Male Reproductive Tract

Maintenance of Sexual Immaturity in Male Mice and Bucks by Immunization Against N-Terminal Peptides of the Follicle-Stimulating Hormone Receptor

Abstract

The follicle-stimulating hormone is one of the two pituitary hormones that control fertility in both sexes. In the male, receptors for FSH (FSHR) are only expressed on testicular Sertoli cells. FSH plays different roles during male life as it functions as a growth factor during development and sustains spermatogenesis in adults. However, the exact role of this hormone as an initiator of male fertility is not fully understood and few data are available concerning its involvement during the peri-pubertal period. We recently produced filamentous phages displaying FSHR fragments overlapping residues 18 to 38 which, if injected in animals, induced anti-FSH receptor immunity capable of inhibiting hormone binding. We employed this strategy to transiently inhibit FSH activity in male mice and male goats of the Saanen and the Mongolian Alpas Cashmere breeds at the pre-pubertal stage. Anti- FSHR peptide immunisation from the age of three weeks delayed the acquisition of fecundity in male mice by up to one week. Once fertile, progeny sizes produced by mating immunised males and untreated females were found to be reduced by up to 60%. In two different breeds of goats, FSHR peptide vaccines were able to maintain circulating testosterone at low pre-pubertal levels for several months, despite no alteration to LH levels, reflecting their ability to delay the onset of puberty. These results support the conclusion that FSH may play a central role in the male at puberty through the control of testosterone production.