The contribution of adrenal and reproductive hormones to the opposing effects of stress on trace conditioning in males versus females

Exposure to an acute stressful experience facilitates classical conditionin g in male rats but impairs conditioning in female rats (T. J. Shors, C. Lew czyk, M. Paczynski, P. R. Mathew, & J. Pickett, 1998; G. E. Wood & T. J. Sh ors. 1998). The authors report that these effects extend to performance on the hippocampal-dependent task of trace conditioning. The stress-induced im pairment of conditioning in females was evident immediately, 24 hr and 48 h r after stress, depending on the stage of estrus. Moreover, the effect coul d be reactivated days later by reexposure to the stressful context. Cortico sterone levels correlated with overall performance in males but not in fema les. Unlike the effect seen in males, adrenalectomy did not prevent the str ess-induced effect on conditioning in females. These data indicate that exp osure to the same experience can have opposite effects on learning in males versus females and that these opposing effects are mediated by differing h ormonal systems.