ACTH-induced reactivation of prior active avoidance training after intermediate intervals in hypophysectomized, adrenalectomized, and sham-operated rats

Negative transfer from active to passive avoidance training. was evident 24 h after active avoidance acquisition in hypox, adx, and sham-operated rats injected with ACTH, corticosterone, or saline prior to 24-h test. No transfer was observed in control rats or in hypox, adx, or sham rats given corticosterone or saline 211z h after active avoidance training. However, hypox, adx, or sham-operated rats given ACTH at 211z-h test exhibited negative transfer from prior active avoidance training. ACTH presented prior to 211z-h test eliminated the Kamin-like effect. These results suggested that ACTH reactivated at 211z h processes related to prior active avoidance responding. A possible theory of the Kamin effect is offered.