Effects of pituitary adenylate cyclase polypeptide (PACAP) on extinction of active avoidance learning in rats: involvement of neurotransmitters

Following a transitory facilitation of extinction from 24 h on, PACAP-38 demonstrated a greatly delayed extinction, which lasted for more than 7 days, while the control animals displayed complete extinction. The data suggest that PACAP-38 facilitates memory retrieval processes in the extinction of the active avoidance reflex.