this seque~~e\\/~~';uggest that the interesting behaviourr~f :the nervous system - its individuality, variability and dynamic forms - may in part result from the stochastic behaviour of its components. I would like to thank Dr. Julio Rubio for reading and commenting on the drafts, Mrs. Doris Beighton for producing the fin...

Regulation of autophagy by AMP-activated protein kinase/ sirtuin 1 pathway reduces spinal cord neurons damage

Directory of Open Access Journals (Sweden)

Peng Yan

2017-09-01

Full Text Available Objective(s: AMP-activated protein kinase/sirtuin 1 (AMPK/SIRT1 signaling pathway has been proved to be involved in the regulation of autophagy in various models. The aim of this study was to evaluate the effect of AMPK/SIRT1 pathway on autophagy after spinal cord injury (SCI. Materials and Methods:The SCI model was established in rats in vivo and the primary spinal cord neurons were subjected to mechanical injury (MI in vitro. The apoptosis in spinal cord tissue and neurons was assessed by TUNEL staining and Hoechst 33342 staining, respectively. The autophagy-related proteins levels were detected by Western blot. The activation of AMPK/SIRT1 pathway was determined by Western blot and immunohistochemical staining. Results: We found that the apoptosis of spinal cord tissue and cell damage of spinal cord neurons was obvious after the trauma. The ratio of LC3II/LC3I and level of p62 were first increased significantly and then decreased after the trauma in vivo and in vitro, indicating the defect in autophagy. The levels of p-AMPK and SIRT1 were increased obviously after the trauma in vivo and in vitro. Further activation of the AMPK/SIRT1 pathway by pretreatment with resveratrol, a confirmed activator of the AMPK/SIRT1 pathway, alleviated the cell damage and promoted the autophagy flux via downregulation of p62 in spinal cord neurons at 24 hr after MI. Conclusion: Our results demonstrate that regulation of autophagy by AMPK/SIRT1 pathway can restrain spinal cord neurons damage, which may be a potential intervention of SCI.

Artificial Induction of Associative Olfactory Memory by Optogenetic and Thermogenetic Activation of Olfactory Sensory Neurons and Octopaminergic Neurons in Drosophila Larvae.

Science.gov (United States)

Honda, Takato; Lee, Chi-Yu; Honjo, Ken; Furukubo-Tokunaga, Katsuo

2016-01-01

The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain.

Urotensin II promotes vagal-mediated bradycardia by activating cardiac-projecting parasympathetic neurons of nucleus ambiguus.

Science.gov (United States)

Brailoiu, Gabriela Cristina; Deliu, Elena; Rabinowitz, Joseph E; Tilley, Douglas G; Koch, Walter J; Brailoiu, Eugen

2014-05-01

Urotensin II (U-II) is a cyclic undecapeptide that regulates cardiovascular function at central and peripheral sites. The functional role of U-II nucleus ambiguus, a key site controlling cardiac tone, has not been established, despite the identification of U-II and its receptor at this level. We report here that U-II produces an increase in cytosolic Ca(2+) concentration in retrogradely labeled cardiac vagal neurons of nucleus ambiguus via two pathways: (i) Ca(2+) release from the endoplasmic reticulum via inositol 1,4,5-trisphosphate receptor; and (ii) Ca(2+) influx through P/Q-type Ca(2+) channels. In addition, U-II depolarizes cultured cardiac parasympathetic neurons. Microinjection of increasing concentrations of U-II into nucleus ambiguus elicits dose-dependent bradycardia in conscious rats, indicating the in vivo activation of the cholinergic pathway controlling the heart rate. Both the in vitro and in vivo effects were abolished by the urotensin receptor antagonist, urantide. Our findings suggest that, in addition, to the previously reported increase in sympathetic outflow, U-II activates cardiac vagal neurons of nucleus ambiguus, which may contribute to cardioprotection. © 2014 International Society for Neurochemistry.

Modafinil enhances thalamocortical activity by increasing neuronal electrotonic coupling

Science.gov (United States)

Urbano, Francisco J.; Leznik, Elena; Llinás, Rodolfo R.

2007-01-01

Modafinil (Provigil, Modiodal), an antinarcoleptic and mood-enhancing drug, is shown here to sharpen thalamocortical activity and to increase electrical coupling between cortical interneurons and between nerve cells in the inferior olivary nucleus. After irreversible pharmacological block of connexin permeability (i.e., by using either 18β-glycyrrhetinic derivatives or mefloquine), modafinil restored electrotonic coupling within 30 min. It was further established that this restoration is implemented through a Ca2+/calmodulin protein kinase II-dependent step. PMID:17640897

Nanomolar bifenthrin alters synchronous Ca2+ oscillations and cortical neuron development independent of sodium channel activity.

Science.gov (United States)

Cao, Zhengyu; Cui, Yanjun; Nguyen, Hai M; Jenkins, David Paul; Wulff, Heike; Pessah, Isaac N

2014-04-01

Bifenthrin, a relatively stable type I pyrethroid that causes tremors and impairs motor activity in rodents, is broadly used. We investigated whether nanomolar bifenthrin alters synchronous Ca(2+) oscillations (SCOs) necessary for activity-dependent dendritic development. Primary mouse cortical neurons were cultured 8 or 9 days in vitro (DIV), loaded with the Ca(2+) indicator Fluo-4, and imaged using a Fluorescence Imaging Plate Reader Tetra. Acute exposure to bifenthrin rapidly increased the frequency of SCOs by 2.7-fold (EC50 = 58 nM) and decreased SCO amplitude by 36%. Changes in SCO properties were independent of modifications in voltage-gated sodium channels since 100 nM bifenthrin had no effect on the whole-cell Na(+) current, nor did it influence neuronal resting membrane potential. The L-type Ca(2+) channel blocker nifedipine failed to ameliorate bifenthrin-triggered SCO activity. By contrast, the metabotropic glutamate receptor (mGluR)5 antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine] normalized bifenthrin-triggered increase in SCO frequency without altering baseline SCO activity, indicating that bifenthrin amplifies mGluR5 signaling independent of Na(+) channel modification. Competitive [AP-5; (-)-2-amino-5-phosphonopentanoic acid] and noncompetitive (dizocilpine, or MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]) N-methyl-d-aspartate antagonists partially decreased both basal and bifenthrin-triggered SCO frequency increase. Bifenthrin-modified SCO rapidly enhanced the phosphorylation of cAMP response element-binding protein (CREB). Subacute (48 hours) exposure to bifenthrin commencing 2 DIV-enhanced neurite outgrowth and persistently increased SCO frequency and reduced SCO amplitude. Bifenthrin-stimulated neurite outgrowth and CREB phosphorylation were dependent on mGluR5 activity since MPEP normalized both responses. Collectively these data identify a new mechanism by which bifenthrin potently alters Ca(2

Silibinin activates AMP-activated protein kinase to protect neuronal cells from oxygen and glucose deprivation-re-oxygenation.

Science.gov (United States)

Xie, Zhi; Ding, Sheng-quan; Shen, Ya-fang

2014-11-14

In this study, we explored the cytoprotective potential of silibinin against oxygen-glucose deprivation (OGD)-induced neuronal cell damages, and studied underling mechanisms. In vitro model of ischemic stroke was created by keeping neuronal cells (SH-SY5Y cells and primary mouse cortical neurons) in an OGD condition followed by re-oxygenation. Pre-treatment of silibinin significantly inhibited OGD/re-oxygenation-induced necrosis and apoptosis of neuronal cells. OGD/re-oxygenation-induced reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) reduction were also inhibited by silibinin. At the molecular level, silibinin treatment in SH-SY5Y cells and primary cortical neurons led to significant AMP-activated protein kinase (AMPK) signaling activation, detected by phosphorylations of AMPKα1, its upstream kinase liver kinase B1 (LKB1) and the downstream target acetyl-CoA Carboxylase (ACC). Pharmacological inhibition or genetic depletion of AMPK alleviated the neuroprotective ability of silibinin against OGD/re-oxygenation. Further, ROS scavenging ability by silibinin was abolished with AMPK inhibition or silencing. While A-769662, the AMPK activator, mimicked silibinin actions and suppressed ROS production and neuronal cell death following OGD/re-oxygenation. Together, these results show that silibinin-mediated neuroprotection requires activation of AMPK signaling. Copyright © 2014 Elsevier Inc. All rights reserved.

GnRH Neuron Activity and Pituitary Response in Estradiol-Induced vs Proestrous Luteinizing Hormone Surges in Female Mice.

Science.gov (United States)

Silveira, Marina A; Burger, Laura L; DeFazio, R Anthony; Wagenmaker, Elizabeth R; Moenter, Suzanne M

2017-02-01

During the female reproductive cycle, estradiol exerts negative and positive feedback at both the central level to alter gonadotropin-releasing hormone (GnRH) release and at the pituitary to affect response to GnRH. Many studies of the neurobiologic mechanisms underlying estradiol feedback have been done on ovariectomized, estradiol-replaced (OVX+E) mice. In this model, GnRH neuron activity depends on estradiol and time of day, increasing in estradiol-treated mice in the late afternoon, coincident with a daily luteinizing hormone (LH) surge. Amplitude of this surge appears lower than in proestrous mice, perhaps because other ovarian factors are not replaced. We hypothesized GnRH neuron activity is greater during the proestrous-preovulatory surge than the estradiol-induced surge. GnRH neuron activity was monitored by extracellular recordings from fluorescently tagged GnRH neurons in brain slices in the late afternoon from diestrous, proestrous, and OVX+E mice. Mean GnRH neuron firing rate was low on diestrus; firing rate was similarly increased in proestrous and OVX+E mice. Bursts of action potentials have been associated with hormone release in neuroendocrine systems. Examination of the patterning of action potentials revealed a shift toward longer burst duration in proestrous mice, whereas intervals between spikes were shorter in OVX+E mice. LH response to an early afternoon injection of GnRH was greater in proestrous than diestrous or OVX+E mice. These observations suggest the lower LH surge amplitude observed in the OVX+E model is likely not attributable to altered mean GnRH neuron activity, but because of reduced pituitary sensitivity, subtle shifts in action potential pattern, and/or excitation-secretion coupling in GnRH neurons. Copyright © 2017 by the Endocrine Society.

A light- and calcium-gated transcription factor for imaging and manipulating activated neurons.

Science.gov (United States)

Wang, Wenjing; Wildes, Craig P; Pattarabanjird, Tanyaporn; Sanchez, Mateo I; Glober, Gordon F; Matthews, Gillian A; Tye, Kay M; Ting, Alice Y

2017-09-01

Activity remodels neurons, altering their molecular, structural, and electrical characteristics. To enable the selective characterization and manipulation of these neurons, we present FLARE, an engineered transcription factor that drives expression of fluorescent proteins, opsins, and other genetically encoded tools only in the subset of neurons that experienced activity during a user-defined time window. FLARE senses the coincidence of elevated cytosolic calcium and externally applied blue light, which together produce translocation of a membrane-anchored transcription factor to the nucleus to drive expression of any transgene. In cultured rat neurons, FLARE gives a light-to-dark signal ratio of 120 and a high- to low-calcium signal ratio of 10 after 10 min of stimulation. Opsin expression permitted functional manipulation of FLARE-marked neurons. In adult mice, FLARE also gave light- and motor-activity-dependent transcription in the cortex. Due to its modular design, minute-scale temporal resolution, and minimal dark-state leak, FLARE should be useful for the study of activity-dependent processes in neurons and other cells that signal with calcium.

CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

Science.gov (United States)

Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

2016-09-01

A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p ACM (p ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

Autaptic pacemaker mediated propagation of weak rhythmic activity across small-world neuronal networks

Science.gov (United States)

Yilmaz, Ergin; Baysal, Veli; Ozer, Mahmut; Perc, Matjaž

2016-02-01

We study the effects of an autapse, which is mathematically described as a self-feedback loop, on the propagation of weak, localized pacemaker activity across a Newman-Watts small-world network consisting of stochastic Hodgkin-Huxley neurons. We consider that only the pacemaker neuron, which is stimulated by a subthreshold periodic signal, has an electrical autapse that is characterized by a coupling strength and a delay time. We focus on the impact of the coupling strength, the network structure, the properties of the weak periodic stimulus, and the properties of the autapse on the transmission of localized pacemaker activity. Obtained results indicate the existence of optimal channel noise intensity for the propagation of the localized rhythm. Under optimal conditions, the autapse can significantly improve the propagation of pacemaker activity, but only for a specific range of the autaptic coupling strength. Moreover, the autaptic delay time has to be equal to the intrinsic oscillation period of the Hodgkin-Huxley neuron or its integer multiples. We analyze the inter-spike interval histogram and show that the autapse enhances or suppresses the propagation of the localized rhythm by increasing or decreasing the phase locking between the spiking of the pacemaker neuron and the weak periodic signal. In particular, when the autaptic delay time is equal to the intrinsic period of oscillations an optimal phase locking takes place, resulting in a dominant time scale of the spiking activity. We also investigate the effects of the network structure and the coupling strength on the propagation of pacemaker activity. We find that there exist an optimal coupling strength and an optimal network structure that together warrant an optimal propagation of the localized rhythm.

DRP1 Suppresses Leptin and Glucose Sensing of POMC Neurons.

Science.gov (United States)

Santoro, Anna; Campolo, Michela; Liu, Chen; Sesaki, Hiromi; Meli, Rosaria; Liu, Zhong-Wu; Kim, Jung Dae; Diano, Sabrina

2017-03-07

Hypothalamic pro-opiomelanocortin (POMC) neurons regulate energy and glucose metabolism. Intracellular mechanisms that enable these neurons to respond to changes in metabolic environment are ill defined. Here we show reduced expression of activated dynamin-related protein (pDRP1), a mitochondrial fission regulator, in POMC neurons of fed mice. These POMC neurons displayed increased mitochondrial size and aspect ratio compared to POMC neurons of fasted animals. Inducible deletion of DRP1 of mature POMC neurons (Drp1 fl/fl -POMC-cre:ER T2 ) resulted in improved leptin sensitivity and glucose responsiveness. In Drp1 fl/fl -POMC-cre:ER T2 mice, POMC neurons showed increased mitochondrial size, ROS production, and neuronal activation with increased expression of Kcnj11 mRNA regulated by peroxisome proliferator-activated receptor (PPAR). Furthermore, deletion of DRP1 enhanced the glucoprivic stimulus in these neurons, causing their stronger inhibition and a greater activation of counter-regulatory responses to hypoglycemia that were PPAR dependent. Together, these data unmasked a role for mitochondrial fission in leptin sensitivity and glucose sensing of POMC neurons. Copyright © 2017 Elsevier Inc. All rights reserved.

Water deprivation increases Fos expression in hypothalamic corticotropin-releasing factor neurons induced by right atrial distension in awake rats.

Science.gov (United States)

Benedetti, Mauricio; Rorato, Rodrigo; Castro, Margaret; Machado, Benedito H; Antunes-Rodrigues, Jose; Elias, Lucila L K

2008-11-01

Atrial mechanoreceptors, sensitive to stretch, contribute in regulating heart rate and intravascular volume. The information from those receptors reaches the nucleus tractus solitarius and then the paraventricular nucleus (PVN), known to have a crucial role in the regulation of cardiovascular function. Neurons in the PVN synthesize CRF, AVP, and oxytocin (OT). Stimulation of atrial mechanoreceptors was performed in awake rats implanted with a balloon at the junction of the superior vena cava and right atrium. Plasma ACTH, AVP, and OT concentrations and Fos, CRF, AVP, and OT immunolabeling in the PVN were determined after balloon inflation in hydrated and water-deprived rats. The distension of the balloon increased the plasma ACTH concentrations, which were higher in water-deprived than in hydrated rats (P neurons in the parvocellular PVN, which was higher in the water-deprived than in the hydrated group (P neurons after distension in hydrated and water-deprived groups, compared with respective controls. In conclusion, parvocellular CRF neurons showed an increase of Fos expression induced by stimulation of right atrial mechanoreceptors, suggesting that CRF participates in the cardiovascular reflex adjustments elicited by volume loading. Activation of CRF neurons in the PVN by cardiovascular reflex is affected by osmotic stimulation.

Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation.

Science.gov (United States)

Rocha, Sandra M; Saraiva, Tatiana; Cristóvão, Ana C; Ferreira, Raquel; Santos, Tiago; Esteves, Marta; Saraiva, Cláudia; Je, Goun; Cortes, Luísa; Valero, Jorge; Alves, Gilberto; Klibanov, Alexander; Kim, Yoon-Seong; Bernardino, Liliana

2016-06-04

Histamine is an amine widely known as a peripheral inflammatory mediator and as a neurotransmitter in the central nervous system. Recently, it has been suggested that histamine acts as an innate modulator of microglial activity. Herein, we aimed to disclose the role of histamine in microglial phagocytic activity and reactive oxygen species (ROS) production and to explore the consequences of histamine-induced neuroinflammation in dopaminergic (DA) neuronal survival. The effect of histamine on phagocytosis was assessed both in vitro by using a murine N9 microglial cell line and primary microglial cell cultures and in vivo. Cells were exposed to IgG-opsonized latex beads or phosphatidylserine (PS) liposomes to evaluate Fcγ or PS receptor-mediated microglial phagocytosis, respectively. ROS production and protein levels of NADPH oxidases and Rac1 were assessed as a measure of oxidative stress. DA neuronal survival was evaluated in vivo by counting the number of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) of mice. We found that histamine triggers microglial phagocytosis via histamine receptor 1 (H1R) activation and ROS production via H1R and H4R activation. By using apocynin, a broad NADPH oxidase (Nox) inhibitor, and Nox1 knockout mice, we found that the Nox1 signaling pathway is involved in both phagocytosis and ROS production induced by histamine in vitro. Interestingly, both apocynin and annexin V (used as inhibitor of PS-induced phagocytosis) fully abolished the DA neurotoxicity induced by the injection of histamine in the SN of adult mice in vivo. Blockade of H1R protected against histamine-induced Nox1 expression and death of DA neurons in vivo. Overall, our results highlight the relevance of histamine in the modulation of microglial activity that ultimately may interfere with neuronal survival in the context of Parkinson's disease (PD) and, eventually, other neurodegenerative diseases which are accompanied by microglia

Predictive features of persistent activity emergence in regular spiking and intrinsic bursting model neurons.

Directory of Open Access Journals (Sweden)

Kyriaki Sidiropoulou

Full Text Available Proper functioning of working memory involves the expression of stimulus-selective persistent activity in pyramidal neurons of the prefrontal cortex (PFC, which refers to neural activity that persists for seconds beyond the end of the stimulus. The mechanisms which PFC pyramidal neurons use to discriminate between preferred vs. neutral inputs at the cellular level are largely unknown. Moreover, the presence of pyramidal cell subtypes with different firing patterns, such as regular spiking and intrinsic bursting, raises the question as to what their distinct role might be in persistent firing in the PFC. Here, we use a compartmental modeling approach to search for discriminatory features in the properties of incoming stimuli to a PFC pyramidal neuron and/or its response that signal which of these stimuli will result in persistent activity emergence. Furthermore, we use our modeling approach to study cell-type specific differences in persistent activity properties, via implementing a regular spiking (RS and an intrinsic bursting (IB model neuron. We identify synaptic location within the basal dendrites as a feature of stimulus selectivity. Specifically, persistent activity-inducing stimuli consist of activated synapses that are located more distally from the soma compared to non-inducing stimuli, in both model cells. In addition, the action potential (AP latency and the first few inter-spike-intervals of the neuronal response can be used to reliably detect inducing vs. non-inducing inputs, suggesting a potential mechanism by which downstream neurons can rapidly decode the upcoming emergence of persistent activity. While the two model neurons did not differ in the coding features of persistent activity emergence, the properties of persistent activity, such as the firing pattern and the duration of temporally-restricted persistent activity were distinct. Collectively, our results pinpoint to specific features of the neuronal response to a given

Totarol prevents neuronal injury in vitro and ameliorates brain ischemic stroke: Potential roles of Akt activation and HO-1 induction

Energy Technology Data Exchange (ETDEWEB)

Gao, Yuanxue; Xu, Xiaojun; Chang, Sai; Wang, Yunjie; Xu, Yazhou; Ran, Siqi [Jiangsu Key Laboratory of Drug Screening, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009 (China); Huang, Zhangjian [Jiangsu Key Laboratory of Drug Discovery for Metabolic Diseases, China Pharmaceutical University, Nanjing 210009 (China); Li, Ping [Jiangsu Key Laboratory of Drug Screening, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009 (China); Li, Jia [National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 189 Guo Shoujing Road, Shanghai 201203 (China); Zhang, Luyong [Jiangsu Key Laboratory of Drug Screening, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009 (China); Saavedra, Juan M. [Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20057 (United States); Liao, Hong, E-mail: liaohong56@hotmail.com [Jiangsu Key Laboratory of Drug Screening, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009 (China); Pang, Tao, E-mail: tpang@cpu.edu.cn [Jiangsu Key Laboratory of Drug Screening, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009 (China); Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20057 (United States)

2015-12-01

The natural product totarol, a phenolic diterpenoid and a major constituent isolated from the sap of Podocarpus totara, has been reported to have a potent antimicrobial activity. In this study, we determined whether totarol possessed an additional neuroprotective activity in vitro and in vivo. We found that totarol prevented glutamate- and oxygen and glucose deprivation-induced neuronal death in primary rat cerebellar granule neuronal cells and cerebral cortical neurons. Totarol increased Akt and GSK-3β phosphorylation, Nrf2 and heme oxygenase-1 (HO-1) protein expressions and suppressed oxidative stress by increasing GSH and SOD activities. The PI3K/Akt inhibitor LY294002 prevented totarol neuroprotective effect by suppressing the totarol-induced changes in HO-1 expression and the activities of GSH and SOD. The HO-1 inhibitor ZnPPIX also prevented totarol-increased GSH and SOD activities. In a model of acute cerebral ischemic injury in Sprague–Dawley rats, produced by occlusion of the middle cerebral artery for 2 h followed by 22 h or 46 h of reperfusion, totarol significantly reduced infarct volume and improved the neurological deficit. In this model, totarol increased HO-1 expression and the activities of GSH and SOD. These observations suggest that totarol may be a novel activator of the Akt/HO-1 pathway protecting against ischemic stroke through reduction of oxidative stress. - Graphical abstract: It is unknown whether the natural product totarol has neuroprotective effects in vitro and in vivo. This study underscores that totarol prevents neuronal injury in vitro, not only by activating PI3K/Akt pathway, but also via induction of Nrf2, HO-1, GSH and SOD expressions. Totarol also ameliorated acute cerebral ischemic injury in a rat ischemic stroke model. The findings highlight that totarol may be exploited for protecting against ischemic stroke through Akt/HO-1 pathway. - Highlights: • Totarol protects glutamate- and OGD-induced neuronal injury in vitro. �

Totarol prevents neuronal injury in vitro and ameliorates brain ischemic stroke: Potential roles of Akt activation and HO-1 induction

International Nuclear Information System (INIS)

Gao, Yuanxue; Xu, Xiaojun; Chang, Sai; Wang, Yunjie; Xu, Yazhou; Ran, Siqi; Huang, Zhangjian; Li, Ping; Li, Jia; Zhang, Luyong; Saavedra, Juan M.; Liao, Hong; Pang, Tao

2015-01-01

The natural product totarol, a phenolic diterpenoid and a major constituent isolated from the sap of Podocarpus totara, has been reported to have a potent antimicrobial activity. In this study, we determined whether totarol possessed an additional neuroprotective activity in vitro and in vivo. We found that totarol prevented glutamate- and oxygen and glucose deprivation-induced neuronal death in primary rat cerebellar granule neuronal cells and cerebral cortical neurons. Totarol increased Akt and GSK-3β phosphorylation, Nrf2 and heme oxygenase-1 (HO-1) protein expressions and suppressed oxidative stress by increasing GSH and SOD activities. The PI3K/Akt inhibitor LY294002 prevented totarol neuroprotective effect by suppressing the totarol-induced changes in HO-1 expression and the activities of GSH and SOD. The HO-1 inhibitor ZnPPIX also prevented totarol-increased GSH and SOD activities. In a model of acute cerebral ischemic injury in Sprague–Dawley rats, produced by occlusion of the middle cerebral artery for 2 h followed by 22 h or 46 h of reperfusion, totarol significantly reduced infarct volume and improved the neurological deficit. In this model, totarol increased HO-1 expression and the activities of GSH and SOD. These observations suggest that totarol may be a novel activator of the Akt/HO-1 pathway protecting against ischemic stroke through reduction of oxidative stress. - Graphical abstract: It is unknown whether the natural product totarol has neuroprotective effects in vitro and in vivo. This study underscores that totarol prevents neuronal injury in vitro, not only by activating PI3K/Akt pathway, but also via induction of Nrf2, HO-1, GSH and SOD expressions. Totarol also ameliorated acute cerebral ischemic injury in a rat ischemic stroke model. The findings highlight that totarol may be exploited for protecting against ischemic stroke through Akt/HO-1 pathway. - Highlights: • Totarol protects glutamate- and OGD-induced neuronal injury in vitro. �

Glucose level determines excitatory or inhibitory effects of adiponectin on arcuate POMC neuron activity and feeding.

Science.gov (United States)

Suyama, Shigetomo; Maekawa, Fumihiko; Maejima, Yuko; Kubota, Naoto; Kadowaki, Takashi; Yada, Toshihiko

2016-08-09

Adiponectin regulates glucose and lipid metabolism, acting against metabolic syndrome and atherosclerosis. Accumulating evidence suggest that adiponectin acts on the brain including hypothalamic arcuate nucleus (ARC), where proopiomelanocortin (POMC) neurons play key roles in feeding regulation. Several studies have examined intracerebroventricular (ICV) injection of adiponectin and reported opposite effects, increase or decrease of food intake. These reports used different nutritional states. The present study aimed to clarify whether adiponectin exerts distinct effects on food intake and ARC POMC neurons depending on the glucose concentration. Adiponectin was ICV injected with or without glucose for feeding experiments and administered to ARC slices with high or low glucose for patch clamp experiments. We found that adiponectin at high glucose inhibited POMC neurons and increased food intake while at low glucose it exerted opposite effects. The results demonstrate that glucose level determines excitatory or inhibitory effects of adiponectin on arcuate POMC neuron activity and feeding.

Activation of the Basal Forebrain by the Orexin/Hypocretin Neurons: Orexin International Symposium

Science.gov (United States)

Arrigoni, Elda; Mochizuki, Takatoshi; Scammell, Thomas E.

2010-01-01

The orexin neurons play an essential role in driving arousal and in maintaining normal wakefulness. Lack of orexin neurotransmission produces a chronic state of hypoarousal characterized by excessive sleepiness, frequent transitions between wake and sleep, and episodes of cataplexy. A growing body of research now suggests that the basal forebrain (BF) may be a key site through which the orexin-producing neurons promote arousal. Here we review anatomical, pharmacological and electrophysiological studies on how the orexin neurons may promote arousal by exciting cortically-projecting neurons of the BF. Orexin fibers synapse on BF cholinergic neurons and orexin-A is released in the BF during waking. Local application of orexins excites BF cholinergic neurons, induces cortical release of acetylcholine, and promotes wakefulness. The orexin neurons also contain and probably co-release the inhibitory neuropeptide dynorphin. We found that orexin-A and dynorphin have specific effects on different classes of BF neurons that project to the cortex. Cholinergic neurons were directly excited by orexin-A, but did not respond to dynorphin. Non-cholinergic BF neurons that project to the cortex seem to comprise at least two populations with some directly excited by orexin that may represent wake-active, GABAergic neurons, whereas others did not respond to orexin but were inhibited by dynorphin and may be sleep-active, GABAergic neurons. This evidence suggests that the BF is a key site through which orexins activate the cortex and promotes behavioral arousal. In addition, orexins and dynorphin may act synergistically in the BF to promote arousal and improve cognitive performance. PMID:19723027

Basal ganglia neuronal activity during scanning eye movements in Parkinson's disease.

Directory of Open Access Journals (Sweden)

Tomáš Sieger

Full Text Available The oculomotor role of the basal ganglia has been supported by extensive evidence, although their role in scanning eye movements is poorly understood. Nineteen Parkinsońs disease patients, which underwent implantation of deep brain stimulation electrodes, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography in a scanning eye movement task by viewing a series of colored pictures selected from the International Affective Picture System. Four patients additionally underwent a visually guided saccade task. Microelectrode recordings were analyzed selectively from the subthalamic nucleus, substantia nigra pars reticulata and from the globus pallidus by the WaveClus program which allowed for detection and sorting of individual neurons. The relationship between neuronal firing rate and eye movements was studied by crosscorrelation analysis. Out of 183 neurons that were detected, 130 were found in the subthalamic nucleus, 30 in the substantia nigra and 23 in the globus pallidus. Twenty percent of the neurons in each of these structures showed eye movement-related activity. Neurons related to scanning eye movements were mostly unrelated to the visually guided saccades. We conclude that a relatively large number of basal ganglia neurons are involved in eye motion control. Surprisingly, neurons related to scanning eye movements differed from neurons activated during saccades suggesting functional specialization and segregation of both systems for eye movement control.

Basal ganglia neuronal activity during scanning eye movements in Parkinson's disease.

Science.gov (United States)

Sieger, Tomáš; Bonnet, Cecilia; Serranová, Tereza; Wild, Jiří; Novák, Daniel; Růžička, Filip; Urgošík, Dušan; Růžička, Evžen; Gaymard, Bertrand; Jech, Robert

2013-01-01

The oculomotor role of the basal ganglia has been supported by extensive evidence, although their role in scanning eye movements is poorly understood. Nineteen Parkinsońs disease patients, which underwent implantation of deep brain stimulation electrodes, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography in a scanning eye movement task by viewing a series of colored pictures selected from the International Affective Picture System. Four patients additionally underwent a visually guided saccade task. Microelectrode recordings were analyzed selectively from the subthalamic nucleus, substantia nigra pars reticulata and from the globus pallidus by the WaveClus program which allowed for detection and sorting of individual neurons. The relationship between neuronal firing rate and eye movements was studied by crosscorrelation analysis. Out of 183 neurons that were detected, 130 were found in the subthalamic nucleus, 30 in the substantia nigra and 23 in the globus pallidus. Twenty percent of the neurons in each of these structures showed eye movement-related activity. Neurons related to scanning eye movements were mostly unrelated to the visually guided saccades. We conclude that a relatively large number of basal ganglia neurons are involved in eye motion control. Surprisingly, neurons related to scanning eye movements differed from neurons activated during saccades suggesting functional specialization and segregation of both systems for eye movement control.

Royal Jelly Reduces Cholesterol Levels, Ameliorates Aβ Pathology and Enhances Neuronal Metabolic Activities in a Rabbit Model of Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Yongming Pan

2018-03-01

Full Text Available Alzheimer’s disease (AD is the most common form of dementia characterized by aggregation of amyloid β (Aβ and neuronal loss. One of the risk factors for AD is high cholesterol levels, which are known to promote Aβ deposition. Previous studies have shown that royal jelly (RJ, a product of worker bees, has potential neuroprotective effects and can attenuate Aβ toxicity. However, little is known about how RJ regulates Aβ formation and its effects on cholesterol levels and neuronal metabolic activities. Here, we investigated whether RJ can reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in an AD rabbit model induced by 2% cholesterol diet plus copper drinking water. Our results suggest that RJ significantly reduced the levels of plasma total cholesterol (TC and low density lipoprotein-cholesterol (LDL-C, and decreased the level of Aβ in rabbit brains. RJ was also shown to markedly ameliorate amyloid deposition in AD rabbits from Aβ immunohistochemistry and thioflavin-T staining. Furthermore, our study suggests that RJ can reduce the expression levels of β-site APP cleaving enzyme-1 (BACE1 and receptor for advanced glycation end products (RAGE, and increase the expression levels of low density lipoprotein receptor-related protein 1 (LRP-1 and insulin degrading enzyme (IDE. In addition, we found that RJ remarkably increased the number of neurons, enhanced antioxidant capacities, inhibited activated-capase-3 protein expression, and enhanced neuronal metabolic activities by increasing N-acetyl aspartate (NAA and glutamate and by reducing choline and myo-inositol in AD rabbits. Taken together, our data demonstrated that RJ could reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in AD rabbits, providing preclinical evidence that RJ treatment has the potential to protect neurons and prevent AD.

Apelin-13 enhances arcuate POMC neuron activity via inhibiting M-current.

Directory of Open Access Journals (Sweden)

Dong Kun Lee

Full Text Available The hypothalamus is a key element of the neural circuits that control energy homeostasis. Specific neuronal populations within the hypothalamus are sensitive to a variety of homeostatic indicators such as circulating nutrient levels and hormones that signal circulating glucose and body fat content. Central injection of apelin secreted by adipose tissues regulates feeding and glucose homeostasis. However, the precise neuronal populations and cellular mechanisms involved in these physiological processes remain unclear. Here we examine the electrophysiological impact of apelin-13 on proopiomelanocortin (POMC neuron activity. Approximately half of POMC neurons examined respond to apelin-13. Apelin-13 causes a dose-dependent depolarization. This effect is abolished by the apelin (APJ receptor antagonist. POMC neurons from animals pre-treated with pertussis toxin still respond to apelin, whereas the Gβγ signaling inhibitor gallein blocks apelin-mediated depolarization. In addition, the effect of apelin is inhibited by the phospholipase C and protein kinase inhibitors. Furthermore, single-cell qPCR analysis shows that POMC neurons express the APJ receptor, PLC-β isoforms, and KCNQ subunits (2, 3 and 5 which contribute to M-type current. Apelin-13 inhibits M-current that is blocked by the KCNQ channel inhibitor. Therefore, our present data indicate that apelin activates APJ receptors, and the resultant dissociation of the Gαq heterotrimer triggers a Gβγ-dependent activation of PLC-β signaling that inhibits M-current.

Endocannabinoids mediate neuron-astrocyte communication.

Science.gov (United States)

Navarrete, Marta; Araque, Alfonso

2008-03-27

Cannabinoid receptors play key roles in brain function, and cannabinoid effects in brain physiology and drug-related behavior are thought to be mediated by receptors present in neurons. Neuron-astrocyte communication relies on the expression by astrocytes of neurotransmitter receptors. Yet, the expression of cannabinoid receptors by astrocytes in situ and their involvement in the neuron-astrocyte communication remain largely unknown. We show that hippocampal astrocytes express CB1 receptors that upon activation lead to phospholipase C-dependent Ca2+ mobilization from internal stores. These receptors are activated by endocannabinoids released by neurons, increasing astrocyte Ca2+ levels, which stimulate glutamate release that activates NMDA receptors in pyramidal neurons. These results demonstrate the existence of endocannabinoid-mediated neuron-astrocyte communication, revealing that astrocytes are targets of cannabinoids and might therefore participate in the physiology of cannabinoid-related addiction. They also reveal the existence of an endocannabinoid-glutamate signaling pathway where astrocytes serve as a bridge for nonsynaptic interneuronal communication.

A very large number of GABAergic neurons are activated in the tuberal hypothalamus during paradoxical (REM sleep hypersomnia.

Directory of Open Access Journals (Sweden)

Emilie Sapin

Full Text Available We recently discovered, using Fos immunostaining, that the tuberal and mammillary hypothalamus contain a massive population of neurons specifically activated during paradoxical sleep (PS hypersomnia. We further showed that some of the activated neurons of the tuberal hypothalamus express the melanin concentrating hormone (MCH neuropeptide and that icv injection of MCH induces a strong increase in PS quantity. However, the chemical nature of the majority of the neurons activated during PS had not been characterized. To determine whether these neurons are GABAergic, we combined in situ hybridization of GAD(67 mRNA with immunohistochemical detection of Fos in control, PS deprived and PS hypersomniac rats. We found that 74% of the very large population of Fos-labeled neurons located in the tuberal hypothalamus after PS hypersomnia were GAD-positive. We further demonstrated combining MCH immunohistochemistry and GAD(67in situ hybridization that 85% of the MCH neurons were also GAD-positive. Finally, based on the number of Fos-ir/GAD(+, Fos-ir/MCH(+, and GAD(+/MCH(+ double-labeled neurons counted from three sets of double-staining, we uncovered that around 80% of the large number of the Fos-ir/GAD(+ neurons located in the tuberal hypothalamus after PS hypersomnia do not contain MCH. Based on these and previous results, we propose that the non-MCH Fos/GABAergic neuronal population could be involved in PS induction and maintenance while the Fos/MCH/GABAergic neurons could be involved in the homeostatic regulation of PS. Further investigations will be needed to corroborate this original hypothesis.

Effects of GABA microinjection into dorsal raphe nucleus on behavior and activity of lateral habenular neurons in mice.

Science.gov (United States)

Xiao, Jinyu; Song, Meiying; Li, Fengdan; Liu, Xiaofeng; Anwar, Alinur; Zhao, Hua

2017-12-01

The dorsal raphe nucleus (DRN) is a key site for 5-hydroxytryptamine (5-HT) synthesis and release. DRN dysfunction has been implicated in several stress-related disorders, including depression and anxiety. The lateral habenular nucleus (LHb) has been shown to inhibit the activity of DRN 5-HT neurons, and thus the LHb-DRN pathway plays an important role in the pathogenesis of depression. Although it is known that the LHb also receives the projection from the 5-HT neuron in the DRN, whether 5-HT neurons in the DRN can influence activity of the LHb in vivo and whether this effect is related to the induced behavioral changes have not been investigated. In the current study, we determined how injecting γ-aminobutyric acid (GABA) into the DRN to inhibit 5-HT neurons affected behavior and the changes in the activity of LHb neurons in mice. We found that GABA injection into the DRN induced depression-like behavior in mice, as indicated by increased immobility time, and decreased climbing time in the forced swimming test and the tail suspension test, decreased time spent in the center and total distance moved in the open field test. Using extracellular single unit recording, we showed that the firing rate of LHb neurons decreased after GABA microinjection into the DRN. Further, c-Fos expression in LHb neurons was inhibited. Together our results indicate that inhibition of DRN 5-HT neurons can cause decreased LHb activity and depression-like behavior in mice, however this depression-like behavior could be independent of the LHb activity. The observed decrease in LHb activity is probably due to the presence of a negative feedback loop between the DRN and the LHb, which may play a role in maintaining emotional homeostasis. Copyright © 2017 Elsevier Inc. All rights reserved.

Metabolic reprogramming during neuronal differentiation from aerobic glycolysis to neuronal oxidative phosphorylation.

Science.gov (United States)

Zheng, Xinde; Boyer, Leah; Jin, Mingji; Mertens, Jerome; Kim, Yongsung; Ma, Li; Ma, Li; Hamm, Michael; Gage, Fred H; Hunter, Tony

2016-06-10

How metabolism is reprogrammed during neuronal differentiation is unknown. We found that the loss of hexokinase (HK2) and lactate dehydrogenase (LDHA) expression, together with a switch in pyruvate kinase gene splicing from PKM2 to PKM1, marks the transition from aerobic glycolysis in neural progenitor cells (NPC) to neuronal oxidative phosphorylation. The protein levels of c-MYC and N-MYC, transcriptional activators of the HK2 and LDHA genes, decrease dramatically. Constitutive expression of HK2 and LDHA during differentiation leads to neuronal cell death, indicating that the shut-off aerobic glycolysis is essential for neuronal survival. The metabolic regulators PGC-1α and ERRγ increase significantly upon neuronal differentiation to sustain the transcription of metabolic and mitochondrial genes, whose levels are unchanged compared to NPCs, revealing distinct transcriptional regulation of metabolic genes in the proliferation and post-mitotic differentiation states. Mitochondrial mass increases proportionally with neuronal mass growth, indicating an unknown mechanism linking mitochondrial biogenesis to cell size.

Modulation of neuronal network activity with ghrelin

NARCIS (Netherlands)

Stoyanova, Irina; Rutten, Wim; le Feber, Jakob

2012-01-01

Ghrelin is a neuropeptide regulating multiple physiological processes, including high brain functions such as learning and memory formation. However, the effect of ghrelin on network activity patterns and developments has not been studied yet. Therefore, we used dissociated cortical neurons plated

Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

NARCIS (Netherlands)

Smeets, P.A.M.; Vidarsdottir, S.; Graaf, C. de; Stafleu, A.; Osch, M.J.P. van; Viergever, M.A.; Pijl, H.; Grond, J. van der

2007-01-01

We previously showed that hypothalamic neuronal activity, as measured by the blood oxygen level-dependent (BOLD) functional MRI signal, declines in response to oral glucose intake. To further explore the mechanism driving changes in hypothalamic neuronal activity in response to an oral glucose load,

Activation of synaptic and extrasynaptic glycine receptors by taurine in preoptic hypothalamic neurons.

Science.gov (United States)

Bhattarai, Janardhan Prasad; Park, Soo Joung; Chun, Sang Woo; Cho, Dong Hyu; Han, Seong Kyu

2015-11-03

Taurine is an essential amino-sulfonic acid having a fundamental function in the brain, participating in both cell volume regulation and neurotransmission. Using a whole cell voltage patch clamp technique, the taurine-activated neurotransmitter receptors in the preoptic hypothalamic area (PHA) neurons were investigated. In the first set of experiments, different concentrations of taurine were applied on PHA neurons. Taurine-induced responses were concentration-dependent. Taurine-induced currents were action potential-independent and sensitive to strychnine, suggesting the involvement of glycine receptors. In addition, taurine activated not only α-homomeric, but also αβ-heteromeric glycine receptors in PHA neurons. Interestingly, a low concentration of taurine (0.5mM) activated glycine receptors, whereas a higher concentration (3mM) activated both glycine and gamma-aminobutyric acid A (GABAA) receptors in PHA neurons. These results suggest that PHA neurons are influenced by taurine and respond via glycine and GABAA receptors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Hyperpolarization-activated current (In is reduced in hippocampal neurons from Gabra5-/- mice.

Directory of Open Access Journals (Sweden)

Robert P Bonin

Full Text Available Changes in the expression of γ-aminobutyric acid type A (GABAA receptors can either drive or mediate homeostatic alterations in neuronal excitability. A homeostatic relationship between α5 subunit-containing GABAA (α5GABAA receptors that generate a tonic inhibitory conductance, and HCN channels that generate a hyperpolarization-activated cation current (Ih was recently described for cortical neurons, where a reduction in Ih was accompanied by a reciprocal increase in the expression of α5GABAA receptors resulting in the preservation of dendritosomatic synaptic function. Here, we report that in mice that lack the α5 subunit gene (Gabra5-/-, cultured embryonic hippocampal pyramidal neurons and ex vivo CA1 hippocampal neurons unexpectedly exhibited a decrease in Ih current density (by 40% and 28%, respectively, compared with neurons from wild-type (WT mice. The resting membrane potential and membrane hyperpolarization induced by blockade of Ih with ZD-7288 were similar in cultured WT and Gabra5-/- neurons. In contrast, membrane hyperpolarization measured after a train of action potentials was lower in Gabra5-/- neurons than in WT neurons. Also, membrane impedance measured in response to low frequency stimulation was greater in cultured Gabra5-/- neurons. Finally, the expression of HCN1 protein that generates Ih was reduced by 41% in the hippocampus of Gabra5-/- mice. These data indicate that loss of a tonic GABAergic inhibitory conductance was followed by a compensatory reduction in Ih. The results further suggest that the maintenance of resting membrane potential is preferentially maintained in mature and immature hippocampal neurons through the homeostatic co-regulation of structurally and biophysically distinct cation and anion channels.

Egalitarian reward contingency in competitive games and primate prefrontal neuronal activity.

Science.gov (United States)

Hosokawa, Takayuki; Watanabe, Masataka

2015-01-01

How people work to obtain a reward depends on the context of the reward delivery, such as the presence/absence of competition and the contingency of reward delivery. Since resources are limited, winning a competition is critically important for organisms' obtaining a reward. People usually expect ordinary performance-reward contingency, with better performers obtaining better rewards. Unordinary reward contingency, such as egalitarianism (equal rewards/no-rewards to both good and poor performers), dampens people's motivation. We previously reported that monkeys were more motivated, and neurons in the lateral prefrontal cortex (LPFC) showed higher outcome-related activity in a competitive than in a noncompetitive game (Hosokawa and Watanabe, 2012). However, monkey's behavior and LPFC neuronal activity have not been examined in a competitive situation with an unordinary performance-reward contingency. Also, the fixed performance-reward contingency in the previous study did not allow us to examine effects of win/loss separately from those of reward/no-reward on prefrontal neuronal activity. Here, we employed the egalitarian competitive situation in which both the winner and loser, or neither of them, got a reward as well as the normal competitive situation in which only the winner got a reward. Monkey's behavioral performance greatly deteriorated in trials with the egalitarian outcome conditions. LPFC neurons showed activities that reflected the normal or egalitarian outcome condition while very few neurons coded win/loss independent of reward/no-reward. Importantly, we found neurons that showed reward-related activity in the normal, but not in the egalitarian outcome conditions, even though the same reward was given to the animal. These results indicate that LPFC may play an important role in monitoring the current reward contingency and integrating it with the performance outcome (win-loss) for better performing the competitive game, and thus for better survival.

Sweet taste receptor serves to activate glucose- and leptin-responsive neurons in the hypothalamic arcuate nucleus and participates in glucose responsiveness.

Directory of Open Access Journals (Sweden)

Daisuke Kohno

2016-11-01

Full Text Available The hypothalamic feeding center plays an important role in energy homeostasis. In the feeding center, whole-body energy signals including hormones and nutrients are sensed, processed, and integrated. As a result, food intake and energy expenditure are regulated. Two types of glucose-sensing neurons exist in the hypothalamic arcuate nucleus (ARC: glucose-excited neurons and glucose-inhibited neurons. While some molecules are known to be related to glucose sensing in the hypothalamus, the mechanism underlying glucose sensing in the hypothalamus are not fully understood. The sweet taste receptor is a heterodimer of taste type 1 receptor 2 (T1R2 and taste type 1 receptor 3 (T1R3 and senses sweet tastes. T1R2 and T1R3 receptors are distributed in multiple organs including the tongue, pancreas, adipose tissue, and hypothalamus. However, the role of sweet taste receptors in the ARC remains to be clarified. To examine the role of sweet taste receptors in the ARC, cytosolic Ca2+ concentration ([Ca2+]i in isolated single ARC neurons were measured using Fura-2 fluorescent imaging. An artificial sweetener, sucralose at 10-5 M-10-2 M dose dependently increased [Ca2+]i in 12-16% of ARC neurons. The sucralose-induced [Ca2+]i increase was suppressed by a sweet taste receptor inhibitor, gurmarin. The sucralose-induced [Ca2+]i increase was inhibited under an extracellular Ca2+-free condition and in the presence of an L-type Ca2+ channel blocker, nitrendipine. Sucralose-responding neurons were activated by high-concentration of glucose. This response to glucose was markedly suppressed by gurmarin. More than half of sucralose-responding neurons were activated by leptin but not ghrelin. Percentage of proopiomelanocortin (POMC neurons among sucralose-responding neurons and sweet taste receptor expressing neurons were low, suggesting that majority of sucralose-responding neurons are non-POMC neurons. These data suggest that sweet taste receptor-mediated cellular

Sweet Taste Receptor Serves to Activate Glucose- and Leptin-Responsive Neurons in the Hypothalamic Arcuate Nucleus and Participates in Glucose Responsiveness.

Science.gov (United States)

Kohno, Daisuke; Koike, Miho; Ninomiya, Yuzo; Kojima, Itaru; Kitamura, Tadahiro; Yada, Toshihiko

2016-01-01

The hypothalamic feeding center plays an important role in energy homeostasis. In the feeding center, whole-body energy signals including hormones and nutrients are sensed, processed, and integrated. As a result, food intake and energy expenditure are regulated. Two types of glucose-sensing neurons exist in the hypothalamic arcuate nucleus (ARC): glucose-excited neurons and glucose-inhibited neurons. While some molecules are known to be related to glucose sensing in the hypothalamus, the mechanisms underlying glucose sensing in the hypothalamus are not fully understood. The sweet taste receptor is a heterodimer of taste type 1 receptor 2 (T1R2) and taste type 1 receptor 3 (T1R3) and senses sweet tastes. T1R2 and T1R3 are distributed in multiple organs including the tongue, pancreas, adipose tissue, and hypothalamus. However, the role of sweet taste receptors in the ARC remains to be clarified. To examine the role of sweet taste receptors in the ARC, cytosolic Ca 2+ concentration ([Ca 2+ ] i ) in isolated single ARC neurons were measured using Fura-2 fluorescent imaging. An artificial sweetener, sucralose at 10 -5 -10 -2 M dose dependently increased [Ca 2+ ] i in 12-16% of ARC neurons. The sucralose-induced [Ca 2+ ] i increase was suppressed by a sweet taste receptor inhibitor, gurmarin. The sucralose-induced [Ca 2+ ] i increase was inhibited under an extracellular Ca 2+ -free condition and in the presence of an L-type Ca 2+ channel blocker, nitrendipine. Sucralose-responding neurons were activated by high-concentration of glucose. This response to glucose was markedly suppressed by gurmarin. More than half of sucralose-responding neurons were activated by leptin but not ghrelin. Percentages of proopiomelanocortin (POMC) neurons among sucralose-responding neurons and sweet taste receptor expressing neurons were low, suggesting that majority of sucralose-responding neurons are non-POMC neurons. These data suggest that sweet taste receptor-mediated cellular activation

Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

NARCIS (Netherlands)

Smeets, P.A.M.; Vidarsdottir, S.; Graaf, de C.; Stafleu, A.; Osch, M.J.P.; Viergever, M.A.; Pijl, H.; Grond, van der J.

2007-01-01

Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion. Am J Physiol Endocrinol Metab 293: E754-E758, 2007. First published June 12, 2007; doi:10.1152/ajpendo.00231.2007. - We previously showed that hypothalamic neuronal activity, as measured by the blood

Transforming Growth Factor β/Activin signaling in neurons increases susceptibility to starvation.

Directory of Open Access Journals (Sweden)

Wen-Bin Alfred Chng

Full Text Available Animals rely on complex signaling network to mobilize its energy stores during starvation. We have previously shown that the sugar-responsive TGFβ/Activin pathway, activated through the TGFβ ligand Dawdle, plays a central role in shaping the post-prandial digestive competence in the Drosophila midgut. Nevertheless, little is known about the TGFβ/Activin signaling in sugar metabolism beyond the midgut. Here, we address the importance of Dawdle (Daw after carbohydrate ingestion. We found that Daw expression is coupled to dietary glucose through the evolutionarily conserved Mio-Mlx transcriptional complex. In addition, Daw activates the TGFβ/Activin signaling in neuronal populations to regulate triglyceride and glycogen catabolism and energy homeostasis. Loss of those neurons depleted metabolic reserves and rendered flies susceptible to starvation.

Transforming Growth Factor β/Activin signaling in neurons increases susceptibility to starvation.

Science.gov (United States)

Chng, Wen-Bin Alfred; Koch, Rafael; Li, Xiaoxue; Kondo, Shu; Nagoshi, Emi; Lemaitre, Bruno

2017-01-01

Animals rely on complex signaling network to mobilize its energy stores during starvation. We have previously shown that the sugar-responsive TGFβ/Activin pathway, activated through the TGFβ ligand Dawdle, plays a central role in shaping the post-prandial digestive competence in the Drosophila midgut. Nevertheless, little is known about the TGFβ/Activin signaling in sugar metabolism beyond the midgut. Here, we address the importance of Dawdle (Daw) after carbohydrate ingestion. We found that Daw expression is coupled to dietary glucose through the evolutionarily conserved Mio-Mlx transcriptional complex. In addition, Daw activates the TGFβ/Activin signaling in neuronal populations to regulate triglyceride and glycogen catabolism and energy homeostasis. Loss of those neurons depleted metabolic reserves and rendered flies susceptible to starvation.

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

Science.gov (United States)

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural

Chronic lithium treatment increased intracellular S100ß levels in rat primary neuronal culture.

Directory of Open Access Journals (Sweden)

Masoumeh Emamghoreishi

2015-02-01

Full Text Available S100ß a neurotrophic factor mainly released by astrocytes, has been implicated in the pathogenesis of bipolar disorder. Thus, lithium may exert its neuroprotective effects to some extent through S100ß. Furthermore, the possible effects of lithium on astrocytes as well as on interactions between neurons and astrocytes as a part of its mechanisms of actions are unknown. This study was undertaken to determine the effect of lithium on S100β in neurons, astrocytes and a mixture of neurons and astrocytes. Rat primary astrocyte, neuronal and mixed neuro-astroglia cultures were prepared from cortices of 18-day's embryos. Cell cultures were exposed to lithium (1mM or vehicle for 1day (acute or 7 days (chronic. RT-PCR and ELISA determined S100β mRNA and intra- and extracellular protein levels. Chronic lithium treatment significantly increased intracellular S100β in neuronal and neuro-astroglia cultures in comparison to control cultures (P<0.05. Acute and chronic lithium treatments exerted no significant effects on intracellular S100β protein levels in astrocytes, and extracellular S100β protein levels in three studied cultures as compared to control cultures. Acute and chronic lithium treatments did not significantly alter S100β mRNA levels in three studied cultures, compared to control cultures. Chronic lithium treatment increased intracellular S100ß protein levels in a cell-type specific manner which may favor its neuroprotective action. The findings of this study suggest that lithium may exert its neuroprotective action, at least partly, by increasing neuronal S100ß level, with no effect on astrocytes or interaction between neurons and astrocytes.

Overexpression of cypin alters dendrite morphology, single neuron activity, and network properties via distinct mechanisms

Science.gov (United States)

Rodríguez, Ana R.; O'Neill, Kate M.; Swiatkowski, Przemyslaw; Patel, Mihir V.; Firestein, Bonnie L.

2018-02-01

Objective. This study investigates the effect that overexpression of cytosolic PSD-95 interactor (cypin), a regulator of synaptic PSD-95 protein localization and a core regulator of dendrite branching, exerts on the electrical activity of rat hippocampal neurons and networks. Approach. We cultured rat hippocampal neurons and used lipid-mediated transfection and lentiviral gene transfer to achieve high levels of cypin or cypin mutant (cypinΔPDZ PSD-95 non-binding) expression cellularly and network-wide, respectively. Main results. Our analysis revealed that although overexpression of cypin and cypinΔPDZ increase dendrite numbers and decrease spine density, cypin and cypinΔPDZ distinctly regulate neuronal activity. At the single cell level, cypin promotes decreases in bursting activity while cypinΔPDZ reduces sEPSC frequency and further decreases bursting compared to cypin. At the network level, by using the Fano factor as a measure of spike count variability, cypin overexpression results in an increase in variability of spike count, and this effect is abolished when cypin cannot bind PSD-95. This variability is also dependent on baseline activity levels and on mean spike rate over time. Finally, our spike sorting data show that overexpression of cypin results in a more complex distribution of spike waveforms and that binding to PSD-95 is essential for this complexity. Significance. Our data suggest that dendrite morphology does not play a major role in cypin action on electrical activity.

Genetic activation, inactivation and deletion reveal a limited and nuanced role for somatostatin-containing basal forebrain neurons in behavioral state control.

Science.gov (United States)

Anaclet, Christelle; De Luca, Roberto; Venner, Anne; Malyshevskaya, Olga; Lazarus, Michael; Arrigoni, Elda; Fuller, Patrick M

2018-05-07

Recent studies have identified an especially important role for basal forebrain GABAergic (BF VGAT ) neurons in the regulation of behavioral waking and fast cortical rhythms associated with cognition. However, BF VGAT neurons comprise several neurochemically and anatomically distinct sub-populations, including parvalbumin- and somatostatin-containing BF VGAT neurons (BF Parv and BF SOM ), and it was recently reported that optogenetic activation of BF SOM neurons increases the probability of a wakefulness to non-rapid-eye movement (NREM) sleep transition when stimulated during the animal's rest period. This finding was unexpected given that most BF SOM neurons are not NREM sleep active and that central administration of the synthetic SOM analog, octreotide, suppresses NREM sleep or increases REM sleep. Here we employed a combination of genetically-driven chemogenetic and optogenetic activation, chemogenetic inhibition and ablation approaches to further explore the in vivo role of BF SOM neurons in arousal control. Our findings indicate that acute activation or inhibition of BF SOM neurons is neither wakefulness- nor NREM sleep-promoting, is without significant effect on the EEG, and that chronic loss of these neurons is without effect on total 24h sleep amounts, although a small but significant increase in waking was observed in the lesioned mice during the early active period. Our in vitro cell recordings further reveal electrophysiological heterogeneity in BF SOM neurons, specifically suggesting at least two distinct sub-populations. Taken together our data support the more nuanced view that BF SOM are electrically heterogeneous and are not NREM sleep- or wake-promoting per se , but may exert, in particular during the early active period, a modest inhibitory influence on arousal circuitry. SIGNIFICANCE STATEMENT The cellular basal forebrain (BF) is a highly complex area of the brain that is implicated in a wide-range of higher-level neurobiological processes

VEGF attenuated increase of outward delayed-rectifier potassium currents in hippocampal neurons induced by focal ischemia via PI3-K pathway.

Science.gov (United States)

Wu, K W; Yang, P; Li, S S; Liu, C W; Sun, F Y

2015-07-09

We recently indicated that the vascular endothelial growth factor (VEGF) protects neurons against hypoxic death via enhancement of tyrosine phosphorylation of Kv1.2, an isoform of the delayed-rectifier potassium channels through activation of the phosphatidylinositol 3-kinase (PI3-K) signaling pathway. The present study investigated whether VEGF could attenuate ischemia-induced increase of the potassium currents in the hippocampal pyramidal neurons of rats after ischemic injury. Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion (MCAO) to induce brain ischemia. The whole-cell patch-clamp technique was used to record the potassium currents of hippocampal neurons in brain slices from the ischemically injured brains of the rats 24h after MCAO. We detected that transient MCAO caused a significant increase of voltage-gated potassium currents (Kv) and outward delayed-rectifier potassium currents (IK), but not outward transient potassium currents (IA), in the ipsilateral hippocampus compared with the sham. Moreover, we found that VEGF could acutely, reversibly and voltage-dependently inhibit the ischemia-induced IK increase. This inhibitory effect of VEGF could be completely abolished by wortmannin, an inhibitor of PI3-K. Our data indicate that VEGF attenuates the ischemia-induced increase of IK via activation of the PI3-K signaling pathway. Published by Elsevier Ltd.

The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

Directory of Open Access Journals (Sweden)

Valerie T. Ramírez

2016-01-01

Full Text Available Mastoparan-7 (Mas-7, an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX- sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95 clustering in neurites and activates Gαo signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC, c-Jun N-terminal kinase (JNK, and calcium-calmodulin dependent protein kinase IIα (CaMKIIα after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gαo subunit signaling in the regulation of synapse formation.

Chronic activation of hypothalamic oxytocin neurons improves cardiac function during left ventricular hypertrophy-induced heart failure.

Science.gov (United States)

Garrott, Kara; Dyavanapalli, Jhansi; Cauley, Edmund; Dwyer, Mary Kate; Kuzmiak-Glancy, Sarah; Wang, Xin; Mendelowitz, David; Kay, Matthew W

2017-09-01

A distinctive hallmark of heart failure (HF) is autonomic imbalance, consisting of increased sympathetic activity, and decreased parasympathetic tone. Recent work suggests that activation of hypothalamic oxytocin (OXT) neurons could improve autonomic balance during HF. We hypothesized that a novel method of chronic selective activation of hypothalamic OXT neurons will improve cardiac function and reduce inflammation and fibrosis in a rat model of HF. Two groups of male Sprague-Dawley rats underwent trans-ascending aortic constriction (TAC) to induce left ventricular (LV) hypertrophy that progresses to HF. In one TAC group, OXT neurons in the paraventricular nucleus of the hypothalamus were chronically activated by selective expression and activation of excitatory DREADDs receptors with daily injections of clozapine N-oxide (CNO) (TAC + OXT). Two additional age-matched groups received either saline injections (Control) or CNO injections for excitatory DREADDs activation (OXT NORM). Heart rate (HR), LV developed pressure (LVDP), and coronary flow rate were measured in isolated heart experiments. Isoproterenol (0.01 nM-1.0 µM) was administered to evaluate β-adrenergic sensitivity. We found that increases in cellular hypertrophy and myocardial collagen density in TAC were blunted in TAC + OXT animals. Inflammatory cytokine IL-1β expression was more than twice higher in TAC than all other hearts. LVDP, rate pressure product (RPP), contractility, and relaxation were depressed in TAC compared with all other groups. The response of TAC and TAC + OXT hearts to isoproterenol was blunted, with no significant increase in RPP, contractility, or relaxation. However, HR in TAC + OXT animals increased to match Control at higher doses of isoproterenol. Activation of hypothalamic OXT neurons to elevate parasympathetic tone reduced cellular hypertrophy, levels of IL-1β, and fibrosis during TAC-induced HF in rats. Cardiac contractility parameters were

Serotonin increases synaptic activity in olfactory bulb glomeruli.

Science.gov (United States)

Brill, Julia; Shao, Zuoyi; Puche, Adam C; Wachowiak, Matt; Shipley, Michael T

2016-03-01

Serotoninergic fibers densely innervate olfactory bulb glomeruli, the first sites of synaptic integration in the olfactory system. Acting through 5HT2A receptors, serotonin (5HT) directly excites external tufted cells (ETCs), key excitatory glomerular neurons, and depolarizes some mitral cells (MCs), the olfactory bulb's main output neurons. We further investigated 5HT action on MCs and determined its effects on the two major classes of glomerular interneurons: GABAergic/dopaminergic short axon cells (SACs) and GABAergic periglomerular cells (PGCs). In SACs, 5HT evoked a depolarizing current mediated by 5HT2C receptors but did not significantly impact spike rate. 5HT had no measurable direct effect in PGCs. Serotonin increased spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) in PGCs and SACs. Increased sEPSCs were mediated by 5HT2A receptors, suggesting that they are primarily due to enhanced excitatory drive from ETCs. Increased sIPSCs resulted from elevated excitatory drive onto GABAergic interneurons and augmented GABA release from SACs. Serotonin-mediated GABA release from SACs was action potential independent and significantly increased miniature IPSC frequency in glomerular neurons. When focally applied to a glomerulus, 5HT increased MC spontaneous firing greater than twofold but did not increase olfactory nerve-evoked responses. Taken together, 5HT modulates glomerular network activity in several ways: 1) it increases ETC-mediated feed-forward excitation onto MCs, SACs, and PGCs; 2) it increases inhibition of glomerular interneurons; 3) it directly triggers action potential-independent GABA release from SACs; and 4) these network actions increase spontaneous MC firing without enhancing responses to suprathreshold sensory input. This may enhance MC sensitivity while maintaining dynamic range. Copyright © 2016 the American Physiological Society.

Orexins depolarize rostral ventrolateral medulla neurons and increase arterial pressure and heart rate in rats mainly via orexin 2 receptors.

Science.gov (United States)

Huang, Shang-Cheng; Dai, Yu-Wen E; Lee, Yen-Hsien; Chiou, Lih-Chu; Hwang, Ling-Ling

2010-08-01

An injection of orexin A or B into the cisterna magna or the rostral ventrolateral medulla (RVLM), where bulbospinal vasomotor neurons are located, elevated arterial pressure (AP) and heart rate (HR). We examined how orexins affected RVLM neurons to regulate cardiovascular functions by using in vitro recordings of neuronal activity of the RVLM and in vivo measurement of cardiovascular functions in rats. Orexin A and B concentration-dependently depolarized RVLM neurons. At 100 nM, both peptides excited 42% of RVLM neurons. Tetrodotoxin failed to block orexin-induced depolarization. In the presence of N-(2-methyl-6-benzoxazolyl)-N'-1, 5-naphthyridin-4-yl urea (SB-334867), an orexin 1 receptor (OX(1)R) antagonist, orexin A depolarized 42% of RVLM neurons with a smaller, but not significantly different, amplitude (4.9 +/- 0.8 versus 7.2 +/- 1.1 mV). In the presence of (2S)-1- (3,4-dihydro-6,7-dimethoxy-2(1H)-isoquinolinyl)-3,3-dimethyl-2-[(4-pyridinylmethyl)amino]-1-butanone hydrochloride (TCS OX2 29), an orexin 2 receptor (OX(2)R) antagonist, orexin A depolarized 25% of RVLM neurons with a significantly smaller amplitude (1.7 +/- 0.5 mV). Coapplication of both antagonists completely eliminated orexin A-induced depolarization. An OX(2)R agonist, [Ala(11),D-Leu(15)]-orexin B, concentration-dependently depolarized RVLM neurons. Regarding neuronal phenotypes, orexins depolarized 88% of adrenergic, 43% of nonadrenergic, and 36 to 41% of rhythmically firing RVLM neurons. Intracisternal TCS OX2 29 (3 and 10 nmol) suppressed intracisternal orexin A-induced increases of AP and HR, whereas intracisternal SB-334867 (3 and 10 nmol) had no effect on the orexin A-induced increase of HR but suppressed the orexin A-induced pressor response at 10 nmol. We concluded that orexins directly excite RVLM neurons, which include bulbospinal vasomotor neurons, and regulate cardiovascular function mainly via the OX(2)R, with a smaller contribution from the OX(1)R.

Central serotonergic neurons activate and recruit thermogenic brown and beige fat and regulate glucose and lipid homeostasis.

Science.gov (United States)

McGlashon, Jacob M; Gorecki, Michelle C; Kozlowski, Amanda E; Thirnbeck, Caitlin K; Markan, Kathleen R; Leslie, Kirstie L; Kotas, Maya E; Potthoff, Matthew J; Richerson, George B; Gillum, Matthew P

2015-05-05

Thermogenic brown and beige adipocytes convert chemical energy to heat by metabolizing glucose and lipids. Serotonin (5-HT) neurons in the CNS are essential for thermoregulation and accordingly may control metabolic activity of thermogenic fat. To test this, we generated mice in which the human diphtheria toxin receptor (DTR) was selectively expressed in central 5-HT neurons. Treatment with diphtheria toxin (DT) eliminated 5-HT neurons and caused loss of thermoregulation, brown adipose tissue (BAT) steatosis, and a >50% decrease in uncoupling protein 1 (Ucp1) expression in BAT and inguinal white adipose tissue (WAT). In parallel, blood glucose increased 3.5-fold, free fatty acids 13.4-fold, and triglycerides 6.5-fold. Similar BAT and beige fat defects occurred in Lmx1b(f/f)ePet1(Cre) mice in which 5-HT neurons fail to develop in utero. We conclude 5-HT neurons play a major role in regulating glucose and lipid homeostasis, in part through recruitment and metabolic activation of brown and beige adipocytes. Copyright © 2015 Elsevier Inc. All rights reserved.