Indiana University-Purdue University Indianapolis (IUPUI) / Alcohol related problems and abuse continue to be serious problems in the U.S. today affecting nearly 17.6 million Americans. Understanding of the specific genes and related behaviors associated with alcohol use may provide substantial preventative measures for those who are at an increased risk. Genetically selected lines such as the high-alcohol preferring (HAP) and low-alcohol preferring (LAP) mice have been created to examine which endophenotypes co-segregate with alcohol preference. One behavioral trait that has been commonly associated with alcohol related problems is impulsivity. Impulsivity is the inability to withhold a response (motor impulsivity) or to act without forethought (cognitive impulsivity). The latter comprises much of the research and literature today using delay discounting models to tease out differences in subject’s wiliness to discount larger reinforcers for smaller immediate reinforcers. This study utilized relatively two newer paradigms associated with motor impulsivity in attempt to test differences in response disinhibition between two independent replicate HAP and LAP lines. It is hypothesized that the genes responsible for alcohol preference would be genetically correlated with motor impulsivity as HAP mice would display a greater degree of response disinhibition. Two independent replicates consisting of 48 mice (24 HAP II and 24 LAP II, representing the 37th generation; 24 HAP III and 24 LAP III, representing the 13th generation) were tested in two separate identical experiments. Each experiment was comprised of three phases. Phase I utilized a fixed interval (FI) 120s procedure for 30 days. After the 30 days of FI exposure mice were immediately moved to phase II for 10 days which implored a differential reinforcement of low rate procedure (DRL) at a time interval of 20s. Phase III used the same procedures as Phase II except the DRL was increased to 32s. As hypothesized, there was a moderate genetic correlation between alcohol preference and impulsivity as the HAP II mice displayed greater response disinhibition throughout all three phases compared to the LAP II mice. No differences were observed amongst the replicate III mice in any of the three phases. The findings from this study provide additional support that a genetic correlation between alcohol preference and impulsivity exists as seen in the delay discounting literature. Though this was observed in only one of the two replicates, interpretations must be taken at caution as the replicate III mice are still in the early stages of selection. It is possible at this stage in the selection process that increases in alcohol over successive generations are associated with selecting for taste until a threshold is met where selection shifts to pharmacologic drinking relevance. Until later generations of replicate III mice are studied where pharmacologic drinking occurs, conclusions from this study provide a moderate genetic correlation between alcohol preference and impulsivity.

Indiana University-Purdue University Indianapolis (IUPUI) / Hypothalamic-pituitary-adrenal (HPA) axis dysfunction is found in heavy alcohol users. Negative urgency is a personality trait reflecting the tendency to act rashly in response to negative emotional states, and is associated with problematic alcohol consumption. The current study examined the relationship between negative urgency and HPA axis functioning following (1) negative mood induction and (2) intravenous alcohol administration among heavy social drinkers (proposed n = 40). I hypothesized the following: (1) Negative mood induction would result in an increase of cortisol release as compared to neutral mood induction; (1a) Negative urgency would be related to increased cortisol release in response to negative mood induction; (1b) Negative urgency would partially mediate the relationship between mood induction and cortisol release; (2) Acute IV alcohol administration would result in increased cortisol levels in the neutral mood condition, but decreased cortisol levels in the negative mood condition; and (2a) Negative urgency would be related to the suppression of cortisol release in the negative mood condition in response to acute IV alcohol administration. Repeated measures analyses of variance, the PROCESS macro, and paired samples t-tests were used to examine study hypotheses. Hypotheses were largely unsupported. Writing mood induction procedures reduced salivary cortisol levels in negative mood (t(35)= 2.49, p= 0.02) and there was a trend decrease in neutral mood (t(35)= 1.87, p= 0.07). Alcohol administration also reduced salivary cortisol levels in both negative mood (t(35)= 3.99, p< 0.01) and neutral mood (t(35)= 2.60, p= 0.01). However, salivary cortisol changes were no different than typical circadian patterns in response to mood induction (t(231)= 0.37, p=0.71) or in response to acute alcohol administration (t(231)= 0.44, p= 0.64). Negative urgency had a trend main effect on salivary cortisol level in response to acute IV alcohol administration, such that those higher in negative urgency were more similar to typical circadian patterns (F(19,28)= 1.59, p=0.13). This could serve as preliminary support for a psychological mechanism for the alcohol sensitivity hypothesis. Overall these findings suggest the current study failed to sufficiently manipulate salivary cortisol levels. Future studies should consider methodological techniques when exploring these relationships, including IV compared to oral alcohol administration, mood compared to stress manipulations, and cortisol compared to other HPA axis biomarkers.

Indiana University-Purdue University Indianapolis (IUPUI) / Research in the alcohol preferring (P) rat has indicated that peri-adolescent alcohol (EtOH) consumption enhances the acquisition of oral operant EtOH self-administration, inhibits the extinction of responding for EtOH, augments EtOH-seeking behaviors, and increases relative reward value of EtOH during adulthood. Experiment 1 was conducted to determine if these adult effects of peri-adolescent EtOH intake could be observed using an Intracranial Self-Administration (ICSA) model. It was hypothesized that an increased sensitivity to the rewarding actions of EtOH would be manifested in peri-adolescent-EtOH-exposed subjects compared to naive subjects when the opportunity to self-administer EtOH to the posterior ventral tegmental area (pVTA) is available in adulthood. The pVTA is a primary site for EtOH’s reinforcing and rewarding properties in the mesolimbic dopamine (DA) system. Experiment 2 was a dose-response examination of the effects of EtOH administered to the pVTA on downstream DA efflux in the nucleus accumbens shell (AcbSh) via a joint Microinjection-Microdialysis (MicroMicro) procedure. Male P rats were given 24-h free-choice exposure to 15% volume/volume EtOH from postnatal day (PD) 30 to PD 60, or remained experimentally naive, with ad lib food and water. By the end of the periadolescent exposure period, average consumption was 7.3 g/kg/day of EtOH. After PD 75, periadolescent-EtOH-exposed and naïve rats were either implanted with an injector guide cannula aimed at the right pVTA for ICSA (Experiment 1), or two cannulae, one aimed at the right pVTA (injector) and one at the ipsilateral AcbSh (microdialysis) for MicroMicro (Experiment 2). Following one week of recovery from surgery, ICSA subjects were placed in standard two-lever (active and inactive) operant chambers. Test sessions were 60 min in duration and occurred every other day for a total of 7 sessions. Rats were randomly assigned to one of 5 groups (n=4-9/group) that self-infused (FR1 schedule) either aCSF (vehicle, 0 mg%), 50, 75, 100, or 150 mg% EtOH during 4 sessions, aCSF only for sessions 5 and 6 (extinction), and the initial concentration again for session 7 (reinstatement). MicroMicro subjects received six days of recovery from surgery, probe implantation the day before testing, and then continuous microdialysis for DA with 15 min microdialysis samples collected before, during, and then two hrs after 10-min pulse microinjection of either aCSF (vehicle, 0 mg%), 50, 75, 100, or 150 mg% EtOH. Neither EtOH-exposed nor naive groups of P rats self-infused the aCSF or 50 mg% EtOH concentration. While the naive group did not self-infuse the 75 or 100 mg% EtOH concentrations, the peri-adolescent EtOH-exposed group of P rats did readily discriminate the active lever from the inactive lever at these concentrations. Both groups self-infused the 150 mg% EtOH concentration. Pulse microinjections of EtOH during the MicroMicro procedure revealed that 75 and 100 mg% concentrations of EtOH increased downstream DA in the AcbSh of EtOH-exposed, but not naïve, subjects. 150 mg% EtOH increased downstream DA in both adolescent treatment groups. Overall, the results indicate that consumption of EtOH by P rats during peri-adolescence increases the reinforcing properties of EtOH in the pVTA in adulthood. The results also indicate that there were differential effects of peri-adolescent EtOH exposure on DA efflux in the AcbSh. This provides evidence that peri-adolescent EtOH-exposure produces long-lasting alterations in neural circuitry involved in EtOH-reinforcement, during adulthood.

Indiana University-Purdue University Indianapolis (IUPUI) / Multiple lines of High Alcohol Preferring (HAP) mice were selectively bred for their intake of 10% ethanol (v/v) during 24-h daily access over a four-week period, with the highest drinking lines exhibiting intakes in excess of 20 g/kg/day. Drinking rhythms and corresponding blood ethanol concentrations (BEC) of the highest drinking HAP lines to those of the C57BL/6J (B6) inbred strain. Adult male and female crossed HAP (cHAP), HAP1 and B6 mice had free-choice access to 10% ethanol and water for 3 weeks prior to bi-hourly assessments of intake throughout the dark portion of a reverse 12:12 light dark cycle. In another cohort of cHAP mice, the same procedure was used to assess bi-hourly ethanol intake, and blood samples were taken across the day to look at the pattern of accumulation in these mice. Finally, considering the high level of intake by cHAP mice, we were interested in assessing whether metabolic and functional tolerance develop following chronic free-choice access, which were assessed using 2.0 and 1.75 g/kg challenge doses of 20% ethanol, respectively. cHAP and HAP1 mice maintained an excessive level of intake throughout the dark portion of the cycle, accumulating mean BEC levels of 261.5 + 18.09 and 217.9 + 25.02 mg/dl at 7-8 hours following lights off, respectively. B6 mice drank comparatively modestly, and did not accumulate high BEC levels (53.63 + 8.15 mg/dl). In the cHAP cohort, mean BECs were 112.47 + 19.91 at 2 hours after lights off, 189.00 + 27.40 at 6 hours after lights off, 193.80 + 29.66 at 10 hours after lights off, and 89.68 + 22.19 at 2 hours after lights on. Further, following 3 weeks of ethanol access, cHAP mice had a faster rate of ethanol metabolism and fewer hind slips than water-only exposed mice (ps < .05). In conclusion, the excessive free-choice drinking demonstrated by the HAP1 and cHAP lines, as well as the pattern of sustained high BECs in cHAP mice, challenge the notion that rodents will not reliably and voluntarily sustain ethanol intake at pharmacologically relevant levels. These results suggest that the highest drinking HAP lines may provide a unique opportunity for modeling the excessive intake that has been observed in alcohol-dependent individuals. Further, we observed that cHAP mice develop both metabolic and functional tolerance to the ataxic effects of ethanol following 3 weeks of free-choice access. Together, these findings support HAP mice as translational rodent model of alcoholism, and provide rationale for exploration of the predisposing factors for excessive consumption, as well as the development of physiological, behavioral, and toxicological outcomes following alcohol exposure.

Indiana University-Purdue University Indianapolis (IUPUI) / It has traditionally been posited that women show a "telescoped" development of alcohol use disorders (Kuhn, 2011). In particular, a number of clinical studies support striking sex differences in the progression from initial use of alcohol to dependence on the compound; with women showing a faster progression through landmark events associated with the development of alcohol addiction (Randall et al., 1999). However, recent studies have challenged this tenet (Keyes et al., 2010). The work presented herein was designed to determine whether females are indeed more vulnerable to the development of behavioral maladaptations following binge drinking and whether sex differences in GABA(A) receptor regulation might underlie this vulnerability. Using a mouse model of binge drinking this dissertation established that, compared to males, females escalate their binge drinking at a faster rate and maintain altered responsivity to the locomotor effects of alcohol after extended abstinence from binge drinking. Female mice also displayed significant increases in ethanol preference and intake in a continuous, two-bottle choice protocol following a shorter history of binge drinking than males. The final goal was to determine if binge drinking results in unique patterns of anxiety- or depressive-like symptoms in males and females and whether these behaviors would be associated with the dimorphic regulation of GABAA receptor subunits across the prefrontal cortex and hippocampus. Male binge drinkers displayed anxiety-like behavior during early withdrawal that dissipated after 2 weeks of abstinence. There were no significant changes in the expression of delta or gamma2 GABAA receptor subunit mRNA at this time point in the regions analyzed. Females also showed temporary anxiety-like behavior during early withdrawal from binge drinking. Additionally, females displayed significant depressive-like behavior after 2 weeks of abstinence from binge drinking. In particular, diestrus-phase females displayed significantly greater immobility in the forced-swim test after ethanol exposure and no longer maintained the reduced swim-time behavior associated with this phase of the cycle at baseline (when compared to the estrus-phase). qPCR analysis of hippocampal tissues from diestrus females supported a significant reduction in expression of gamma2 GABA(A) subunit mRNA after binge drinking. This effect was not noted for RNA isolated from hippocampal tissues taken during the estrus phase of bingers. These final data suggest possible interaction of estrous-cycle and binge drinking history that may result in the unique expression of deficits following binge drinking for females. Taken together, this work supports sex and estrous dependent effects of binge drinking on behavior and gene regulation.