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McArdle CJ, Arnone AA, Heaney CF, Raab-Graham KF. A paradoxical switch: the implications of excitatory GABAergic signaling in neurological disorders. Front Psychiatry 2024; 14:1296527. [PMID: 38268565 PMCID: PMC10805837 DOI: 10.3389/fpsyt.2023.1296527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 12/04/2023] [Indexed: 01/26/2024] Open
Abstract
Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. In the mature brain, inhibitory GABAergic signaling is critical in maintaining neuronal homeostasis and vital human behaviors such as cognition, emotion, and motivation. While classically known to inhibit neuronal function under physiological conditions, previous research indicates a paradoxical switch from inhibitory to excitatory GABAergic signaling that is implicated in several neurological disorders. Various mechanisms have been proposed to contribute to the excitatory switch such as chloride ion dyshomeostasis, alterations in inhibitory receptor expression, and modifications in GABAergic synaptic plasticity. Of note, the hypothesized mechanisms underlying excitatory GABAergic signaling are highlighted in a number of neurodevelopmental, substance use, stress, and neurodegenerative disorders. Herein, we present an updated review discussing the presence of excitatory GABAergic signaling in various neurological disorders, and their potential contributions towards disease pathology.
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Affiliation(s)
- Colin J. McArdle
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Alana A. Arnone
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
- Department of General Surgery, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Chelcie F. Heaney
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
| | - Kimberly F. Raab-Graham
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, United States
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Elhampour L, Azarbayjani MA, Nasehi M, Peeri M. Concurrent Effects of Exercise and Curcumin on Spatial Learning and Memory in Sensitized Male Mice Following Morphine Administration. Galen Med J 2019; 8:e1072. [PMID: 34466459 PMCID: PMC8343884 DOI: 10.31661/gmj.v8i0.1072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/21/2018] [Accepted: 02/21/2018] [Indexed: 11/25/2022] Open
Abstract
Background: Exercise and Curcumin have positive effects on spatial memory and cognition independently. The present study aims to investigate whether the combination of ineffectual dosage of these factors can affect cognition and as a solvent if DMSO is involved in Curcumin effects. Materials and Methods: Male NMRI mice (1-month-old) swam (1 week) for 60 minutes (5days/week) and injected with morphine (2.5 mg/ml/kg, intraperitoneal) for five days. Spatial learning and memory were assessed by Moris Water Maze test on the 10th day after stopping morphine injection. Results: The findings revealed that exercise, dimethyl sulfoxide (DMSO), and Curcumin increased memory formation induced by 2.5 mg/ml/kg morphine. DMSO+exercise decreased memory formation induced by morphine, but curcumin +exercise could return the effect of DMSO on the cognition. Conclusion:
As a solvent, DMSO had independent effects on memory, which lead to memory impairment in combination with exercise. Therefore, considering its unpredictable effects on cognitive performance, it should be replaced with another solvent or might be used carefully in behavioral experiments.
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Affiliation(s)
- Laleh Elhampour
- Department of Exercise Physiology, Tehran Central Branch, Islamic Azad University, Tehran, Iran
| | | | - Mohammad Nasehi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
- Correspondence to: Mohammad Nasehi, Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran Telephone Number: +9821-66402569 Email Address:
| | - Maghsoud Peeri
- Department of Exercise Physiology, Tehran Central Branch, Islamic Azad University, Tehran, Iran
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3
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Tsukahara T, Kawase T, Yoshida H, Bukawa W, Kan T, Toyoda A. Preliminary investigation of the effect of oral supplementation of Lactobacillus plantarum strain SNK12 on mRNA levels of neurotrophic factors and GABA receptors in the hippocampus of mice under stress-free and sub-chronic mild social defeat-stressing conditions. Biosci Biotechnol Biochem 2019; 83:2345-2354. [PMID: 31524073 DOI: 10.1080/09168451.2019.1659717] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The effect of Lactobacillus plantarum SNK12 (CPLP) supplementation on mRNA levels of hippocampal neurotrophic factors and gamma aminobutyric acid receptors (GABAR) was tested. In Experiment 1, stress-free, unsupplemented and CPLP (4 × 108 cells/head)-supplemented male C57BL/6J (B6) mice were the experimental animals. In Experiment 2, intruder (male, B6) mice [negative control; unsupplemented, sub-chronic mild social defeat stress (sCSDS)-induced; and CPLP-supplemented, sCSDS-induced] were exposed to aggressor mice (adult male Slc:ICR). mRNA levels of neurotrophic factors and GABAR in hippocampal samples of these mice were analyzed. In CPLP-supplemented mice of both experiments, mRNA levels of bdnf, nt-3, and GABAR were upregulated. Moreover, a tendency toward the improvement of habituation ability (Experiment 1) and behavior (Experiment 2) was observed in mice, which may be associated with upregulated neurotrophic factors and GABAR. We demonstrated that oral supplementation of CPLP to stress-free and stress-induced mice upregulated mRNA levels of hippocampal neurotrophic factors and GABAR.
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Affiliation(s)
| | | | | | - Wakoto Bukawa
- Non-Profit Organization, The Japanese Association of Clinical Research on Supplements, Saitama, Japan
| | | | - Atsushi Toyoda
- College of Agriculture, Ibaraki University, Ibaraki, Japan.,United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
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Ch'ng SS, Fu J, Brown RM, Smith CM, Hossain MA, McDougall SJ, Lawrence AJ. Characterization of the relaxin family peptide receptor 3 system in the mouse bed nucleus of the stria terminalis. J Comp Neurol 2019; 527:2615-2633. [PMID: 30947365 DOI: 10.1002/cne.24695] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/19/2019] [Accepted: 03/27/2019] [Indexed: 01/17/2023]
Abstract
The bed nucleus of the stria terminalis (BNST) is a critical node involved in stress and reward-related behaviors. Relaxin family peptide receptor 3 (RXFP3) signaling in the BNST has been implicated in stress-induced alcohol seeking behavior. However, the neurochemical phenotype and connectivity of BNST RXFP3-expressing (RXFP3+) cells have yet to be elucidated. We interrogated the molecular signature and electrophysiological properties of BNST RXFP3+ neurons using a RXFP3-Cre reporter mouse line. BNST RXFP3+ cells are circumscribed to the dorsal BNST (dBNST) and are neurochemically heterogeneous, comprising a mix of inhibitory and excitatory neurons. Immunohistochemistry revealed that ~48% of BNST RXFP3+ neurons are GABAergic, and a quarter of these co-express the calcium-binding protein, calbindin. A subset of BNST RXFP3+ cells (~41%) co-express CaMKIIα, suggesting this subpopulation of BNST RXFP3+ neurons are excitatory. Corroborating this, RNAscope® revealed that ~35% of BNST RXFP3+ cells express vVGluT2 mRNA, indicating a subpopulation of RXFP3+ neurons are glutamatergic. RXFP3+ neurons show direct hyperpolarization to bath application of a selective RXFP3 agonist, RXFP3-A2, while around 50% of cells were depolarised by exogenous corticotrophin releasing factor. In behaviorally naive mice the majority of RXFP3+ neurons were Type II cells exhibiting Ih and T type calcium mediated currents. However, chronic swim stress caused persistent plasticity, decreasing the proportion of neurons that express these channels. These studies are the first to characterize the BNST RXFP3 system in mouse and lay the foundation for future functional studies appraising the role of the murine BNST RXFP3 system in more complex behaviors.
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Affiliation(s)
- Sarah S Ch'ng
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Jingjing Fu
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Robyn M Brown
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Craig M Smith
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | | | - Stuart J McDougall
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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Maguire J. Neuroactive Steroids and GABAergic Involvement in the Neuroendocrine Dysfunction Associated With Major Depressive Disorder and Postpartum Depression. Front Cell Neurosci 2019; 13:83. [PMID: 30906252 PMCID: PMC6418819 DOI: 10.3389/fncel.2019.00083] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/19/2019] [Indexed: 12/21/2022] Open
Abstract
Stress and previous adverse life events are well-established risk factors for depression. Further, neuroendocrine disruptions are associated with both major depressive disorder (MDD) and postpartum depression (PPD). However, the mechanisms whereby stress contributes to the underlying neurobiology of depression remains poorly understood. The hypothalamic-pituitary-adrenal (HPA) axis, which mediates the body's neuroendocrine response to stress, is tightly controlled by GABAergic signaling and there is accumulating evidence that GABAergic dysfunction contributes to the impact of stress on depression. GABAergic signaling plays a critical role in the neurobiological effects of stress, not only by tightly controlling the activity of the HPA axis, but also mediating stress effects in stress-related brain regions. Deficits in neuroactive steroids and neurosteroids, some of which are positive allosteric modulators of GABAA receptors (GABAARs), such as allopregnanolone and THDOC, have also been implicated in MDD and PPD, further supporting a role for GABAergic signaling in depression. Alterations in neurosteroid levels and GABAergic signaling are implicated as potential contributing factors to neuroendocrine dysfunction and vulnerability to MDD and PPD. Further, potential novel treatment strategies targeting these proposed underlying neurobiological mechanisms are discussed. The evidence summarized in the current review supports the notion that MDD and PPD are stress-related psychiatric disorders involving neurosteroids and GABAergic dysfunction.
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Affiliation(s)
- Jamie Maguire
- Neuroscience Department, Tufts University School of Medicine, Boston, MA, United States
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Locci A, Pinna G. Neurosteroid biosynthesis down-regulation and changes in GABA A receptor subunit composition: a biomarker axis in stress-induced cognitive and emotional impairment. Br J Pharmacol 2017; 174:3226-3241. [PMID: 28456011 DOI: 10.1111/bph.13843] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/05/2017] [Accepted: 04/12/2017] [Indexed: 12/26/2022] Open
Abstract
By rapidly modulating neuronal excitability, neurosteroids regulate physiological processes, such as responses to stress and development. Excessive stress affects their biosynthesis and causes an imbalance in cognition and emotions. The progesterone derivative, allopregnanolone (Allo) enhances extrasynaptic and postsynaptic inhibition by directly binding at GABAA receptors, and thus, positively and allosterically modulates the function of GABA. Allo levels are decreased in stress-induced psychiatric disorders, including depression and post-traumatic stress disorder (PTSD), and elevating Allo levels may be a valid therapeutic approach to counteract behavioural dysfunction. While benzodiazepines are inefficient, selective serotonin reuptake inhibitors (SSRIs) represent the first choice treatment for depression and PTSD. Their mechanisms to improve behaviour in preclinical studies include neurosteroidogenic effects at low non-serotonergic doses. Unfortunately, half of PTSD and depressed patients are resistant to current prescribed 'high' dosage of these drugs that engage serotonergic mechanisms. Unveiling novel biomarkers to develop more efficient treatment strategies is in high demand. Stress-induced down-regulation of neurosteroid biosynthesis and changes in GABAA receptor subunit expression offer a putative biomarker axis to develop new PTSD treatments. The advantage of stimulating Allo biosynthesis relies on the variety of neurosteroidogenic receptors to be targeted, including TSPO and endocannabinoid receptors. Furthermore, stress favours a GABAA receptor subunit composition with higher sensitivity for Allo. The use of synthetic analogues of Allo is a valuable alternative. Pregnenolone or drugs that stimulate its levels increase Allo but also sulphated steroids, including pregnanolone sulphate which, by inhibiting NMDA tonic neurotransmission, provides neuroprotection and cognitive benefits. In this review, we describe current knowledge on the effects of stress on neurosteroid biosynthesis and GABAA receptor neurotransmission and summarize available pharmacological strategies that by enhancing neurosteroidogenesis are relevant for the treatment of SSRI-resistant patients. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.
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Affiliation(s)
- Andrea Locci
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Graziano Pinna
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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Maguire J. Stress-induced plasticity of GABAergic inhibition. Front Cell Neurosci 2014; 8:157. [PMID: 24936173 PMCID: PMC4047962 DOI: 10.3389/fncel.2014.00157] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 05/19/2014] [Indexed: 12/18/2022] Open
Abstract
GABAergic neurotransmission is highly plastic, undergoing dynamic alterations in response to changes in the environment, such as following both acute and chronic stress. Stress-induced plasticity of GABAergic inhibition is thought to contribute to changes in neuronal excitability associated with stress, which is particularly relevant for stress-related disorders and seizure susceptibility. Here we review the literature demonstrating several mechanisms altering GABAergic inhibition associated with stress, including brain region-specific alterations in GABAA receptor (GABAAR) subunit expression, changes in chloride homeostasis, and plasticity at GABAergic synapses. Alterations in the expression of specific GABAAR subunits have been documented in multiple brain regions associated with acute or chronic stress. In addition, recent work demonstrates stress-induced alterations in GABAergic inhibition resulting from plasticity in intracellular chloride levels. Acute and chronic stress-induced dephosphorylation and downregulation of the K+/Cl− co-transporter, KCC2, has been implicated in compromising GABAergic control of corticotropin-releasing hormone (CRH) neurons necessary for mounting the physiological response to stress. Acute stress also unmasks the capacity for both long-term potentiation and long-term depression, in distinct temporal windows, at GABAergic synapses on parvocellular neuroendocrine cells (PNCs) in the paraventricular nucleus (PVN) of the hypothalamus. This review highlights the complexity in the plasticity of GABAergic neurotransmission associated with stress and the relationship to neuronal excitability, including alterations in GABAAR expression, synaptic plasticity at GABAergic synapses, and changes in chloride homeostasis.
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Affiliation(s)
- Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine Boston, MA, USA
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Gabapentin inhibits γ-amino butyric acid release in the locus coeruleus but not in the spinal dorsal horn after peripheral nerve injury in rats. Anesthesiology 2012; 116:1347-53. [PMID: 22487864 DOI: 10.1097/aln.0b013e318254e6fd] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Gabapentin reduces acute postoperative and chronic neuropathic pain, but its sites and mechanisms of action are unclear. Based on previous electrophysiologic studies, the authors tested whether gabapentin reduced γ-amino butyric acid (GABA) release in the locus coeruleus (LC), a major site of descending inhibition, rather than in the spinal cord. METHODS Male Sprague-Dawley rats with or without L5-L6 spinal nerve ligation (SNL) were used. Immunostaining for glutamic acid decarboxylase and GABA release in synaptosomes and microdialysates were examined in the LC and spinal dorsal horn. RESULTS Basal GABA release and expression of glutamic acid decarboxylase increased in the LC but decreased in the spinal dorsal horn after SNL. In microdialysates from the LC, intravenously administered gabapentin decreased extracellular GABA concentration in normal and SNL rats. In synaptosomes prepared from the LC, gabapentin and other α2δ ligands inhibited KCl-evoked GABA release in normal and SNL rats. In microdialysates from the spinal dorsal horn, intravenous gabapentin did not alter GABA concentrations in normal rats but slightly increased them in SNL rats. In synaptosomes from the spinal dorsal horn, neither gabapentin nor other α2δ ligands affected KCl-evoked GABA release in normal and SNL rats. DISCUSSION These results suggest that peripheral nerve injury induces plasticity of GABAergic neurons differently in the LC and spinal dorsal horn and that gabapentin reduces presynaptic GABA release in the LC but not in the spinal dorsal horn. The current study supports the idea that gabapentin activates descending noradrenergic inhibition via disinhibition of LC neurons.
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Asiaei M, Solati J, Salari AA. Prenatal exposure to lps leads to long-lasting physiological consequences in male offspring. Dev Psychobiol 2011; 53:828-38. [DOI: 10.1002/dev.20568] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 04/25/2011] [Indexed: 11/11/2022]
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Axonal remodeling for motor recovery after traumatic brain injury requires downregulation of γ-aminobutyric acid signaling. Cell Death Dis 2011; 2:e133. [PMID: 21412279 PMCID: PMC3101813 DOI: 10.1038/cddis.2011.16] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Remodeling of the remnant neuronal network after brain injury possibly mediates spontaneous functional recovery; however, the mechanisms inducing axonal remodeling during spontaneous recovery remain unclear. Here, we show that altered γ-aminobutyric acid (GABA) signaling is crucial for axonal remodeling of the contralesional cortex after traumatic brain injury. After injury to the sensorimotor cortex in mice, we found a significant decrease in the expression of GABAAR-α1 subunits in the intact sensorimotor cortex for 2 weeks. Motor functions, assessed by grid walk and cylinder tests, spontaneously improved in 4 weeks after the injury to the sensorimotor cortex. With motor recovery, corticospinal tract (CST) axons from the contralesional cortex sprouted into the denervated side of the cervical spinal cord at 2 and 4 weeks after the injury. To determine the functional implications of the changes in the expression of GABAAR-α1 subunits, we infused muscimol, a GABA R agonist, into the contralesional cortex for a week after the injury. Compared with the vehicle-treated mice, we noted significantly inhibited recovery in the muscimol-treated mice. Further, muscimol infusion greatly suppressed the axonal sprouting into the denervated side of the cervical spinal cord. In conclusion, recovery of motor function and axonal remodeling of the CST following cortical injury requires suppressed GABAAR subunit expression and decreased GABAergic signaling.
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O'Mahony CM, Clarke G, Gibney S, Dinan TG, Cryan JF. Strain differences in the neurochemical response to chronic restraint stress in the rat: Relevance to depression. Pharmacol Biochem Behav 2011; 97:690-9. [DOI: 10.1016/j.pbb.2010.11.012] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 11/13/2010] [Accepted: 11/16/2010] [Indexed: 10/18/2022]
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Juvenile stress-induced alteration of maturation of the GABAA receptor alpha subunit in the rat. Int J Neuropsychopharmacol 2008; 11:891-903. [PMID: 18364065 DOI: 10.1017/s1461145708008559] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Profound evidence indicates that GABAA receptors are important in the control of physiological response to stress and anxiety. The alpha subunit type composition contributes significantly to the functional characterization of the GABAA receptors. The alpha2, alpha3, alpha5 subunits are predominately expressed in the brain during embryonic and early postnatal periods of normal rats, whilst alpha1 are most prominent during later developmental stages. In the present study, we examined the long-term effects of juvenile stress on GABA alpha subunit expression in adulthood in the amygdala and hippocampus. We applied the elevated platform stress paradigm at juvenility and used the open-field and startle response tests to assess anxiety level in adulthood. Juvenile stress effects without behavioural tests in adulthood were also examined since previous studies indicated that the mere exposure to these tests might be stressful for rats, enhancing the effects of the juvenile exposure to stress. In adulthood, we quantitatively determined the level of expression of alpha1, alpha2 and alpha3 in the hippocampus and amygdala. Our results indicate that subjecting juvenile stressed rats to additional challenges in adulthood results in an immature-like expression profile of these subunits. To test for potential functional implications of these alterations we examined the effects of the anxiolytic (diazepam) and the sedative (brotizolam) benzodiazepines on juvenile stressed and control rats following additional challenges in adulthood. Juvenile stressed rats were more sensitive to diazepam and less sensitive to brotizolam, suggesting that the alterations in GABA alpha subunit expression in these animals have functional consequences.
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Lund IV, Hu Y, Raol YH, Benham RS, Faris R, Russek SJ, Brooks-Kayal AR. BDNF selectively regulates GABAA receptor transcription by activation of the JAK/STAT pathway. Sci Signal 2008; 1:ra9. [PMID: 18922788 DOI: 10.1126/scisignal.1162396] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The gamma-aminobutyric acid (GABA) type A receptor (GABA(A)R) is the major inhibitory neurotransmitter receptor in the brain. Its multiple subunits show regional, developmental, and disease-related plasticity of expression; however, the regulatory networks controlling GABA(A)R subunit expression remain poorly understood. We report that the seizure-induced decrease in GABA(A)R alpha1 subunit expression associated with epilepsy is mediated by the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway regulated by brain-derived neurotrophic factor (BDNF). BDNF- and seizure-dependent phosphorylation of STAT3 cause the adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB) family member ICER (inducible cAMP early repressor) to bind with phosphorylated CREB at the Gabra1:CRE site. JAK/STAT pathway inhibition prevents the seizure-induced decrease in GABA(A)R alpha1 abundance in vivo and, given that BDNF is known to increase the abundance of GABA(A)R alpha4 in a JAK/STAT-independent manner, indicates that BDNF acts through at least two distinct pathways to influence GABA(A)R-dependent synaptic inhibition.
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Affiliation(s)
- Ingrid V Lund
- Neuroscience Graduate Group and Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Heldt SA, Ressler KJ. Training-induced changes in the expression of GABAA-associated genes in the amygdala after the acquisition and extinction of Pavlovian fear. Eur J Neurosci 2008; 26:3631-44. [PMID: 18088283 DOI: 10.1111/j.1460-9568.2007.05970.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Previous work suggests the gamma-aminobutyric acid (GABA)ergic system may be dynamically regulated during emotional learning. In the current study we examined training-induced changes in the expression of GABA(A)-related genes and the binding of GABA receptor radioligands in the amygdala after the acquisition and extinction of Pavlovian fear. Using in situ hybridization, we examined the expression pattern changes of mRNAs for GABAergic markers in the lateral, basolateral and central subdivisions of the amygdala in C57Bl/6J mice. These markers included GABA-synthesizing enzymes (GAD67 and GAD65), major GABA(A) receptor subunits (alpha1, alpha2, alpha3, alpha5, beta2 and gamma2) and the expression of mRNAs that are involved in a variety of GABA-related intracellular processes, including GABA transporter-1 (GAT1), GABA(A) receptor-associated protein and the GABA(A) clustering protein, gephyrin. With fear conditioning, we found decreased mRNA levels of alpha1, alpha5 and GAD67, as well as deceased benzodiazepine binding in the amygdala. Fear extinction induced an increase in mRNA levels of alpha2, beta2, GAD67 and gephyrin, as well as a decrease in GAT1. Together, these findings indicate that the acquisition of fear induced a downregulation of mRNA markers related to a decrease in amygdala GABAergic function, whereas the acquisition of fear extinction produced an upregulation of GABAergic markers related to enhanced GABAergic transmission.
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Affiliation(s)
- Scott A Heldt
- Center for Behavioral Neuroscience, Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA.
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Abstract
This review assesses the parallel data on the role of gamma-aminobutyric acid (GABA) in depression and anxiety. We review historical and new data from both animal and human experimentation which have helped define the key role for this transmitter in both these mental pathologies. By exploring the overlap in these conditions in terms of GABAergic neurochemistry, neurogenetics, brain circuitry, and pharmacology, we develop a theory that the two conditions are intrinsically interrelated. The role of GABAergic agents in demonstrating this interrelationship and in pointing the way to future research is discussed.
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Affiliation(s)
- Allan V Kalueff
- Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland, USA
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Hu Y, Lund IV, Gravielle MC, Farb DH, Brooks-Kayal AR, Russek SJ. Surface expression of GABAA receptors is transcriptionally controlled by the interplay of cAMP-response element-binding protein and its binding partner inducible cAMP early repressor. J Biol Chem 2008; 283:9328-40. [PMID: 18180303 DOI: 10.1074/jbc.m705110200] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The regulated expression of type A gamma-aminobutyric acid (GABA) receptor (GABA(A)R) subunit genes plays a critical role in neuronal maturation and synaptogenesis. It is also associated with a variety of neurological diseases. Changes in GABA(A) receptor alpha1 subunit gene (GABRA1) expression have been reported in animal models of epilepsy, alcohol abuse, withdrawal, and stress. Understanding the genetic mechanism behind such changes in alpha subunit expression will lead to a better understanding of the role that signal transduction plays in control over GABA(A)R function and brings with it the promise of providing new therapeutic tools for the prevention or cure of a variety of neurological disorders. Here we show that activation of protein kinase C increases alpha1 subunit levels via phosphorylation of CREB (pCREB) that is bound to the GABRA1 promoter (GABRA1p). In contrast, activation of protein kinase A decreases levels of alpha1 even in the presence of pCREB. Decrease of alpha1 is dependent upon the inducible cAMP early repressor (ICER) as directly demonstrated by ICER-induced down-regulation of endogenous alpha1-containing GABA(A)Rs at the cell surface of cortical neurons. Taken together with the fact that there are less alpha1gamma2-containing GABA(A)Rs in neurons after protein kinase A stimulation and that activation of endogenous dopamine receptors down-regulates alpha1 subunit mRNA levels subsequent to induction of ICER, our studies identify a transcriptional mechanism for regulating the cell surface expression of alpha1-containing GABA(A)Rs that is dependent upon the formation of CREB heterodimers.
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Affiliation(s)
- Yinghui Hu
- Laboratory of Translational Epilepsy, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA
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Zheng G, Zhang X, Chen Y, Zhang Y, Luo W, Chen J. Evidence for a role of GABAA receptor in the acute restraint stress-induced enhancement of spatial memory. Brain Res 2007; 1181:61-73. [PMID: 17916335 DOI: 10.1016/j.brainres.2007.08.077] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Revised: 08/16/2007] [Accepted: 08/26/2007] [Indexed: 11/17/2022]
Abstract
Stress exerts complex effects on learning and memory; however, the understanding of the molecular mechanisms involved in stress effects on brain and behavior is rather limited. In this study, we investigated the regulation of the activation of MAPK (mitogen-activated protein kinase) cascades in the rat brain by GABAA receptor in a learning and memory task under acute restraint stress conditions. We found that the acute restraint stress improved the performance of the rats in the Morris water maze. Furthermore, the acute restraint stress significantly increased the phosphorylation of ERK and JNK in the hippocampus and prefrontal cortex (PFC), but not in the striatum. The increase paralleled the time course of the decrease of the level of GABAA receptor alpha1 subunit. The increase of P-ERK levels was inhibited by the agonist of GABAA receptor, muscimol, and further increased by the antagonist of the receptor, bicuculline. However, neither muscimol nor bicuculline affected the levels of P-JNK and P-p38. Finally, injection of muscimol partly reversed the acute restraint stress-induced enhancement of performance in the Morris water maze, and injection of bicuculline improved it. These results demonstrated that the changes in ERK phosphorylation in hippocampus and PFC were regulated by GABAA receptor in a learning and memory paradigm under acute restraint stress conditions.
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Affiliation(s)
- Gang Zheng
- Department of Occupational and Environmental Health, Fourth Military Medical University, 17 Changlexi Road, Xi'an 710032, China
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18
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de Groote L, Linthorst ACE. Exposure to novelty and forced swimming evoke stressor-dependent changes in extracellular GABA in the rat hippocampus. Neuroscience 2007; 148:794-805. [PMID: 17693036 DOI: 10.1016/j.neuroscience.2007.06.030] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 05/23/2007] [Accepted: 07/27/2007] [Indexed: 11/26/2022]
Abstract
In the hippocampus, a brain structure critically important in the stress response, GABA controls neuronal activity not only via synaptic inhibition, but also via tonic inhibition through stimulation of extrasynaptic GABA receptors. The extracellular level of GABA may represent a major determinant for tonic inhibition and, therefore, it is surprising that its responsiveness to stress has hardly been investigated. To clarify whether hippocampal extracellular GABA levels change in response to acute stress, we conducted an in vivo microdialysis study in rats. We found that dialysate GABA levels respond to various neuropharmacological manipulations such as reuptake inhibition, elevated concentrations of K(+), tetrodotoxin and baclofen, indicating that a large proportion of hippocampal extracellular GABA depends on neuronal release and that GABA re-uptake plays a role in determining the extracellular levels of this neurotransmitter. Next, rats were exposed to a novel cage or to forced swimming in 25 degrees C water. Interestingly, these two stressors resulted in opposite effects. Novelty caused a fast increase in GABA (120% of baseline), whereas forced swimming resulted in a profound decrease (70% of baseline). To discriminate between the psychological and physical aspects (i.e. the effects on body temperature) of forced swimming, another group of animals was forced to swim at 35 degrees C. This stressor, like novelty, caused an increase in hippocampal GABA, suggesting a stimulatory effect of psychological stress. The effects of novelty could not be blocked by the corticotropin-releasing factor receptor antagonist D-Phe-CRF(12-41). These results are the first to demonstrate stressor-dependent changes in hippocampal extracellular GABA; an observation which may be of particular significance for GABAergic tonic inhibition of hippocampal neurons.
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Affiliation(s)
- L de Groote
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, Department of Clinical Science at South Bristol, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
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19
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Boyce-Rustay JM, Cameron HA, Holmes A. Chronic swim stress alters sensitivity to acute behavioral effects of ethanol in mice. Physiol Behav 2007; 91:77-86. [PMID: 17363014 DOI: 10.1016/j.physbeh.2007.01.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 01/09/2007] [Accepted: 01/31/2007] [Indexed: 11/28/2022]
Abstract
Epidemiological data support a strong link between stress, stress-related disorders and risk for alcoholism. However, precisely how stress might impact sensitivity to the intoxicating effects of ethanol or the willingness to voluntary consume ethanol remains unclear. The present study assessed the effects of daily exposure to forced swim stress on subsequent sensitivity to the sedative/hypnotic, hypothermic, ataxic (measured using accelerating rotarod), and anxiolytic-like (measured using elevated plus-maze) effects of ethanol, and ethanol consumption and preference in a two-bottle choice paradigm, in male C57BL/6J mice. Stress effects on the sedative/hypnotic effects of the barbiturate pentobarbital were also tested. Results showed that chronic (fourteen days) but not acute (one or three days) swim stress significantly potentiated the sedative/hypnotic and hypothermic effects of 4 g/kg, but not 3 g/kg, ethanol. The sedative/hypnotic effects of pentobarbital were attenuated by chronic swim stress. Irrespective of chronicity, swim stress did not alter the ataxic or anxiolytic-like effects of ethanol, or alter ethanol self-administration either during or after stress. These data provide further evidence that stress alters the intoxicating effects of high doses of ethanol in a behaviorally selective manner.
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Affiliation(s)
- Janel M Boyce-Rustay
- Section on Behavioral Science and Genetics, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, United States.
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20
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Fahey JM, Pritchard GA, Reddi JM, Pratt JS, Grassi JM, Shader RI, Greenblatt DJ. The effect of chronic lorazepam administration in aging mice. Brain Res 2006; 1118:13-24. [PMID: 16989785 DOI: 10.1016/j.brainres.2006.08.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Revised: 02/14/2006] [Accepted: 08/05/2006] [Indexed: 11/21/2022]
Abstract
To assess benzodiazepine tolerance in aged animals, lorazepam or vehicle was administered chronically to male Crl: CD-1(ICR)BR mice. Pharmacodynamic and neurochemical endpoints were examined on days 1 and 14 of drug administration. There was no age-related significant difference in plasma lorazepam levels. Young and middle-aged animals demonstrated behavioral tolerance to lorazepam, while the aged animals showed a similar trend which failed to reach significance. In addition, aged animals also showed a trend toward tolerance to the anticonvulsant effects of lorazepam. There were no changes in alpha1 mRNA levels in cortex or hippocampus following administration of lorazepam when compared to vehicle-treated animals in any age group. Aged animals, however, had an initial increase in alpha1 mRNA expression in cortex and hippocampus on day 1 of vehicle treatment followed by decreased expression on day 14. These age-related changes were abolished by lorazepam administration. In summary, age-related sensitivity to the effects of lorazepam was not demonstrated in the present study. However, comparison of these data to other studies indicates that the effect of chronic benzodiazepine treatment may be specific to the benzodiazepine administered, the technique used to quantify mRNA expression changes, the subunits of the GABA(A) receptor investigated and the brain region analyzed. The phenomenon of benzodiazepine sensitivity in the elderly is an area of research which remains controversial and may well be compound specific. Determining benzodiazepines that do not produce pharmacodynamic sensitivity, such as lorazepam, may allow more careful prescribing and dosing of these drugs, and perhaps even the development of specific agents which could avoid this sensitivity.
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Affiliation(s)
- Jeanne M Fahey
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine and the Division of Clinical Pharmacology, Tufts-New England Medical Center, Boston, MA 02111, USA.
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21
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Chadda R, Devaud LL. Differential effects of mild repeated restraint stress on behaviors and GABA(A) receptors in male and female rats. Pharmacol Biochem Behav 2005; 81:854-63. [PMID: 16039700 DOI: 10.1016/j.pbb.2005.06.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Revised: 05/06/2005] [Accepted: 06/03/2005] [Indexed: 11/20/2022]
Abstract
We previously reported that the very mild stress of individual housing influenced seizure risk and gamma-amino butyric acid (GABA(A)) receptor activity differentially between male and female rats. The aim of the present set of studies was to assess sex differences in behavioral responses to a more pronounced type of stressor, repeated restraint stress. We also wanted to determine the role of GABA(A) receptors in effects of this stressor. Our data suggest that repeated restraint stress afforded short-term protection against seizure induction in both male and female rats. Moreover, this protection was more persistent in female than male rats. This stress paradigm also elicited a reduction in general activity in male rats, whereas female rats displayed prolonged increased activity following the repeated restraint stress exposure. However, there were limited effects on anxiety-like behaviors, as determined by time spent in the open arms on the elevated plus maze. Sex differences in stress-induced increases in plasma corticosterone levels were observed, which generally correlated with sex differences in behavioral measures. There were no significant effects of the repeated restraint stress exposure on benzodiazepine/GABA(A) receptor density or affinity nor on receptor function. Taken together, these findings provide additional evidence to support the important influences of sex in responding to stress and highlight the need to consider this context when addressing the role of stress in health issues for women and men.
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Affiliation(s)
- Ritu Chadda
- Department of Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello, ID 83209-8334, United States
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22
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Kohen R, Kirov S, Navaja GP, Happe HK, Hamblin MW, Snoddy JR, Neumaier JF, Petty F. Gene expression profiling in the hippocampus of learned helpless and nonhelpless rats. THE PHARMACOGENOMICS JOURNAL 2005; 5:278-91. [PMID: 16010284 DOI: 10.1038/sj.tpj.6500322] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In the learned helplessness (LH) animal model of depression, failure to attempt escape from avoidable environmental stress, LH, indicates behavioral despair, whereas nonhelpless (NH) behavior reflects behavioral resilience to the effects of environmental stress. Comparing hippocampal gene expression with large-scale oligonucleotide microarrays, we found that stress-resilient (NH) rats, although behaviorally indistinguishable from controls, showed a distinct gene expression profile compared to LH, sham stressed, and naïve control animals. Genes that were confirmed as differentially expressed in the NH group by quantitative PCR strongly correlated in their levels of expression across all four animal groups. Differential expression could not be confirmed at the protein level. We identified several shared degenerate sequence motifs in the 3' untranslated region (3'UTR) of differentially expressed genes that could be a factor in this tight correlation of expression levels among differentially expressed genes.
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MESH Headings
- Adaptor Proteins, Vesicular Transport
- Animals
- Behavior, Animal/physiology
- Depression/genetics
- Depression/physiopathology
- Disease Models, Animal
- Electroshock
- Gene Expression
- Gene Expression Profiling
- Helplessness, Learned
- Hippocampus/metabolism
- Male
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mitogen-Activated Protein Kinase 9/genetics
- Mitogen-Activated Protein Kinase 9/metabolism
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Oligonucleotide Array Sequence Analysis
- Promoter Regions, Genetic
- RNA, Messenger/analysis
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Stress, Psychological/genetics
- Stress, Psychological/physiopathology
- Untranslated Regions
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Affiliation(s)
- R Kohen
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, 98108, USA.
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23
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Briones-Aranda A, Rocha L, Picazo O. Alterations in GABAergic function following forced swimming stress. Pharmacol Biochem Behav 2005; 80:463-70. [PMID: 15740789 DOI: 10.1016/j.pbb.2005.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Revised: 01/06/2005] [Accepted: 01/07/2005] [Indexed: 12/01/2022]
Abstract
Forced swimming induces alterations in the GABA brain concentration and could change the sensitivity of the GABA/benzodiazepine receptor-chloride ionophore complex to benzodiazepines. This change in sensitivity could be explained by the allopregnanolone release that takes place during stress. The current study was carried out to determine whether forced swimming is able to modify the anti-anxiety effect of diazepam and to explore the possible relation of this change to allopregnanolone, the GABA concentration or/and the GABA/benzodiazepine receptor density. Unstressed and stressed mice, injected with the vehicle or diazepam, were evaluated in the exploratory behavior test. Diazepam induced clear anxiolytic actions at all doses in unstressed animals, but such an effect was not observed in stressed animals. The injection of allopregnanolone 24 h before the anxiety test blocked the effect of this benzodiazepine. Forced swimming decreased GABA concentrations in the hippocampus and the thalamus-hypothalamus region, besides decreasing the [(3)H]flunitrazepam labeling in both the hypothalamus and amygdala. These results show that forced swimming abolishes the anti-anxiety effect of diazepam.
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Affiliation(s)
- Alfredo Briones-Aranda
- Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Diaz Mirón, Col. Sto. Tomás, 11340 México City, México
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24
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Stone DJ, Walsh JP, Sebro R, Stevens R, Pantazopolous H, Benes FM. Effects of pre- and postnatal corticosterone exposure on the rat hippocampal GABA system. Hippocampus 2002; 11:492-507. [PMID: 11732703 DOI: 10.1002/hipo.1066] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Several lines of evidence have implicated prenatal stress and the hippocampal GABA system in the pathophysiology of schizophrenia, and prenatal stress is believed to increase the risk for schizophrenia through alterations of this neurotransmitter. To explore this hypothesis, we treated male rats pre- and/or postnatally (P48 and P60) with either corticosterone (CORT) or vehicle to establish three study groups: VVV, receiving vehicle at all three time points; VCC, receiving vehicle prenatally and CORT at both postnatal timepoints; and CCC, receiving CORT at all three timepoints. Animals were sacrificed at either 24 h or 5 days after final injection and examined for mRNA levels of GAD65, GAD67, and the GABA(A) receptor subunits alpha2 and gamma2. At 24 h, GAD65 mRNA was decreased in CA1, CA2, CA4, and dentate gyrus (DG) of VCC rats; this effect was either decreased or reversed in CCC-treated animals. No effect was detected in GAD67 mRNA at 24 h. At 5 days, CORT treatment increased GAD67 mRNA levels in CA1, CA3, and DG. Prenatal treatment with CORT was associated with increased responsiveness only in CA3 and DG. For the GABAA receptor, alpha2 subunit mRNA did not show any change in response to CORT treatment, while that for the gamma2 subunit was decreased in CA2 of both VCC- and CCC-treated animals. Consistent with gamma2 subunit mRNA decreases, benzodiazepine (BZ) receptor binding activity was decreased in CA2 with CORT treatment. Prenatal CORT exposure neither increased nor decreased this effect. These results demonstrate that CORT administration is associated with a complex regulation of mRNA expression for pre- and postnatal aspects of the hippocampal GABA system. Under these conditions, prenatal exposure to CORT may sensitize some of these effects, but does not fundamentally alter the nature of this response.
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Affiliation(s)
- D J Stone
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA
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25
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Abstract
Knowledge of the genetic and molecular events underlying the neuroendocrine and behavioural sequelae of the response to stress has advanced rapidly over recent years. The response of an individual to a stressful experience is a polygenic trait, but also involves non-genetic sources of variance. Using a combination of top-down (quantitative trait locus [QTL] and microarray analysis) and bottom-up (gene targeting, transgenesis, antisense technology and random mutagenesis) strategies, we are beginning to dissect the molecular players in the mediation of the stress response. Given the wealth of the data obtained from mouse mutants, this review will primarily focus on the contributions made by transgenesis and knockout studies, but the relative contribution of QTL studies and microarray studies will also be briefly addressed. From these studies it is evident that several neuroendocrine and behavioural alterations induced by stress can be modelled in mouse mutants with alterations in hypothalamic-pituitary-adrenal axis activity or other, extrahypothalamic, neurotransmitter systems known to be involved in the stress response. The relative contribution of these models to understanding the stress response and their limitations will be discussed.
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Affiliation(s)
- T Steckler
- CNS Discovery, Janssen Research Foundation, Turnhioutseweg 30, B-2340 Beerse, Belgium.
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26
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Abstract
Dual hybridization histochemical studies were conducted to investigate the extent of colocalization of mRNA transcripts encoding the alpha1-2 and beta1-3 subunits of the gamma aminobutyric acid (GABA)(A) receptor with those for corticotropin-releasing hormone (CRH) within the rat hypothalamic paraventricular nucleus (PVN). A vast majority of CRH neurons (>94.5%) were found to express transcripts specific for the the alpha2, beta1 and beta3 subunits; mRNAs for the alpha1 and beta2 subunits of the GABA(A) receptor were detected within 53.3% and 65.7% of PVN CRH neurons, respectively. The results may have important implications for studies aimed at understanding GABAergic influences upon the hypothalamic-pituitary-adrenocortical (HPA) axis. Hypophysiotropic CRH neurons serve as the origin of the final common pathway for glucocorticoid secretion in response to stressful stimuli, and GABAergic afferents have been implicated in afferent control of these neurons. The subunit composition of GABA(A) receptors at this key regulatory locus may affect the efficacy of a major inhibitory input, and thus the magnitude and/or duration of stress-induced glucocorticoid secretion. The present findings reveal basal expression patterns of transcripts encoding several subunits of the GABA(A) receptor within stress-integrative CRH neurons, data which may be used to guide regulatory studies of GABAergic influences on the HPA axis under a variety of conditions.
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Affiliation(s)
- W E Cullinan
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, USA.
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27
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Oh S, Ho IK. Changes of [3H]muscimol binding and GABA(A) receptor beta2-subunit mRNA level by tolerance to and withdrawal from pentobarbital in rats. Neurochem Res 1999; 24:1603-9. [PMID: 10591412 DOI: 10.1023/a:1021168519387] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Effects of continuous pentobarbital administration on binding characteristics of [3H]muscimol were examined by autoradiography, and levels of GABA(A) receptor beta2-subunit mRNA were investigated by in situ hybridization histochemistry in the rat brain. In order to eliminate the induction of hepatic metabolism by systemic administration of pentobarbital, an i.c.v. infusion model of tolerance to and withdrawal from pentobarbital was used. An experimental model of barbiturate tolerance and withdrawal was developed using i.c.v. infusion of pentobarbital (300 microg/10 microl/hr for 7 days) by osmotic minipumps and abrupt withdrawal from pentobarbital. The levels of [3H]muscimol binding were elevated in cingulate of frontal cortex (46%) and granule layer of cerebellum (32%) of rats 24-hr after withdrawal from pentobarbital, while it was only elevated in cingulate (58%) of tolerant rats. The GABA(A) receptor beta2-subunit mRNA was increased in the withdrawal rats only: in the cortex (9-14%), hippocampus (15-21%), inferior colliculus (21%), and granule layer of cerebellum (24%). These results show the involvement of GABA(A) receptor and its beta2-subunit up-regulations in pentobarbital withdrawal rats, and suggest that the levels of [3H]muscimol binding and GABA(A) receptor beta2-subunit mRNA are altered in a region-specific manner during pentobarbital withdrawal.
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Affiliation(s)
- S Oh
- Division of Neuroscience, Medical Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
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28
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Revilla V, Soria C, Aller MI, Calvo P, Fernández-López A. Effect of surgical stress on benzodiazepine receptors as a consequence of placebo pellet implantation in rat: an autoradiographic study. Brain Res Bull 1999; 49:413-8. [PMID: 10483918 DOI: 10.1016/s0361-9230(99)00073-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This paper reports modifications in benzodiazepine (BZ) receptors induced by minimally invasive surgery, such as pellet implantation, a widely used surgical process for chronic drug administration. The intrinsic stress induced by this manipulation on BZ receptors was analysed in an autoradiographic saturation study determining the affinity (K(D)) and total number (Bmax) of binding sites of a number of brain areas from the mesencephalon, cerebral cortex, hippocampus, and cerebellum. The radioligand used for the study was [3H]flunitrazepam, which permitted overall characterization of BZ binding sites. Use of the specific BZ1 agonist zolpidem as an inhibitor of this radioligand permitted the direct characterization of subtype 2 (BZ2) and the indirect characterization of subtype 1 receptor (BZ1). Significant increases in Bmax and K(D) values were observed in pellet-implanted animals with respect to those not implanted. The results support the notion of an up-regulation of these receptors, mainly in BZ1 receptors, following sustained desensitization as a result of the surgical stress induced by pellet implantation.
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Affiliation(s)
- V Revilla
- Departmento de Biología Celular, Universidad de León, Spain
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29
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Sundström I, Bäckström T, Wang M, Olsson T, Seippel L, Bixo M. Premenstrual syndrome, neuroactive steroids and the brain. Gynecol Endocrinol 1999; 13:206-20. [PMID: 10451814 DOI: 10.3109/09513599909167557] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- I Sundström
- Department of Obstetrics and Gynecology and Medicine, University of Umeå, Sweden
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30
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Chew LJ, Gallo V. Regulation of ion channel expression in neural cells by hormones and growth factors. Mol Neurobiol 1998; 18:175-225. [PMID: 10206469 DOI: 10.1007/bf02741300] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Voltage-and ligand-gated ion channels are key players in synaptic transmission and neuron-glia communication in the nervous system. Expression of these proteins can be regulated at several levels (transcriptional, translational, or posttranslational) and by multiple extracellular factors in the developing and mature nervous system. A wide variety of hormones and growth factors have been identified as important in neural cell differentiation, which is a complex process involving the acquisition of cell-type-specific ion channel phenotypes. Much literature has already accumulated describing the structural and functional characteristics of ion channels, but relatively little is known about the factors that influence their synthesis and cell surface expression, although this area has generated considerable interest in the context of neural cell development. This article reviews several examples of regulated expression of these channels by cellular factors, namely peptide growth factors and steroid hormones, and discusses, where applicable, current understanding of molecular mechanisms underlying such regulation of voltage-and neurotransmitter-gated ion channels.
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Affiliation(s)
- L J Chew
- Laboratory of Cellular and Molecular Neurophysiology, NICHD, NIH, Bethesda, MD 20892-4495, USA
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31
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Zhang L, Rubinow DR, Ma W, Marks JM, Feldman AN, Barker JL, Tathan TA. GABA receptor subunit mRNA expression in brain of conflict, yoked control and control rats. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1998; 58:16-26. [PMID: 9685573 DOI: 10.1016/s0169-328x(98)00061-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Animal conflict models have been used for years as a preclinical screen for predicting anxiolytic therapeutic efficacy. Anxiolytics, including benzodiazepines, increase punished responding. This suggests that the punished behavior may be mediated by the GABA receptor. To evaluate this hypothesis, we performed in situ hybridization histochemistry studies of GABA receptor subunits (alpha1-alpha4) and synthetic enzymes glutamic acid decarboxylase (GAD65 and GAD67) in four groups of rats: conflict (punishment), yoked controls (rats shocked without conflict training history), fixed interval only controls (rats that worked for food but were not shocked) and untreated controls. With conflict behavioral training, bilateral reduction of mRNA for the GABAA alpha1 subunit was seen relative to controls in the cortex, thalamus and hippocampus. In contrast, alteration of alpha2 mRNA levels appeared only in the yoked control group, with increased levels seen in the thalamus and cortex and decreased levels in the hippocampus. There were no differences in the alpha2 mRNA level between the control and the conflict behavioral trained animals. Further, no significant differences were found between groups in the mRNA levels for the alpha3 subunit, alpha4 subunit, GAD65, and GAD67. These results suggest that the behaviors related to conflict and uncontrollable aversive stimuli (yoked control group) are accompanied and perhaps mediated by selective changes in the GABAA alpha1 or alpha2 subunits, respectively. These findings highlight the potential usefulness of the conflict model as a means of elucidating the biological underpinnings of anxiety disorder. Published by Elsevier Science B.V. All rights reserved.
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Affiliation(s)
- L Zhang
- Behavioral Endocrinology Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1276, USA
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32
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Thielen RJ, McBride WJ, Chernet E, Lumeng L, Li TK. Regional densities of benzodiazepine sites in the CNS of alcohol-naive P and NP rats. Pharmacol Biochem Behav 1997; 57:875-82. [PMID: 9259019 DOI: 10.1016/s0091-3057(96)00464-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The regional densities of benzodiazepine (BDZ) recognition sites coupled to GABAA receptors were studied in ethanol-naive alcohol-preferring (P) and -nonpreferring (NP) lines of rats by using quantitative autoradiography to measure the amount of 2 nM [3H]flunitrazepam (FNZ) binding in the absence and presence of 100 microM GABA. Lower values (p < 0.025) for [3H]FNZ binding (in the absence of GABA) were observed in the prefrontal cortex, layer 4 of the parietal cortex, and the nucleus accumbens shell of the P relative to the NP line. GABA significantly (p < 0.025) stimulated [3H]FNZ binding in all 50 central nervous system regions examined in both the P and the NP rats. The largest percent increases (190-220%) were observed in the prefrontal, cingulate, frontal, and parietal cortices; shell and core nucleus accumbens; caudate putamen; dorsal lateral, intermediate lateral, ventral lateral, and medial septal nuclei; and lateral hypothalamus. In several layers of the frontal and parietal cortices, a 25-30% greater net or percent increase (p < 0.025) in GABA-enhanced [3H]FNZ binding was observed in the P rats compared with the NP rats. In contrast, lower net or percent increases (p < 0.025) in GABA-enhanced [3H]FNZ binding were found in the entorhinal cortex, the mediodorsal thalamus, and the dorsal CA3 area and middle dentate gyrus of the posterior hippocampus of the P line relative to the NP line. The present findings suggest that there are innate regional differences between P and NP rats in the densities and/or affinities of BDZ recognition sites and in the coupling between the GABAA and BDZ binding sites.
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Affiliation(s)
- R J Thielen
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, USA
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Lino de Oliveira C, Guimarães FS, Del Bel EA. c-jun mRNA expression in the hippocampal formation induced by restraint stress. Brain Res 1997; 753:202-8. [PMID: 9125404 DOI: 10.1016/s0006-8993(96)01490-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effect of restraint stress on c-jun mRNA expression in the hippocampal formation was investigated by in situ hybridization, dot blot and northern blot. c-jun mRNA expression increased after 60 min of forced restraint in the dentate gyrus, CA1 and CA3 regions of the hippocampal formation. The effect in the dentate gyrus was attenuated by pre-stress i.c.v. injection of the anxiolytic benzodiazepine midazolam (20 nmol/2 microl) or the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-7-phosphonoheptanoic acid (AP-7, 5 nmol/2 microl), but not by the 5-HT1A agonist, (+/-) 8-hydroxy-dipropylaminotetralin (8-OH-DPAT, 20 nmol/2 microl). These results suggest that the hippocampal formation is activated during restraint stress, and that this activation is modulated by benzodiazepine/GABA-A or NMDA receptors.
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Affiliation(s)
- C Lino de Oliveira
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto,SP, Brazil
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34
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Plasticity in GABAA receptor subunit mRNA expression by hypothalamic magnocellular neurons in the adult rat. J Neurosci 1996. [PMID: 8756419 DOI: 10.1523/jneurosci.16-16-04872.1996] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The magnocellular hypothalamic neurons exhibit a substantial degree of structural and functional plasticity over the time of pregnancy, parturition, and lactation. This study has used in situ hybridization techniques to examine whether the content of alpha 1, alpha 2, beta 2, gamma 2 GABAA receptor subunit mRNAs expressed by these cells fluctuates over this period. A process of regional, followed by cellular and then topographical, analyses within the supraoptic (SON) and posterior paraventricular (PVN) nuclei revealed that an increase in magnocellular alpha 1 subunit mRNA content occurred during the course of pregnancy up to day 19, after which a decline in expression was detected on the day of parturition. Significant fluctuations of this nature were observed only in the oxytocin neuron-enriched regions of the SON and PVN. The expression of alpha 2, beta 2, and gamma 2 subunit mRNAs in the SON and PVN and of all subunit mRNAs in the cingulate cortex did not change over this period. During lactation, gamma 2 subunit mRNA content within the PVN increased significantly on day 14 of lactation as compared with day 7, and topographical analysis suggested that it involved principally magnocellular vasopressin neurons. These results demonstrate the cell-and subunit-specific regulation of GABAA receptor mRNA expression within the hypothalamic magnocellular system. In particular, they suggest that fluctuations in alpha 1 subunit expression may contribute to the marked variations in electrical activity exhibited by magnocellular oxytocin neurons at the time of parturition. More generally, they provide evidence in support of GABAA receptor plasticity within a physiological context in the adult rat brain.
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Clément Y. Structural and pharmacological aspects of the GABAA receptor: involvement in behavioral pathogenesis. JOURNAL OF PHYSIOLOGY, PARIS 1996; 90:1-13. [PMID: 8803850 DOI: 10.1016/0928-4257(96)87164-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The gamma-aminobutyric acidA (GABAA) receptor is a complex hetero-oligomeric protein. It is composed of several subunits which assemble to form a functional chloride channel. The precise molecular organization of the receptor is as yet unknown. In the first part, we review recent literature dealing with the molecular and pharmacological aspects of the GABAA receptor, the second part will review some of the pathologies probably associated with gene defects and/or quantitative differential expression of transcripts encoding GABAA receptor subunits.
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Affiliation(s)
- Y Clément
- URA-CNRS 1957, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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Affiliation(s)
- A L Morrow
- Department of Psychiatry University of North Carolina School of Medicine, Chapel Hill 27599-7178, USA
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Orchinik M, Weiland NG, McEwen BS. Chronic exposure to stress levels of corticosterone alters GABAA receptor subunit mRNA levels in rat hippocampus. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1995; 34:29-37. [PMID: 8750858 DOI: 10.1016/0169-328x(95)00118-c] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Chronic exposure to stress levels of corticosteroids alters many aspects of hippocampal function and may lead to neurodegeneration. Male rats were treated for 10 days with corticosterone (CORT) or vehicle pellets, and mRNA levels for six gamma-aminobutyric acid (GABAA) receptor subunits were measured. Effects of castration on subunit mRNA levels in CORT- and vehicle-treated animals were also examined. In situ hybridization studies demonstrated that mRNA levels for hippocampal GABAA receptor alpha 1, alpha 2, beta 1, beta 2, beta 3, and gamma 2 subunits were differentially altered by CORT treatment. Levels of alpha 1 and alpha 2 mRNA decreased in the dentate gyrus, and beta 1 mRNA levels decreased in CA1 and dentate gyrus of CORT-, compared to vehicle-treated, animals. In contrast, beta 2 subunit levels increased in all hippocampal regions examined, beta 3 levels increased in the dentate gyrus, and gamma 2 levels increased in CA1-CA3. The alpha 1, beta 1, and beta 2 mRNA levels all increased in the cingulate cortex of CORT-treated animals. There was no significant effect of gonadal state on any of the subunits examined, but there was a significant negative correlation between testosterone levels and mRNA levels of alpha 1, alpha 2 and beta 3 in specific regions. These data demonstrate that chronic exposure to stress levels of CORT produces complex changes in the mRNA levels of multiple GABAA receptor subunits, independently of the CORT-induced suppression of circulating testosterone.
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Affiliation(s)
- M Orchinik
- Laboratory of Neuroendocrinology, Rockefeller University, New York, NY 10021, USA
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Rabow LE, Russek SJ, Farb DH. From ion currents to genomic analysis: recent advances in GABAA receptor research. Synapse 1995; 21:189-274. [PMID: 8578436 DOI: 10.1002/syn.890210302] [Citation(s) in RCA: 405] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gamma-aminobutyric acid type A (GABAA) receptor represents an elementary switching mechanism integral to the functioning of the central nervous system and a locus for the action of many mood- and emotion-altering agents such as benzodiazepines, barbiturates, steroids, and alcohol. Anxiety, sleep disorders, and convulsive disorders have been effectively treated with therapeutic agents that enhance the action of GABA at the GABAA receptor or increase the concentration of GABA in nervous tissue. The GABAA receptor is a multimeric membrane-spanning ligand-gated ion channel that admits chloride upon binding of the neurotransmitter GABA and is modulated by many endogenous and therapeutically important agents. Since GABA is the major inhibitory neurotransmitter in the CNS, modulation of its response has profound implications for brain functioning. The GABAA receptor is virtually the only site of action for the centrally acting benzodiazepines, the most widely prescribed of the anti-anxiety medications. Increasing evidence points to an important role for GABA in epilepsy and various neuropsychiatric disorders. Recent advances in molecular biology and complementary information derived from pharmacology, biochemistry, electrophysiology, anatomy and cell biology, and behavior have led to a phenomenal growth in our understanding of the structure, function, regulation, and evolution of the GABAA receptor. Benzodiazepines, barbiturates, steroids, polyvalent cations, and ethanol act as positive or negative modulators of receptor function. The description of a receptor gene superfamily comprising the subunits of the GABAA, nicotinic acetylcholine, and glycine receptors has led to a new way of thinking about gene expression and receptor assembly in the nervous system. Seventeen genetically distinct subunit subtypes (alpha 1-alpha 6, beta 1-beta 4, gamma 1-gamma 4, delta, p1-p2) and alternatively spliced variants contribute to the molecular architecture of the GABAA receptor. Mysteriously, certain preferred combinations of subunits, most notably the alpha 1 beta 2 gamma 2 arrangement, are widely codistributed, while the expression of other subunits, such as beta 1 or alpha 6, is severely restricted to specific neurons in the hippocampal formation or cerebellar cortex. Nervous tissue has the capacity to exert control over receptor number, allosteric uncoupling, subunit mRNA levels, and posttranslational modifications through cellular signal transduction mechanisms under active investigation. The genomic organization of the GABAA receptor genes suggests that the present abundance of subtypes arose during evolution through the duplication and translocations of a primordial alpha-beta-gamma gene cluster. This review describes these varied aspects of GABAA receptor research with special emphasis on contemporary cellular and molecular discoveries.
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Affiliation(s)
- L E Rabow
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Massachusetts 02118, USA
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Morrow AL. Regulation of GABAA receptor function and gene expression in the central nervous system. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1995; 38:1-41. [PMID: 8537199 DOI: 10.1016/s0074-7742(08)60523-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- A L Morrow
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill 27599, USA
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Titze-de-Almeida R, de Oliveira CL, Shida HW, Guimarães FS, Del Bel EA. Midazolam and the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-7-phosphonoheptanoic acid (AP-7) attenuate stress-induced expression of c-fos mRNA in the dentate gyrus. Cell Mol Neurobiol 1994; 14:373-80. [PMID: 7788644 DOI: 10.1007/bf02088717] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
1. The effects of restraint stress on c-fos mRNA expression in the dentate gyrus were investigated by in situ hybridization. 2. Confirming previous findings, c-fos mRNA expression increased after 30 min of forced restraint. 3. This effect was attenuated by a previous i.c.v. injection of the anxiolytic benzodiazepine midazolam (20 nmol/2 microliters) or the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-7-phosphonoheptanoic acid (AP-7; 5 nmol/2 microliters). 4. These results suggest that the dentate gyrus is activated during restraint stress and that this activation may be modulated by benzodiazepine gamma-aminobutyric acidA (GABAA) or NMDA receptors.
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Affiliation(s)
- R Titze-de-Almeida
- Department of Pharmacology, School of Medicine, Ribeirão Preto, SP, Brazil
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Tseng YT, Wellman SE, Ho IK. Differential effects on GABAA receptor gamma 2-subunit messenger RNA by tolerance to and withdrawal from pentobarbital--an in situ hybridization study. Life Sci 1993; 53:PL321-6. [PMID: 8412506 DOI: 10.1016/0024-3205(93)90627-f] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The heterogeneity of the GABAA receptors has been confirmed structurally and functionally. The present study demonstrates the pharmacological heterogeneity of the GABAA receptors. Rats were rendered tolerant to pentobarbital by continuous intracerebroventricular infusion via osmotic minipumps and abruptly withdrawn from pentobarbital. In situ hybridization of mRNA coding for the GABAA receptor gamma 2-subunit showed decreases of mRNA levels in superior and inferior colliculus in pentobarbital tolerant rats compared to rats in withdrawal. In rats 24-hr after withdrawal from pentobarbital, increases of mRNA levels in neocortex, piriform cortex and in granular and Purkinje cell layers of the cerebellum were observed. These results indicate the fast adaptation of GABA synapses in response to abrupt withdrawal from chronic pentobarbital treatment. The differential responsiveness seen in different areas further confirms the pharmacological heterogeneity of the GABAA receptors. The observed increases and decreases of mRNA may underlie, at least in part, the previously reported changes in Bmax of GABAA receptor ligand binding sites.
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Affiliation(s)
- Y T Tseng
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216
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