Testicular function of actively immunized male rats with LH releasing hormone (LHRH): A possible role of prolactin on regulation of spermatogenesis

The effect of testosterone propionate (TP) on the recovery of spermatogenesis was compared in 3 types of experimentally induced gonadotropin-deficient rats; 1. hypophysectomized rats, 2. rats actively immunized to LHRH and 3. hypophysectomized and immunized rats bearing a pituitary isograft. In order to immunize animals to LHRH, deamidated LHRH conjungated with BSA (LHRH-BSA) was injected intradermaly to male rats 4 times at 2 week intervals and additional booster injections contained once a month. Anti-LHRH titer was the highest on the 12th week and the titer remained at a relatively high levels thereafter. A remarkable decrease in testicular weight and testosterone production was achieved in 10 weeks associated with a drop in serum LH and FSH levels. In long term immunized rat (LIM rats) which had been immunized for more than 3 months, testicular atrophy advanced to a similar extent to that in long term hypophysectomized rats (HX rats). The administration of TP (1 mg/day) sc for 30 days restored spermatogenesis in LIM rats. The simultaneous administration of anti-LH and -FSH sera in addition to TP did not affect the restoration of spermatogenesis in LIM rats. The same TP treatment in HX rats, however, failed to restore spermatogenesis. Spermatogenesis was reinitiated after TP treatment if immunized-hypophysectomized rats received a pituitary isograft. Though the serum PRL level in LIM rats was one fifth of that in normal rats, a 2.5-fold rise in the PRL level was observed after TP treatment. These results suggest that PRL is involved in the process of spermatogenesis.