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Blednov YA, Shawlot W, Homanics GE, Osterndorff-Kahanek EA, Mason S, Mayfield J, Smalley JL, Moss SJ, Messing RO. The PDE4 inhibitor apremilast modulates ethanol responses in Gabrb1-S409A knock-in mice via PKA-dependent and independent mechanisms. Neuropharmacology 2024; 257:110035. [PMID: 38876310 PMCID: PMC11387004 DOI: 10.1016/j.neuropharm.2024.110035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 06/05/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024]
Abstract
We previously showed that the PDE4 inhibitor apremilast reduces ethanol consumption in mice by protein kinase A (PKA) and GABAergic mechanisms. Preventing PKA phosphorylation of GABAA β3 subunits partially blocked apremilast-mediated decreases in drinking. Here, we produced Gabrb1-S409A mice to render GABAA β1 subunits resistant to PKA-mediated phosphorylation. Mass spectrometry confirmed the presence of the S409A mutation and lack of changes in β1 subunit expression or phosphorylation at other residues. β1-S409A male and female mice did not differ from wild-type C57BL/6J mice in expression of Gabrb1, Gabrb2, or Gabrb3 subunits or in behavioral characteristics. Apremilast prolonged recovery from ethanol ataxia to a greater extent in Gabrb1-S409A mice but prolonged recovery from zolpidem and propofol to a similar extent in both genotypes. Apremilast shortened recovery from diazepam ataxia in wild-type but prolonged recovery in Gabrb1-S409A mice. In wild-type mice, the PKA inhibitor H89 prevented apremilast modulation of ataxia by ethanol and diazepam, but not by zolpidem. In Gabrb1-S409A mice, inhibiting PKA or EPAC2 (exchange protein directly activated by cAMP) partially reversed apremilast potentiation of ethanol, diazepam, and zolpidem ataxia. Apremilast prevented acute tolerance to ethanol ataxia in both genotypes, but there were no genotype differences in ethanol consumption before or after apremilast. In contrast to results in Gabrb3-S408A/S409A mice, PKA phosphorylation of β1-containing GABAA receptors is not required for apremilast's effects on acute tolerance or on ethanol consumption but is required for its ability to decrease diazepam intoxication. Besides PKA we identified EPAC2 as an additional cAMP-dependent mechanism by which apremilast regulates responses to GABAergic drugs.
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Affiliation(s)
- Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - William Shawlot
- Center for Biomedical Research Support, Mouse Genetic Engineering Facility, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Gregg E Homanics
- Departments of Anesthesiology & Perioperative Medicine, Neurobiology, and Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | | | - Sonia Mason
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Joshua L Smalley
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Robert O Messing
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin, Austin, TX, 78712, USA.
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Uusi-Oukari M, Korpi ER. GABAergic mechanisms in alcohol dependence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 175:75-123. [PMID: 38555121 DOI: 10.1016/bs.irn.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The target of alcohol's effect on the central nervous system has been sought for more than 50 years in the brain's GABA system. The behavioral and emotional effects of alcohol in humans and rodents are very similar to those of barbiturates and benzodiazepines, and GABAA receptors have been shown to be one of the sites of alcohol action. The mechanisms of GABAergic inhibition have been a hotspot of research but have turned out to be complex and controversial. Genetics support the involvement of some GABAA receptor subunits in the development of alcohol dependence and in alcohol use disorders (AUD). Since the effect of alcohol on the GABAA system resembles that of a GABAergic positive modulator, it may be possible to develop GABAergic drug treatments that could substitute for alcohol. The adaptation mechanisms of the GABA system and the plasticity of the brain are a big challenge for drug development: the drugs that act on GABAA receptors developed so far also may cause adaptation and development of additional addiction. Human polymorphisms should be studied further to get insight about how they affect receptor function, expression or other factors to make reasonable predictions/hypotheses about what non-addictive interventions would help in alcohol dependence and AUD.
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Affiliation(s)
- Mikko Uusi-Oukari
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
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Crofton EJ, O'Buckley TK, Bohnsack JP, Morrow AL, Herman MA. Divergent Population-Specific Effects of Chronic Ethanol Exposure on Excitability and Inhibitory Transmission in Male and Female Rat Central Amygdala. J Neurosci 2023; 43:7056-7068. [PMID: 37657933 PMCID: PMC10586533 DOI: 10.1523/jneurosci.0717-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/09/2023] [Accepted: 08/26/2023] [Indexed: 09/03/2023] Open
Abstract
The central nucleus of the amygdala (CeA) is implicated in alcohol use disorder (AUD) and AUD-associated plasticity. The CeA is a primarily GABAergic nucleus that is subdivided into lateral and medial compartments with genetically diverse subpopulations. GABAA receptors are heteromeric pentamers with subunits conferring distinct physiological characteristics. GABAA receptor signaling in the CeA has been implicated in ethanol-associated plasticity; however, population-specific changes in inhibitory signaling and subunit expression remain unclear. Here, we combined electrophysiology with single-cell gene expression analysis of population markers and GABAA receptor subunits to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure. We found that chronic ethanol exposure and withdrawal produced global changes in GABAA receptor subunit expression at the transcript and protein levels, increased excitability in female CeA neurons, and increased inhibitory synaptic transmission in male CeA neurons. When we examined CeA neurons at the single-cell level we found heterogenous populations, as previously reported. We observed ethanol-induced increases in excitability only in somatostatin neurons in the CeA of females, decreases in excitability only in the protein kinase C delta (PKCd) population in males, and ethanol-induced increases in inhibitory transmission in male PKCd and calbindin 2-expressing CeA neurons. There were no population-specific differences in GABAA receptor (Gabr) subunits in males but reduced GabrA5 expression in female somatostatin neurons. Collectively, these findings suggest that defined CeA populations display differential ethanol sensitivity in males and females, which may play a role in sex differences in vulnerability to AUD or expression of AUD pathology.SIGNIFICANCE STATEMENT The CeA is involved in the effects of ethanol in the brain; however, the population-specific changes in CeA activity remain unclear. We used recordings of CeA neuronal activity and single-cell gene expression to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure and found sex- and population-specific effects of chronic ethanol exposure and withdrawal. Specifically, female CeA neurons displayed increased excitability in the somatostatin CeA population, whereas male CeA neurons displayed increased inhibitory control in both PKCd and calbindin populations and decreased excitability in the PKCd population. These findings identify CeA populations that display differential sensitivity to ethanol exposure, which may contribute to sex differences in vulnerability to alcohol use disorder.
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Affiliation(s)
- Elizabeth J Crofton
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Psychology and Neuroscience, Emmanuel College, Boston, Massachusetts 02115
| | - Todd K O'Buckley
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - John P Bohnsack
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - A Leslie Morrow
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Melissa A Herman
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Pedraza N, Monserrat MV, Ferrezuelo F, Torres-Rosell J, Colomina N, Miguez-Cabello F, Párraga JP, Soto D, López-Merino E, García-Vilela C, Esteban JA, Egea J, Garí E. Cyclin D1-Cdk4 regulates neuronal activity through phosphorylation of GABAA receptors. Cell Mol Life Sci 2023; 80:280. [PMID: 37684532 PMCID: PMC10491536 DOI: 10.1007/s00018-023-04920-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 09/10/2023]
Abstract
Nuclear Cyclin D1 (Ccnd1) is a main regulator of cell cycle progression and cell proliferation. Interestingly, Ccnd1 moves to the cytoplasm at the onset of differentiation in neuronal precursors. However, cytoplasmic functions and targets of Ccnd1 in post-mitotic neurons are unknown. Here we identify the α4 subunit of gamma-aminobutyric acid (GABA) type A receptors (GABAARs) as an interactor and target of Ccnd1-Cdk4. Ccnd1 binds to an intracellular loop in α4 and, together with Cdk4, phosphorylates the α4 subunit at threonine 423 and serine 431. These modifications upregulate α4 surface levels, increasing the response of α4-containing GABAARs, measured in whole-cell patch-clamp recordings. In agreement with this role of Ccnd1-Cdk4 in neuronal signalling, inhibition of Cdk4 or expression of the non-phosphorylatable α4 decreases synaptic and extra-synaptic currents in the hippocampus of newborn rats. Moreover, according to α4 functions in synaptic pruning, CCND1 knockout mice display an altered pattern of dendritic spines that is rescued by the phosphomimetic α4. Overall, our findings molecularly link Ccnd1-Cdk4 to GABAARs activity in the central nervous system and highlight a novel role for this G1 cyclin in neuronal signalling.
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Affiliation(s)
- Neus Pedraza
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain.
| | - Ma Ventura Monserrat
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Francisco Ferrezuelo
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Jordi Torres-Rosell
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Neus Colomina
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Federico Miguez-Cabello
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Javier Picañol Párraga
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - David Soto
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Esperanza López-Merino
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Celia García-Vilela
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - José A Esteban
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Joaquim Egea
- Molecular and Developmental Neurobiology, Dept. Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Rovira Roure 80, 25198, Lleida, Spain
| | - Eloi Garí
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain.
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Blednov YA, Da Costa A, Mason S, Mayfield J, Moss SJ, Messing RO. Apremilast-induced increases in acute ethanol intoxication and decreases in ethanol drinking in mice involve PKA phosphorylation of GABA A β3 subunits. Neuropharmacology 2022; 220:109255. [PMID: 36152689 PMCID: PMC9810330 DOI: 10.1016/j.neuropharm.2022.109255] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/23/2022] [Accepted: 09/10/2022] [Indexed: 01/05/2023]
Abstract
We previously showed that apremilast, an FDA-approved PDE4 inhibitor, selectively alters behavioral responses to ethanol and certain GABAergic drugs in a PKA-dependent manner in C57BL6/J mice. Here, we investigated if PKA phosphorylation of β3 GABAA receptor subunits is involved in apremilast regulation of ethanol, propofol, or diazepam responses. Apremilast prolonged rotarod ataxia and loss of the righting reflex by ethanol and propofol in wild-type mice, but not in β3-S408A/S409A knock-in mice. In contrast, apremilast hastened recovery from the ataxic and sedative effects of diazepam in both genotypes. These findings suggest that apremilast modulation of ethanol and propofol behaviors in wild-type mice is mediated by β3 subunit phosphorylation, whereas its actions on diazepam responses involve a different mechanism. The PKA inhibitor H-89 prevented apremilast modulation of ethanol-induced ataxia. Apremilast sensitized wild-type males to ethanol-induced ataxia and decreased acute functional tolerance (AFT) in females but had no effect in β3-S408A/S409A mice of either sex. These results could not be attributed to genotype differences in blood ethanol clearance. There were also no baseline genotype differences in ethanol consumption and preference in two different voluntary drinking procedures. However, the ability of apremilast to reduce ethanol consumption was diminished in β3-S408A/S409A mice. Our results provide strong evidence that PKA-dependent phosphorylation of β3 GABAA receptor subunits is an important mechanism by which apremilast increases acute sensitivity to alcohol, decreases AFT, and decreases ethanol drinking.
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Affiliation(s)
- Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Adriana Da Costa
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Sonia Mason
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Robert O Messing
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin, Austin, TX, 78712, USA.
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Regulation of GABA A Receptors Induced by the Activation of L-Type Voltage-Gated Calcium Channels. MEMBRANES 2021; 11:membranes11070486. [PMID: 34209589 PMCID: PMC8304739 DOI: 10.3390/membranes11070486] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 12/30/2022]
Abstract
GABAA receptors are pentameric ion channels that mediate most synaptic and tonic extrasynaptic inhibitory transmissions in the central nervous system. There are multiple GABAA receptor subtypes constructed from 19 different subunits in mammals that exhibit different regional and subcellular distributions and distinct pharmacological properties. Dysfunctional alterations of GABAA receptors are associated with various neuropsychiatric disorders. Short- and long-term plastic changes in GABAA receptors can be induced by the activation of different intracellular signaling pathways that are triggered, under physiological and pathological conditions, by calcium entering through voltage-gated calcium channels. This review discusses several mechanisms of regulation of GABAA receptor function that result from the activation of L-type voltage gated calcium channels. Calcium influx via these channels activates different signaling cascades that lead to changes in GABAA receptor transcription, phosphorylation, trafficking, and synaptic clustering, thus regulating the inhibitory synaptic strength. These plastic mechanisms regulate the interplay of synaptic excitation and inhibition that is crucial for the normal function of neuronal circuits.
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Jiang M, Sun Y, Lei Y, Hu F, Xia Z, Liu Y, Ma Z, Gu X. GPR30 receptor promotes preoperative anxiety-induced postoperative hyperalgesia by up-regulating GABA A-α4β1δ subunits in periaqueductal gray in female rats. BMC Anesthesiol 2020; 20:93. [PMID: 32321426 PMCID: PMC7175561 DOI: 10.1186/s12871-020-01017-7] [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: 11/05/2019] [Accepted: 04/16/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND G-protein coupled estrogen receptor 30 (GPR30) was proved the specific estrogen receptor relating to mechanical hyperalgesia. Studies have shown that the GABAA receptor subunits α4, β1, and δ in the periaqueductal gray (PAG) neurons promote the descending facilitation system. This study inquired into whether and how GPR30 and GABAA-α4β1δ in the PAG promote preoperative anxiety-induced postoperative hyperalgesia in female rats. METHODS All the female rats were subjected to the single prolonged stress (SPS) to stimulate preoperative anxiety. Subsequently, mechanical allodynia was evaluated before and after the incision, based on the paw withdrawal mechanical threshold (PWMT). The selective GPR30 agonist G1 and antagonist G15 were locally microinjected into the PAG. The expression of GPR30, protein kinase A (PKA), and GABAA receptor subunits α4, β1, and δ in the PAG neurons were detected using western blotting and immunofluorescence. RESULTS Behavioral testing revealed that Group S and Group I decreased the nociceptive threshold levels of PWMT in female rats. PWMT in Group S + I decreased more than that of Group S and Group I. Further, results of western blotting showed the expression of GPR30, PKA, and GABAA α4, β1, and δ subunits significantly up-regulated in Group S + I, and immunofluorescence indicated that the neurons of PAG in Group S + I appeared simultaneously immunopositive for GPR30 and GABAA α4, β1, and δ receptors. After microinjection of G1 into the PAG, female rats with plantar incision continued to exhibit significant hyperalgesia until postoperative 48 h. On the other hand, microinjection of G15 with SPS and plantar incision procedure relieved postoperative hyperalgesia in female rats. Western blotting demonstrated that intra-PAG injection of G15 markedly decreased the GPR30, PKA, and GABAA α4, β1, and δ levels in Group G15 + I. CONCLUSIONS Our results indicate that the GPR30-PKA-GABAAα4β1δ pathway in the PAG promotes preoperative anxiety-induced postoperative hyperalgesia in female rats. This mechanism might be a potential novel therapeutic target for hyperalgesia in females.
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Affiliation(s)
- Ming Jiang
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China
| | - Yu'e Sun
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China
| | - Yishan Lei
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China
| | - Fan Hu
- Analytical & Testing Center, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Zhengrong Xia
- Analytical & Testing Center, Nanjing Medical University, Nanjing, Jiangsu Province, China
| | - Yue Liu
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China
| | - Zhengliang Ma
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China
| | - Xiaoping Gu
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, Jiangsu Province, China.
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GABAa receptor subunits expression in silver catfish (Rhamdia quelen) brain and its modulation by Nectandra grandiflora Nees essential oil and isolated compounds. Behav Brain Res 2019; 376:112178. [PMID: 31454673 DOI: 10.1016/j.bbr.2019.112178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 11/23/2022]
Abstract
Studies using silver catfish (Rhamdia quelen) as experimental models are often applied to screen essential oils (EO) with GABAergic-mediated effects. However, the expression of GABAa receptors in the silver catfish brain remains unknown. Thus, we assessed whether silver catfish express GABAa receptor subunits associated with sedation/anesthetic process and/or neurological diseases. Additionally, we evaluated the brain expression of GABAa receptor subunits in fish sedated with Nectandra grandiflora EO and its isolated compounds, the fish anesthetic (+)-dehydrofukinone (DHF), and dehydrofukinone epoxide (DFX), eremophil-11-en-10-ol (ERM) and selin-11-en-4-α-ol (SEL), which have GABAa-mediated anxiolytic-like effects in mice. The expression of the subunits gabra1, gabra2, gabra3, gabrb1, gabrd and gabrg2 in the silver catfish brain were assessed after a 24h-sedation bath by real time PCR. Since qPCR data rarely describes mechanisms of action, which are usually found through interactions with receptors, we also performed an antagonist-driven experiment using flumazenil (FMZ). Real-time PCR detected the mRNA expression of all targeted genes in R. quelen brain. The expression of gabra1 was decreased in fish sedated with ERM; EO increased gabra2, gabra3, gabrb1 and gabrg2 expression; SEL increased gabrb1, gabrd and gabrg2 expression. EO and compounds DFX, SEL and ERM induced sustained sedation in fish and FMZ-bath prompted the recovery from ERM- and DFX-induced sedation. Our results suggest that the EO, SEL, ERM and DFX sedative effects involve interaction with the GABAergic system. Our findings support the use of the silver catfish as robust and reliable experimental model to evaluate the efficacy of drugs with putative GABAergic-mediated effects.
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cAMP-EPAC-Dependent Regulation of Gephyrin Phosphorylation and GABA AR Trapping at Inhibitory Synapses. iScience 2019; 22:453-465. [PMID: 31835170 PMCID: PMC6926171 DOI: 10.1016/j.isci.2019.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/11/2019] [Accepted: 11/05/2019] [Indexed: 01/13/2023] Open
Abstract
GABAA and glycine receptors are thought to compete for gephyrin-binding sites at mixed inhibitory synapses. Changes in the occupancy of one receptor type are therefore expected to have opposite effects on the clustering of the other receptors. This does not explain, however, whether different receptors can be regulated independently from one another. Here we show that cAMP-dependent signaling reduces gephyrin phosphorylation at residue S270 in spinal cord neurons. Although no ultrastructural changes of the synaptic scaffold were detected using super-resolution imaging, gephyrin de-phosphorylation was associated with a selective increase in GABAAR diffusion and the loss of the receptors from synapses. As opposed to the PKA-dependent dispersal of α3-containing GlyRs, the regulation of gephyrin phosphorylation and GABAAR dynamics acts via non-canonical EPAC signaling. Subtype-specific changes in receptor mobility can thus differentially contribute to changes in inhibitory synaptic strength, such as the disinhibition of spinal cord neurons during inflammatory processes.
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Menthol Increases Bendiocarb Efficacy Through Activation of Octopamine Receptors and Protein Kinase A. Molecules 2019; 24:molecules24203775. [PMID: 31635151 PMCID: PMC6832705 DOI: 10.3390/molecules24203775] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 12/31/2022] Open
Abstract
Great effort is put into seeking a new and effective strategies to control insect pests. One of them is to combine natural products with chemical insecticides to increase their effectiveness. In the study presented, menthol which is an essential oil component was evaluated on its ability to increase the efficiency of bendiocarb, carbamate insecticide. A multi-approach study was conducted using biochemical method (to measure acetylcholinesterase enzyme activity), electrophysiological technique (microelectrode recordings in DUM neurons in situ), and confocal microscopy (for calcium imaging). In the electrophysiological experiments, menthol caused hyperpolarization, which was blocked by an octopamine receptor antagonist (phentolamine) and an inhibitor of protein kinase A (H-89). It also raised the intracellular calcium level. The effect of bendiocarb was potentiated by menthol and this phenomenon was abolished by phentolamine and H-89 but not by protein kinase C inhibitor (bisindolylmaleimide IX). The results indicate that menthol increases carbamate insecticide efficiency by acting on octopamine receptors and triggering protein kinase A phosphorylation pathway.
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Hughes BA, Bohnsack JP, O'Buckley TK, Herman MA, Morrow AL. Chronic Ethanol Exposure and Withdrawal Impair Synaptic GABA A Receptor-Mediated Neurotransmission in Deep-Layer Prefrontal Cortex. Alcohol Clin Exp Res 2019; 43:822-832. [PMID: 30860602 DOI: 10.1111/acer.14015] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 03/05/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND The prefrontal cortex (PFC) acts as an integrative hub for the processing of cortical and subcortical input into meaningful efferent signaling, permitting complex associative behaviors. PFC dysfunction is consistently observed with ethanol (EtOH) dependence and is a core component of the pathology of alcohol use disorders in current models of addiction. While intracortical gamma-aminobutryric acid (GABA)ergic neurotransmission is understood to be essential for maintaining coordinated network activity within the cortex, relatively little is known regarding functional GABAergic adaptations in PFC during EtOH dependence. METHODS In the present study, male and female (> postnatal day 60) Sprague-Dawley rats were administered EtOH (5.0 g/kg; intragastric gavage) for 14 to 15 consecutive days. Twenty-four hours after the final administration, animals were sacrificed and brains extracted for electrophysiological recordings of isolated GABAA receptor-mediated currents or analysis of GABAA receptor subunit protein expression in deep-layer PFC neurons. RESULTS Chronic EtOH exposure significantly attenuated activity-dependent spontaneous GABAA receptor-mediated inhibitory postsynaptic current (IPSC) frequency with no effect on amplitude. Furthermore, analysis of IPSC decay kinetics revealed a significant enhancement of IPSC decay time that was associated with decrements in expression of the α1 GABAA receptor subunit, indicative of further impaired phasic inhibition. These phenomena occurred irrespective of neuron projection destination and sex. Based on previous observations by our laboratory of an epigenetic mechanism for EtOH-induced changes in cortical GABAA receptor subunit expression, the histone deacetylase inhibitor Trichostatin A was administered to water- and EtOH-exposed animals, and prevented EtOH-induced changes in spontaneous IPSC frequency, IPSC decay kinetics, and GABAA receptor subunit expression. CONCLUSIONS Taken together, these results demonstrate that chronic EtOH exposure impairs synaptic inhibitory neurotransmission in deep-layer pyramidal neurons of the medial PFC in both male and female rats. These maladaptations occur in neurons projecting to numerous regions implicated in the sequelae of EtOH dependence, offering a mechanistic link between the manifestation of PFC dysfunction and negative affective states observed with extended consumption.
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Affiliation(s)
- Benjamin A Hughes
- Department of Psychiatry , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Pharmacology , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Bowles Center for Alcohol Studies , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John Peyton Bohnsack
- Department of Pharmacology , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Bowles Center for Alcohol Studies , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Todd K O'Buckley
- Bowles Center for Alcohol Studies , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Melissa A Herman
- Department of Pharmacology , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Bowles Center for Alcohol Studies , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - A Leslie Morrow
- Department of Psychiatry , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Department of Pharmacology , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.,Bowles Center for Alcohol Studies , School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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12
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Wang Y, Wang Y, Chen Z. Double-edged GABAergic synaptic transmission in seizures: The importance of chloride plasticity. Brain Res 2018; 1701:126-136. [PMID: 30201259 DOI: 10.1016/j.brainres.2018.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/04/2018] [Accepted: 09/06/2018] [Indexed: 12/18/2022]
Abstract
GABAergic synaptic inhibition, which is a critical regulator of neuronal excitability, is closely involved in epilepsy. Interestingly, fast GABAergic transmission mediated by Cl- permeable GABAA receptors can bi-directionally exert both seizure-suppressing and seizure-promoting actions. Accumulating evidence suggests that chloride plasticity, the driving force of GABAA receptor-mediated synaptic transmission, contributes to the double-edged role of GABAergic synapses in seizures. Large amounts of Cl- influx can overwhelm Cl- extrusion during seizures not only in healthy tissue in a short-term "activity-dependent" manner, but also in chronic epilepsy in a long-term, irreversible "pathology-dependent" manner related to the dysfunction of two chloride transporters: the chloride importer NKCC1 and the chloride exporter KCC2. In this review, we address the importance of chloride plasticity for the "activity-dependent" and "pathology-dependent" mechanisms underlying epileptic events and provide possible directions for further research, which may be clinically important for the design of GABAergic synapse-targeted precise therapeutic interventions for epilepsy.
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Affiliation(s)
- Ying Wang
- Institute of Pharmacology & Toxicology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology & Toxicology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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13
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Lagrange AH, Hu N, Macdonald RL. GABA beyond the synapse: defining the subtype-specific pharmacodynamics of non-synaptic GABA A receptors. J Physiol 2018; 596:4475-4495. [PMID: 30019335 PMCID: PMC6138284 DOI: 10.1113/jp276187] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 07/12/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Physiologically relevant combinations of recombinant GABAA receptor (GABAR) subunits were expressed in HEK293 cells. Using whole-cell voltage clamp and rapid drug application, we measured the GABAR-subtype-specific properties to convey either synaptic or extrasynaptic signalling in a range of physiological contexts. α4βδ GABARs are optimally tuned to submicromolar tonic GABA and transient surges of micromolar GABA concentrations. α5β2γ2l GABARs are better suited to higher tonic GABA levels, but also convey robust responses to brief synaptic and perisynaptic GABA fluctuations. α1β2/3δ GABARs function well at prolonged, micromolar (>2 μm) GABA levels, but not to low tonic (<1 μm GABA) or synaptic/transient GABAergic signalling. These results help illuminate the context- and isoform-specific modes of GABAergic signalling in the brain. ABSTRACT GABAA receptors (GABARs) mediate a remarkable diversity of signalling modalities in vivo. Yet most published work characterizing responses to GABA has focused on the properties needed to convey fast, phasic synaptic inhibition. We therefore aimed to characterize the most prevalent (α4βδ, α5β3γ2L) and least prevalent (α1β2δ) non-synaptic GABAR currents, using whole-cell voltage clamp recordings of recombinant GABAR expressed in HEK293 cells and drug application protocols to recapitulate the GABA concentration profiles occurring during both fast synaptic and slow extrasynaptic signalling. We found that α4βδ GABARs were very sensitive to submicromolar GABA, with a rank order potency of α4β2δ ≥ α4β1δ ≈ α4β3δ GABARs. In comparison, the GABA EC50 was up to 20 times higher for α1β2γ2L GABARs, with α1β2δ and α5β3γ2L GABARs having intermediate GABA potency. Both α4βδ and α5β3γ2L GABAR currents exhibited slow, but substantial, desensitization as well as prolonged rates of deactivation. These GABAR current properties defined distinct 'dynamic ranges' of responsiveness to changing GABA for α4β2δ (0.1-1 μm), α5β3γ2L (0.5-7 μm) and α1β2γ2L (0.6-9 μm) GABARs. Finally, α1β2δ GABARs were notable for their relative lack of desensitization and extremely quick deactivation. In summary, our results help delineate the roles that specific GABARs may play in mediating non-synaptic GABA signals. Since ambient GABA levels may be altered during development as well as by drugs and disease states, these findings may help future efforts to understand disrupted inhibition underlying a variety of neurological illnesses, such as epilepsy.
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Affiliation(s)
- Andre H. Lagrange
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- PharmacologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Program in NeuroscienceVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Tennessee Valley Healthcare Systems Veterans AdministrationNashvilleTN37201USA
| | - NingNing Hu
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
| | - Robert L. Macdonald
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Molecular Physiology and BiophysicsVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- PharmacologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
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14
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Gravielle MC. Regulation of GABAA receptors by prolonged exposure to endogenous and exogenous ligands. Neurochem Int 2018; 118:96-104. [DOI: 10.1016/j.neuint.2018.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 02/08/2023]
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15
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Histone deacetylases mediate GABA A receptor expression, physiology, and behavioral maladaptations in rat models of alcohol dependence. Neuropsychopharmacology 2018; 43. [PMID: 29520058 PMCID: PMC5983537 DOI: 10.1038/s41386-018-0034-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Alcohol use disorders are chronic debilitating diseases characterized by severe withdrawal symptoms that contribute to morbidity and relapse. GABAA receptor (GABAAR) adaptations have long been implicated in the chronic effects of alcohol and contribute to many withdrawal symptoms associated with alcohol dependence. In rodents, GABAAR hypofunction results from decreases in Gabra1 expression, although the underlying mechanism controlling Gabra1 expression after chronic ethanol exposure is still unknown. We found that chronic ethanol exposure using either ethanol gavage or two-bottle choice voluntary access paradigms decreased Gabra1 expression and increased Hdac2 and Hdac3 expression. Administration of the HDAC inhibitor trichostatin A (TSA) after chronic ethanol exposure prevents the decrease in Gabra1 expression and function as well as the increase in Hdac2 and Hdac3 expression in both the cortex and the medial prefrontal cortex (mPFC). Chronic ethanol exposure and withdrawal, but not acute ethanol exposure or acute withdrawal, cause a selective upregulation of HDAC2 and HDAC3 associated with the Gabra1 promoter that accompanies a decrease in H3 acetylation of the Gabra1 promoter and the reduction in GABAAR α1 subunit expression. TSA administration prevented each of these molecular events as well as behavioral manifestations of ethanol dependence, including tolerance to zolpidem-induced loss of righting reflex, reduced open-arm time in the elevated plus maze, reduced center-time and locomotor activity in the open-field assay, and TSA reduced voluntary ethanol consumption. The results show how chronic ethanol exposure regulates the highly prominent GABAAR α1 subunit by an epigenetic mechanism that represents a potential treatment modality for alcohol dependence.
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16
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Chen J, He Y, Wu Y, Zhou H, Su LD, Li WN, Olsen RW, Liang J, Zhou YD, Shen Y. Single Ethanol Withdrawal Regulates Extrasynaptic δ-GABA A Receptors Via PKCδ Activation. Front Mol Neurosci 2018; 11:141. [PMID: 29755316 PMCID: PMC5932167 DOI: 10.3389/fnmol.2018.00141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/09/2018] [Indexed: 11/23/2022] Open
Abstract
Alcohol (ethanol, EtOH) is one of the most widely abused drugs with profound effects on brain function and behavior. GABAA receptors (GABAARs) are one of the major targets for EtOH in the brain. Temporary plastic changes in GABAARs after withdrawal from a single EtOH exposure occur both in vivo and in vitro, which may be the basis for chronic EtOH addiction, tolerance and withdrawal symptoms. Extrasynaptic δ-GABAAR endocytosis is implicated in EtOH-induced GABAAR plasticity, but the mechanisms by which the relative abundance and localization of specific GABAARs are altered by EtOH exposure and withdrawal remain unclear. In this study, we investigated the mechanisms underlying rapid regulation of extrasynaptic δ-GABAAR by a single EtOH withdrawal in cultured rat hippocampal neurons. Thirty-minutes EtOH (60 mM) exposure increased extrasynaptic tonic current (Itonic) amplitude without affecting synaptic GABAAR function in neurons. In contrast, at 30 min after withdrawal, Itonic amplitude and responsiveness to acute EtOH were both reduced. Similar results occurred in neurons with okadaic acid (OA) or phorbol 12,13-dibutyrate (PDBu) exposure. Protein kinase C (PKC) inhibition prevented the reduction of Itonic amplitude and the tolerance to acute EtOH, as well as the reduction of GABAAR-δ subunit abundance induced by a single EtOH withdrawal. Moreover, EtOH withdrawal selectively increased PKCδ level, whereas PKCδ inhibition specifically rescued the EtOH-induced alterations in GABAAR-δ subunit level and δ-GABAAR function. Together, we provided strong evidence for the important roles of PKCδ in the rapid regulation of extrasynaptic δ-GABAAR induced by a single EtOH withdrawal.
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Affiliation(s)
- Juan Chen
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yang He
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yan Wu
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Hang Zhou
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Li-Da Su
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Wei-Nan Li
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jing Liang
- Titus Family Department of Clinical Pharmacy, USC School of Pharmacy, University of Southern California, Los Angeles, CA, United States
| | - Yu-Dong Zhou
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Shen
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
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17
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García-Martín E, Ramos MI, Cornejo-García JA, Galván S, Perkins JR, Rodríguez-Santos L, Alonso-Navarro H, Jiménez-Jiménez FJ, Agúndez JAG. Missense Gamma-Aminobutyric Acid Receptor Polymorphisms Are Associated with Reaction Time, Motor Time, and Ethanol Effects in Vivo. Front Cell Neurosci 2018; 12:10. [PMID: 29445327 PMCID: PMC5797743 DOI: 10.3389/fncel.2018.00010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 01/08/2018] [Indexed: 01/15/2023] Open
Abstract
Background: The Gamma-aminobutyric acid type A receptor (GABA-A receptor) is affected by ethanol concentrations equivalent to those reached during social drinking. At these concentrations, ethanol usually causes impairment in reaction and motor times in most, but not all, individuals. Objectives: To study the effect of GABA-A receptor variability in motor and reaction times, and the effect of low ethanol doses. Methods: Two hundred and fifty healthy subjects received one single dose of 0.5 g/Kg ethanol per os. Reaction and motor times were determined before ethanol challenge (basal), and when participants reached peak ethanol concentrations. We analyzed all common missense polymorphisms described in the 19 genes coding for the GABA-A receptor subunits by using TaqMan probes. Results: The GABRA6 rs4454083 T/C polymorphisms were related to motor times, with individuals carrying the C/C genotype having faster motor times, both, at basal and at peak ethanol concentrations. The GABRA4 rs2229940 T/T genotype was associated to faster reaction times and with lower ethanol effects, determined as the difference between basal reaction time and reaction time at peak concentrations. All these associations remained significant after correction for multiple comparisons. No significant associations were observed for the common missense SNPs GABRB3 rs12910925, GABRG2 rs211035, GABRE rs1139916, GABRP rs1063310, GABRQ rs3810651, GABRR1 rs12200969 or rs1186902, GABRR2 rs282129, and GABRR3 rs832032. Conclusions: This study provides novel information supporting a role of missense GABA-A receptor polymorphisms in reaction time, motor time and effects of low ethanol doses in vivo.
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Affiliation(s)
- Elena García-Martín
- Department of Pharmacology, Universidad de Extremadura, Cáceres, Spain.,ARADyAL Network, Instituto de Salud Carlos III, Madrid, Spain
| | - María I Ramos
- Department of Psychiatry, Universidad de Extremadura, Badajoz, Spain
| | - José A Cornejo-García
- ARADyAL Network, Instituto de Salud Carlos III, Madrid, Spain.,Research Laboratory, Instituto de Investigación Biomédica de Málaga, Regional University Hospital of Malaga, UMA, Malaga, Spain
| | - Segismundo Galván
- Department of Pharmacology, Universidad de Extremadura, Cáceres, Spain
| | - James R Perkins
- ARADyAL Network, Instituto de Salud Carlos III, Madrid, Spain.,Research Laboratory, Instituto de Investigación Biomédica de Málaga, Regional University Hospital of Malaga, UMA, Malaga, Spain
| | | | | | | | - José A G Agúndez
- Department of Pharmacology, Universidad de Extremadura, Cáceres, Spain.,ARADyAL Network, Instituto de Salud Carlos III, Madrid, Spain
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18
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Feng HJ, Forman SA. Comparison of αβδ and αβγ GABA A receptors: Allosteric modulation and identification of subunit arrangement by site-selective general anesthetics. Pharmacol Res 2017; 133:289-300. [PMID: 29294355 DOI: 10.1016/j.phrs.2017.12.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 12/27/2022]
Abstract
GABAA receptors play a dominant role in mediating inhibition in the mature mammalian brain, and defects of GABAergic neurotransmission contribute to the pathogenesis of a variety of neurological and psychiatric disorders. Two types of GABAergic inhibition have been described: αβγ receptors mediate phasic inhibition in response to transient high-concentrations of synaptic GABA release, and αβδ receptors produce tonic inhibitory currents activated by low-concentration extrasynaptic GABA. Both αβδ and αβγ receptors are important targets for general anesthetics, which induce apparently different changes both in GABA-dependent receptor activation and in desensitization in currents mediated by αβγ vs. αβδ receptors. Many of these differences are explained by correcting for the high agonist efficacy of GABA at most αβγ receptors vs. much lower efficacy at αβδ receptors. The stoichiometry and subunit arrangement of recombinant αβγ receptors are well established as β-α-γ-β-α, while those of αβδ receptors remain controversial. Importantly, some potent general anesthetics selectively bind in transmembrane inter-subunit pockets of αβγ receptors: etomidate acts at β+/α- interfaces, and the barbiturate R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB) acts at α+/β- and γ+/β- interfaces. Thus, these drugs are useful as structural probes in αβδ receptors formed from free subunits or concatenated subunit assemblies designed to constrain subunit arrangement. Although a definite conclusion cannot be drawn, studies using etomidate and R-mTFD-MPAB support the idea that recombinant α1β3δ receptors may share stoichiometry and subunit arrangement with α1β3γ2 receptors.
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Affiliation(s)
- Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
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19
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Bohnsack JP, Patel VK, Morrow AL. Ethanol Exposure Regulates Gabra1 Expression via Histone Deacetylation at the Promoter in Cultured Cortical Neurons. J Pharmacol Exp Ther 2017; 363:1-11. [PMID: 28798030 DOI: 10.1124/jpet.117.242446] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/08/2017] [Indexed: 12/23/2022] Open
Abstract
γ-Aminobutyric acid A receptors (GABAA-Rs) mediate the majority of inhibitory neurotransmission in the adult brain. The α1-containing GABAA-Rs are the most prominent subtype in the adult brain and are important in both homeostatic function and several disease pathologies including alcohol dependence, epilepsy, and stress. Ethanol exposure causes a decrease of α1 transcription and peptide expression both in vivo and in vitro, but the mechanism that controls the transcriptional regulation is unknown. Because ethanol is known to activate epigenetic regulation of gene expression, we tested the hypothesis that ethanol regulates α1 expression through histone modifications in cerebral cortical cultured neurons. We found that class I histone deacetylases (HDACs) regulate ethanol-induced changes in α1 gene and protein expression as pharmacologic inhibition or knockdown of HDAC1-3 prevents the effects of ethanol exposure. Targeted histone acetylation associated with the Gabra1 promoter using CRISPR (clustered regularly interspaced palindromic repeat) dCas9-P300 (a nuclease-null Cas9 fused with a histone acetyltransferase) increases histone acetylation and prevents the decrease of Gabra1 expression. In contrast, there was no effect of a mutant histone acetyltransferase or generic transcriptional activator or targeting P300 to a distant exon. Conversely, using a dCas9-KRAB construct that increases repressive methylation (H3K9me3) does not interfere with ethanol-induced histone deacetylation. Overall our results indicate that ethanol deacetylates histones associated with the Gabra1 promoter through class I HDACs and that pharmacologic, genetic, or epigenetic intervention prevents decreases in α1 expression in cultured cortical neurons.
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Affiliation(s)
- John Peyton Bohnsack
- Department of Pharmacology (J.P.B., A.L.M.), Department of Psychiatry (A.L.M.), and Bowles Center for Alcohol Studies (J.P.B., V.K.P., A.L.M.), University of North Carolina, Chapel Hill, North Carolina
| | - Vraj K Patel
- Department of Pharmacology (J.P.B., A.L.M.), Department of Psychiatry (A.L.M.), and Bowles Center for Alcohol Studies (J.P.B., V.K.P., A.L.M.), University of North Carolina, Chapel Hill, North Carolina
| | - A Leslie Morrow
- Department of Pharmacology (J.P.B., A.L.M.), Department of Psychiatry (A.L.M.), and Bowles Center for Alcohol Studies (J.P.B., V.K.P., A.L.M.), University of North Carolina, Chapel Hill, North Carolina
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20
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Zhang T, Chen T, Chen P, Zhang B, Hong J, Chen L. MPTP-Induced Dopamine Depletion in Basolateral Amygdala via Decrease of D2R Activation Suppresses GABA A Receptors Expression and LTD Induction Leading to Anxiety-Like Behaviors. Front Mol Neurosci 2017; 10:247. [PMID: 28824377 PMCID: PMC5545577 DOI: 10.3389/fnmol.2017.00247] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/24/2017] [Indexed: 11/13/2022] Open
Abstract
Anxiety disorders commonly occur in Parkinson’s disease. Using field potential recording and patch-clamp recording, we evaluated influence of MPTP-reduced dopaminergic afferent in basolateral amygdala (BLA), a main region for affective regulation, on excitatory–inhibitory circuits and synaptic plasticity. Field excitatory post-synaptic potential (fEPSP) slopes at external capsule-BLA synapses were increased in MPTP-mice with decreases in paired-pulse facilitation and long-term potentiation amplitude, which were corrected by bath-application of D2R agonist quinpirole or cannabinoid type 1 receptors agonist WIN55,212-2, but not D1R agonist SKF38393. Compared to single waveform fEPSP in control mice, a multi-spike waveform fEPSP was observed in MPTP-mice with prolongation of duration and an increase in paired-pulse inhibition, which were recovered by BLA-injection of quinpirole for 2 days rather than bath-application. Density of GABA-evoked current (IGABA) in BLA principal neurons and GABAAR-α2 subunit expression were reduced in MPTP-mice, which were recovered by administration of quinpirole. Decline of PKC phosphorylation in BLA of MPTP-mice was corrected by bath-application of quinpirole, but not SKF38393. In MPTP-mice, BLA-injection of quinpirole or PKC activator PMA could recover GABAAR expression, which was sensitive to PKC inhibitor GF109203X. The impairment of long-term depression (LTD) in MPTP-mice was rescued by bath-application of GABAAR agonist muscimol or BLA-injection of quinpirole and PMA. Finally, BLA-injection of muscimol, quinpirole or PMA relieved anxiety-like behaviors in MPTP-mice. The results indicate that the MPTP-induced dopamine depletion in BLA principal neurons through reducing D2R-mediated PKC phosphorylation suppresses GABAAR expression and activity, which impairs GABAAR-mediated inhibition and LTD induction leading to anxiety-like behaviors.
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Affiliation(s)
- Tingting Zhang
- State Key Lab of Reproductive Medicine, Nanjing Medical UniversityNanjing, China.,Department of Physiology, Nanjing Medical UniversityNanjing, China
| | - Tingting Chen
- State Key Lab of Reproductive Medicine, Nanjing Medical UniversityNanjing, China.,Department of Physiology, Nanjing Medical UniversityNanjing, China
| | - Peipei Chen
- Department of Physiology, Nanjing Medical UniversityNanjing, China
| | - Baofeng Zhang
- Department of Physiology, Nanjing Medical UniversityNanjing, China
| | - Juan Hong
- State Key Lab of Reproductive Medicine, Nanjing Medical UniversityNanjing, China.,Department of Physiology, Nanjing Medical UniversityNanjing, China
| | - Ling Chen
- State Key Lab of Reproductive Medicine, Nanjing Medical UniversityNanjing, China.,Department of Physiology, Nanjing Medical UniversityNanjing, China
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21
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Roberto M, Varodayan FP. Synaptic targets: Chronic alcohol actions. Neuropharmacology 2017; 122:85-99. [PMID: 28108359 DOI: 10.1016/j.neuropharm.2017.01.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/23/2016] [Accepted: 01/14/2017] [Indexed: 01/02/2023]
Abstract
Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".
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22
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Kaplan JS, Mohr C, Hostetler CM, Ryabinin AE, Finn DA, Rossi DJ. Alcohol Suppresses Tonic GABAA Receptor Currents in Cerebellar Granule Cells in the Prairie Vole: A Neural Signature of High-Alcohol-Consuming Genotypes. Alcohol Clin Exp Res 2016; 40:1617-26. [PMID: 27426857 DOI: 10.1111/acer.13136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/21/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND Evidence indicates that the cerebellum plays a role in genetic predilection to excessive alcohol (ethanol [EtOH]) consumption in rodents and humans, but the molecular mechanisms mediating such predilection are not understood. We recently determined that EtOH has opposite actions (enhancement or suppression) on tonic GABAA receptor (GABAA R) currents in cerebellar granule cells (GCs) in low- and high-EtOH-consuming rodents, respectively, and proposed that variation in GC tonic GABAA R current responses to EtOH contributes to genetic variation in EtOH consumption phenotype. METHODS Voltage-clamp recordings of GCs in acutely prepared slices of cerebellum were used to evaluate the effect of EtOH on GC tonic GABAA R currents in another high-EtOH-consuming rodent, prairie voles (PVs). RESULTS EtOH (52 mM) suppressed the magnitude of the tonic GABAA R current in 57% of cells, had no effect in 38% of cells, and enhanced the tonic GABAA R current in 5% of cells. This result is similar to GCs from high-EtOH-consuming C57BL/6J (B6) mice, but it differs from the enhancement of tonic GABAA R currents by EtOH in low-EtOH-consuming DBA/2J (D2) mice and Sprague Dawley (SD) rats. EtOH suppression of tonic GABAA R currents was not affected by the sodium channel blocker, tetrodotoxin (500 nM), and was independent of the frequency of phasic GABAA R-mediated currents, suggesting that suppression is mediated by postsynaptic actions on GABAA Rs, rather than a reduction of GABA release. Finally, immunohistochemical analysis of neuronal nitric oxide synthase (nNOS; which can mediate EtOH enhancement of GABA release) demonstrated that nNOS expression in the GC layer of PV cerebellum was similar to the levels seen in B6 mice, both being significantly reduced relative to D2 mice and SD rats. CONCLUSIONS Combined, these data highlight the GC GABAA R response to EtOH in another species, the high-EtOH-consuming PV, which correlates with EtOH consumption phenotype and further implicates the GC GABAA R system as a contributing mechanism to high EtOH consumption.
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Affiliation(s)
- Joshua S Kaplan
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon.,VA Portland Health Care System, Portland, Oregon
| | - Claudia Mohr
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon.,Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
| | - Caroline M Hostetler
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon.,VA Portland Health Care System, Portland, Oregon
| | - Andrey E Ryabinin
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon
| | - Deborah A Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon.,VA Portland Health Care System, Portland, Oregon
| | - David J Rossi
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon.,Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington
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Carlson SL, Bohnsack JP, Morrow AL. Ethanol Regulation of Synaptic GABAA α4 Receptors Is Prevented by Protein Kinase A Activation. J Pharmacol Exp Ther 2016; 357:10-6. [PMID: 26857960 DOI: 10.1124/jpet.115.230417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/28/2016] [Indexed: 02/06/2023] Open
Abstract
Ethanol alters GABAA receptor trafficking and function through activation of protein kinases, and these changes may underlie ethanol dependence and withdrawal. In this study, we used subsynaptic fraction techniques and patch-clamp electrophysiology to investigate the biochemical and functional effects of protein kinase A (PKA) and protein kinase C (PKC) activation by ethanol on synaptic GABAA α4 receptors, a key target of ethanol-induced changes. Rat cerebral cortical neurons were grown for 18 days in vitro and exposed to ethanol and/or kinase modulators for 4 hours, a paradigm that recapitulates GABAergic changes found after chronic ethanol exposure in vivo. PKA activation by forskolin or rolipram during ethanol exposure prevented increases in P2 fraction α4 subunit abundance, whereas inhibiting PKA had no effect. Similarly, in the synaptic fraction, activation of PKA by rolipram in the presence of ethanol prevented the increase in synaptic α4 subunit abundance, whereas inhibiting PKA in the presence of ethanol was ineffective. Conversely, PKC inhibition in the presence of ethanol prevented the ethanol-induced increases in synaptic α4 subunit abundance. Finally, we found that either activating PKA or inhibiting PKC in the presence of ethanol prevented the ethanol-induced decrease in GABA miniature inhibitory postsynaptic current decay τ1, whereas inhibiting PKA had no effect. We conclude that PKA and PKC have opposing effects in the regulation of synaptic α4 receptors, with PKA activation negatively modulating, and PKC activation positively modulating, synaptic α4 subunit abundance and function. These results suggest potential targets for restoring normal GABAergic functioning in the treatment of alcohol use disorders.
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Affiliation(s)
- Stephen L Carlson
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - John Peyton Bohnsack
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - A Leslie Morrow
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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