Individual return to Leydig cell function after GnRH-immunization of boars.
Immunization of boars against GnRH inhibits synthesis of testicular anabolic steroids and the sex odour androstenone. Time between second vaccination and return of Leydig cell function is unknown. Six catheterized boars received the second dose (Improvac) at 26 weeks of age (day 0). Titre, LH, testicular steroids, and IGF-I were determined in blood until testosterone exceeded 0.5 ng/mL again in all boars. At week 10 the titre was low again. Return of testicular function was preceded by increased pulsatile secretion of LH but onset of steroid synthesis was delayed and highly variable (10-24 weeks) and was not related to the initial antibody titre. A major reason for delayed onset of Leydig cell function apparently is a variable refractoriness against LH.
Claus
Rolf
R
Universität Hohenheim, Institut für Tierhaltung und Tierzüchtung, Garbenstrasse 17, 70599 Stuttgart, Germany. thsekret@uni-hohenheim.de
Rottner
Silke
S
Rueckert
Christine
C
D000818:Animals; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007985:Leydig Cells / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D013552:Swine; D045165:Testosterone Congeners / Q000097:blood; D013997:Time Factors; D022642:Vaccines, Contraceptive / Q000276:immunology*
D045165:Testosterone Congeners; D022642:Vaccines, Contraceptive; D007987:Gonadotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone