Identity of Prolactin Inhibiting Factor (PIF) and Luteinizing Hormone-Releasing Factor (LRF).

Abstract
Summary Preparations of hypothalamic luteinizing hormone releasing factor (LRF) of bovine and ovine origin, found active on the basis of in vivo as well as in vitro tests, did not have an inhibitory effect on pituitary prolactin release in vitro. The results indicate that LRF and prolactin inhibiting factor (PIF) are not the same.