Rats treated chronically with the benzodiazepine, diazepam or with ethanol exhibit reduced variability of behavior

The hypothesis that chronic treatment with diazepam or with ethanol reduces behavioral variability, was tested on rats in a radial maze. Eight groups (n = 6) of male Sprague-Dawley rats were given one of eight treatments of diazepam (0.0, 1.5, 3.0 or 6.0 mg/kg, IP, -30 min) or of 10% ethanol (0.0, 1.0, 1.5, or 2.0 g/kg, IP, -15 min) for 2 sessions of baseline and 18 sessions of acquisition. Each session consisted of 3 trials of 8 rewards each. Emptied food wells were immediately rebaited so that an entry into any arm produced a reward of 2 food pellets. Both diazepam and ethanol produced a dose-dependent reduction in the variability of arm choice, reduction in the variability of angle of turn between arms, and reduction in the variability of goal-directed behavior. Correlations between these measures suggested they were not independent. The implications of these reductions in behavioral variability for other effects of anxiolytic drugs are described.