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Maguire JL, Mennerick S. Neurosteroids: mechanistic considerations and clinical prospects. Neuropsychopharmacology 2024; 49:73-82. [PMID: 37369775 PMCID: PMC10700537 DOI: 10.1038/s41386-023-01626-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/15/2023] [Accepted: 05/17/2023] [Indexed: 06/29/2023]
Abstract
Like other classes of treatments described in this issue's section, neuroactive steroids have been studied for decades but have risen as a new class of rapid-acting, durable antidepressants with a distinct mechanism of action from previous antidepressant treatments and from other compounds covered in this issue. Neuroactive steroids are natural derivatives of progesterone but are proving effective as exogenous treatments. The best understood mechanism is that of positive allosteric modulation of GABAA receptors, where subunit selectivity may promote their profile of action. Mechanistically, there is some reason to think that neuroactive steroids may separate themselves from liabilities of other GABA modulators, although research is ongoing. It is also possible that intracellular targets, including inflammatory pathways, may be relevant to beneficial actions. Strengths and opportunities for further development include exploiting non-GABAergic targets, structural analogs, enzymatic production of natural steroids, precursor loading, and novel formulations. The molecular mechanisms of behavioral effects are not fully understood, but study of brain network states involved in emotional processing demonstrate a robust influence on affective states not evident with at least some other GABAergic drugs including benzodiazepines. Ongoing studies with neuroactive steroids will further elucidate the brain and behavioral effects of these compounds as well as likely underpinnings of disease.
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Affiliation(s)
- Jamie L Maguire
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA, 02111, USA
| | - Steven Mennerick
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA.
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Sikes-Keilp C, Rubinow DR. GABA-ergic Modulators: New Therapeutic Approaches to Premenstrual Dysphoric Disorder. CNS Drugs 2023; 37:679-693. [PMID: 37542704 DOI: 10.1007/s40263-023-01030-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/20/2023] [Indexed: 08/07/2023]
Abstract
Premenstrual dysphoric disorder (PMDD) is characterized by the predictable onset of mood and physical symptoms secondary to gonadal steroid fluctuation during the luteal phase of the menstrual cycle. Although menstrual-related affective dysfunction is responsible for considerable functional impairment and reduction in quality of life worldwide, currently approved treatments for PMDD are suboptimal in their effectiveness. Research over the past two decades has suggested that the interaction between allopregnanolone, a neurosteroid derivative of progesterone, and the gamma-aminobutyric acid (GABA) system represents an important relationship underlying symptom genesis in reproductive-related mood disorders, including PMDD. The objective of this narrative review is to discuss the plausible link between changes in GABAergic transmission secondary to the fluctuation of allopregnanolone during the luteal phase and mood impairment in susceptible individuals. As part of this discussion, we explore promising findings from early clinical trials of several compounds that stabilize allopregnanolone signaling during the luteal phase, including dutasteride, a 5-alpha reductase inhibitor; isoallopregnanolone, a GABA-A modulating steroid antagonist; and ulipristal acetate, a selective progesterone receptor modulator. We then reflect on the implications of these therapeutic advances, including how they may promote our knowledge of affective regulation more generally. We conclude that these and other studies of PMDD may yield critical insight into the etiopathogenesis of affective disorders, considering that (1) symptoms in PMDD have a predictable onset and offset, allowing for examination of affective state kinetics, and (2) GABAergic interventions in PMDD can be used to better understand the relationship between mood states, network regulation, and the balance between excitatory and inhibitory signaling in the brain.
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Affiliation(s)
- Christopher Sikes-Keilp
- Department of Psychiatry, University of North Carolina Hospitals, 101 Manning Drive, Chapel Hill, NC, 27514, USA.
| | - David R Rubinow
- Department of Psychiatry, University of North Carolina Hospitals, 101 Manning Drive, Chapel Hill, NC, 27514, USA
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Walton NL, Antonoudiou P, Barros L, Dargan T, DiLeo A, Evans-Strong A, Gabby J, Howard S, Paracha R, Sánchez EJ, Weiss GL, Kong D, Maguire JL. Impaired Endogenous Neurosteroid Signaling Contributes to Behavioral Deficits Associated With Chronic Stress. Biol Psychiatry 2023; 94:249-261. [PMID: 36736870 PMCID: PMC10363189 DOI: 10.1016/j.biopsych.2023.01.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/21/2022] [Accepted: 01/14/2023] [Indexed: 02/04/2023]
Abstract
BACKGROUND Chronic stress is a major risk factor for psychiatric illnesses, including depression. However, the pathophysiological mechanisms whereby stress leads to mood disorders remain unclear. Allopregnanolone acts as a positive allosteric modulator preferentially on δ subunit-containing GABAA (gamma-aminobutyric acid A) receptors. Accumulating clinical and preclinical evidence supports the antidepressant effects of exogenous administration of allopregnanolone analogs; yet, the role of endogenous allopregnanolone in the pathophysiology of depression remains unknown. METHODS We utilized a chronic unpredictable stress (CUS) mouse model, followed by behavioral and biochemical assays, to examine whether altered neurosteroid signaling contributes to behavioral outcomes following CUS. We subsequently performed in vivo CRISPR (clustered regularly interspaced short palindromic repeats) knockdown of rate-limiting enzymes involved in allopregnanolone synthesis, 5α-reductase type 1 and 2 (5α1/2), in addition to lentiviral overexpression of 5α1/2 in the basolateral amygdala (BLA) of mice that underwent CUS to assess the impact of 5α1/2 on behavioral outcomes. RESULTS The expression of δ subunit-containing GABAA receptors and endogenous levels of allopregnanolone were reduced in the BLA following CUS. Treatment with an exogenous allopregnanolone analog, SGE-516, was sufficient to increase allopregnanolone levels in the BLA following CUS. Knockdown of 5α1/2 in the BLA mimicked the behavioral outcomes associated with CUS. Conversely, overexpression of 5α1/2 in the BLA improved behavioral outcomes following CUS. CONCLUSIONS Our findings demonstrate that chronic stress impairs endogenous neurosteroid signaling in the BLA, which is sufficient to induce behavioral deficits. Further, these studies suggest that allopregnanolone-based treatments may directly target the underlying pathophysiology of mood disorders suggesting that targeting endogenous neurosteroidogenesis may offer a novel therapeutic strategy.
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Affiliation(s)
- Najah L Walton
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Pantelis Antonoudiou
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Lea Barros
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts; Building Diversity in Biomedical Sciences Program, Tufts University School of Medicine, Boston, Massachusetts; Department of Biology, Hamilton College, Clinton, New York
| | - Tauryn Dargan
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Alyssa DiLeo
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Aidan Evans-Strong
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Jenah Gabby
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts; Building Diversity in Biomedical Sciences Program, Tufts University School of Medicine, Boston, Massachusetts; Louis Stokes Alliance for Minority Participation, Tufts University, Medford, Massachusetts
| | - Samantha Howard
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts; Division of Endocrinology, Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Rumzah Paracha
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Edgardo J Sánchez
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts; Building Diversity in Biomedical Sciences Program, Tufts University School of Medicine, Boston, Massachusetts; Department of Chemistry, University of Puerto Rico, Cayey, Puerto Rico
| | - Grant L Weiss
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts
| | - Dong Kong
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts; Division of Endocrinology, Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jamie L Maguire
- Department of Neuroscience, Program of Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts.
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Can animal models resemble a premenstrual dysphoric condition? Front Neuroendocrinol 2022; 66:101007. [PMID: 35623450 DOI: 10.1016/j.yfrne.2022.101007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 04/22/2022] [Accepted: 05/19/2022] [Indexed: 11/23/2022]
Abstract
Around 80% of women worldwide suffer mild Premenstrual Disorders (PMD) during their reproductive life. Up to a quarter are affected by moderate to severe symptoms, and between 3% and 8% experience a severe form. It is classified as premenstrual syndrome (PMS) with predominantly physical symptoms and premenstrual dysphoric disorder (PMDD) with psychiatric symptoms. The present review analyzes the factors associated with PMD and the Hypothalamus-Pituitary-Ovarian or Hypothalamus-Pituitary-adrenal axis and discusses the main animal models used to study PMDD. Evidence shows that the ovarian hormones participate in PMDD symptoms, and several points of regulation of their synthesis, metabolism, and target sites could be altered. PMDD is complex and implies several factors that require consideration when this condition is modeled in animals. Of particular interest are those points related to areas that may represent opportunities to develop new approximations to understand the mechanisms involved in PMDD and possible treatments.
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Floris G, Asuni GP, Talani G, Biggio F, Pisu MG, Zanda MT, Contu L, Maciocco E, Serra M, Follesa P. Increased Voluntary Alcohol Consumption in Mice Lacking GABA B(1) Is Associated With Functional Changes in Hippocampal GABA A Receptors. Front Behav Neurosci 2022; 16:893835. [PMID: 35755407 PMCID: PMC9218813 DOI: 10.3389/fnbeh.2022.893835] [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: 03/10/2022] [Accepted: 05/09/2022] [Indexed: 11/26/2022] Open
Abstract
Gamma-aminobutyric acid type B receptor (GABABR) has been extensively involved in alcohol use disorders; however, the mechanisms by which this receptor modulates alcohol drinking behavior remain murky. In this study, we investigate alcohol consumption and preference in mice lacking functional GABABR using the 2-bottle choice paradigm. We found that GABAB(1), knockout (KO), and heterozygous (HZ) mice drank higher amounts of an alcoholic solution, preferred alcohol to water, and reached higher blood alcohol concentrations (BACs) compared to wild-type (WT) littermates. The GABABR agonist GHB significantly reduced alcohol consumption in the GABAB(1) HZ and WT but not in the KO mice. Next, because of a functional crosstalk between GABABR and δ-containing GABAA receptor (δ-GABAAR), we profiled δ subunit mRNA expression levels in brain regions in which the crosstalk was characterized. We found a loss of the alcohol-sensitive GABAAR δ subunit in the hippocampus of the GABAB(1) KO alcohol-naïve mice that was associated with increased ɣ2 subunit abundance. Electrophysiological recordings revealed that these molecular changes were associated with increased phasic inhibition, suggesting a potential gain of synaptic GABAAR responsiveness to alcohol that has been previously described in an animal model of excessive alcohol drinking. Interestingly, voluntary alcohol consumption did not revert the dramatic loss of hippocampal δ-GABAAR occurring in the GABAB(1) KO mice but rather exacerbated this condition. Finally, we profiled hippocampal neuroactive steroids levels following acute alcohols administration in the GABAB(1) KO and WT mice because of previous involvement of GABABR in the regulation of cerebral levels of these compounds. We found that systemic administration of alcohol (1.5 g/kg) did not produce alcohol-induced neurosteroid response in the GABAB(1) KO mice but elicited an expected increase in the hippocampal level of progesterone and 3α,5α-THP in the WT controls. In conclusion, we show that genetic ablation of the GABAB(1) subunit results in increased alcohol consumption and preference that were associated with functional changes in hippocampal GABAAR, suggesting a potential mechanism by which preference for alcohol consumption is maintained in the GABAB(1) KO mice. In addition, we documented that GABAB(1) deficiency results in lack of alcohol-induced neurosteroids, and we discussed the potential implications of this finding in the context of alcohol drinking and dependence.
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Affiliation(s)
- Gabriele Floris
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Gino Paolo Asuni
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Giuseppe Talani
- Institute of Neuroscience-Cagliari, National Research Council, Cagliari, Italy
| | - Francesca Biggio
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | | | - Mary Tresa Zanda
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Liliana Contu
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Elisabetta Maciocco
- Institute of Neuroscience-Cagliari, National Research Council, Cagliari, Italy
| | - Mariangela Serra
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Paolo Follesa
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
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Pinna G, Almeida FB, Davis JM. Allopregnanolone in Postpartum Depression. Front Glob Womens Health 2022; 3:823616. [PMID: 35558166 PMCID: PMC9088875 DOI: 10.3389/fgwh.2022.823616] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 02/01/2022] [Indexed: 12/27/2022] Open
Abstract
Postpartum depression (PPD) is a debilitating psychiatric disorder characterized by a high worldwide prevalence and serious long-term negative outcomes for both mothers and children. The lack of a specific treatment and overreliance on pharmacotherapy with limited efficacy and delayed treatment response has constituted a complication in the management of PPD. Recently, the Food and Drug Administration (FDA) in the USA approved a synthetic formulation of the GABAergic neurosteroid allopregnanolone, administered intravenously (brexanolone) for the rapid, long-lasting and effective treatment of PPD. Hereinafter, we review findings on allopregnanolone biosynthesis and GABAA receptor plasticity in the pathophysiology of PPD. We also discuss evidence supporting the efficacy of brexanolone for the treatment of PPD, which opens a promising new horizon for neurosteroid-based therapeutics for mood disorders.
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Affiliation(s)
- Graziano Pinna
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- *Correspondence: Graziano Pinna ;
| | - Felipe B. Almeida
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- Graduate Program in Health Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Brazil
| | - John M. Davis
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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Lambert PM, Lu X, Zorumski CF, Mennerick S. Physiological markers of rapid antidepressant effects of allopregnanolone. J Neuroendocrinol 2022; 34:e13023. [PMID: 34423498 PMCID: PMC8807818 DOI: 10.1111/jne.13023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 02/04/2023]
Abstract
The rise of ketamine and brexanolone as rapid antidepressant treatments raises the question of common mechanisms. Both drugs act without the long onset time of traditional antidepressants such as selective serotonin reuptake inhibitors. The drugs also share the interesting feature of benefit that persists beyond the initial drug lifetime. Here, we briefly review literature on functional changes that may mark the triggering mechanism of rapid antidepressant actions. Because ketamine has a longer history of study as a rapid antidepressant, we use this literature as a template to guide hypotheses about common action. Brexanolone has the complication of being a formulation of a naturally occurring neurosteroid; thus, endogenous levels need to be considered when studying the impact of exogenous administration. We conclude that network disinhibition and increased high-frequency oscillations are candidates to mediate acute triggering effects of rapid antidepressants.
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Affiliation(s)
- Peter M Lambert
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Xinguo Lu
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Charles F Zorumski
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Steven Mennerick
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis School of Medicine, St Louis, MO, USA
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8
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Wu K, Han W, Tian Q, Li Y, Lu W. Activity- and sleep-dependent regulation of tonic inhibition by Shisa7. Cell Rep 2021; 34:108899. [PMID: 33761345 PMCID: PMC8025742 DOI: 10.1016/j.celrep.2021.108899] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/22/2020] [Accepted: 03/03/2021] [Indexed: 02/08/2023] Open
Abstract
Tonic inhibition mediated by extrasynaptic γ-aminobutyric acid type A receptors (GABAARs) critically regulates neuronal excitability and brain function. However, the mechanisms regulating tonic inhibition remain poorly understood. Here, we report that Shisa7 is critical for tonic inhibition regulation in hippocampal neurons. In juvenile Shisa7 knockout (KO) mice, α5-GABAAR-mediated tonic currents are significantly reduced. Mechanistically, Shisa7 is crucial for α5-GABAAR exocytosis. Additionally, Shisa7 regulation of tonic inhibition requires protein kinase A (PKA) that phosphorylates Shisa7 serine 405 (S405). Importantly, tonic inhibition undergoes activity-dependent regulation, and Shisa7 is required for homeostatic potentiation of tonic inhibition. Interestingly, in young adult Shisa7 KOs, basal tonic inhibition in hippocampal neurons is unaltered, largely due to the diminished α5-GABAAR component of tonic inhibition. However, at this stage, tonic inhibition oscillates during the daily sleep/wake cycle, a process requiring Shisa7. Together, these data demonstrate that intricate signaling mechanisms regulate tonic inhibition at different developmental stages and reveal a molecular link between sleep and tonic inhibition.
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Affiliation(s)
- Kunwei Wu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Qingjun Tian
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Basu T, Maguire J, Salpekar JA. Hypothalamic-pituitary-adrenal axis targets for the treatment of epilepsy. Neurosci Lett 2021; 746:135618. [PMID: 33429002 DOI: 10.1016/j.neulet.2020.135618] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/25/2020] [Accepted: 12/29/2020] [Indexed: 12/20/2022]
Abstract
Stress is a common seizure trigger in persons with epilepsy. The body's physiological response to stress is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and involves a hormonal cascade that includes corticotropin releasing hormone (CRH), adrenocorticotropin releasing hormone (ACTH) and the release of cortisol (in humans and primates) or corticosterone (in rodents). The prolonged exposure to stress hormones may not only exacerbate pre-existing medical conditions including epilepsy, but may also increase the predisposition to psychiatric comorbidities. Hyperactivity of the HPA axis negatively impacts the structure and function of the temporal lobe of the brain, a region that is heavily involved in epilepsy and mood disorders like anxiety and depression. Seizures themselves damage temporal lobe structures, further disinhibiting the HPA axis, setting off a vicious cycle of neuronal damage and increasing susceptibility for subsequent seizures and psychiatric comorbidity. Treatments targeting the HPA axis may be beneficial both for epilepsy and for associated stress-related comorbidities such as anxiety or depression. This paper will highlight the evidence demonstrating dysfunction in the HPA axis associated with epilepsy which may contribute to the comorbidity of psychiatric disorders and epilepsy, and propose treatment strategies that may dually improve seizure control as well as alleviate stress related psychiatric comorbidities.
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Affiliation(s)
- Trina Basu
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, United States
| | - Jay A Salpekar
- Kennedy Krieger Institute, Johns Hopkins University Medical School, Baltimore, MD 21205, United States.
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10
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Silva J, Shao AS, Shen Y, Davies DL, Olsen RW, Holschneider DP, Shao XM, Liang J. Modulation of Hippocampal GABAergic Neurotransmission and Gephyrin Levels by Dihydromyricetin Improves Anxiety. Front Pharmacol 2020; 11:1008. [PMID: 32742262 PMCID: PMC7364153 DOI: 10.3389/fphar.2020.01008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/22/2020] [Indexed: 12/11/2022] Open
Abstract
Anxiety disorders are the most common mental illness in the U.S. and are estimated to consume one-third of the country’s mental health spending. Although anxiolytic therapies are available, many patients exhibit treatment-resistance, relapse, or substantial side effects. An urgent need exists to explore the underlying mechanisms of chronic anxiety and to develop alternative therapies. Presently, we identified dihydromyricetin (DHM), a flavonoid that has anxiolytic properties in a mouse model of isolation-induced anxiety. Socially isolated mice demonstrated increased anxiety levels and reduced exploratory behavior measured by elevated plus-maze and open-field tests. Socially isolated mice showed impaired GABAergic neurotransmission, including reduction in GABAA receptor-mediated extrasynaptic tonic currents, as well as amplitude and frequency of miniature inhibitory postsynaptic currents measured by whole-cell patch-clamp recordings from hippocampal slices. Furthermore, intracellular ATP levels and gephyrin expression decreased in anxious animals. DHM treatment restored ATP and gephyrin expression, GABAergic transmission and synaptic function, as well as decreased anxiety-like behavior. Our findings indicate broader roles for DHM in anxiolysis, GABAergic neurotransmission, and synaptic function. Collectively, our data suggest that reduction in intracellular ATP and gephyrin contribute to the development of anxiety, and represent novel treatment targets. DHM is a potential candidate for pharmacotherapy for anxiety disorders.
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Affiliation(s)
- Joshua Silva
- Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy, Los Angeles, CA, United States
| | - Amy S Shao
- Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Yi Shen
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Daryl L Davies
- Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy, Los Angeles, CA, United States
| | - Richard W Olsen
- Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Daniel P Holschneider
- Psychiatry and The Behavioral Sciences, University of Southern California, Los Angeles, CA, United States
| | - Xuesi M Shao
- Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Jing Liang
- Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy, Los Angeles, CA, United States
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11
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Social experience and sex-dependent regulation of aggression in the lateral septum by extrasynaptic δGABA A receptors. Psychopharmacology (Berl) 2020; 237:329-344. [PMID: 31691846 PMCID: PMC7024004 DOI: 10.1007/s00213-019-05368-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 09/22/2019] [Indexed: 10/25/2022]
Abstract
RATIONALE Understanding the neurobiological mechanisms mediating dominance and competitive aggression is essential to understanding the development and treatment of various psychiatric disorders. Previous research suggests that these mechanisms are both sexually differentiated and influenced substantially by social experience. In numerous species, GABAA receptors in the lateral septum have been shown to play a significant role in aggression in males. However, very little is known about the role of these GABAA receptors in female aggression, the role of social experience on GABAA receptor-mediated aggression, or the roles of different GABAA subtypes in regulating aggression. OBJECTIVES Thus, in the following set of experiments, we determined the role of social experience in modulating GABAA receptor-induced aggression in both male and female Syrian hamsters, with a particular focus on the GABAA receptor subtype mediating these effects. RESULTS Activation of GABAA receptors in the dorsal lateral septum increased aggression in both males and females. Social housing, however, significantly decreased the ability of GABAA receptor activation to induce aggression in males but not females. No significant differences were observed in the effects of GABAA receptor activation in dominant versus subordinate group-housed hamsters. Finally, examination of potential GABAA receptor subtype specificity revealed that social housing decreased the ratio of δ extrasynaptic to γ2 synaptic subunit GABAA receptor mRNA expression in the anterior dorsal lateral septum, while activation of δ extrasynaptic, but not γ2 synaptic, GABAA receptors in the dorsal lateral septum increased aggression. CONCLUSIONS These data suggest that social experience can have profound effects on the neuronal mechanisms mediating aggression, especially in males, and that δ extrasynaptic GABAA receptors may be an important therapeutic target in disorders characterized by high levels of aggression.
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Morrow AL, Boero G, Porcu P. A Rationale for Allopregnanolone Treatment of Alcohol Use Disorders: Basic and Clinical Studies. Alcohol Clin Exp Res 2020; 44:320-339. [PMID: 31782169 PMCID: PMC7018555 DOI: 10.1111/acer.14253] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/19/2019] [Indexed: 12/17/2022]
Abstract
For many years, research from around the world has suggested that the neuroactive steroid (3α,5α)-3-hydroxypregnan-20-one (allopregnanolone or 3α,5α-THP) may have therapeutic potential for treatment of various symptoms of alcohol use disorders (AUDs). In this critical review, we systematically address all the evidence that supports such a suggestion, delineate the etiologies of AUDs that are addressed by treatment with allopregnanolone or its precursor pregnenolone, and the rationale for treatment of various components of the disease based on basic science and clinical evidence. This review presents a theoretical framework for understanding how endogenous steroids that regulate the effects of stress, alcohol, and the innate immune system could play a key role in both the prevention and the treatment of AUDs. We further discuss cautions and limitations of allopregnanolone or pregnenolone therapy with suggestions regarding the management of risk and the potential for helping millions who suffer from AUDs.
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Affiliation(s)
- A. Leslie Morrow
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Giorgia Boero
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
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13
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Boero G, Porcu P, Morrow AL. Pleiotropic actions of allopregnanolone underlie therapeutic benefits in stress-related disease. Neurobiol Stress 2019; 12:100203. [PMID: 31879693 PMCID: PMC6920111 DOI: 10.1016/j.ynstr.2019.100203] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/15/2019] [Accepted: 11/21/2019] [Indexed: 01/20/2023] Open
Abstract
For several years, research from around the world has suggested that the neuroactive steroid (3α,5α)-3-hydroxypregnan-20-one (allopregnanolone) may have therapeutic potential for treatment of various stress-related diseases including post-traumatic stress disorder (PTSD), depression, alcohol use disorders (AUDs), as well as neurological and psychiatric conditions that are worsened in the presence of stress, such as multiple sclerosis, schizophrenia, and seizure disorders. In this review, we make the argument that the pleiotropic actions of allopregnanolone account for its ability to promote recovery in such a wide variety of illnesses. Likewise, the allopregnanolone precursors, pregnenolone and progesterone, share many actions of allopregnanolone. Of course, pregnenolone and progesterone lack direct effects on GABAA receptors, but these compounds are converted to allopregnanolone in vivo. This review presents a theoretical framework for understanding how endogenous neurosteroids that regulate 1) γ-aminobutyric acid (GABA)A receptors, 2) corticotropin releasing factor (CRF) and 3) pro-inflammatory signaling in the innate immune system and brain could play a key role in both the prevention and treatment of stress-related disease. We further discuss cautions and limitations of allopregnanolone or precursor therapy as well as the need for more clinical studies.
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Affiliation(s)
- Giorgia Boero
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC, 27599, USA
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
| | - A Leslie Morrow
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC, 27599, USA
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14
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Tomaselli G, Vallée M. Stress and drug abuse-related disorders: The promising therapeutic value of neurosteroids focus on pregnenolone-progesterone-allopregnanolone pathway. Front Neuroendocrinol 2019; 55:100789. [PMID: 31525393 DOI: 10.1016/j.yfrne.2019.100789] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/14/2019] [Accepted: 09/09/2019] [Indexed: 02/06/2023]
Abstract
The pregnenolone-progesterone-allopregnanolone pathway is receiving increasing attention in research on the role of neurosteroids in pathophysiology, particularly in stress-related and drug use disorders. These disorders involve an allostatic change that may result from deficiencies in allostasis or adaptive responses, and may be downregulated by adjustments in neurotransmission by neurosteroids. The following is an overview of findings that assess how pregnenolone and/or allopregnanolone concentrations are altered in animal models of stress and after consumption of alcohol or cannabis-type drugs, as well as in patients with depression, anxiety, post-traumatic stress disorder or psychosis and/or in those diagnosed with alcohol or cannabis use disorders. Preclinical and clinical evidence shows that pregnenolone and allopregnanolone, operating according to a different or common pharmacological profile involving GABAergic and/or endocannabinoid system, may be relevant biomarkers of psychiatric disorders for therapeutic purposes. Hence, ongoing clinical trials implicate synthetic analogs of pregnenolone or allopregnanolone, and also modulators of neurosteroidogenesis.
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Affiliation(s)
- Giovanni Tomaselli
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", 146 Rue Léo Saignat, 33000 Bordeaux, France; University of Bordeaux, 33000 Bordeaux, France
| | - Monique Vallée
- INSERM U1215, Neurocentre Magendie, Group "Physiopathology and Therapeutic Approaches of Stress-Related Disease", 146 Rue Léo Saignat, 33000 Bordeaux, France; University of Bordeaux, 33000 Bordeaux, France.
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15
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Abstract
The term neurosteroid refers to rapid membrane actions of steroid hormones and their derivatives that can modulate physiological functions and behavior via their interactions with ligand-gated ion channels. This chapter will highlight recent advances pertaining to the modulatory effects of a select group of neurosteroids that are primarily potent positive allosteric modulators of γ-aminobutyric acidA receptors (GABAARs). Nanomolar concentrations of neurosteroids, which occur in vivo, potentiate phasic and tonic forms of GABAAR-mediated inhibition, indicating that both synaptic and extrasynaptic GABAARs possess sensitivity to neurosteroids and contribute to the overall ability of neurosteroids to modulate central nervous system excitability. Common effects of alcohol and neurosteroids at GABAARs have stimulated research on the ability of neurosteroids to modulate alcohol's acute and chronic effects. Background on neurosteroid pharmacology and biosynthetic enzymes will be provided as it relates to experimental findings. Data will be summarized on alcohol and neurosteroid interactions across neuroanatomical regions and models of intoxication, consumption, dependence, and withdrawal. Evidence supports independent regulation of neurosteroid synthesis between periphery and brain as well as across brain regions following acute alcohol administration and during withdrawal. Local mechanisms for fine-tuning neuronal excitability via manipulation of neurosteroid synthesis exert predicted behavioral and electrophysiological responses on GABAAR-mediated inhibition. Collectively, targeting neurosteroidogenesis may be a beneficial treatment strategy for alcohol use disorders.
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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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17
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Almeida FB, Gomez R, Barros HMT, Nin MS. Hemisphere-dependent Changes in mRNA Expression of GABA A Receptor Subunits and BDNF after Intra-prefrontal Cortex Allopregnanolone Infusion in Rats. Neuroscience 2018; 397:56-66. [PMID: 30481569 DOI: 10.1016/j.neuroscience.2018.11.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 11/05/2018] [Accepted: 11/19/2018] [Indexed: 02/08/2023]
Abstract
Allopregnanolone is a neurosteroid implicated in mood disorders such as depression and anxiety. It acts as a GABAA receptor (GABAAR)-positive allosteric modulator and changes the expression of GABAAR subunits and of brain-derived neurotrophic factor (BDNF) in different brain regions. It has been demonstrated that such neurochemical changes may have an asymmetrical pattern regarding brain hemispheres. The aim of this study was to verify the behavioral and hemisphere-specific neurochemical effects of the bilateral intra-prefrontal cortex (intra-PFC) infusion of allopregnanolone in rats. Rats were exposed to the forced swim test and to the grooming microstructure test, followed by the right and left hemisphere-specific quantification of mRNA expression by Real-Time PCR of δ and γ2 GABAAR subunits and BDNF in the PFC and in the hippocampus. Though we did not observe any significant effects in the behavioral tests, intra-PFC allopregnanolone infusion bilaterally increased the mRNA expression of the δ subunit in the same area and of BDNF in the hippocampus. Both mRNA expressions of the γ2 subunit and BDNF were higher in the right than in the left PFC of control animals, and the hemisphere differences were not seen after allopregnanolone infusion. Overall hippocampal BDNF expression was also higher in the right hemisphere, but this asymmetry was not normalized by allopregnanolone. No asymmetries or changes were observed in the hippocampal mRNA expression of GABAAR subunits. These results point to a hemisphere-dependent regulation of GABAAR subunits and BDNF that can be modulated by intra-PFC allopregnanolone infusion, even in the absence of associated behavioral effects.
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Affiliation(s)
- Felipe Borges Almeida
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil; Departamento de Farmacociências, Laboratório de Neuropsicofarmacologia, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil.
| | - Rosane Gomez
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Farmacologia e Terapêutica, Universidade Federal do Rio Grande do Sul - UFRGS, Rua Sarmento Leite 500, 90050-170 Porto Alegre, RS, Brazil
| | - Helena Maria Tannhauser Barros
- Programa de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil; Departamento de Farmacociências, Laboratório de Neuropsicofarmacologia, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil
| | - Maurício Schüler Nin
- Departamento de Farmacociências, Laboratório de Neuropsicofarmacologia, Universidade Federal de Ciências da Saúde de Porto Alegre - UFCSPA, Rua Sarmento Leite 245, 90050-170 Porto Alegre, RS, Brazil; Curso de Farmácia, Centro Universitário Metodista do IPA, Rua Coronel Joaquim Pedro Salgado 80, 90420-060 Porto Alegre, RS, Brazil
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Locci A, Geoffroy P, Miesch M, Mensah-Nyagan AG, Pinna G. Social Isolation in Early versus Late Adolescent Mice Is Associated with Persistent Behavioral Deficits That Can Be Improved by Neurosteroid-Based Treatment. Front Cell Neurosci 2017; 11:208. [PMID: 28900387 PMCID: PMC5581875 DOI: 10.3389/fncel.2017.00208] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/30/2017] [Indexed: 01/10/2023] Open
Abstract
Early trauma and stress exposure during a critical period of life may increase the risk of major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) in adulthood. The first-choice treatment for MDD and PTSD are selective serotonin reuptake inhibitor (SSRI) antidepressants. Unfortunately, half of MDD and PTSD patients show resistance to the therapeutic effects of these drugs and more efficient treatments are essential. Both MDD and PTSD patients present reduced levels of allopregnanolone (Allo), a potent endogenous positive allosteric modulator of GABA action at GABAA receptors which are normalized by SSRIs in treatment responders. Thus, Allo analogs or drugs that stimulate its levels may offer an alternative in treating SSRIs-non-responders. We tested several drugs on the aggressive behavior of early and late adolescent socially-isolated (SI) mice, a model of PTSD. Isolation in early adolescence (PND 21) induced more severe aggression than mice isolated at PND 45. A single non-sedating administration of S-fluoxetine (S-FLX; 0.375–1.5 mg/kg), or of the Allo analogs ganaxolone (GNX; 10 mg/kg), BR351 (1–5 mg/kg), or BR297 (0.3125–2.5 mg/kg), or of the endocannabinoid, N-palmitoylethanolamine (PEA; 5–20 mg/kg) all decreased aggression more effectively in late than early adolescent SI mice. Importantly, the number of drug non-responders was higher in early than late SI mice for all the drugs tested. The non-responder rate was more elevated (12–64%) after S-FLX treatment, while 100% of mice responded to a single administration of PEA at the dose range of 15–20 mg/kg. Moreover, GNX, BR351, and BR297’s antiaggressive effect persisted longer than S-FLX in both late and early SI mice. All drugs tested failed to alter locomotor activity of SI mice. Our results show that drugs that mimic Allo’s action or that induce Allo biosynthesis may be valuable for the treatment of “SSRIs non-responder” patients.
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Affiliation(s)
- Andrea Locci
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, ChicagoIL, United States
| | - Philippe Geoffroy
- Laboratoire de Chimie Organique Synthétique, UMR 7177, Institut de Chimie de l'Université de StrasbourgStrasbourg, France
| | - Michel Miesch
- Laboratoire de Chimie Organique Synthétique, UMR 7177, Institut de Chimie de l'Université de StrasbourgStrasbourg, France
| | - Ayikoe-Guy Mensah-Nyagan
- Biopathologie de la Myéline, Neuroprotection et Stratégies Thérapeutiques, INSERM U1119, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de StrasbourgStrasbourg, France
| | - Graziano Pinna
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, ChicagoIL, United States
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19
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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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20
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Rasmusson AM, Marx CE, Pineles SL, Locci A, Scioli-Salter ER, Nillni YI, Liang JJ, Pinna G. Neuroactive steroids and PTSD treatment. Neurosci Lett 2017; 649:156-163. [PMID: 28215878 DOI: 10.1016/j.neulet.2017.01.054] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 01/22/2017] [Accepted: 01/23/2017] [Indexed: 01/08/2023]
Abstract
This review highlights early efforts to translate pre-clinical and clinical findings regarding the role of neuroactive steroids in stress adaptation and PTSD into new therapeutics for PTSD. Numerous studies have demonstrated PTSD-related alterations in resting levels or the reactivity of neuroactive steroids and their targets. These studies also have demonstrated substantial variability in the dysfunction of specific neuroactive steroid systems among PTSD subpopulations. These variabilities have been related to the developmental timing of trauma, severity and type of trauma, genetic background, sex, reproductive state, lifestyle influences such as substance use and exercise, and the presence of comorbid conditions such as depression and chronic pain. Nevertheless, large naturalistic studies and a small placebo-controlled interventional study have revealed generally positive effects of glucocorticoid administration in preventing PTSD after trauma, possibly mediated by glucocorticoid receptor-mediated effects on other targets that impact PTSD risk, including other neuroactive steroid systems. In addition, clinical and preclinical studies show that administration of glucocorticoids, 17β-estradiol, and GABAergic neuroactive steroids or agents that enhance their synthesis can facilitate extinction and extinction retention, depending on dose and timing of dose in relation to these complex PTSD-relevant recovery processes. This suggests that clinical trials designed to test neuroactive steroid therapeutics in PTSD may benefit from such considerations; typical continuous dosing regimens may not be optimal. In addition, validated and clinically accessible methods for identifying specific neuroactive steroid system abnormalities at the individual level are needed to optimize both clinical trial design and precision medicine based treatment targeting.
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Affiliation(s)
- Ann M Rasmusson
- National Center for PTSD, Women's Health Science Division, Department of Veterans Affairs 150 South Huntington Avenue, Boston, MA 02135, USA; VA Boston Healthcare System 150 South Huntington Avenue, Boston, MA 02135, USA; Boston University School of Medicine 72 E Concord St, Boston, MA 02118, USA.
| | - Christine E Marx
- Durham VA Medical Center, VA Mid-Atlantic MIRECC,and Duke University Medical Center, 508 Fulton Street, Durham, NC 27705, USA
| | - Suzanne L Pineles
- National Center for PTSD, Women's Health Science Division, Department of Veterans Affairs 150 South Huntington Avenue, Boston, MA 02135, USA; Boston University School of Medicine 72 E Concord St, Boston, MA 02118, USA
| | - Andrea Locci
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Str., Chicago, IL 60612, USA
| | - Erica R Scioli-Salter
- VA Boston Healthcare System 150 South Huntington Avenue, Boston, MA 02135, USA; Boston University School of Medicine 72 E Concord St, Boston, MA 02118, USA
| | - Yael I Nillni
- National Center for PTSD, Women's Health Science Division, Department of Veterans Affairs 150 South Huntington Avenue, Boston, MA 02135, USA; Boston University School of Medicine 72 E Concord St, Boston, MA 02118, USA
| | - Jennifer J Liang
- Boston University School of Medicine 72 E Concord St, Boston, MA 02118, USA
| | - Graziano Pinna
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor Str., Chicago, IL 60612, USA
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21
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Locci A, Porcu P, Talani G, Santoru F, Berretti R, Giunti E, Licheri V, Sanna E, Concas A. Neonatal estradiol exposure to female rats changes GABA A receptor expression and function, and spatial learning during adulthood. Horm Behav 2017; 87:35-46. [PMID: 27769760 DOI: 10.1016/j.yhbeh.2016.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 10/04/2016] [Accepted: 10/14/2016] [Indexed: 12/27/2022]
Abstract
Exposure of female rats to estradiol during the perinatal period has profound effects on GABAergic neurotransmission that are crucial to establish sexually dimorphic brain characteristics. We previously showed that neonatal β-estradiol 3-benzoate (EB) treatment decreases brain concentrations of the neurosteroid allopregnanolone, a potent positive modulator of extrasynaptic GABAA receptors (GABAAR). We thus evaluated whether neonatal EB treatment affects GABAAR expression and function in the hippocampus of adult female rats. Neonatal EB administration increased the expression of extrasynaptic α4/δ subunit-containing GABAARs and the modulatory action of THIP on tonic currents mediated by these receptors. The same treatment decreased the expression of synaptic α1/α4/γ2 subunit-containing receptors, as well as phasic currents. These effects of neonatal EB treatment are not related to ambient allopregnanolone concentrations per se, given that vehicle-treated rats in diestrus, which have opposite neurosteroid levels than EB-treated rats, show similar changes in GABAARs. Rather, these changes may represent a compensatory mechanism to counteract the long-term reduction in allopregnanolone concentrations, induced by neonatal EB. Given that both α4/δ receptors and allopregnanolone are involved in memory consolidation, we evaluated whether neonatal EB treatment alters performance in the Morris water maze test during adulthood. Neonatal EB treatment decreased the latency and the cumulative search error to reach the platform, as well as thigmotaxis, suggesting improved learning, and also enhanced memory performance during the probe trial. These enduring changes in GABAAR plasticity may be relevant for the regulation of neuronal excitability in the hippocampus and for the etiology of psychiatric disorders that originate in development and show sex differences.
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Affiliation(s)
- Andrea Locci
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Giuseppe Talani
- Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Francesca Santoru
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Roberta Berretti
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Elisa Giunti
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Valentina Licheri
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Enrico Sanna
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy
| | - Alessandra Concas
- Department of Life and Environment Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy; Neuroscience Institute, National Research Council of Italy (CNR), Cittadella Universitaria, 09042 Monserrato, Cagliari, Italy.
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22
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Piantadosi SC, French BJ, Poe MM, Timić T, Marković BD, Pabba M, Seney ML, Oh H, Orser BA, Savić MM, Cook JM, Sibille E. Sex-Dependent Anti-Stress Effect of an α5 Subunit Containing GABA A Receptor Positive Allosteric Modulator. Front Pharmacol 2016; 7:446. [PMID: 27920723 PMCID: PMC5118774 DOI: 10.3389/fphar.2016.00446] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 11/08/2016] [Indexed: 12/21/2022] Open
Abstract
Rationale: Current first-line treatments for stress-related disorders such as major depressive disorder (MDD) act on monoaminergic systems and take weeks to achieve a therapeutic effect with poor response and low remission rates. Recent research has implicated the GABAergic system in the pathophysiology of depression, including deficits in interneurons targeting the dendritic compartment of cortical pyramidal cells. Objectives: The present study evaluates whether SH-053-2’F-R-CH3 (denoted “α5-PAM”), a positive allosteric modulator selective for α5-subunit containing GABAA receptors found predominantly on cortical pyramidal cell dendrites, has anti-stress effects. Methods: Female and male C57BL6/J mice were exposed to unpredictable chronic mild stress (UCMS) and treated with α5-PAM acutely (30 min prior to assessing behavior) or chronically before being assessed behaviorally. Results: Acute and chronic α5-PAM treatments produce a pattern of decreased stress-induced behaviors (denoted as “behavioral emotionality”) across various tests in female, but not in male mice. Behavioral Z-scores calculated across a panel of tests designed to best model the range and heterogeneity of human symptomatology confirmed that acute and chronic α5-PAM treatments consistently produce significant decreases in behavioral emotionality in several independent cohorts of females. The behavioral responses to α5-PAM could not be completely accounted for by differences in drug brain disposition between female and male mice. In mice exposed to UCMS, expression of the Gabra5 gene was increased in the frontal cortex after acute treatment and in the hippocampus after chronic treatment with α5-PAM in females only, and these expression changes correlated with behavioral emotionality. Conclusion: We showed that acute and chronic positive modulation of α5 subunit-containing GABAA receptors elicit anti-stress effects in a sex-dependent manner, suggesting novel therapeutic modalities.
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Affiliation(s)
- Sean C Piantadosi
- Center for Neuroscience, University of PittsburghPittsburgh, PA, USA; Department of Psychiatry, University of PittsburghPittsburgh, PA, USA
| | - Beverly J French
- Department of Psychiatry, University of Pittsburgh Pittsburgh, PA, USA
| | - Michael M Poe
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee Milwaukee, WI, USA
| | - Tamara Timić
- Department of Pharmacology, University of Belgrade Belgrade, Serbia
| | - Bojan D Marković
- Department of Pharmaceutical Chemistry, University of Belgrade Belgrade, Serbia
| | - Mohan Pabba
- Neurobiology of Depression and Aging, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health Toronto, ON, Canada
| | - Marianne L Seney
- Department of Psychiatry, University of Pittsburgh Pittsburgh, PA, USA
| | - Hyunjung Oh
- Center for Neuroscience, University of PittsburghPittsburgh, PA, USA; Department of Psychiatry, University of PittsburghPittsburgh, PA, USA; Neurobiology of Depression and Aging, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental HealthToronto, ON, Canada
| | - Beverley A Orser
- Department of Anesthesia-Department of Physiology, University of Toronto Toronto, ON, Canada
| | - Miroslav M Savić
- Department of Pharmacology, University of Belgrade Belgrade, Serbia
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee Milwaukee, WI, USA
| | - Etienne Sibille
- Center for Neuroscience, University of PittsburghPittsburgh, PA, USA; Department of Psychiatry, University of PittsburghPittsburgh, PA, USA; Neurobiology of Depression and Aging, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental HealthToronto, ON, Canada; Department of Psychiatry- Department of Pharmacology and Toxicology, University of TorontoToronto, ON, Canada
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Gilpin NW, Weiner JL. Neurobiology of comorbid post-traumatic stress disorder and alcohol-use disorder. GENES BRAIN AND BEHAVIOR 2016; 16:15-43. [PMID: 27749004 DOI: 10.1111/gbb.12349] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/03/2016] [Accepted: 10/07/2016] [Indexed: 12/12/2022]
Abstract
Post-traumatic stress disorder (PTSD) and alcohol-use disorder (AUD) are highly comorbid in humans. Although we have some understanding of the structural and functional brain changes that define each of these disorders, and how those changes contribute to the behavioral symptoms that define them, little is known about the neurobiology of comorbid PTSD and AUD, which may be due in part to a scarcity of adequate animal models for examining this research question. The goal of this review is to summarize the current state-of-the-science on comorbid PTSD and AUD. We summarize epidemiological data documenting the prevalence of this comorbidity, review what is known about the potential neurobiological basis for the frequent co-occurrence of PTSD and AUD and discuss successes and failures of past and current treatment strategies. We also review animal models that aim to examine comorbid PTSD and AUD, highlighting where the models parallel the human condition, and we discuss the strengths and weaknesses of each model. We conclude by discussing key gaps in our knowledge and strategies for addressing them: in particular, we (1) highlight the need for better animal models of the comorbid condition and better clinical trial design, (2) emphasize the need for examination of subpopulation effects and individual differences and (3) urge cross-talk between basic and clinical researchers that is reflected in collaborative work with forward and reverse translational impact.
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Affiliation(s)
- N W Gilpin
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA.,Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA
| | - J L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Talani G, Biggio F, Licheri V, Locci V, Biggio G, Sanna E. Isolation Rearing Reduces Neuronal Excitability in Dentate Gyrus Granule Cells of Adolescent C57BL/6J Mice: Role of GABAergic Tonic Currents and Neurosteroids. Front Cell Neurosci 2016; 10:158. [PMID: 27378855 PMCID: PMC4904037 DOI: 10.3389/fncel.2016.00158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 05/30/2016] [Indexed: 01/03/2023] Open
Abstract
Early-life exposure to stress, by impacting on a brain still under development, is considered a critical factor for the increased vulnerability to psychiatric disorders and abuse of psychotropic substances during adulthood. As previously reported, rearing C57BL/6J weanling mice in social isolation (SI) from their peers for several weeks, a model of prolonged stress, is associated with a decreased plasma and brain levels of neuroactive steroids such as 3α,5α-THP, with a parallel up-regulation of extrasynaptic GABAA receptors (GABAAR) in dentate gyrus (DG) granule cells compared to group-housed (GH) mice. In the present study, together with the SI-induced decrease in plasma concentration of both progesterone and 3α,5α-THP, and an increase in THIP-stimulated GABAergic tonic currents, patch-clamp analysis of DG granule cells revealed a significant decrease in membrane input resistance and action potential (AP) firing rate, in SI compared to GH mice, suggesting that SI exerts an inhibitory action on neuronal excitability of these neurons. Voltage-clamp recordings of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) revealed a SI-associated decrease in frequency as well as a shift from paired-pulse (PP) depression to PP facilitation (PPF) of evoked EPSCs, indicative of a reduced probability of glutamate release. Daily administration of progesterone during isolation reverted the changes in plasma 3α,5α-THP as well as in GABAergic tonic currents and neuronal excitability caused by SI, but it had only a limited effect on the changes in the probability of presynaptic glutamate release. Overall, the results obtained in this work, together with those previously published, indicate that exposure of mice to SI during adolescence reduces neuronal excitability of DG granule cells, an effect that may be linked to the increased GABAergic tonic currents as a consequence of the sustained decrease in plasma and hippocampal levels of neurosteroids. All these changes may be consistent with cognitive deficits observed in animals exposed to such type of prolonged stress.
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Affiliation(s)
- Giuseppe Talani
- Institute of Neuroscience, National Research Council of Italy Monserrato, Cagliari, Italy
| | - Francesca Biggio
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato Italy
| | - Valentina Licheri
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato Italy
| | - Valentina Locci
- Department of Biomedical Science, University of Sassari Sassari, Italy
| | - Giovanni Biggio
- Institute of Neuroscience, National Research Council of ItalyMonserrato, Cagliari, Italy; Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, MonserratoItaly
| | - Enrico Sanna
- Institute of Neuroscience, National Research Council of ItalyMonserrato, Cagliari, Italy; Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, MonserratoItaly
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Lee V, MacKenzie G, Hooper A, Maguire J. Reduced tonic inhibition in the dentate gyrus contributes to chronic stress-induced impairments in learning and memory. Hippocampus 2016; 26:1276-1290. [PMID: 27163381 DOI: 10.1002/hipo.22604] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/30/2016] [Accepted: 05/06/2016] [Indexed: 11/11/2022]
Abstract
It is well established that stress impacts the underlying processes of learning and memory. The effects of stress on memory are thought to involve, at least in part, effects on the hippocampus, which is particularly vulnerable to stress. Chronic stress induces hippocampal alterations, including but not limited to dendritic atrophy and decreased neurogenesis, which are thought to contribute to chronic stress-induced hippocampal dysfunction and deficits in learning and memory. Changes in synaptic transmission, including changes in GABAergic inhibition, have been documented following chronic stress. Recently, our laboratory demonstrated shifts in EGABA in CA1 pyramidal neurons following chronic stress, compromising GABAergic transmission and increasing excitability of these neurons. Interestingly, here we demonstrate that these alterations are unique to CA1 pyramidal neurons, since we do not observe shifts in EGABA following chronic stress in dentate gyrus granule cells. Following chronic stress, there is a decrease in the expression of the GABAA receptor (GABAA R) δ subunit and tonic GABAergic inhibition in dentate gyrus granule cells, whereas there is an increase in the phasic component of GABAergic inhibition, evident by an increase in the peak amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). Given the numerous changes observed in the hippocampus following stress, it is difficult to pinpoint the pertinent contributing pathophysiological factors. Here we directly assess the impact of a reduction in tonic GABAergic inhibition of dentate gyrus granule cells on learning and memory using a mouse model with a decrease in GABAA R δ subunit expression specifically in dentate gyrus granule cells (Gabrd/Pomc mice). Reduced GABAA R δ subunit expression and function in dentate gyrus granule cells is sufficient to induce deficits in learning and memory. Collectively, these findings suggest that the reduction in GABAA R δ subunit-mediated tonic inhibition in dentate gyrus granule cells contributes, at least in part, to deficits in learning and memory associated with chronic stress. These findings have significant implications regarding the pathophysiological mechanisms underlying impairments in learning and memory associated with stress and suggest a role for GABAA R δ subunit containing receptors in dentate gyrus granule cells. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vallent Lee
- Medical Scientist Training Program and Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, United States
| | - Georgina MacKenzie
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Andrew Hooper
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
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Follesa P, Floris G, Asuni GP, Ibba A, Tocco MG, Zicca L, Mercante B, Deriu F, Gorini G. Chronic Intermittent Ethanol Regulates Hippocampal GABA(A) Receptor Delta Subunit Gene Expression. Front Cell Neurosci 2015; 9:445. [PMID: 26617492 PMCID: PMC4637418 DOI: 10.3389/fncel.2015.00445] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/26/2015] [Indexed: 12/26/2022] Open
Abstract
Chronic ethanol consumption causes structural and functional reorganization in the hippocampus and induces alterations in the gene expression of gamma-aminobutyric acid type A receptors (GABAARs). Distinct forced intermittent exposure models have been used previously to investigate changes in GABAAR expression, with contrasting results. Here, we used repeated cycles of a Chronic Intermittent Ethanol paradigm to examine the relationship between voluntary, dependence-associated ethanol consumption, and GABAAR gene expression in mouse hippocampus. Adult male C57BL/6J mice were exposed to four 16-h ethanol vapor (or air) cycles in inhalation chambers alternated with limited-access two-bottle choice between ethanol (15%) and water consumption. The mice exposed to ethanol vapor showed significant increases in ethanol consumption compared to their air-matched controls. GABAAR alpha4 and delta subunit gene expression were measured by qRT-PCR at different stages. There were significant changes in GABAAR delta subunit transcript levels at different time points in ethanol-vapor exposed mice, while the alpha4 subunit levels remained unchanged. Correlated concurrent blood ethanol concentrations suggested that GABAAR delta subunit mRNA levels fluctuate depending on ethanol intoxication, dependence, and withdrawal state. Using a vapor-based Chronic Intermittent Ethanol procedure with combined two-bottle choice consumption, we corroborated previous evidences showing that discontinuous ethanol exposure affects GABAAR delta subunit expression but we did not observe changes in alpha4 subunit. These findings indicate that hippocampal GABAAR delta subunit expression changes transiently over the course of a Chronic Intermittent Ethanol paradigm associated with voluntary intake, in response to ethanol-mediated disturbance of GABAergic neurotransmission.
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Affiliation(s)
- Paolo Follesa
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Gabriele Floris
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Gino P Asuni
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Antonio Ibba
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | - Maria G Tocco
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | - Luca Zicca
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | | | - Franca Deriu
- Department of Biomedical Sciences, University of Sassari Sassari, Italy
| | - Giorgio Gorini
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
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27
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MacKenzie G, Maguire J. Chronic stress shifts the GABA reversal potential in the hippocampus and increases seizure susceptibility. Epilepsy Res 2015; 109:13-27. [PMID: 25524838 PMCID: PMC4272449 DOI: 10.1016/j.eplepsyres.2014.10.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 09/16/2014] [Accepted: 10/01/2014] [Indexed: 10/24/2022]
Abstract
The most commonly reported precipitating factor for seizures is stress. However, the underlying mechanisms whereby stress triggers seizures are not yet fully understood. Here we demonstrate a potential mechanism underlying changes in neuronal excitability in the hippocampus following chronic stress, involving a shift in the reversal potential for GABA (EGABA) associated with a dephosphorylation of the potassium chloride co-transporter, KCC2. Mice subjected to chronic restraint stress (30min/day for 14 consecutive days) exhibit an increase in serum corticosterone levels which is associated with increased susceptibility to seizures induced with kainic acid (20mg/kg). Following chronic stress, but not acute stress, we observe a dephosphorylation of KCC2 residue S940, which regulates KCC2 cell surface expression and function, in the hippocampus. To determine the impact of alterations in KCC2 expression following chronic stress, we performed gramicidin perforated patch recordings to measure changes in EGABA and neuronal excitability of principal hippocampal neurons. We observe a depolarizing shift in EGABA in hippocampal CA1 pyramidal neurons after chronic stress. In addition, there is an increase in the intrinsic excitability of CA1 pyramidal neurons, evident by a shift in the input-output curve which could be reversed with the NKCC1 inhibitor, bumetanide. These data uncover a potential mechanism involving chronic stress-induced plasticity in chloride homeostasis which may contribute to stress-induced seizure susceptibility.
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Affiliation(s)
- Georgina MacKenzie
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA.
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28
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Biggio G, Pisu MG, Biggio F, Serra M. Allopregnanolone modulation of HPA axis function in the adult rat. Psychopharmacology (Berl) 2014; 231:3437-44. [PMID: 24658404 DOI: 10.1007/s00213-014-3521-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/25/2014] [Indexed: 11/26/2022]
Abstract
RATIONALE GABAergic neuronal circuits regulate neuroendocrine stress response, and the most potent positive endogenous modulator of GABAA receptor function is allopregnanolone. This neurosteroid acts in a nongenomic manner to selectively increase the inhibitory signal meditated by GABAA receptors; in addition, it also induces long-lasting changes in the expression of specific GABAA receptor subunits in various brain regions, with consequent changes in receptor function. OBJECTIVE The objective of this review is to summarize our findings on emotional state and stress responsiveness in three animal models in which basal brain concentrations of allopregnanolone differ. It is postulated that individual differences in allopregnanolone levels can influence general resilience. RESULTS The results showed that there is an apparent correlation between endogenous levels of brain allopregnanolone and basal and stress-stimulated HPA axis activity. CONCLUSION The relationship between endogenous brain levels of allopregnanolone and HPA axis activity and function sustains the therapeutic potential of this neurosteroid for the treatment of stress-associated disorders.
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29
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Altered expression of δGABAA receptors in health and disease. Neuropharmacology 2014; 88:24-35. [PMID: 25128850 DOI: 10.1016/j.neuropharm.2014.08.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/28/2014] [Accepted: 08/03/2014] [Indexed: 01/08/2023]
Abstract
γ-Aminobutyric acid type A receptors that contain the δ subunit (δGABAA receptors) are expressed in multiple types of neurons throughout the central nervous system, where they generate a tonic conductance that shapes neuronal excitability and synaptic plasticity. These receptors regulate a variety of important behavioral functions, including memory, nociception and anxiety, and may also modulate neurogenesis. Given their functional significance, δGABAA receptors are considered to be novel therapeutic targets for the treatment of memory dysfunction, pain, insomnia and mood disorders. These receptors are highly responsive to sedative-hypnotic drugs, general anesthetics and neuroactive steroids. A further remarkable feature of δGABAA receptors is that their expression levels are highly dynamic and fluctuate substantially during development and in response to physiological changes including stress and the reproductive cycle. Furthermore, the expression of these receptors varies in pathological conditions such as alcoholism, fragile X syndrome, epilepsy, depression, schizophrenia, mood disorders and traumatic brain injury. Such fluctuations in receptor expression have significant consequences for behavior and may alter responsiveness to therapeutic drugs. This review considers the alterations in the expression of δGABAA receptors associated with various states of health and disease and the implications of these changes.
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30
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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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31
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Talani G, Licheri V, Masala N, Follesa P, Mostallino MC, Biggio G, Sanna E. Increased voluntary ethanol consumption and changes in hippocampal synaptic plasticity in isolated C57BL/6J mice. Neurochem Res 2013; 39:997-1004. [PMID: 24343529 DOI: 10.1007/s11064-013-1216-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 11/29/2022]
Abstract
Social isolation (SI) is a notable model of prolonged mild stress, characterized by multiple neurochemical and behavioral alterations, that appears particularly suitable for studying different aspects of the interplay between stress and ethanol (EtOH) consumption in order to characterize potential molecular mechanisms, including changes in the function of inhibitory GABAergic synapses, underlying such interaction. In C57BL/6J mice, SI is associated with an altered hippocampal concentration of the neuroactive steroids 3α-hydroxy-5α-pregnan-20-one (3α-5α-THP), an increased expression of the α4 and δ subunit of γ-aminobutyric acid type A receptors (GABAARs) in the dentate gyrus (DG), and a parallel enhancement of the stimulatory action of 4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridin-3-ol (THIP) on GABAergic tonic currents recorded in voltage-clamped DG granule cells (DGGCs). In addition, SI in C57BL/6J mice determines an increase in voluntary EtOH consumption and EtOH preference when compared to group-housed (GH) control animals. Furthermore, in hippocampal slices of SI mice we also observed a marked reduction of both cellular excitability and long term potentiation (LTP) in pyramidal neurons of the CA1 hippocampal sub-region, effects that were prevented by the long term treatment of SI mice with the neuroactive steroid precursor progesterone. In this article, we summarize some of our recent findings on the effects of SI in C57BL/6J mice on voluntary EtOH intake, regulation of GABAARs gene expression and function and hippocampal long term synaptic plasticity.
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Affiliation(s)
- Giuseppe Talani
- Institute of Neuroscience, National Research Council, 09042, Monserrato, Cagliari, Italy,
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The role of allopregnanolone in depression and anxiety. Prog Neurobiol 2013; 113:79-87. [PMID: 24215796 DOI: 10.1016/j.pneurobio.2013.09.003] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/21/2013] [Accepted: 09/21/2013] [Indexed: 12/22/2022]
Abstract
Neuroactive steroids such as allopregnanolone do not only act as transcriptional factors in the regulation of gene expression after intracellular back-oxidation into the 5-α pregnane steroids but may also alter neuronal excitability through interactions with specific neurotransmitter receptors. In particular, certain 3α-reduced metabolites of progesterone such as 3α,5α-tetrahydroprogesterone (allopregnanolone) and 3α,5β-tetrahydroprogesterone (pregnanolone) are potent positive allosteric modulators of the GABA(A) receptor complex. During the last years, the downregulation of neurosteroid biosynthesis has been intensively discussed to be a possible contributor to the development of anxiety and depressive disorder. Reduced levels of allopregnanolone in the peripheral blood or cerebrospinal fluid were found to be associated with major depression, anxiety disorders, premenstrual dysphoric disorder, negative symptoms in schizophrenia, or impulsive aggression. The importance of allopregnanolone for the regulation of emotion and its therapeutical use in depression and anxiety may not only involve GABAergic mechanisms, but probably also includes enhancement of neurogenesis, myelination, neuroprotection, and regulatory effects on HPA axis function. Certain pharmacokinetic obstacles limit the therapeutic use of natural neurosteroids (low bioavailability, oxidation to the ketone). Until now synthetic neuroactive steroids could not be established in the treatment of anxiety disorders or depression. However, the translocator protein (18 kDa) (TSPO) which is important for neurosteroidogenesis has been identified as a potential novel target. TSPO ligands such as XBD 173 increase neurosteroidogenesis and have anxiolytic effects with a favorable side effect profile.
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Carver CM, Reddy DS. Neurosteroid interactions with synaptic and extrasynaptic GABA(A) receptors: regulation of subunit plasticity, phasic and tonic inhibition, and neuronal network excitability. Psychopharmacology (Berl) 2013; 230:151-88. [PMID: 24071826 PMCID: PMC3832254 DOI: 10.1007/s00213-013-3276-5] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 08/29/2013] [Indexed: 12/25/2022]
Abstract
RATIONALE Neurosteroids are steroids synthesized within the brain with rapid effects on neuronal excitability. Allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are three widely explored prototype endogenous neurosteroids. They have very different targets and functions compared to conventional steroid hormones. Neuronal γ-aminobutyric acid (GABA) type A (GABA(A)) receptors are one of the prime molecular targets of neurosteroids. OBJECTIVE This review provides a critical appraisal of recent advances in the pharmacology of endogenous neurosteroids that interact with GABA(A) receptors in the brain. Neurosteroids possess distinct, characteristic effects on the membrane potential and current conductance of the neuron, mainly via potentiation of GABA(A) receptors at low concentrations and direct activation of receptor chloride channel at higher concentrations. The GABA(A) receptor mediates two types of inhibition, now characterized as synaptic (phasic) and extrasynaptic (tonic) inhibition. Synaptic release of GABA results in the activation of low-affinity γ2-containing synaptic receptors, while high-affinity δ-containing extrasynaptic receptors are persistently activated by the ambient GABA present in the extracellular fluid. Neurosteroids are potent positive allosteric modulators of synaptic and extrasynaptic GABA(A) receptors and therefore enhance both phasic and tonic inhibition. Tonic inhibition is specifically more sensitive to neurosteroids. The resulting tonic conductance generates a form of shunting inhibition that controls neuronal network excitability, seizure susceptibility, and behavior. CONCLUSION The growing understanding of the mechanisms of neurosteroid regulation of the structure and function of the synaptic and extrasynaptic GABA(A) receptors provides many opportunities to create improved therapies for sleep, anxiety, stress, epilepsy, and other neuropsychiatric conditions.
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Affiliation(s)
- Chase Matthew Carver
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, 2008 Medical Research and Education Building, 8447 State Highway 47, Bryan, TX, 77807-3260, USA
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Huberfeld G, Le Duigou C, Le Van Quyen M, Navarro V, Baulac M, Miles R. The paradox of the paroxysm: can seizure precipitants help explain human ictogenesis? Neuroscientist 2013; 19:523-40. [PMID: 23881918 DOI: 10.1177/1073858413497430] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An epileptic brain is permanently in a diseased state, but seizures occur rarely and without warning. Here we examine this paradox, common to paroxysmal diseases. We review the problem in the context of the prototypic acquired epilepsies of the medial temporal lobe. We ask how an epileptic temporal lobe differs from a healthy one and examine biological mechanisms that may explain the transition to seizure. Attempts to predict seizure timing from analyses of brain electrical activity suggest that the neurological processes involved may be initiated significantly before a seizure. Furthermore, whereas seizures are said to occur without warning, some patients say they know when a seizure is imminent. Several factors, including sleep deprivation, oscillations in hormonal levels, or withdrawal from drugs, increase the probability of a seizure. We ask whether these seizure precipitants might act through common neuronal mechanisms. Several precipitating factors seem to involve relief from a neurosteroid modulation of gamma-amino butyric acid receptor type A (GABAA) receptors. We propose tests of this hypothesis.
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Affiliation(s)
- Gilles Huberfeld
- INSERM U975, Institut du Cerveau et la Moëlle Epinière, Paris, France
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35
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Pisu MG, Garau A, Olla P, Biggio F, Utzeri C, Dore R, Serra M. Altered stress responsiveness and hypothalamic-pituitary-adrenal axis function in male rat offspring of socially isolated parents. J Neurochem 2013; 126:493-502. [DOI: 10.1111/jnc.12273] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 04/02/2013] [Accepted: 04/02/2013] [Indexed: 10/26/2022]
Affiliation(s)
| | - Anna Garau
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Pierluigi Olla
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Francesca Biggio
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Cinzia Utzeri
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Riccardo Dore
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
| | - Mariangela Serra
- C.N.R.; Institute of Neuroscience; Cagliari Italy
- Department of Life and Environmental Sciences; University of Cagliari; Cagliari Italy
- Center of Excellence for Neurobiology of Dependence; University of Cagliari; Cagliari Italy
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36
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Nin MS, Ferri MK, Couto-Pereira NS, Souza MF, Azeredo LA, Agnes G, Gomez R, Barros HMT. The effect of intra-nucleus accumbens administration of allopregnanolone on δ and γ2 GABA(A) receptor subunit mRNA expression in the hippocampus and on depressive-like and grooming behaviors in rats. Pharmacol Biochem Behav 2012; 103:359-66. [PMID: 22981694 DOI: 10.1016/j.pbb.2012.09.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 08/24/2012] [Accepted: 09/01/2012] [Indexed: 10/27/2022]
Abstract
Alterations in GABA(A) receptor expression have been associated with the allopregnanolone (3α-hydroxy-5α-pregnan-20-one; 3α,5α-THP) antidepressant-like effect in rats. The present study aimed to verify the effect of bilateral, intra-nucleus accumbens core (intra-AcbC) administration of the neurosteroid allopregnanolone on behaviors in the forced swim and grooming microstructure tests and in the δ and γ2 GABA(A) receptor subunit mRNA expression in right and left hippocampus of rats. The results of this study showed that bilateral, intra-AcbC allopregnanolone administration (5μg/rat) presented antidepressant-like activity in the forced swim test concomitant with an increase in climbing. Allopregnanolone at doses of 1.25 and 5μg/rat also decreased the percentage of correct transitions in the grooming microstructure test. Both δ and γ2 GABA(A) subunit expressions increased in the rat hippocampus after allopregnanolone intra-AcbC treatment. Our findings point to asymmetrical GABA(A) receptor expression changes in the hippocampus of animals treated with allopregnanolone. Further investigation should evaluate the antidepressant-like effect of allopregnanolone not only in other directly infused regions but also with respect to changes in other brain areas of the limbic system to understand allopregnanolone's mechanism of action.
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Affiliation(s)
- Maurício S Nin
- Programa de Pós Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, Sarmento Leite, 245, 90050-170, Porto Alegre, RS, Brazil.
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Brickley SG, Mody I. Extrasynaptic GABA(A) receptors: their function in the CNS and implications for disease. Neuron 2012; 73:23-34. [PMID: 22243744 DOI: 10.1016/j.neuron.2011.12.012] [Citation(s) in RCA: 497] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2011] [Indexed: 12/30/2022]
Abstract
Over the past two decades, research has identified extrasynaptic GABA(A) receptor populations that enable neurons to sense the low ambient GABA concentrations present in the extracellular space in order to generate a form of tonic inhibition not previously considered in studies of neuronal excitability. The importance of this tonic inhibition in regulating states of consciousness is highlighted by the fact that extrasynaptic GABA(A) receptors (GABA(A)Rs) are believed to be key targets for anesthetics, sleep-promoting drugs, neurosteroids, and alcohol. The neurosteroid sensitivity of these extrasynaptic GABA(A)Rs may explain their importance in stress-, ovarian cycle-, and pregnancy-related mood disorders. Moreover, disruptions in network dynamics associated with schizophrenia, epilepsy, and Parkinson's disease may well involve alterations in the tonic GABA(A)R-mediated conductance. Extrasynaptic GABA(A)Rs may therefore present a therapeutic target for treatment of these diseases, with the potential to enhance cognition and aid poststroke functional recovery.
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Affiliation(s)
- Stephen G Brickley
- Division of Cell & Molecular Biology, South Kensington Campus, Imperial College, London SW7 2AZ, UK.
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Helms CM, Rossi DJ, Grant KA. Neurosteroid influences on sensitivity to ethanol. Front Endocrinol (Lausanne) 2012; 3:10. [PMID: 22654852 PMCID: PMC3356014 DOI: 10.3389/fendo.2012.00010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 01/11/2012] [Indexed: 12/23/2022] Open
Abstract
This review will highlight a variety of mechanisms by which neurosteroids affect sensitivity to ethanol, including physiological states associated with activity of the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes, and the effects of chronic exposure to ethanol, in addition to behavioral implications. To date, γ-aminobutyric acid (GABA(A)) receptor mechanisms are a major focus of the modulation of ethanol effects by neuroactive steroids. While NMDA receptor mechanisms are gaining prominence in the literature, these complex data would be best discussed separately. Accordingly, GABA(A) receptor mechanisms are emphasized in this review with brief mention of some NMDA receptor mechanisms to point out contrasting neuroactive steroid pharmacology. Overall, the data suggest that neurosteroids are virtually ubiquitous modulators of inhibitory neurotransmission. Neurosteroids appear to affect sensitivity to ethanol in specific brain regions and, consequently, specific behavioral tests, possibly related to the efficacy and potency of ethanol to potentiate the release of GABA and increase neurosteroid concentrations. Although direct interaction of ethanol and neuroactive steroids at common receptor binding sites has been suggested in some studies, this proposition is still controversial. It is currently difficult to assign a specific mechanism by which neuroactive steroids could modulate the effects of ethanol in particular behavioral tasks.
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Affiliation(s)
- Christa M. Helms
- Division of Neuroscience, Oregon National Primate Research CenterBeaverton, OR, USA
- *Correspondence: Christa M. Helms, Division of Neuroscience, Oregon National Primate Research Center, L-584, 505 North-West 185th Avenue, Beaverton, OR 97006, USA. e-mail:
| | - David J. Rossi
- Department of Behavioral Neuroscience, Oregon Health and Science UniversityPortland, OR, USA
| | - Kathleen A. Grant
- Division of Neuroscience, Oregon National Primate Research CenterBeaverton, OR, USA
- Department of Behavioral Neuroscience, Oregon Health and Science UniversityPortland, OR, USA
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Pisu MG, Mostallino MC, Dore R, Maciocco E, Secci PP, Serra M. Effects of voluntary ethanol consumption on emotional state and stress responsiveness in socially isolated rats. Eur Neuropsychopharmacol 2011; 21:414-25. [PMID: 21067904 PMCID: PMC3044778 DOI: 10.1016/j.euroneuro.2010.07.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 06/04/2010] [Accepted: 07/20/2010] [Indexed: 01/15/2023]
Abstract
Social isolation of rats immediately after weaning is thought to represent an animal model of anxiety-like disorders. This mildly stressful condition reduces the cerebrocortical and plasma concentrations of 3α-hydroxy-5α-pregnan-20-one (3α,5α-TH PROG) as well as increases the sensitivity of rats to the effects of acute ethanol administration on the concentrations of this neuroactive steroid. We further investigated the effects of voluntary consumption of ethanol at concentrations increasing from 2.5 to 10% over 4 weeks of isolation. Isolated rats showed a reduced ethanol preference compared with group-housed animals. Ethanol consumption did not affect the isolation-induced down-regulation of BDNF or Arc, but it attenuated the increase in the cerebrocortical concentration of 3α,5α-TH PROG induced by foot-shock stress in both isolated and group-housed animals as well as increased the percentage of number of entries made by socially isolated rats into the open arms in the elevated plus-maze test. Ethanol consumption did not affect expression of the α₄ subunit of the GABA(A) receptor in the hippocampus of group-housed or isolated rats, whereas it up-regulated the δ subunit throughout the hippocampus under both conditions. The results suggest that low consumption of ethanol may ameliorate some negative effects of social isolation on stress sensitivity and behavior.
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Affiliation(s)
| | | | - Riccardo Dore
- Department of Experimental Biology, University of Cagliari, Cagliari 09100, Italy
| | | | | | - Mariangela Serra
- Department of Experimental Biology, University of Cagliari, Cagliari 09100, Italy
- Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari 09100, Italy
- C.N.R., Institute of Neuroscience, Cagliari 09100, Italy
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Pisu MG, Dore R, Mostallino MC, Loi M, Pibiri F, Mameli R, Cadeddu R, Secci PP, Serra M. Down-regulation of hippocampal BDNF and Arc associated with improvement in aversive spatial memory performance in socially isolated rats. Behav Brain Res 2011; 222:73-80. [PMID: 21420441 DOI: 10.1016/j.bbr.2011.03.021] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 03/09/2011] [Accepted: 03/10/2011] [Indexed: 10/18/2022]
Abstract
Rats deprived of social contact with other rats at a young age experience a form of prolonged stress that leads to long-lasting changes in behavioral profile. Such isolation is thought to be anxiogenic for these normally gregarious animals, and the abnormal reactivity of isolated rats to environmental stimuli is thought to be a product of prolonged stress. We now show that isolation of rats at weaning reduced immobility time in the forced swim test, decreased sucrose intake and preference, and down-regulated both brain-derived neurotrophic factor (BDNF) and activity-regulated cytoskeletal associated protein (Arc) in the hippocampus. In the Morris water maze, isolated rats showed a reduced latency to reach the hidden platform during training, indicative of an improved learning performance, compared with group-housed rats. The cumulative search error during place training trials indicated a reliable difference between isolated and group-housed rats on days 4 and 5. The probe trial revealed a significant decrease of the average proximity to the target location in the isolated rats suggesting an improvement in spatial memory. Isolated rats also showed an increase in the plasma level of corticosterone on the 5th day of training and increased expression of BDNF and Arc in the hippocampus on both days 1 and 5. These results show that social isolation from weaning in rats results in development of depressive-like behavior but has a positive effect on spatial learning, supporting the existence of a facilitating effect of stress on cognitive function.
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Sanna E, Talani G, Obili N, Mascia MP, Mostallino MC, Secci PP, Pisu MG, Biggio F, Utzeri C, Olla P, Biggio G, Follesa P. Voluntary Ethanol Consumption Induced by Social Isolation Reverses the Increase of α(4)/δ GABA(A) Receptor Gene Expression and Function in the Hippocampus of C57BL/6J Mice. Front Neurosci 2011; 5:15. [PMID: 21347217 PMCID: PMC3039156 DOI: 10.3389/fnins.2011.00015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 01/25/2011] [Indexed: 11/20/2022] Open
Abstract
Post-weaning social isolation (SI) is a model of prolonged mild stress characterized by behavioral and neurochemical alterations. We used SI in C57BL/6J mice to investigate the effects of ethanol (EtOH) in the free-choice drinking paradigm on gene expression and function of γ-aminobutyric acid type A receptors (GABAARs) and the role of neuroactive steroids in the actions of EtOH in the hippocampus. SI stress induced a marked reduction in hippocampal 3α-hydroxy-5α-pregnan-20-one (3α,5α-TH PROG) and was associated with molecular and functional changes of the GABAAR. The gene expression of the α4 and δ subunits was increased in the hippocampus of SI C57BL/6J mice; the expression of the γ2 subunit was decreased whereas that of the α1 did not change. Patch-clamp recordings in dentate gyrus (DG) granule cells obtained from SI C57BL/6J mice revealed a greater enhancement of tonic currents induced by α-(4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridin-3-ol (THIP) compared to that in control C57BL/6J mice. These neurochemical, molecular and functional changes observed in SI C57BL/6J mice were associated with an increased EtOH intake and EtOH preference. Nevertheless, the increase in EtOH consumption did not restore the reduction in hippocampal 3α,5α-TH PROG induced by SI. EtOH self-administration blocked the changes in gene expression of the α4 subunit but not those of the δ and γ2 subunits induced by SI. In addition, EtOH self-administration did not block the SI-induced changes in GABAAR-mediated tonic inhibition in hippocampal granule cells but increased the frequency of basal GABAergic sIPSCs in DG granule cells. We conclude that self-administration of EtOH selectively abolishes the increase of α4 subunit but not other neurochemical, molecular, and functional modifications induced by SI prolonged mild stress.
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Affiliation(s)
- Enrico Sanna
- Section of Neuroscience, Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari Monserrato, Cagliari, Italy
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Talani G, Biggio G, Sanna E. Enhanced Sensitivity to Ethanol-Induced Inhibition of LTP in CA1 Pyramidal Neurons of Socially Isolated C57BL/6J Mice: Role of Neurosteroids. Front Endocrinol (Lausanne) 2011; 2:56. [PMID: 22649377 PMCID: PMC3355925 DOI: 10.3389/fendo.2011.00056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 10/03/2011] [Indexed: 11/27/2022] Open
Abstract
Ethanol (EtOH) induced impairment of long-term potentiation (LTP) in the rat hippocampus is prevented by the 5α-reductase inhibitor finasteride, suggesting that this effect of EtOH is dependent on the increased local release of neurosteroids such as 3α,5α-THP that promote GABA-mediated transmission. Given that social isolation (SI) in rodents is associated with altered plasma and brain levels of such neurosteroids as well as with an enhanced neurosteroidogenic action of EtOH, we examined whether the inhibitory effect of EtOH on LTP at CA3-CA1 hippocampal excitatory synapses is altered in C57BL/6J mice subjected to SI for 6 weeks in comparison with group-housed (GH) animals. Extracellular recording of field excitatory postsynaptic potentials (fEPSPs) as well as patch-clamp analysis were performed in hippocampal slices prepared from both SI and GH mice. Consistent with previous observations, recording of fEPSPs revealed that the extent of LTP induced in the CA1 region of SI mice was significantly reduced compared with that in GH animals. EtOH (40 mM) inhibited LTP in slices from SI mice but not in those from GH mice, and this effect of EtOH was abolished by co-application of 1 μM finasteride. Current-clamp analysis of CA1 pyramidal neurons revealed a decrease in action potential (AP) frequency and an increase in the intensity of injected current required to evoke the first AP in SI mice compared with GH mice, indicative of a decrease in neuronal excitability associated with SI. Together, our data suggest that SI results in reduced levels of neuronal excitability and synaptic plasticity in the hippocampus. Furthermore, the increased sensitivity to the neurosteroidogenic effect of EtOH associated with SI likely accounts for the greater inhibitory effect of EtOH on LTP in SI mice. The increase in EtOH sensitivity induced by SI may be important for the changes in the effects of EtOH on anxiety and on learning and memory associated with the prolonged stress attributable to SI.
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Affiliation(s)
- Giuseppe Talani
- Section of Neuroscience, Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, MonserratoCagliari, Italy
- *Correspondence: Giuseppe Talani, Department of Experimental Biology, University of Cagliari, Cittadella Universitaria di Monserrato, Cagliari 09042, Italy. e-mail:
| | - Giovanni Biggio
- Section of Neuroscience, Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, MonserratoCagliari, Italy
- Institute of Neuroscience, National Research Council of Italy, MonserratoCagliari, Italy
| | - Enrico Sanna
- Section of Neuroscience, Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, MonserratoCagliari, Italy
- Institute of Neuroscience, National Research Council of Italy, MonserratoCagliari, Italy
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King SR, Stocco DM. Steroidogenic acute regulatory protein expression in the central nervous system. Front Endocrinol (Lausanne) 2011; 2:72. [PMID: 22649383 PMCID: PMC3355896 DOI: 10.3389/fendo.2011.00072] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 10/24/2011] [Indexed: 11/13/2022] Open
Abstract
Locally produced neurosteroids are proposed to have many functions in the central nervous system. The identification of the steroidogenic acute regulatory protein in steroid-producing neural cells provides a new tool to understand the sites, regulation, and importance of their synthesis.
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Affiliation(s)
- Steven R. King
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences CenterLubbock, TX, USA
| | - Douglas M. Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences CenterLubbock, TX, USA
- *Correspondence: Douglas M. Stocco, Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA. e-mail:
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Boyd KN, Kumar S, O'Buckley TK, Porcu P, Morrow AL. Ethanol induction of steroidogenesis in rat adrenal and brain is dependent upon pituitary ACTH release and de novo adrenal StAR synthesis. J Neurochem 2009; 112:784-96. [PMID: 20021565 DOI: 10.1111/j.1471-4159.2009.06509.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanisms of ethanol actions that produce its behavioral sequelae involve the synthesis of potent GABAergic neuroactive steroids, specifically the GABAergic metabolites of progesterone, (3alpha,5alpha)-3-hydroxypregnan-20-one (3alpha,5alpha-THP), and deoxycorticosterone, (3alpha,5alpha)-3,21-dihydroxypregnan-20-one. We investigated the mechanisms that underlie the effect of ethanol on adrenal steroidogenesis. We found that ethanol effects on plasma pregnenolone, progesterone, 3alpha,5alpha-THP and cortical 3alpha,5alpha-THP are highly correlated, exhibit a threshold of 1.5 g/kg, but show no dose dependence. Ethanol increases plasma adrenocorticotropic hormone (ACTH), adrenal steroidogenic acute regulatory protein (StAR), and adrenal StAR phosphorylation, but does not alter levels of other adrenal cholesterol transporters. The inhibition of ACTH release, de novo adrenal StAR synthesis or cytochrome P450 side chain cleavage activity prevents ethanol-induced increases in GABAergic steroids in plasma and brain. ACTH release and de novo StAR synthesis are independently regulated following ethanol administration and both are necessary, but not sufficient, for ethanol-induced elevation of plasma and brain neuroactive steroids. As GABAergic steroids contribute to ethanol actions and ethanol sensitivity, the mechanisms of this effect of ethanol may be important factors that contribute to the behavioral actions of ethanol and risk for alcohol abuse disorders.
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Affiliation(s)
- Kevin N Boyd
- Curriculum in Toxicology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Morrow AL, Biggio G, Serra M, Becker HC, Lopez MF, Porcu P, Alward SE, O'Buckley TK. The role of neuroactive steroids in ethanol/stress interactions: proceedings of symposium VII at the Volterra conference on alcohol and stress, May 2008. Alcohol 2009; 43:521-30. [PMID: 19913195 PMCID: PMC2778608 DOI: 10.1016/j.alcohol.2009.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 03/17/2009] [Accepted: 04/09/2009] [Indexed: 11/19/2022]
Abstract
This report summarizes the proceedings of the symposium VII on the role of neuroactive steroids in stress/alcohol interactions. The production of GABAergic neuroactive steroids, including (3alpha,5alpha)-3-hydroxypregnan-20-one and (3alpha,5alpha)-3,21-dihydroxypregnan-20-one is a consequence of both acute stress and acute ethanol exposure. Acute, but not chronic ethanol administration elevates brain levels of these steroids and enhances GABA(A) receptor activity. Neuroactive steroids modulate acute anticonvulsant effects, sedation, spatial memory impairment, anxiolytic-like, antidepressant-like, and reinforcing properties of ethanol in rodents. Furthermore, these steroids participate in the homeostatic regulation of the hypothalamic-pituitary-adrenal axis. Therefore, it is not surprising that neuroactive steroids are involved in ethanol/stress interactions. Nevertheless, the interactions are complex and not well understood. This symposium addressed the role of neuroactive steroids in both stress and alcohol responses and their interactions. Professor Giovanni Biggio of the University of Cagliari, Italy presented the effects of juvenile isolation stress on neuroactive steroids, GABA(A) receptor expression, and ethanol sensitivity. Professor Howard Becker of the Medical University of South Carolina, USA presented evidence for neuroactive steroid involvement in ethanol dependence and drinking behavior. Professor Patrizia Porcu of the University of North Carolina, USA described a potential neuroactive steroid biomarker that may predict heavy drinking in monkeys and mice. These presentations provide a framework for new theories on the nature of ethanol/stress interactions that may be amenable to therapeutic interventions.
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Affiliation(s)
- A Leslie Morrow
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA.
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Sanna E, Mostallino MC, Murru L, Carta M, Talani G, Zucca S, Mura ML, Maciocco E, Biggio G. Changes in expression and function of extrasynaptic GABAA receptors in the rat hippocampus during pregnancy and after delivery. J Neurosci 2009; 29:1755-65. [PMID: 19211882 PMCID: PMC6666282 DOI: 10.1523/jneurosci.3684-08.2009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 09/09/2008] [Accepted: 12/20/2008] [Indexed: 11/21/2022] Open
Abstract
Pregnancy is associated with changes in mood and anxiety level as well as with marked hormonal fluctuations. Increases in the brain concentrations of neuroactive steroids during pregnancy in rats are accompanied by changes in expression of subunits of the GABA type A receptor (GABA(A)-R) in the brain. Granule cells of the dentate gyrus (DGGCs) exhibit two components of inhibitory GABAergic transmission: a phasic component mediated by synaptic GABA(A)-Rs, and a tonic component mediated by extrasynaptic GABA(A)-Rs. Recordings of GABAergic currents were obtained from hippocampal slices prepared from rats in estrus, at pregnancy day 15 (P15) or P19, or at 2 d after delivery. Exogenous GABA or 3alpha,5alpha-THP induced an increase in tonic current in DGGCs that was significantly greater at P19 than in estrus. Neither tonic nor phasic currents were affected by pregnancy in CA1 pyramidal cells. Immunohistochemical analysis revealed a marked increase in the abundance of the delta subunit of the GABA(A)-R and a concomitant decrease in that of the gamma(2) subunit in the hippocampus at P19. Expression of the alpha(4) subunit did not change during pregnancy but was increased 2 d after delivery. Treatment of rats from P12 to P18 with the 5alpha-reductase inhibitor finasteride prevented the changes in tonic current and in delta and gamma(2) subunit expression normally apparent at P19. These data suggest that the number of extrasynaptic GABA(A)-Rs is increased in DGGCs during late pregnancy as a consequence of the associated marked fluctuations in the brain levels of neuroactive steroids.
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Affiliation(s)
- Enrico Sanna
- Department of Experimental Biology, Section of Neuroscience, University of Cagliari, and National Research Council, Institute of Neuroscience, 09123 Cagliari, Italy.
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Tuveri A, Paoletti AM, Orrù M, Melis GBB, Marotto MF, Zedda P, Marrosu F, Sogliano C, Marra C, Biggio G, Concas A. Reduced serum level of THDOC, an anticonvulsant steroid, in women with perimenstrual catamenial epilepsy. Epilepsia 2008; 49:1221-9. [PMID: 18325018 DOI: 10.1111/j.1528-1167.2008.01555.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Seizure exacerbation in catamenial epilepsy (CE) is associated with the decrease in progesterone secretion and increase in estradiol secretion during the premenstrual period. Moreover, experimental evidence suggests that tetrahydrodeoxycorticosterone (THDOC), a positive modulator of the type A receptor for gamma-aminobutyric acid (GABA), and dehydroepiandrosterone sulfate (DHEAS), a negative modulator of this receptor, might play a crucial role in modulating seizure frequency during the menstrual cycle. Following these studies it seems of interest to investigate possible variations, among other hormonal parameters, of THDOC and DHEAS in CE patients. METHODS The serum concentrations of progesterone (P4), pregnenolone, allopregnanolone (AP), THDOC, DHEAS, cortisol, and DHEAS/cortisol ratio were measured throughout the menstrual cycle at the 7th, 11th, 15th, 19th, 23rd, and 27th day from the onset of spontaneous menstrual blood loss in young premenopausal women with CE (n = 17) and age-matched controls (n = 13). RESULTS At each time of the study, the serum concentration of THDOC and the DHEAS/cortisol ratio were lower (p < 0.05) in women with CE than in control women. The concentrations of P4, pregnenolone, and AP did not differ between the two groups of subjects. CONCLUSIONS The reduced serum concentration of THDOC and the reduced DHEAS/cortisol ratio detected throughout the menstrual cycle in women with CE might play a role in CE. Moreover, the peculiar pattern of CE seizure exacerbation might suggest that these neuroendocrine variations are worth investigating in other epileptic syndromes, particularly in those characterized by relevant and uncontrolled variations in seizure frequency.
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Affiliation(s)
- Antonella Tuveri
- Department of Cardiovascular and Neurological Sciences, University of Cagliari, Cagliari, Italy
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Pisu MG, Mostallino MC, Dore R, Mura ML, Maciocco E, Russo E, De Sarro G, Serra M. Neuroactive steroids and GABAA receptor plasticity in the brain of the WAG/Rij rat, a model of absence epilepsy. J Neurochem 2008; 106:2502-14. [PMID: 18624910 DOI: 10.1111/j.1471-4159.2008.05538.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of neuroactive steroids and GABA(A) receptors in the generation of spontaneous spike-and-wave discharges (SWDs) was investigated in the WAG/Rij rat model of absence epilepsy. The plasma, cerebrocortical, and thalamic concentrations of the progesterone metabolite 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-TH PROG) were increased in the WAG/Rij rat at 2 months of age compared with those in control (Wistar) rats. In contrast, the brain and peripheral levels of 3alpha,5alpha-tetrahydrodeoxycorticosterone (3alpha,5alpha-TH DOC) did not differ between the two rat strains at this age. At 6 months of age, when absence epilepsy worsens in WAG/Rij rats, the plasma concentration of 3alpha,5alpha-TH PROG remained high whereas that of 3alpha,5alpha-TH DOC had increased, the cerebrocortical levels of both 3alpha,5alpha-TH PROG and 3alpha,5alpha-TH DOC had increased, and the thalamic concentrations of these metabolites had decreased. At 6 months of age the expression of the alpha(4) and delta subunits of the GABA(A) receptor in relay nuclei was increased. Finally, chronic stress induced by social isolation elicited a reduction in the amount of 3alpha,5alpha-TH PROG in the thalamus of 2-month-old WAG/Rij rats that was associated with a reduction in the number and overall duration of SWDs at 6 months of age. Absence epilepsy in the WAG/Rij rat is thus associated with changes in the abundance of neuroactive steroids and in the expression of specific GABA(A) receptor subunits in the thalamus, a brain area key to the pathophysiology of this condition.
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Eva C, Mele P, Collura D, Nai A, Pisu MG, Serra M, Biggio G. Modulation of neuropeptide Y and Y1 receptor expression in the amygdala by fluctuations in the brain content of neuroactive steroids during ethanol drinking discontinuation in Y1R/LacZ transgenic mice. J Neurochem 2007; 104:1043-54. [PMID: 18036156 DOI: 10.1111/j.1471-4159.2007.05077.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous studies have shown that GABAergic neuroactive steroids increase Y1 receptor (Y1R) gene expression in the amygdala of Y1R/LacZ transgenic mice, harbouring the murine Y1R gene promoter linked to a LacZ reporter gene. As ethanol is known to increase GABAergic neuroactive steroids, we investigated the relationship between fluctuations in the brain content of neuroactive steroids induced by chronic voluntary ethanol consumption or ethanol discontinuation and both the level of neuropeptide Y (NPY) immunoreactivity and Y1R gene expression in the amygdala of Y1R/LacZ transgenic mice. Ethanol discontinuation (48 h) after voluntary consumption of consecutive solutions of 3%, 6%, 10% and 20% (v/v) ethanol over 4 weeks produced an anxiety-like behaviour as measured by elevated plus maze. Voluntary ethanol intake increased the cerebrocortical concentration of the progesterone metabolite 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-TH PROG) that returned to control level 48 h after discontinuation of ethanol intake. Ethanol discontinuation significantly decreased NPY immunoreactivity and concomitantly increased Y1R/LacZ transgene expression in the amygdala, whereas chronic ethanol intake failed to affect these parameters. The 5alpha-reductase inhibitor finasteride prevented both the increase in the cerebrocortical concentration of 3alpha,5alpha-TH PROG apparent after 4 weeks of ethanol intake and the changes in NPY immunoreactivity and transgene expression induced by ethanol discontinuation. Data suggest that 3alpha,5alpha-TH PROG plays an important role in the changes in NPY-Y1R signalling in the amygdala during ethanol discontinuation.
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Affiliation(s)
- Carola Eva
- Dipartimento di Anatomia, Farmacologia e Medicina Legale, Sezione di Farmacologia, Università di Torino, Torino, Italy, and Neuroscience Institute of Torino, Università di Torino, Torino, Italy.
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Biggio G, Concas A, Follesa P, Sanna E, Serra M. Stress, ethanol, and neuroactive steroids. Pharmacol Ther 2007; 116:140-71. [PMID: 17555824 PMCID: PMC3000046 DOI: 10.1016/j.pharmthera.2007.04.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 04/06/2007] [Indexed: 12/27/2022]
Abstract
Neurosteroids play a crucial role in stress, alcohol dependence and withdrawal, and other physiological and pharmacological actions by potentiating or inhibiting neurotransmitter action. This review article focuses on data showing that the interaction among stress, ethanol, and neuroactive steroids may result in plastic molecular and functional changes of GABAergic inhibitory neurotransmission. The molecular mechanisms by which stress-ethanol-neuroactive steroids interactions can produce plastic changes in GABA(A) receptors have been studied using different experimental models in vivo and in vitro in order to provide useful evidence and new insights into the mechanisms through which acute and chronic ethanol and stress exposure modulate the activity of GABAergic synapses. We show detailed data on a) the effect of acute and chronic stress on peripheral and brain neurosteroid levels and GABA(A) receptor gene expression and function; b) ethanol-stimulated brain steroidogenesis; c) plasticity of GABA(A) receptor after acute and chronic ethanol exposure. The implications of these new mechanistic insights to our understanding of the effects of ethanol during stress are also discussed. The understanding of these neurochemical and molecular mechanisms may shed new light on the physiopathology of diseases, such as anxiety, in which GABAergic transmission plays a pivotal role. These data may also lead to the need for new anxiolytic, hypnotic and anticonvulsant selective drugs devoid of side effects.
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Affiliation(s)
- Giovanni Biggio
- Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, Cagliari, Italy.
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