Effects of Steroids on Extinction of an Avoidance Response in Rats.: A Structure–Activity Relationship Study

Abstract

Publisher Summary This chapter discusses the effects of steroids on the extinction of an avoidance response in rats. The effect of adrenocortical steroids on the extinction of the conditioned avoidance response (CAR) might be the result of glucocorticoid activity rather than of mineralocorticoid activity, because the effect of aldosterone on extinction is small. ACTH exhibits an opposite effect—that is, it delays extinction of the CAR. The facilitating effect of dexamethasone and corticosterone on extinction of the CAR, however, is not caused by inhibition of pituitary ACTH release because the steroids also facilitate extinction of the CAR in hypophysectomized animals. This shows that metabolites of progesterone are also effective in suppressing a conditioned avoidance performance of rats. This suggests that the effect of steroids on extinction of the CAR is not specific for adrenocortical hormones. The purpose of the experiments described in the chapter was to determine the relationship between structure and behavioral activity by using various chemically related steroids.