Positively Correlated miRNA-miRNA Regulatory Networks in Mouse Frontal Cortex During Early Stages of Alcohol Dependence

Although the study of gene regulation via the action of specific microRNAs (miRNAs) has experienced a boom in recent years, the analysis of genome-wide interaction networks among miRNAs and respective targeted mRNAs has lagged behind. MicroRNAs simultaneously target many transcripts and fine-tune the expression of genes through cooperative/combinatorial targeting. Therefore, they have a large regulatory potential that could widely impact development and progression of diseases, as well as contribute unpredicted collateral effects due to their natural, pathophysiological, or treatment-induced modulation. We support the viewpoint that whole mirnome-transcriptome interaction analysis is required to better understand the mechanisms and potential consequences of miRNA regulation and/or deregulation in relevant biological models. In this study, we tested the hypotheses that ethanol consumption induces changes in miRNA-mRNA interaction networks in the mouse frontal cortex and that some of the changes observed in the mouse are equivalent to changes in similar brain regions from human alcoholics. Results: miRNA-mRNA interaction networks responding to ethanol insult were identified by differential expression analysis and weighted gene coexpression network analysis (WGCNA). Important pathways (coexpressed modular networks detected by WGCNA) and hub genes central to the neuronal response to ethanol are highlighted, as well as key miRNAs that regulate these processes and therefore represent potential therapeutic targets for treating alcohol addiction. Importantly, we discovered a conserved signature of changing miRNAs between ethanol-treated mice and human alcoholics, which provides a valuable tool for future biomarker/diagnostic studies in humans. We report positively correlated miRNA-mRNA expression networks that suggest an adaptive, targeted miRNA response due to binge ethanol drinking. Conclusions: This study provides new evidence for the role of miRNA regulation in brain homeostasis and sheds new light on current understanding of the development of alcohol dependence. To our knowledge this is the first report that activated expression of miRNAs correlates with activated expression of mRNAs rather than with mRNA downregulation in an in vivo model. We speculate that early activation of miRNAs designed to limit the effects of alcohol-induced genes may be an essential adaptive response during disease progression.NIAAA 5R01AA012404, 5P20AA017838, 5U01AA013520, P01AA020683, 5T32AA007471-24/25Waggoner Center for Alcohol and Addiction Researc

CNS cell-type localization and LPS response of TLR signaling pathways [version 1; referees: 2 approved]

Background: Innate immune signaling in the brain has emerged as a contributor to many central nervous system (CNS) pathologies, including mood disorders, neurodegenerative disorders, neurodevelopmental disorders, and addiction. Toll-like receptors (TLRs), a key component of the innate immune response, are particularly implicated in neuroimmune dysfunction. However, most of our understanding about TLR signaling comes from the peripheral immune response, and it is becoming clear that the CNS immune response is unique. One controversial aspect of neuroimmune signaling is which CNS cell types are involved. While microglia are the CNS cell-type derived from a myeloid lineage, studies suggest that other glial cell types and even neurons express TLRs, although this idea is controversial. Furthermore, recent work suggests a discrepancy between RNA and protein expression within the CNS. Methods: To elucidate the CNS cell-type localization of TLRs and their downstream signaling molecules, we isolated microglia and astrocytes from the brain of adult mice treated with saline or the TLR4 ligand lipopolysaccharide (LPS). Glial mRNA and protein expression was compared to a cellular-admixture to determine cell-type enrichment. Results: Enrichment analysis revealed that most of the TLR pathway genes are localized in microglia and changed in microglia following immune challenge. However, expression of Tlr3 was enriched in astrocytes, where it increased in response to LPS. Furthermore, attempts to determine protein cell-type localization revealed that many antibodies are non-specific and that antibody differences are contributing to conflicting localization results. Conclusions: Together these results highlight the cell types that should be looked at when studying TLR signaling gene expression and suggest that non-antibody approaches need to be used to accurately evaluate protein expression

GABAA Receptors Containing ρ1 Subunits Contribute to In Vivo Effects of Ethanol in Mice

Yuri A. Blednov, Jillian M. Benavidez, Mendy Black, Courtney R. Leiter, Elizabeth Osterndorff-Kahanek, David Johnson, Cecilia M. Borghese, R. Adron Harris, Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of AmericaJane R. Hanrahan, Mary Chebib, Faculty of Pharmacy, The University of Sydney, Sydney NSW, AustraliaGraham A. R. Johnston, Department of Pharmacology, The University of Sydney, Sydney NSW, AustraliaGABAA receptors consisting of ρ1, ρ2, or ρ3 subunits in homo- or hetero-pentamers have been studied mainly in retina but are detected in many brain regions. Receptors formed from ρ1 are inhibited by low ethanol concentrations, and family-based association analyses have linked ρ subunit genes with alcohol dependence. We determined if genetic deletion of ρ1 in mice altered in vivo ethanol effects. Null mutant male mice showed reduced ethanol consumption and preference in a two-bottle choice test with no differences in preference for saccharin or quinine. Null mutant mice of both sexes demonstrated longer duration of ethanol-induced loss of righting reflex (LORR), and males were more sensitive to ethanol-induced motor sedation. In contrast, ρ1 null mice showed faster recovery from acute motor incoordination produced by ethanol. Null mutant females were less sensitive to ethanol-induced development of conditioned taste aversion. Measurement of mRNA levels in cerebellum showed that deletion of ρ1 did not change expression of ρ2, α2, or α6 GABAA receptor subunits. (S)-4-amino-cyclopent-1-enyl butylphosphinic acid (“ρ1” antagonist), when administered to wild type mice, mimicked the changes that ethanol induced in ρ1 null mice (LORR and rotarod tests), but the ρ1 antagonist did not produce these effects in ρ1 null mice. In contrast, (R)-4-amino-cyclopent-1-enyl butylphosphinic acid (“ρ2” antagonist) did not change ethanol actions in wild type but produced effects in mice lacking ρ1 that were opposite of the effects of deleting (or inhibiting) ρ1. These results suggest that ρ1 has a predominant role in two in vivo effects of ethanol, and a role for ρ2 may be revealed when ρ1 is deleted. We also found that ethanol produces similar inhibition of function of recombinant ρ1 and ρ2 receptors. These data indicate that ethanol action on GABAA receptors containing ρ1/ρ2 subunits may be important for specific effects of ethanol in vivo.This work was supported by NIH grants AA013520 and AA06399. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Waggoner Center for Alcohol and Addiction ResearchEmail: [email protected]

Genetic and Pharmacologic Manipulation of TLR4 Has Minimal Impact on Ethanol Consumption in Rodents

Toll-like receptor 4 (TLR4) is a critical component of innate immune signaling and has been implicated in alcohol responses in preclinical and clinical models. Members of the Integrative Neuroscience Initiative on Alcoholism (INIA-Neuroimmune) consortium tested the hypothesis that TLR4 mediates excessive ethanol drinking using the following models: (1) Tlr4 knock-out (KO) rats, (2) selective knockdown of Tlr4 mRNA in mouse nucleus accumbens (NAc), and (3) injection of the TLR4 antagonist (+)-naloxone in mice. Lipopolysaccharide (LPS) decreased food/water intake and body weight in ethanol-naive and ethanol-trained wild-type (WT), but not Tlr4 KO rats. There were no consistent genotypic differences in two-bottle choice chronic ethanol intake or operant self-administration in rats before or after dependence. In mice, (+)-naloxone did not decrease drinking-in-the-dark and only modestly inhibited dependence-driven consumption at the highest dose. Tlr4 knockdown in mouse NAc did not decrease drinking in the two-bottle choice continuous or intermittent access tests. However, the latency to ethanol-induced loss of righting reflex increased and the duration decreased in KO versus WT rats. In rat central amygdala neurons, deletion of Tlr4 altered GABAA receptor function, but not GABA release. Although there were no genotype differences in acute ethanol effects before or after chronic intermittent ethanol exposure, genotype differences were observed after LPS exposure. Using different species and sexes, different methods to inhibit TLR4 signaling, and different ethanol consumption tests, our comprehensive studies indicate that TLR4 may play a role in ethanol-induced sedation and GABAA receptor function, but does not regulate excessive drinking directly and would not be an effective therapeutic target., SIGNIFICANCE STATEMENT Toll-like receptor 4 (TLR4) is a key mediator of innate immune signaling and has been implicated in alcohol responses in animal models and human alcoholics. Members of the Integrative Neuroscience Initiative on Alcoholism (INIA-Neuroimmune) consortium participated in the first comprehensive study across multiple laboratories to test the hypothesis that TLR4 regulates excessive alcohol consumption in different species and different models of chronic, dependence-driven, and binge-like drinking. Although TLR4 was not a critical determinant of excessive drinking, it was important in the acute sedative effects of alcohol. Current research efforts are directed at determining which neuroimmune pathways mediate excessive alcohol drinking and these findings will help to prioritize relevant pathways and potential therapeutic targets

Deletion of the fyn-Kinase Gene Alters Sensitivity to GABAergic Drugs: Dependence on ␤2/␤3 GABA A Receptor Subunits

ABSTRACT Tyrosine phosphorylation can modulate GABA A receptor function, and deletion of the fyn-kinase gene alters GABAergic function in olfactory bulb neurons, as reported by Kitazawa, Yagi, Miyakawa, Niki, and Kawai (J Neurophysiol 1998;79:137-142). Our goal was to determine whether fyn gene deletion altered behavioral and functional actions of compounds that act on GABA A receptors. Such evidence might suggest a role for fyn-kinase in modulating GABA A receptor function, possibly via direct interactions between the kinase and receptor. Using the loss of righting reflex test, we found that null mutants were less sensitive to the hypnotic effects of THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), a GABA A receptor agonist. Subunit specificity was suggested by the observation that null mutants were also less sensitive to the hypnotic effects of etomidate, a GABAergic compound that is selective for receptors possessing ␤2 and/or ␤3 receptor subunits. The genotypes did not differ in sensitivity to zolpidem, an ␣1-selective GABAergic drug. GABA A receptor functional assays ( 36 Cl Ϫ influx) supported our behavioral results; the actions of the GABA A agonists, THIP and muscimol, were reduced in the cerebellar membranes of fyn-null mutant mice. Importantly, similar results were seen with etomidate. Binding of [ 3 H]flunitrazepam supported the idea that this is due to a decrease in functional GABA A receptor density. These data suggest that fyn-kinase may alter the function of GABA A receptors, perhaps via actions on ␤2 and/or ␤3 receptor subunits. Fyn-kinase, a member of the src family of nonreceptor tyrosine kinases, is localized at the growth cones and postsynaptic membranes of neurons and can be found in a number of brain regions including the olfactory bulb, cerebellum, hippocampus, and limbic system The present studies examined the potential interaction between fyn-kinase and GABA A receptors in fyn-null mutant and wild-type mice. We assessed hypnotic sensitivity to the GABA A receptor agonist, tetrahydroisoxazolo [5,4-c]pyridin-3-ol (THIP), and the GABA A receptor positive allosteric modulators, alfaxalone, pentobarbital, and flurazepam. Because we were interested in establishing whether the changes in GABAergic sensitivity were subunit-selective, we also assessed the hypnotic effects of the ␣1-selective drug, zolpidem, and the ␤2/␤3-selective drug, etomidate. GABA A receptor function was assessed by measuring muscimol and THIP stimulation, as well as etomidate potentiation of muscimolstimulated, 36 Cl Ϫ flux in fyn-deficient and wild-type mice. GABA A receptor binding using [ 3 H]flunitrazepam was also performed in fyn-null mutant and wild-type mice. These experiments were supported by National Institute on Alcohol Abuse and Alcoholism (AA07471, AA13520, AA06399). Article, publication date, and citation information can be found a

Chronic self-administration of alcohol results in elevated ΔFosB: comparison of hybrid mice with distinct drinking patterns

All authors are with the Waggoner Center for Alcoholism and Addiction Research, Institute for Neuroscience, University of Texas at Austin, Austin, TX, 78712, USA -- Angela R. Ozburn is with the Department of Psychiatry, University of Pittsburgh Medical Center, 450 Technology Dr. Ste. 223, Pittsburgh, PA, 15219-3143, USABackground: The inability to reduce or regulate alcohol intake is a hallmark symptom for alcohol use disorders. Research on novel behavioral and genetic models of experience-induced changes in drinking will further our knowledge on alcohol use disorders. Distinct alcohol self-administration behaviors were previously observed when comparing two F1 hybrid strains of mice: C57BL/6J x NZB/B1NJ (BxN) show reduced alcohol preference after experience with high concentrations of alcohol and periods of abstinence while C57BL/6J x FVB/NJ (BxF) show sustained alcohol preference. These phenotypes are interesting because these hybrids demonstrate the occurrence of genetic additivity (BxN) and overdominance (BxF) in ethanol intake in an experience dependent manner. Specifically, BxF exhibit sustained alcohol preference and BxN exhibit reduced alcohol preference after experience with high ethanol concentrations; however, experience with low ethanol concentrations produce sustained alcohol preference for both hybrids. In the present study, we tested the hypothesis that these phenotypes are represented by differential production of the inducible transcription factor, ΔFosB, in reward, aversion, and stress related brain regions. Results: Changes in neuronal plasticity (as measured by ΔFosB levels) were experience dependent, as well as brain region and genotype specific, further supporting that neuronal circuitry underlies motivational aspects of ethanol consumption. BxN mice exhibiting reduced alcohol preference had lower ΔFosB levels in the Edinger-Westphal nucleus than mice exhibiting sustained alcohol preference, and increased ΔFosB levels in central medial amygdala as compared with control mice. BxN mice showing sustained alcohol preference exhibited higher ΔFosB levels in the ventral tegmental area, Edinger-Westphal nucleus, and amygdala (central and lateral divisions). Moreover, in BxN mice ΔFosB levels in the Edinger-Westphal nucleus and ventral tegmental regions significantly positively correlated with ethanol preference and intake. Additionally, hierarchical clustering analysis revealed that many ethanol-naïve mice with overall low ΔFosB levels are in a cluster, whereas many mice displaying sustained alcohol preference with overall high ΔFosB levels are in a cluster together. Conclusions: By comparing and contrasting two alcohol phenotypes, this study demonstrates that the reward- and stress-related circuits (including the Edinger-Westphal nucleus, ventral tegmental area, amygdala) undergo significant plasticity that manifests as reduced alcohol preference.Waggoner Center for Alcohol and Addiction [email protected]

Ethanol consumption and gene expression changes in liver and prefrontal cortex.

<p>(A) Average daily ethanol intake for three ethanol treatments. The Chronic treatment (open circles) is continuous two bottle choice drinking, CI is chronic intermittent two bottle choice with access to alcohol every other day and DID is a limited daily access (2 hr or 4 hr) to alcohol. Only data for days of ethanol consumption are shown. (B) Change in ethanol intake between the first and last 4 days of each treatment (mean ± SEM). Asterisks identify a significant change in ethanol intake (paired t test, p≤0.05). (C) Total ethanol consumed (average of all animals) and the number of genes differentially expressed (DE, p<0.05) in PFC and liver in each treatment (open bars are prefrontal cortex, filled bars are liver). Values are mean ± SEM, for n = 10 (Chronic and DID), n = 11 (CI). For some values, error bars are smaller than the symbols.</p