title: Regulation of pituitary and brain enkephalin systems by estrogen.
abstract: The roles of estrogen in the regulation of pituitary and brain enkephalin systems were studied. A sex-related difference in the levels of enkephalins was observed in the anterior lobe of rat pituitary. Administration of estradiol to male rats caused a marked reduction in the levels of enkephalins in the anterior lobe. Ovariectomy produced a significant increase in the enkephalin levels of the same region but this increase was completely prevented by replacement with estradiol. These results suggest a physiological role of estrogen in the regulation of pituitary enkephalin systems. Repeated injections of haloperidol elicited effects similar to those of estrogen on the pituitary and brain enkephalin levels; namely, striatal enkephalin levels were increased whereas pituitary enkephalin levels were decreased after long-term treatment with these two compounds. These results raise the possibility that the regulation of estrogen on enkephalin systems may in part be mediated through a dopaminergic mechanism.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002369:Castration; D003342:Corpus Striatum / Q000187:drug effects; D004743:Enkephalin, Leucine / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D012737:Sex Factors
chemical_list: D004745:Enkephalins; D004958:Estradiol; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D006220:Haloperidol