hCG suppression of LH receptors and responsiveness of testicular tissue to hCG.

摘要: A single injection of 75 IU human chorionic gonadotropin (hCG) into adult male rats caused a dramatic reduction in the concentration membrane receptors for luteinizing hormone (LH) testis. The mean receptor level reached nadir which was 5--10% that control testes, 3 days after injection, it gradually returned toward normal. This cannot be due to increased competition by injected hCG since no decrease observed at time when circulating levels were maximum (2--24 h injection). Furthermore, had been maximally reduced, or below detection. Reduction number LH binding sites testis associated with decreased responsiveness testicular tissue as measured hCG-stimulated testosterone production vitro. inhibitory effect large quantities on its own is suggested possible explantation previously low concentrations feminized (tfm) rat. syndrome characterized high endogenous plasma (Sherins et al., 1971).