title: Effect of human calcitonin on the secretion of luteinizing hormone in orchiectomized rats.
abstract: The effect of human calcitonin (hCT) on the secretion of luteinizing hormone (LH) was examined in castrated rats. Male rats were orchiectomized (Orch) 2 weeks before they were treated with a single bolus injection of gonadotropin-releasing hormone (GnRH, 1 microgram/kg of body weight), hCT (3.4 ng/kg), or the combination of GnRH and hCT through a right jugular vein catheter. Blood samples (0.5 ml each time) were collected immediately before (0-min) and then at 15, 30, 60, 120 and 180 min after hormone injection. Plasma LH concentration was measured with a radioimmunoassay technique. Plasma calcium concentration was determined in an automatic analyzer. hCT significantly diminished both the basal and GnRH-stimulated levels of plasma LH without any relation to the reduced plasma levels of calcium. These results clearly demonstrated a plasma calcium-unrelated inhibitory effect of hCT on LH secretion.
authors.affiliation: Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
authors.forename: J J
authors.initials: JJ
authors.lastname: Chen
authors.forename: S C
authors.initials: SC
authors.lastname: Tsai
authors.forename: C C
authors.initials: CC
authors.lastname: Lu
authors.forename: K Y
authors.initials: KY
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Chien
authors.forename: C L
authors.initials: CL
authors.lastname: Tsai
authors.forename: P S
authors.initials: PS
authors.lastname: Wang
authors.forename: E J
authors.initials: EJ
authors.lastname: Chien
mesh_terms: D000818:Animals; D002116:Calcitonin / Q000494:pharmacology*; D002118:Calcium / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012636:Secretory Rate / Q000187:drug effects; D013737:Testis / Q000502:physiology*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D002116:Calcitonin; D002118:Calcium