Interactive effects of diazepam and ethanol on baboon match-to-sample performance

Four juvenile male baboons were trained to perform a match-to-sample (MTS) discrimination task. Diazepam (DZ) at doses of 0.5, 1.0, 2.0, 4.0, or 6.0 mg/kg resulted in a significant (p less than 0.05) increase in the mean response times (MRT) during the 2 hr test session in terms of percent change from baseline performance under nondrug conditions measured the day prior to drug treatment. Effects were maximal at 2.0 mg/kg diazepam and no further effects were observed at 4.0 or 6.0 mg/kg. Administration of 0.25 mg/kg of diazepam had no effect on MTS performance. Exposure to 0.5 g/kg of ethanol (EtOH) had no effect on response time, while 1.0 g/kg EtOH significantly (p less than 0.05) increased response time. Baboons receiving combined treatment with 0.5 or 1.0 g/kg EtOH plus 1.0 mg/kg diazepam displayed a significant (p less than 0.05) percent increase in mean response time compared to that observed under baseline conditions on the day prior to drug treatment. The 0.5 g/kg EtOH and 1.0 mg/kg diazepam combination increased MRT to an extent comparable to the effect observed at the same dose of diazepam alone. Effects observed with 1.0 mg/kg diazepam and 1.0 g/kg EtOH were similar to those produced by the DZ alone. Combinations of 0.5 g/kg EtOH and 0.5 mg/kg diazepam, 1.0 g/kg EtOH and 0.25 mg/kg diazepam, and 1.0 g/kg EtOH and 0.5 mg/kg diazepam had no significant effect on response times.(ABSTRACT TRUNCATED AT 250 WORDS)