Anxiolytic actions of diazepam, but not of buspirone, are influenced by gender and the endocrine stage

Abstract

The effect of diazepam (1.0 mg/kg, ip) and buspirone (5.0 mg/kg, ip) on the burying behaviour latency (denoting actions on the animals' reactivity) and on the cumulative burying behaviour (directly reflecting the experimental anxiety levels), were analyzed in male-, intact females, at proestrus and metoestrus, and in neonatally-androgenized-rats. Androgenization was performed by injecting 60 μg/rat of testosterone propionate on day 5 after delivery. Two main groups of neonatally-androgenized rats were established: A group of animals showing permanent oestrus from the vaginal opening (acyclic females) and a group presenting the delayed anovulatory syndrome. Diazepam produced a clear reduction in experimental anxiety in males and neonatally-androgenized-females. Particularly important was the anxiolytic effect of diazepam on acyclic females that was accompanied by a significant increase in burying behaviour latency. Conversely, buspirone induced a clear reduction in burying behaviour, without modifying its latency, in all groups regardless of the gender and the neonatal treatment. Data are discussed on the basis of the androgen participation on the anxiolytic drug effects. A possible age-related benzodiazepine actions in females is suggested.