Relation of gonadotropin secretion by pituitary grafts to spermatogenesis in hypophysectomized rats

In hypophysectomized male rats, 2 anterior pituitary (AP) grafts placed underneath the kidney capsule partially prevented atrophy of the testes and ventral prostate during a 17 day post-implantation period. Spermatogenesis was partially maintained as revealed by histological examination of the testes. The AP grafts released small amounts of LH and FSH and substantial amounts of prolactin as determined by radioimmunoassay. Serum LH and FSH were undetectable in the hypophysectomized rats with no AP grafts. Inhibition of prolactin release by daily injections of ergocornine methanesulfonate (ERG) did not significantly alter serum levels of FSH and LH, spermatogenesis or testes and ventral prostate weights, indicating that circulating levels of prolactin were not responsible for the partial maintenance of spermatogenesis and prostate weight in these rats. Daily injections of ovine prolactin also had no effect on spermatogenesis or prolactin also had no effect on spermatogenesis or prostate weight in the hypophysectomized rats, and there was no change in the histological appearance of the testes and prostate. These observations indicate that secretion of gonadotropins and not prolactin by AP grafts accounts for the partial maintenance of spermatogenesis and prostate weight in hypophysectomized, AP-grafted male rats during the experimental period studied.