Abstract
Intraventricular administration of peptide histidine isoleucine (PHI) (200 ng, 1, 5 and 10 μg/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 μg/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 −7M) 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.
Published Version
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