Effects of induced peripheral anosmia on gonadal maturation in prepubertal male rabbits

The effect of induced peripheral anosmia on gonadal development and maturation was investigated in sexually immature male rabbits. Furthermore, the effect of agents promoting gonadal maturation (LHRH, hMG or methyl testosterone) on testicular development was examined in anosmic rabbits. Peripheral anosmia was induced by spraying the olfactory mucosa with 5% ZnSO4 solution; its effects were evaluated after a 45-day period, corresponding to the duration of spermatogenesis. Evaluation was based on measurement of body-weight, testicular size, testicular biopsy score count (TBSC) and a standard LHRH test (0 and 30 min) involving measurement of the blood levels of FSH, LH and testosterone before and at the end of the test. Markedly lower final and incremental values were noted in anosmic, compared to intact, animals for body-weight (P less than 0.001), TBSC (P less than 0.001), FSH (P less than 0.01) and LH (P less than 0.05). On the other hand, treatment of the anosmic rabbits with 0.9% saline, resulted in lower FSH, TBSC and testicular size increments than in rabbits treated with LHRH, hMG or testosterone, while testosterone levels and body-weight increments were similar in all groups. These findings indicate that induced peripheral anosmia is probably responsible for the inadequate gonadal maturation in prepubertal anosmic male rabbits. This relationship was confirmed by the observed stimulatory effect of administration of agents activating pituitary gonadotrophin secretion or gonadal function in anosmic animals.