Age-dependent changes in the mechanisms controlling prolactin secretion and phosphatidylinositol turnover in male rats: effect of phosphatidylserine.
The present study was undertaken in order to better characterize the functional state of anterior pituitary gland in young and old rats by using prolactin secretion and incorporation of radioactive phosphate into phosphatidylinositol (PI) as markers. The in vitro incorporation of radiolabeled phosphate into anterior pituitary PI was significantly (p less than 0.01) greater in young (3-5 months) than in aged (24-25 months) male Sprague-Dawley rats. No significant difference was found in the incorporation by pituitary tissue of 32P into phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Also, the extent of prolactin secretion from isolated pituitary was significantly greater in young than in aged rats, while the prolactin pituitary content was significantly higher in aged animals. In vitro dopamine (DA) decreased the incorporation of 32P into PI, both in young and old pituitary glands, and inhibited prolactin secretion into the incubation medium. Brain cortex-phosphatidylserine (BC-PS), a pharmacologically active purified phospholipid, capable of stimulating the dopaminergic system in the hypothalamus and of decreasing prolactin secretion both in humans and rats in vitro and in vivo, inhibited the incorporation of labeled phosphate into PI of pituitary glands from either young or old rats, but did not alter the prolactin secretion from the glands incubated in vitro. Baseline prolactin plasma levels did not differ significantly between young and old rats either when blood was collected from the trunk after decapitation or underwent sampling from chronically cannulated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
D000375:Aging / Q000378:metabolism*; D000818:Animals; D004298:Dopamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008081:Liposomes / Q000494:pharmacology; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010718:Phosphatidylserines / Q000494:pharmacology*; D010761:Phosphorus Radioisotopes; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism; D013134:Spiperone / Q000378:metabolism
D008081:Liposomes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D010761:Phosphorus Radioisotopes; D011954:Receptors, Dopamine; D013134:Spiperone; D011388:Prolactin; D004298:Dopamine