Unique Pituitary Peptides with Behavioral-affecting Activity

Abstract

Publisher Summary This chapter highlights the unique pituitary peptides with behavioral-affecting activity. Initial screening studies for behavioral-affecting activity were performed on hypophysectomized rats. Four unique porcine pituitary peptides are isolated and partially characterized, which upon subcutaneous administration potently facilitate acquisition of conditioned avoidance responses in hypophysectomized rats and inhibit extinction of avoidance responses in intact rats. The profound deficit in acquisition and retention of conditioned avoidance responses (CARS) imposed on rats by hypophysectomy can be substantially reversed by subcutaneous administration of corticotrophin (ACTH) and certain subunits thereof, as well as by the melanotrophins and pitressin. The potent behavioral effects of synthetic corticotrophin subunits in conjunction with an apparent lack of peripheral action suggested the possible existence of naturally occurring pituitary peptides with similar biological activity. The availability of a porcine pituitary extract in a large quantity afforded the opportunity to undertake a search for such compounds.