Acute hCG administration induces seminiferous tubule damage in the adult rat.

In order to study the early (or short time) effects of an hCG stimulation on the seminiferous tubules of the adult rat, a single dose of 100, 200 or 400 IU hCG was administered to eighty to ninety day old rats of the Sherman strain. The histological analysis revealed a tubular damage already noticeable six hours after the injection. This precocious lesion becomes more pronounced two to five days later, consisting of degeneration and hypocellularity of the germinal epithelium, margination of the chromatin in round spermatids and formation of multinuclear giant cells. This damage involves big areas of the testis, particularly of peripheral location. The analysis performed three months after the acute stimulation still showed tubular regressive changes, thus indicating an incomplete reversion of the damage. Changes in the hormonal environment of hCG treated rats were found. Serum testosterone significantly increased from 6 to 72 hours following a 200 IU hCG injection. A severe diminution of serum FSH levels and a significant increase of the serum estradiol were observed. Intratesticular administration of estradiol benzoate was able to reproduce the tubular damage in some animals, while restoration of FSH circulating levels by simultaneous administration of hCG and purified hFSH did not prevent the changes induced by hCG alone. These results suggest that the high intratesticular level of estradiol and not the lowering of serum FSH might be the mechanism responsible for the described testicular injury.