IMMUNIZATION AGAINST EXON-1 DECAPEPTIDES FROM THE LUTROPIN CHORIOGONADOTROPIN RECEPTOR OR THE FOLLITROPIN RECEPTOR AS POTENTIAL MALE CONTRACEPTIVE/

Pituitary gonadotropin hormones lutropin (LH) and follitropin (FSH) co ntrol steroidogenesis and gametogenesis in male and female gonads thro ugh interaction with G protein-coupled receptors, LHR and FSHR. In the male, LH acts on Leydig cells and is mostly responsible for the acqui sition of puberty and the production of androgens while FSH, together with androgens, regulates spermatogenesis within Sertoli cells. We hav e engineered filamentous phages displaying mouse LHR and human FSHR de capeptides chosen in hormone binding regions. Peptides from both recep tors displayed on phages belong either to the receptor specific exon 1 (amino acids 18-27) or to the homologous exon 4 (amino acids 98-107). Vaccination of prepubertal BALB/c male mice with hybrid phages using sub-cutaneous or intraperitoneal injections induced immunity against r eceptors. Anti-receptor immunization produced agonist or antagonist ef fects depending only on the circulating levels of the antibodies. Both anti-LHR and anti-FSHR vaccines induced efficient as well as reversib le male contraception, through different mechanisms: targeting LH rece ptors inhibited or hyperstimulated Leydig cell testosterone production while targeting FSH receptors did not affect testosterone levels.