Sperm antibodies in rat models of male hormonal contraception and vasectomy

The presence of sperm antibodies correlates with nearly every pathological condition of the male reproductive tract. In the seasonal breeder, mink, a decrease in gonadotrophin secretion and testicular regression also induces sperm antibodies. Because the Sertoli cells and the principal cells of the epididymis (i.e. the cells mainly responsible for protection of germ cells from autoimmune destruction) are dependent on androgens, and because the androgen concentration decreases in both the testis and epididymis during male hormonal contraception, the presence of IgG class sperm antibodies in serum was studied in rats during the suppression and recovery phases of testosterone contraception and after vasectomy. Five-centimetre long testosterone implants were placed under the dorsal skin of rats under pentobarbitone anaesthesia. The control rats received empty implants. All implants were left in the rats for 27 or 53 days. The total number of testicular antigens detected by sera from the vasectomized rats increased significantly until 66 days post-operation, and then decreased to the levels of intact rats. The number of testicular antigens detected by sera from rats receiving contraceptive doses of testosterone did not increase before the testosterone capsules were removed, but at 40 days post removal of the silastic capsules, the number of antigens detected by the sera was significantly higher than in intact rats and at 77 days post removal of the silastic capsules, the number of antigens detected by the sera was significantly higher than at 27 days after starting testosterone administration. No significant changes in the number of antigens detected by the sera could be observed after the implanting of empty capsules or after their removal. Vasectomy mostly induced antibodies against testicular antigens in the molecular ratio ranges of 70-82, 25-33 and 21-24.5 kD. Antibodies against antigens in these molecular ratio ranges were not significantly induced during or after treatment with contraceptive doses of testosterone. Cell nuclei with apoptotic morphology could be observed in the seminiferous tubules of the vasectomized rats, but DNA in situ 3'-end labelling of testes could not confirm any differences between the testes of vasectomized and sham-operated rats or between testosterone-treated and empty implant-treated rats. CD3+ T cells could not be observed in the testes of any of the treatment groups. These results suggest that the immunological conditions remain stable in the testes after vasectomy and during testosterone treatment, but that the animals are more prone to develop autoantibodies after vasectomy and during recovery from treatment with exogenous testosterone.