Drugs Alcohol solution for oral self-administration was prepared by diluting 95% ethanol in tap water. U50,488, nor-BNI, and yohimbine HCl were dissolved in distilled water, while antalarmin was suspended in 10% cremophor in saline; drugs were injected i.p. in a volume of 1 mL/kg. Nor-BNI, U50,488, and antalarmin were obtained from the NIDA Drug Supply Program (Baltimore, MD) and yohimbine was obtained from Sigma-Aldrich (St. Louis, MO). The doses of yohimbine and antalarmin and their pretreatment times were based on our published studies

(Le et al. 2005, 2009; Marinelli et Inhibitors,research,lifescience,medical al. 2007a) and those for U50,488 and nor-BNI were based on previous reports (Redila and Chavkin 2008; VX-680 datasheet Schank et al. 2012). Statistical analysis Statistical analyses were performed separately on the numbers of responses made on the previously active and inactive levers during the reinstatement tests. Data Inhibitors,research,lifescience,medical were analyzed with analysis of variances (ANOVAs) and significant interactions (P < 0.05) were followed by Newman-Keuls post hoc tests. Experiment

1: Effects of U50,488 on reinstatement Twelve rats were trained to self-administer alcohol and received extinction sessions as described above. A within design was used with U50,488 dose (vehicle, 2.5 and 5.0 mg/kg, i.p.) as Inhibitors,research,lifescience,medical the factor. Once the extinction criterion was reached, rats received Inhibitors,research,lifescience,medical vehicle (water) or one of the doses of U50,488, 30 min before 1-h reinstatement test sessions conducted in the operant chambers, in counterbalanced order with at least 2 days between each test. On the days between the drug tests, rats were injected i.p. with water and received drug-free extinction sessions. Experiment 2: Effect of nor-BNI on reinstatement of alcohol seeking induced by U50,488 Twenty-three rats (n = 7–8 per group) were trained to self-administer Inhibitors,research,lifescience,medical alcohol and received extinction sessions. In this and in the following experiments, rats were assigned to matched groups based on alcohol intake

and extinction responding. A mixed design was used with the between factor of nor-BNI pretreatment condition (vehicle, nor-BNI 2 h, nor-BNI 24 h) and within factor of U50,488 pretreatment condition (vehicle, 5 mg/kg, i.p.). crotamiton One group of animals received injections of nor-BNI vehicle or nor-BNI (10 mg/kg, i.p.) 2 h before the U50,488 vehicle or U50,488 injections. The other group received nor-BNI 24 h prior to U50,488 vehicle or U50,488 injections. Thirty minutes after the U50,488 vehicle or U50,488 injections, rats were placed in the operant chambers for the 1-h reinstatement test session. In order to minimize the use of animals in Experiments 2 and 3, we did not include a 24 h nor-BNI vehicle condition; we have found that baseline extinction responding is extremely stable from day to day once the extinction criterion is reached.