Influence of the post-ovariectomy time frame on the experimental anxiety and the behavioural actions of some anxiolytic agents.

This study analyzes the long-term effects of ovariectomy on the basal experimental anxiety of rats and the influence of this condition on the anxiolytic properties of diazepam and the 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Rats ovariectomized 3, 6 and 12 weeks previously, were tested in the burying behaviour paradigm and in an automatic activity counter. The highest values of time spent burying were observed in the 12-week group. In general, the 12-week group was more responsive to diazepam than the 3-week group, while 8-OH-DPAT showed similar effects on time spent burying, independently of how long ago the ovariectomy was done. Detection of anxiogenic-like behaviours by the shock-probe burying test in rats after chronic absence of gonadal hormones could help in the understanding of mood changes associated with human menopause.