Effects of PRL and FSH on LH binding and number of Leydig cells in hypophysectomized mice

The effects of PRL and FSH on testicular LH receptors were studied in hypophysectomized (hypox) mice. From the eleventh day after hypophysectomy, they were given 100 μg ovine (o) PRL and/or 2 μg oFSH in two injections per day for 10 days. Hypophysectomy reduced the weight of testis, epididymides and seminal vesicles, and the LH binding to the testis. Treatment with oPRL and/or oFSH in hypox mice resulted in an increase in the weight of testis and epididymides, and the LH binding per testis. There was no difference between the testicular LH binding in oFSH- and oPRL-treated mice. Histological examination showed that oPRL and/or oFSH treatment in hypox mice restored normal spermatogenesis. Administration of oFSH to hypox mice led to an increase in the number of typical Leydig cells, whereas oPRL was not effective. These results suggest that either PRL or FSH stimulates the LH binding to the testis, but that the action of PRL and FSH on the increase in testicular LH binding is different.