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Effects of Human Chorionic Gonadotropin, Prolactin, and Bromocriptine on Photoperiodinduced Testicular Regression and Recrudescence in Golden Hmsters

1980; Wiley; Volume: 1; Issue: 3 Linguagem: Inglês

10.1002/j.1939-4640.1980.tb00019.x

2047-2927

Andrzej Bartke, M. P. HOGAN, C. B. CUTTY,

Sexual Differentiation and Disorders

Exposure of adult male hamsters to short day‐length (short photoperiod) causes atrophy of their reproductive systems. Hamsters were transferred from long to short photoperiod and, starting two months later, injected three times a week for three weeks with saline, 1.25, 5, or 20 IU of human chorionic gonadotropin (hCG). Treatment with 5 or 20 IU hCG resulted in significant increases in the weights of the testes and the seminal vesicles. In another group of animals, identical doses of hCG were injected starting at the time of transfer from long to short photoperiod. After 14 weeks of treatment, testicular weight was significantly greater in animals given 20 IU hCG than In animals injected with saline, although it approximated only 50% of testicular weight In adult males kept in long photoperiod. Since we have previously obtained very similar results using prolactin (PRL) producing ectopic pituitary homografts, it was of interest to examine the interaction of pituitary grafts and hCG. Male hamsters were transferred to a short photoperiod and treated with a transplant of one pituitary from an adult female hamster plus 5 IU hCG three times a week or with hCG alone. After 15 weeks, the weights of the testes and the seminal vesides were significantly greater In grafted hCG‐treated hamsters than in those animals treated with hCG only. Testicular weight in animals given both grafts and hCG corresponded to approximately 75% of testicular weight in long photoperiod controls, while seminal vesicle weights in these two groups did not differ. To examine the role of endogenous PRL in long photoperiod‐induced testicular recrudescence, hamsters which had been exposed to a short photoperiod for two months were returned to a long photoperiod and treated daily with bromocriptlne (Sandoz CB‐154, an inhibitor of PRL release) or with vehicle. After three weeks, the weights of the testes and the seminal vesicles were significantly lower in bromocriptine‐treated than in control hamsters, but after five and a half weeks these differences were no longer evident. We conclude that (1) suppression of the release of both PRL and gonadotropins is responsible for gonadal regression in short photoperiod, and (2) stimulation of PRL secretion contributes to recrudescence of the male reproductive system in long photoperiod.