Alcohol self-administration in rats: Modulation by temporal parameters related to repeated mild social defeat stress.

Clinical evidence often points to stress as a cause or an antecedent to the development of drinking problems. Yet, animal models of alcohol drinking have yielded inconsistent evidence for a direct contribution of stress, and many studies have shown that stress suppresses alcohol consumption. The aim of the present study was to examine alcohol reward in animals exposed to repeated, mild social stress, and to determine whether alcohol drinking changes as a function of the temporal parameters of alcohol access relative to the stressor. Male Long-Evans rats, trained to self-administer a 6% (wt/vol) alcohol solution using a sucrose-fading procedure, were exposed to five brief (5min) episodes of contact with an aggressive male. Full contact with the resident was limited to a single episode of defeat, whereas the following four encounters occurred with the subjects behind a protective wire mesh cage. Alcohol self-administration was measured 1 week prior to stress (baseline), on each day of stress exposure, and 1 week following stress. Separate groups of animals were randomly assigned to self-administer alcohol immediately prior, immediately following, or 2h following defeat stress. Stress preferentially increased alcohol drinking on stress-exposure days, and further elevated the amount consumed 1 week following stress. Temporal parameters of alcohol access relative to the stressor were found to be important. Average alcohol consumption was greatest for animals drinking 2h postdefeat, whereas animals drinking immediately prior to or following the stressor did not show a significant increase in alcohol consumption. Results suggest that mild social defeat stress is sufficient to elicit increases in alcohol consumption in nonpreferring strains of rodents, provided alcohol access occurs at an optimal time interval after the social defeat experience.

Long-term citalopram maintenance in mice: selective reduction of alcohol-heightened aggression.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) alleviate many affective disturbances in human clinical populations and are used in animal models to study the influence of serotonin (5-HT) on aggressive behavior and impulsivity. OBJECTIVE: We hypothesized that long-term SSRI treatment may reduce aggressive behavior escalated by alcohol consumption in mice. Therefore, aggression was tested in male CFW mice to determine whether repeated citalopram (CIT) administration reduces alcohol-heightened aggression. MATERIALS AND METHODS: Resident male mice self-administered alcohol by performing an operant response on a panel placed in their home cage that delivered a 6% alcohol solution. Mice repeatedly confronted an intruder 15 min after self-administration of either 1 g/kg alcohol (EtOH) or water (H(2)O). Aggressive behaviors were higher in most mice when tests occurred after EtOH intake relative to H(2)O. Once baseline aggression was established, animals were injected (i.p.) twice daily with 10 mg/kg CIT or saline (SAL) for 32 days. Every 4 days throughout the CIT treatment period, aggressive encounters occurred 6 h after CIT injections, with testing conditions alternating between EtOH and H(2)O intake. RESULTS: Aggression was only modestly affected by CIT in the first 2 weeks of treatment. However, by day 17 of CIT treatment, alcohol-heightened aggressive behavior was abolished, while baseline aggression remained stable. These data lend support for the role of the 5-HT transporter in the control of alcohol-related aggressive behavior, and the time course of effects suggests that a change in density of 5HT(1A) autoreceptors is necessary before antidepressant drugs produce beneficial outcomes.

Use of an analog task to study effects of diazepam on taste perception, consummatory behaviors, and risk taking in a social context.

In the present study, the authors examined the effects of diazepam (Valium) on various physical, social, and emotional variables within the framework of a task designed to test risk-taking behavior. Participants received either 10 mg of diazepam or a placebo. After the participants tasted strong-flavored liquids, they were able to engage in a risky behavior (i.e., drinking from a confederate's "used" water bottle). Half the participants received additional verbal pressure to drink from the bottle. The authors expected that diazepam would increase health-risk behavior, but the results were inconsistent with that prediction. The second goal of the experiment was to explore diazepam's effects on arousal, mood, social anxiety, and taste. Diazepam users exhibited differences in taste perception and social anxiety, which might in part explain the health-risk results.