Sex steroid inhibition of LH induction of the LH receptor.
Testosterone and estrogen were tested as possible mediators of the prolactin-dependent LH induction of LH receptors in hypophysectomized adult male rats. Animals were injected s.c. with saline, prolactin (100 micrograms/day), or combinations of testosterone (1 mg/day) or estrogen (1 mg/day) and prolactin for 7 days following a 7-day period of hypophysectomy. Twenty-four hours after the last saline or prolactin injection, the animals were given a single i.p. injection of either saline or oLH (10 micrograms) to evaluate LH-induced LH receptor induction. Membrane preparations from testicular homogenates were incubated with [125I]hCG as the binding ligand for determination of the receptor response and capacity. Neither testosterone nor estrogen were able to mimic the ability of prolactin to allow LH to induce the LH receptor. However, both testosterone and estrogen significantly inhibited prolactin-mediated, LH induction of its homologous receptor.
Zipf
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WB
Department of Pediatrics and Physiology, Ohio State University Children's Hospital, Columbus 43205.
Hussein
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MO
D000818:Animals; D006063:Chorionic Gonadotropin / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D007016:Hypophysectomy; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D011388:Prolactin / Q000037:antagonists & inhibitors; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011974:Receptors, LH / Q000187:drug effects / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology*
D006063:Chorionic Gonadotropin; D004967:Estrogens; D011974:Receptors, LH; D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone