Age-related decline in receptivity in normal, neonatally androgenized female and male hamsters

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

The effect of diazepam (1.0 mg/kg, i.p.) and buspirone (5.0 mg/kg, i.p.) 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 micrograms/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.

Perinatal androgen manipulations do not affect feminine behavioral potentials in voles

Adult voles show sexual differences in their behavioral responses to estrogen. To determine whether this sexual dimorphism is related to early androgen exposure as it is in other rodents, female voles were treated neonatally with testosterone. In addition, males were castrated neonatally or treated perinatally with either the antiandrogen, flutamide or with the antiaromatase, ATD. When androgenized females were treated with estrogen in adulthood, they exhibited normal sexual behaviors. Males deprived of androgen or treated with ATD during development did not display feminine behaviors when injected with estrogen in adulthood. These results suggest that the organizational hypothesis of sexual differentiation cannot explain the development of feminine behavior potentials in the vole. It is possible that the development of feminine behaviors in voles requires exposure to ovarian hormones during prepubertal development.