Further evidence that peptide histidine isoleucine (PHI) may function as a prolactin releasing factor in rats.
Intraventricular administration of peptide histidine isoleucine (PHI) (200 ng, 1, 5 and 10 micrograms/rat) resulted in a significant and dose-related increase in plasma prolactin (PRL) levels in urethane-anesthetized rats and in conscious rats with intraatrial and intraventricular catheters. Intravenous injection of PHI (10 micrograms/rat) also raised plasma PRL levels in these animals. In in vitro studies, PRL release from superfused rat anterior pituitary cells was stimulated by PHI (10(-9), 10(-8) and 10(-7) M) in a dose-related manner. The stimulating effect of PHI (10(-7)M) on PRL release in vitro was as potent as that of vasoactive intestinal polypeptide (VIP) (10(-7) M) and was observed even in the presence of dopamine (10(-7) M). These results suggest that PHI plays a stimulating role in regulating PRL secretion by acting, at least in part, directly on the pituitary in the rat.
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D010451:Peptide PHI; D010455:Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000097:blood* / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D010451:Peptide PHI; D010455:Peptides; D014660:Vasoactive Intestinal Peptide; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D004298:Dopamine