Age-related effects of diazepam on retention of inhibitory avoidance and shuttle avoidance tasks in rats

We investigated the effect of diazepam on memory of 30 days-old and 60-70 days-old female Wistar rats, using two behavioral tasks: step-down inhibitory avoidance (IA) and shuttle avoidance (SA). Diazepam (0.2, 1.0 or 5.0 mg/kg) or its vehicle were given i.p., 60 min prior to the training session. Training-test interval was 24 h. Diazepam impaired the retention of IA in 30 days-old rats at the three doses used, while retention of SA was not impaired by any dose. In the 60-70 days-old animals, diazepam at the dose of 0.2 mg/kg was facilitatory in IA and had no effect on SA, while doses of 1.0 mg/kg and 5.0 mg/kg impaired retention of both tasks. We suggest that these age-dependent effects of diazepam on memory of IA and SA could be related to developmental changes in brain GABAA receptors.