title: Prostaglandin-stimulated LH release in cyclic and ovariectomized rats.
abstract: The ability of prostaglandin (PG) E2 treatment to stimulate luteinizing hormone (LH) release was compared in cyclic (4-day) and ovariectomized rats. PGE2 (500 micrograms) was injected sc and plasma LH concentration was determined in serial jugular blood samples. Administration of PGE2 at 13.30 h on each day of the oestrous cycle resulted in a significantly greater increase in plasma LH levels at pro-oestrus and oestrus than at dioestrus 1 and 2. This differential response by the hypothalamo-hypophyseal axis during the oestrous cycle implicates regulatory activity by ovarian steroid feedback. In oestrogen-primed ovariectomized rats, PGE2 administration stimulated a significant increase in plasma LH, but similar treatment in non-primed castrates decreased plasma LH levels. This finding suggests a major role for oestrogen in regulating this response.
mesh_terms: D000818:Animals; D002369:Castration; D004971:Estrus; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D007279:Injections, Subcutaneous; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D011458:Prostaglandins E / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
chemical_list: D011458:Prostaglandins E; D007986:Luteinizing Hormone