[Studies on the existence of renin in the human testis]

Recent reports have shown the existence of renin in Leydig cells of the rat testis and immunoreactive renin activity in the human testis. But we could not rule out the possibility that the renin found in the testis is contamination of plasma components by endocytosis. In the present study we tried to demonstrate the renin production in the human testis by the following experiments. At first, we measured the plasma renin activity and testosterone in the internal spermatic vein simultaneously after treatment with hCG and obtained the results that suggested hCG-induced renin secretion in the human testis. Next, we showed the hCG-dependent renin production from the cultured human Leydig cell tumors in vitro. Thirdly, we demonstrated the existence of renin mRNA in the human testisusing reverse transcriptase-polymerase chain reaction (RT-PCR). Fourthly, we detected significant signals of human renin mRNA in the human testicular tissues by in situ hybridization. From the above results, it was demonstrated that the human renin gene was hCG-dependently expressed in the human testis.