Chronic treatment with desipramine induces an estrous cycle-dependent anxiolytic-like action in the burying behavior, but not in the elevated plus-maze test

The effect of chronic desipramine (DMI, 2.5 mg/kg x 21-26 days) treatment i n female rats in two anxiety paradigms was assessed: the burying behavior ( BB) and the elevated plus-maze (EPM) tests. In the BE test DMI produced a s ignificant decrease in burying in ovariectomized rats, an effect considered as anxiolytic-like. In cycling females, DMI also reduced the cumulative BE most notably in proestrus rats. However, in diestrus rats no anxiolytic-li ke actions were observed. In addition, DMI increased BE latencies in proest rus and estrus rats. In the EPM test, DMI produced anxiolytic-like actions only in ovariectomized rats, while no significant actions were found in cyc ling females. Finally, the chronic treatment with DMI produced a general re duction in the ambulatory behavior of rats in all estrous cycle phases. Res ults are discussed on the basis of the differences between both anxiety par adigms and the probable relationship between the steroids secreted during p roestrus and chronic DMI treatment. (C) 1999 Elsevier Science Inc.