DIFFERENTIAL-EFFECTS OF THE ADMINISTRATION OF HUMAN CHORIONIC-GONADOTROPIN TO POSTNATAL RATS

Neonatal and prepubertal male rats were treated with human chorionic g onadotropin (hCG, 5 IU/g body weight per day) on days 2-4 or 20-22. De pending on the date of treatment, different groups of rats were sacrif iced at 5, 23, 30 and 100 days of age, in order to study the short- an d long-term effects of the treatment with hCG on the development of th e testes and sex accessory organs. Rats treated with hCG on days 2-4 s howed increased number and size of foetal Leydig cells at 5 days of ag e. However, long-term effects include decreased numbers of adult-type Leydig cells, decreased weight of the testes and sex accessory organs, decreased basal and hCG-stimulated testosterone secretion, and delaye d balano-preputial separation. In contrast, animals treated with hCG o n days 20-22 showed similar short- and long-term effects, consisting o f increased number of adult-type Leydig cells and macrophages, increas ed weight of the testes and sex accessory organs and advanced balano-p reputial separation. In adulthood, both groups showed normal reproduct ive function. These results seem to indicate that the effects of hCG t reatment in prepubertal rats are dependent on the type of Leydig cell stimulated, and suggest that foetal Leydig cells play a regulatory rol e in the early postnatal testicular development.