Indiana University-Purdue University Indianapolis (IUPUI) / Habit expression is emerging as a theory of addiction: subjects begin to use drugs to attain positive reinforcing effects but continue to use in spite of negative effects because the behavior becomes habitual, and therefore divorced from its outcome. Many studies have shown that a history of drug and alcohol use lead to expedited acquisition of a habit, but the acute effects of these drugs on behavior is still unknown. Behaviors that result from acute intoxication, such as increased aggression, risky sexual behavior, and impaired judgment, could be interpreted as habitual: actions performed without regard for the outcome. Therefore, we studied the transition from goal-directed to habitual behavior, when a response is made regardless of outcome value, and how acute intoxication of ethanol (EtOH), amphetamine (AMP), nicotine (NIC), and yohimbine (YOH) affect the resulting behavior. Through a series of four experiments, selectively bred crossed High Alcohol Preferring (cHAP) mice were trained on an operant task to self-administer 1% banana solution, which was subsequently devalued via LiCl CTA. EtOH (1 & 1.5 g/kg), AMP (2.0 mg/kg), NIC (0.5 mg/kg), YOH (1.0 mg/kg), or SAL were administered prior to baseline and post-devaluation tests. We found that acute EtOH at 1- and 1.5-g/kg doses facilitated the expression of a habit, whereas all other pretreatments resulted in devaluation. These data may indicate a unique role for EtOH in facilitating the retrieval of habitual over outcome-based associations. This could shed light on why intoxicated individuals display impaired judgment and a mechanism by which relapse after a period of abstinence can occur.

<p>Some individuals with alcohol use disorder (AUD) continue to drink because they have developed a habit in which they are not considering the consequences of their actions. Habitual actions persist despite changes in reward and are often studied using devaluation procedures. Stress hormones, such as corticotropin releasing factor (CRF), have been linked to AUD when examining binge-like drinking and withdrawal in rodents. Stress has been examined in the switch from goal-directed to habitual behavior, and CRF has often mimicked the effects of stress exposure. This study looked at the possible direct effects of CRF on habit expression in rats using an operant paradigm. Finding possible novel mechanisms of habit could create an avenue for future novel treatment options. Female and male Long Evans rats were trained on a variable interval schedule using sucrose as a reward. Rats then underwent devaluation procedures including both sensory-specific satiety and conditioned taste aversion (CTA) to test for habitual behaviors. Prior to an extinction session post-CTA, animals were treated with either 20 mg/kg R121919, a CRF1 receptor antagonist, or vehicle. A second extinction session was conducted where animals received the alternative treatment. Lever presses were recorded as a measure of goal-directed or habitual behavior. Sensory-specific satiety devaluation tests revealed that animals were not sensitive to devaluation. This was further supported by both post-CTA extinction sessions. R121919 had no effect on lever pressing in either devalued or valued groups. Further research is needed to explore how a CRF receptor antagonist may affect habit formation or the transition from goal-directed to habit behaviors. Future studies should also examine any possible interaction effects CRF may have with alcohol or stress on habitual behaviors.</p>