Stressor controllability and the pituitary-adrenal system.

Stressor controllability can alter both behavior and pituitary-adrenal activity. Potential mediation of these behavioral effects by differential pituitary-adrenal output requires that the precise conditions that lead to differential behavioral consequences also produce differential pituitary-adrenal activity. Both plasma ACTH and corticosterone levels were measured at various times following escapable and yoked inescapable electric shock conditions known to produce differential behavioral outcomes. The escapable and inescapable shock procedures did not produce a detectable differential effect. Both shock conditions produced equivalent elevation of ACTH and corticosterone. Neither decay rates nor the ACTH and corticosterone response to shock reexposure differed among shocked groups.