Passive immunization of rams ( Ovis aries) against GnRH: effects on antibody titer, serum concentrations of testosterone, and sexual behavior

• Published in: Animal reproduction science Vol. 71; no. 3; pp. 203 - 215
• Main Authors: Parthasarathy, V, Price, E.O, Orihuela, A, Dally, M.R, Adams, T.E
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 17-06-2002
• Subjects: Animals; Anti-GnRH; Antibodies - blood; Female; Gonadotropin-Releasing Hormone - immunology; Gonadotropin-Releasing Hormone - physiology; Immunization, Passive; Kinetics; Male; Orchiectomy - veterinary; Ovariectomy - veterinary; Passive immunization; Rams; Sexual behavior; Sexual Behavior, Animal; Sheep; Sheep - physiology; Testosterone; Testosterone - blood; Testosterone; Sheep; Rams; Anti-GnRH; Passive immunization; Sexual behavior
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/S0378-4320(02)00028-3

The effect of immunoneutralization of gonadotropin-releasing hormone (GnRH) on serum concentrations of testosterone and sexual behavior was evaluated in sexually mature male sheep. In Experiment 1, GnRH1 rams (
n=16) were passively immunized against GnRH (300
ml antiserum), control rams were either passively immunized against keyhole limpet hemocyanin (KLH,
n=15) or surgically castrated (Wethers1,
n=4). Sexual performance of the rams was assessed weekly for 3 weeks before and 6 weeks after immunization, using ovarihystertomized ewes actively immunized against GnRH.
Experiment 2 evaluated the effects of repeated immunization. Rams were immunized with two aliquots (400 and 300
ml, respectively) of anti-GnRH sera (GnRH,
n=5) or normal sheep serum (NSS,
n=4), 2 weeks apart. Surgically castrated animals were used as a second control group (Wethers2). Administration of anti-GnRH sera, but neither anti-KLH nor NSS sera, resulted in marked reduction (
P<0.05) in serum concentrations of testosterone. Sexual behavior was not consistently affected by administration of one aliquot of anti-GnRH sera, however repeated immunizations resulted in more persistent reduction in serum concentrations of testosterone and more consistent suppression of sexual behavior.