Ethanol and chronic diazepam interactions on conflict behavior in rats

Four groups of five rats each received training on the Geller-Seifter procedure and then received 0.5, 1.0 or 2.0 mg/kg diazepam (DZ) or vehicle, respectively, 15 min prior to the behavior sessions for 14 days. On Day 14 of DZ treatment rats also were administered 2.0 g/kg of ethanol (EtOH) 30 min prior to testing. Significant dose-related decreases in lever pressing occurred between groups over the 13 days of DZ treatment during the pre- and posttone periods. However, a significant effect attributable to days occurred only in the pretone period. During the tone period, the dose-related effects were greater but the variability also increased and specific contrasts between individual means were not significant. The largest increases in lever pressing associated with an anxiolytic effect occurred with 1.0 mg/kg of DZ at Day 6. On Day 14, all animals received 2.0 g/kg of EtOH and their performance was compared to performance on Day 13. During the pre- and posttone periods, the EtOH resulted in significantly less lever pressing in the control, 0.5 and 2.0 mg/kg DZ groups, indicating a sedative effect. Rats treated with 1.0 mg/kg of DZ did not exhibit this EtOH reduction in lever pressing. During the tone or conflict period, a significant dose-related increase in lever pressing due to the EtOH was observed. The increase in the control group was not significant. During repeated exposure to DZ there was a small but significant decrease in number of reinforcements which was enhanced by the EtOH at the 0.5 and 2.0 mg/kg DZ doses but not at 1.0 mg/kg DZ.(ABSTRACT TRUNCATED AT 250 WORDS)