RNA-Seq Analysis of Genetic and Transcriptome Network Effects of Dual-Trait Selection for Ethanol Preference and Withdrawal Using SOT and NOT Genetic Models.

BACKGROUND: Genetic factors significantly affect alcohol consumption and vulnerability to withdrawal. Furthermore, some genetic models showing predisposition to severe withdrawal are also predisposed to low ethanol (EtOH) consumption and vice versa, even when tested independently in naïve animals. METHODS: Beginning with a C57BL/6J × DBA/2J F2 intercross founder population, animals were simultaneously selectively bred for both high alcohol consumption and low acute withdrawal (SOT line), or vice versa (NOT line). Using randomly chosen fourth selected generation (S4) mice (N = 18-22/sex/line), RNA-Seq was employed to assess genome-wide gene expression in ventral striatum. The MegaMUGA array was used to detect genome-wide genotypic differences. Differential gene expression and the weighted gene co-expression network analysis were implemented as described elsewhere (Genes Brain Behav 16, 2017, 462). RESULTS: The new selection of the SOT and NOT lines was similar to that reported previously (Alcohol Clin Exp Res 38, 2014, 2915). One thousand eight hundred and sixteen transcripts were detected as differentially expressed between the lines. For genes more highly expressed in the SOT line, there was enrichment in genes associated with cell adhesion, synapse organization, and postsynaptic membrane. The genes with a cell adhesion annotation included 23 protocadherins, Mpdz and Dlg2. Genes with a postsynaptic membrane annotation included Gabrb3, Gphn, Grid1, Grin2b, Grin2c, and Grm3. The genes more highly expressed in the NOT line were enriched in a network module (red) with annotations associated with mitochondrial function. Several of these genes were module hub nodes, and these included Nedd8, Guk1, Elof1, Ndufa8, and Atp6v1f. CONCLUSIONS: Marked effects of selection on gene expression were detected. The NOT line was characterized by higher expression of hub nodes associated with mitochondrial function. Genes more highly expressed in the SOT aligned with previous findings, for example, Colville and colleagues (Genes Brain Behav 16, 2017, 462) that both high EtOH preference and consumption are associated with effects on cell adhesion and glutamate synaptic plasticity.

Lifetime Psychotropic Medication Use Among Service Members and Veterans With and Without History of Mild Traumatic Brain Injury: A Pilot Study.

INTRODUCTION: Military Service Members, Veterans, and other patient populations who experience traumatic brain injury (TBI) may have increased risk of early neurodegenerative diseases relative to those without TBI history. Some evidence suggests that exposure to psychotropic medications may play a role in this association. The Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium (LIMBIC-CENC) prospective longitudinal study provides an ideal setting to examine the effects of psychotropic medication exposure on long-term neurological health of those with and without mild TBI history. In this study, we sought to develop and pilot test a self-report electronic survey instrument to measure participants' psychotropic medication histories for use across LIMBIC-CENC study sites. MATERIALS AND METHODS: We developed a new survey instrument measuring psychotropic medication history and fielded it among Service Members and Veterans enrolled in a single site of the LIMBIC-CENC study to evaluate response rates and patterns, and to compare survey responses to prescription data extracted from participants' Veterans Affair (VA) records. Descriptive statistics estimated survey respondents' lifetime psychotropic medication exposures by their TBI history and other demographic and clinical characteristics of interest. We also compared survey responses to participants' VA outpatient prescription records to estimate sensitivity and negative predictive values (NPVs) for participants' self-reported medication exposures relative to this single prescription data source. RESULTS: Among 310 Veterans enrolled at the study site, 249 completed the survey (response rate = 80%), of whom 248 also had VA health records and were included in the analysis. Most (69%) had a history of mild TBI. Over three-fourths of survey respondents (78%) reported ever having used prescription opioids, 26% reported benzodiazepines, 50% reported muscle relaxants, 42% reported antidepressants, 13% reported non-benzodiazepine sedative-hypnotics, 15% reported stimulants, 7% reported mood stabilizers, and 6% reported antipsychotics. Veterans with, versus without, a history of mild TBI were more likely to self-report psychotropic medication history as well as have confirmed receipt of VA prescriptions for each medication class. Using VA records as a criterion standard, the sensitivity of the survey for detecting VA prescriptions ranged from 19% to 84%, while the NPVs ranged from 64% to 97%. Sensitivity and NPVs were similar for participants with, versus without, mild TBI history. CONCLUSIONS: Service Members and Veterans may receive psychotropic medications from multiple sources over their lifetimes. Valid methods to examine and quantify these exposures among those with a history of TBI are important, particularly as we evaluate causes of neurodegenerative disorders in this population over time. The measurement of Veterans' lifetime psychotropic medication exposures using a self-report survey, in combination with health care records, holds promise as a valid approach, but further testing and refinement are needed.

Scn4b regulates the hypnotic effects of ethanol and other sedative drugs.

The voltage-gated sodium channel subunit ß4 (SCN4B) regulates neuronal activity by modulating channel gating and has been implicated in ethanol consumption in rodent models and human alcoholics. However, the functional role for Scn4b in ethanol-mediated behaviors is unknown. We determined if genetic global knockout (KO) or targeted knockdown of Scn4b in the central nucleus of the amygdala (CeA) altered ethanol drinking or related behaviors. We used four different ethanol consumption procedures (continuous and intermittent two-bottle choice (2BC), drinking-in-the dark and chronic intermittent ethanol vapor) and found that male and female Scn4b KO mice did not differ from their wild-type (WT) littermates in ethanol consumption in any of the tests. Knockdown of Scn4b mRNA in the CeA also did not alter 2BC ethanol drinking. However, Scn4b KO mice showed longer duration of the loss of righting reflex induced by ethanol, gaboxadol, pentobarbital and ketamine. KO mice showed slower recovery to basal levels of handling-induced convulsions after ethanol injection, which is consistent with the increased sedative effects observed in these mice. However, Scn4b KO mice did not differ in the severity of acute ethanol withdrawal. Acoustic startle responses, ethanol-induced hypothermia and clearance of blood ethanol also did not differ between the genotypes. There were also no functional differences in the membrane properties or excitability of CeA neurons from Scn4b KO and WT mice. Although we found no evidence that Scn4b regulates ethanol consumption in mice, it was involved in the acute hypnotic effects of ethanol and other sedatives.

Effects of sodium butyrate on methamphetamine-sensitized locomotor activity.

Neuroadaptations associated with behavioral sensitization induced by repeated exposure to methamphetamine (MA) appear to be involved in compulsive drug pursuit and use. Increased histone acetylation, an epigenetic effect resulting in altered gene expression, may promote sensitized responses to psychostimulants. The role of histone acetylation in the expression and acquisition of MA-induced locomotor sensitization was examined by measuring the effect of histone deacetylase inhibition by sodium butyrate (NaB). For the effect on expression, mice were treated repeatedly with MA (10 days of 2mg/kg MA) or saline (10 days), and then vehicle or NaB (630 mg/kg, intraperitoneally) was administered 30 min prior to MA challenge and locomotor response was measured. NaB treatment increased the locomotor response to MA in both acutely MA treated and sensitized animals. For acquisition, NaB was administered 30 min prior to each MA exposure (10 days of 1 or 2mg/kg), but not prior to the MA challenge test. Treatment with NaB during the sensitization acquisition period significantly increased locomotor activation by MA in sensitized mice only. NaB alone did not significantly alter locomotor activity. Acute NaB or MA, but not the combination, increased striatal acetylation at histone H4. Repeated treatment with MA, but not NaB or MA plus NaB, increased striatal acetylation at histone H3. Although increased histone acetylation may alter the expression of genes involved in acute locomotor response to MA and in the acquisition of MA-induced sensitization, results for acetylation at H3 and H4 showed little correspondence with behavior.