title: Luteinizing hormone release in intact and castrate rams is altered with immunoneutralization of endogenous estradiol.
abstract: Changes in the dynamics of luteinizing hormone (LH) release in the adult ram following immunoneutralization of endogenous estradiol were investigated. Castrate rams were actively immunized against estradiol-6-bovine serum albumin for 7 months and then their patterns of episodic LH release and LH response to multiple injections of gonadotropin-releasing hormone (GnRH, two 5-micrograms doses given iv 2 h apart) were assessed (April). In comparison with control rams immunized against rabbit gamma globulin, estradiol-immunized rams (antibody titre approximately 1:5000) exhibited more frequent LH releases (11.7 +/- 0.3 vs. 9.3 +/- 0.8 pulses/8 h, P less than 0.05) and a greater LH response to the first GnRH injection (peak delta value 190 +/- 8 vs. 130 +/- 25 ng/mL, P less than 0.01). Estradiol antiserum collected from the castrate rams was used in the passive immunization of intact rams (antibody titre approximately 1:200) for 1 month (beginning mid-July). Although episodic LH release was always similar for control and immunized rams, testosterone levels in the latter group increased approximately 150%. In contrast with the castrate ram response, GnRH treatment (two 5-micrograms doses given iv 80 min apart) produced a "self-priming" effect on LH release in the intact rams, an effect that was dampened with estradiol immunoneutralization. Consequently, peak 2:peak 1 ratios for delta value and 80-min mean incremental increase were much smaller (P less than 0.01) for the immunized rams (approximately 2:1 vs. 4:1 for the control rams).(ABSTRACT TRUNCATED AT 250 WORDS)
authors: McGill University Centre for the Study of Reproduction, Department of Animal Science, Macdonald College, Ste-Anne-de-Bellevue, Qué., Canada.
authors: L M
authors: LM
authors: Sanford
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D004958:Estradiol / Q000276:immunology / Q000502:physiology*; D007106:Immune Sera; D007114:Immunization; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy; D012756:Sheep
chemical_list: D000936:Antigen-Antibody Complex; D007106:Immune Sera; D004958:Estradiol; D007986:Luteinizing Hormone