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Vlkolinsky R, Khom S, Vozella V, Bajo M, Roberto M. Withdrawal from chronic alcohol impairs the serotonin-mediated modulation of GABAergic transmission in the infralimbic cortex in male rats. Neurobiol Dis 2024; 199:106590. [PMID: 38996987 DOI: 10.1016/j.nbd.2024.106590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/14/2024] Open
Abstract
The infralimbic cortex (IL) is part of the medial prefrontal cortex (mPFC), exerting top-down control over structures that are critically involved in the development of alcohol use disorder (AUD). Activity of the IL is tightly controlled by γ-aminobutyric acid (GABA) transmission, which is susceptible to chronic alcohol exposure and withdrawal. This inhibitory control is regulated by various neuromodulators, including 5-hydroxytryptamine (5-HT; serotonin). We used chronic intermittent ethanol vapor inhalation exposure, a model of AUD, in male Sprague-Dawley rats to induce alcohol dependence (Dep) followed by protracted withdrawal (WD; 2 weeks) and performed ex vivo electrophysiology using whole-cell patch clamp to study GABAergic transmission in layer V of IL pyramidal neurons. We found that WD increased frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs), whereas miniature IPSCs (mIPSCs; recorded in the presence of tetrodotoxin) were unaffected by either Dep or WD. The application of 5-HT (50 μM) increased sIPSC frequencies and amplitudes in naive and Dep rats but reduced sIPSC frequencies in WD rats. Additionally, 5-HT2A receptor antagonist M100907 and 5-HT2C receptor antagonist SB242084 reduced basal GABA release in all groups to a similar extent. The blockage of either 5-HT2A or 5-HT2C receptors in WD rats restored the impaired response to 5-HT, which then resembled responses in naive rats. Our findings expand our understanding of synaptic inhibition in the IL in AUD, indicating that antagonism of 5-HT2A and 5-HT2C receptors may restore GABAergic control over IL pyramidal neurons. SIGNIFICANCE STATEMENT: Impairment in the serotonergic modulation of GABAergic inhibition in the medial prefrontal cortex contributes to alcohol use disorder (AUD). We used a well-established rat model of AUD and ex vivo whole-cell patch-clamp electrophysiology to characterize the serotonin modulation of GABAergic transmission in layer V infralimbic (IL) pyramidal neurons in ethanol-naive, ethanol-dependent (Dep), and ethanol-withdrawn (WD) male rats. We found increased basal inhibition following WD from chronic alcohol and altered serotonin modulation. Exogenous serotonin enhanced GABAergic transmission in naive and Dep rats but reduced it in WD rats. 5-HT2A and 5-HT2C receptor blockage in WD rats restored the typical serotonin-mediated enhancement of GABAergic inhibition. Our findings expand our understanding of synaptic inhibition in the infralimbic neurons in AUD.
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Affiliation(s)
- Roman Vlkolinsky
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Sophia Khom
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Pharmaceutical Sciences, University of Vienna, Vienna, 1090, Austria.
| | - Valentina Vozella
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Michal Bajo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Marisa Roberto
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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Patel RR, Gandhi P, Spencer K, Salem NA, Erikson CM, Borgonetti V, Vlkolinsky R, Rodriguez L, Nadav T, Bajo M, Roberts AJ, Dayne Mayfield R, Roberto M. Functional and morphological adaptation of medial prefrontal corticotropin releasing factor receptor 1-expressing neurons in male mice following chronic ethanol exposure. Neurobiol Stress 2024; 31:100657. [PMID: 38983690 PMCID: PMC11231756 DOI: 10.1016/j.ynstr.2024.100657] [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: 03/27/2024] [Revised: 06/13/2024] [Accepted: 06/15/2024] [Indexed: 07/11/2024] Open
Abstract
Chronic ethanol dependence and withdrawal activate corticotropin releasing factor (CRF)-containing GABAergic neurons in the medial prefrontal cortex (mPFC), which tightly regulate glutamatergic pyramidal neurons. Using male CRF1:GFP reporter mice, we recently reported that CRF1-expressing (mPFCCRF1+) neurons predominantly comprise mPFC prelimbic layer 2/3 pyramidal neurons, undergo profound adaptations following chronic ethanol exposure, and regulate anxiety and conditioned rewarding effects of ethanol. To explore the effects of acute and chronic ethanol exposure on glutamate transmission, the impact of chronic alcohol on spine density and morphology, as well as persistent changes in dendritic-related gene expression, we employed whole-cell patch-clamp electrophysiology, diOlistic labeling for dendritic spine analysis, and dendritic gene expression analysis to further characterize mPFCCRF1+ and mPFCCRF1- prelimbic layer 2/3 pyramidal neurons. We found increased glutamate release in mPFCCRF1+ neurons with ethanol dependence, which recovered following withdrawal. In contrast, we did not observe significant changes in glutamate transmission in neighboring mPFCCRF1- neurons. Acute application of 44 mM ethanol significantly reduced glutamate release onto mPFCCRF1+ neurons, which was observed across all treatment groups. However, this sensitivity to acute ethanol was only evident in mPFCCRF1- neurons during withdrawal. In line with alterations in glutamate transmission, we observed a decrease in total spine density in mPFCCRF1+ neurons during dependence, which recovered following withdrawal, while again no changes were observed in mPFCCRF- neurons. Given the observed decreases in mPFCCRF1+ stubby spines during withdrawal, we then identified persistent changes at the dendritic gene expression level in mPFCCRF1+ neurons following withdrawal that may underlie these structural adaptations. Together, these findings highlight the varying responses of mPFCCRF1+ and mPFCCRF1- cell-types to acute and chronic ethanol exposure, as well as withdrawal, revealing specific functional, morphological, and molecular adaptations that may underlie vulnerability to ethanol and the lasting effects of ethanol dependence.
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Affiliation(s)
- Reesha R Patel
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Pauravi Gandhi
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Kathryn Spencer
- Core Microscopy Facility, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Nihal A Salem
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Chloe M Erikson
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Vittoria Borgonetti
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Roman Vlkolinsky
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Larry Rodriguez
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Tali Nadav
- Animal Models Core Facility, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Michal Bajo
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Amanda J Roberts
- Animal Models Core Facility, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - R Dayne Mayfield
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Marisa Roberto
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA, 92037, USA
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Dugan MP, Maiya R, Fleischer C, Bajo M, Snyder AE, Koduri A, Srinivasan S, Roberto M, Messing RO. Brain-specific serine/threonine-protein kinase 1 is a substrate of protein kinase C epsilon involved in sex-specific ethanol and anxiety phenotypes. Addict Biol 2024; 29:e13388. [PMID: 38497285 PMCID: PMC10950061 DOI: 10.1111/adb.13388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/08/2024] [Accepted: 02/13/2024] [Indexed: 03/19/2024]
Abstract
Protein kinase C epsilon (PKCε) regulates behavioural responses to ethanol and plays a role in anxiety-like behaviour, but knowledge is limited on downstream substrates of PKCε that contribute to these behaviours. We recently identified brain-specific serine/threonine-protein kinase 1 (BRSK1) as a substrate of PKCε. Here, we test the hypothesis that BRSK1 mediates responses to ethanol and anxiety-like behaviours that are also PKCε dependent. We used in vitro kinase assays to further validate BRSK1 as a substrate of PKCε and used Brsk1-/- mice to assess the role of BRSK1 in ethanol- and anxiety-related behaviours and in physiological responses to ethanol. We found that BRSK1 is phosphorylated by PKCε at a residue identified in a chemical genetic screen of PKCε substrates in mouse brain. Like Prkce-/- mice, male and female Brsk1-/- mice were more sensitive than wild-type to the acute sedative-hypnotic effect of alcohol. Unlike Prkce-/- mice, Brsk1-/- mice responded like wild-type to ataxic doses of ethanol. Although in Prkce-/- mice ethanol consumption and reward are reduced in both sexes, they were reduced only in female Brsk1-/- mice. Ex vivo slice electrophysiology revealed that ethanol-induced facilitation of GABA release in the central amygdala was absent in male Brsk1-/- mice similar to findings in male Prkce-/- mice. Collectively, these results indicate that BRSK1 is a target of PKCε that mediates some PKCε-dependent responses to ethanol in a sex-specific manner and plays a role distinct from PKCε in anxiety-like behaviour.
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Affiliation(s)
- Michael P. Dugan
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Rajani Maiya
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
- Department of PhysiologyLouisiana State University Health Sciences CenterNew OrleansLouisianaUSA
| | - Caleb Fleischer
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Michal Bajo
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Angela E. Snyder
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Ashwin Koduri
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Sathvik Srinivasan
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Marisa Roberto
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Robert O. Messing
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
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Ardinger CE, Chen Y, Kimbrough A, Grahame NJ, Lapish CC. Sex Differences in Neural Networks Recruited by Frontloaded Binge Alcohol Drinking. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.08.579387. [PMID: 38370732 PMCID: PMC10871329 DOI: 10.1101/2024.02.08.579387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Frontloading is an alcohol drinking pattern where intake is skewed toward the onset of access. The goal of the current study was to identify brain regions involved in frontloading. Whole brain imaging was performed in 63 C57Bl/6J (32 female and 31 male) mice that underwent 8 days of binge drinking using the drinking-in-the-dark (DID) model. On days 1-7, three hours into the dark cycle, mice received 20% (v/v) alcohol or water for two hours. Intake was measured in 1-minute bins using volumetric sippers, which facilitated analyses of drinking patterns. On day 8 mice were perfused 80 minutes into the DID session and brains were extracted. Brains were then processed to stain for Fos protein using iDISCO+. Following light sheet imaging, ClearMap2.1 was used to register brains to the Allen Brain Atlas and detect Fos+ cells. For brain network analyses, day 8 drinking patterns were used to characterize mice as frontloaders or non-frontloaders using a recently developed change-point analysis. Based on this analysis the groups were female frontloaders (n = 20), female non-frontloaders (n = 2), male frontloaders (n = 13) and male non-frontloaders (n = 8). There were no differences in total alcohol intake in animals that frontloaded versus those that did not. Only two female mice were characterized as non-frontloaders, thus preventing brain network analysis of this group. Functional correlation matrices were calculated for each group from log10 Fos values. Euclidean distances were calculated from these R values and hierarchical clustering was used to determine modules (highly connected groups of brain regions). In males, alcohol access decreased modularity (3 modules in both frontloaders and non-frontloaders) as compared to water drinkers (7 modules). In females, an opposite effect was observed. Alcohol access (9 modules for frontloaders) increased modularity as compared to water drinkers (5 modules). These results suggest sex differences in how alcohol consumption reorganizes the functional architecture of neural networks. Next, key brain regions in each network were identified. Connector hubs, which primarily facilitate communication between modules, and provincial hubs, which facilitate communication within modules, were of specific interest for their important and differing roles. In males, 4 connector hubs and 17 provincial hubs were uniquely identified in frontloaders (i.e., were brain regions that did not have this status in male non-frontloaders or water drinkers). These represented a group of hindbrain regions (e.g., locus coeruleus and the pontine gray) functionally connected to striatal/cortical regions (e.g., cortical amygdalar area) by the paraventricular nucleus of the thalamus. In females, 16 connector and 17 provincial hubs were uniquely identified which were distributed across 8 of the 9 modules in the female frontloader alcohol drinker network. Only one brain region (the nucleus raphe pontis) was a connector hub in both sexes, suggesting that frontloading in males and females may be driven by different brain regions. In conclusion, alcohol consumption led to fewer, but more densely connected, groups of brain regions in males but not females, and recruited different hub brain regions between the sexes. These results suggest that alcohol frontloading leads to a reduction in network efficiency in male mice.
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Affiliation(s)
- Cherish E Ardinger
- Addiction Neuroscience, Department of Psychology and Indiana Alcohol Research Center, Indiana University - Purdue University Indianapolis, Indianapolis, IN
| | - Yueyi Chen
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN
| | - Adam Kimbrough
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN
- Weldon School of Biomedical Engineering, College of Engineering, Purdue University, West Lafayette, IN
- Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, IN
| | - Nicholas J Grahame
- Addiction Neuroscience, Department of Psychology and Indiana Alcohol Research Center, Indiana University - Purdue University Indianapolis, Indianapolis, IN
| | - Christopher C Lapish
- Addiction Neuroscience, Department of Psychology and Indiana Alcohol Research Center, Indiana University - Purdue University Indianapolis, Indianapolis, IN
- Stark Neuroscience Research Institute, Indiana University - Purdue University Indianapolis, Indianapolis, IN
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