Effects of active immunization against GnRH on LH, FSH and prolactin storage, secretion and response to their secretagogues in pony geldings.

Abstract

Six pony geldings were actively immunized against GnRH conjugated to bovine serum albumin (BSA) to study 1) the relative dependency of LH and FSH storage, secretion and response to GnRH analog on GnRH bioavailability and 2) the effects of reduced GnRH bioavailability on GnRH storage in the hypothalamus. Five geldings were immunized against BSA. Geldings were immunized in December and 4, 8, 14, 20, 26 and 32 wk later. Ponies immunized against GnRH had increased (P less than .01) GnRH binding in plasma within 6 wk. By June, plasma concentrations of LH and FSH in ponies immunized against GnRH had decreased (P less than .02) by 86 and 59%, respectively, relative to ponies immunized against BSA. The LH response to an injection of GnRH analog, which did not bind to anti-GnRH antibodies, was reduced (P less than .005) by 90% in ponies immunized against GnRH relative to ponies immunized against BSA. In contrast, the FSH response to GnRH analog was similar (P greater than .1) for both groups. Immunization against GnRH reduced (P less than .05) weight of the anterior pituitary (AP) by 31%, LH content in AP by 91% and FSH content in AP by 55% relative to ponies immunized against BSA. There was no effect of GnRH immunization on prolactin characteristics or on GnRH concentrations in the median eminence, preoptic area or body of the hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of testicular function and sexual behavior by vaccination against GnRH (Equity™) in the adult stallion

“…These results confirm the essential role of testosterone for spermatogenesis and epididymal function but leaves the question open why the changes in semen quality were highly variable between individual stallions despite constant low testosterone concentrations for more than 6 months. A possible explanation might be the different effect of GnRH immunization on pituitary LH and FSH secretion (Garza et al, 1986;Rabb et al, 1990). Because FSH is less affected by GnRH, circulating FSH together with low testosterone concentrations may be sufficient to maintain spermatogenesis.…”

ORIGINAL ARTICLE: The Single‐Shot GnRH Immunocontraceptive Vaccine (GonaCon™) in White‐Tailed Deer: Comparison of Several GnRH Preparations

“…Many different proteins and coupling techniques have been used (as discussed in the section), but in many cases, much of the resultant antibody production targeted the carrier protein and not the GnRH peptide. Therefore the vaccines required a primary and several booster doses to produce a 6‐month‐long response 21,26,41 …”

Involvement of glucocorticoids in testicular involution after active immunization of boars against GnRH

“…In rodents, GnRH immunization led to a decrease of FSH in blood plasma down to non-detectable levels (McLachlan et al 1994a). In other species including sheep, goat, bull and horse, FSH concentrations were decreased to a varying degree but levels that suggest a physiological function were still maintained (Rabb et al 1990, Brown et al 1994, Godfrey et al 1996, Finnerty et al 1998. For the pig it was reported that immunization inhibited LH, whereas plasma and pituitary FSH contents were not affected at all (Awoniyi et al 1988).…”