Reevaluation of the Effect of Follicle-Stimulating Hormone on the Steroidogenic Capacity of the Testis: The Effects of Neuraminidase-Treated FSH Preparations

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Abstract
The ability of FSH treatment to increase the amount of androgen produced by the testis in response to maximum LH stimulation may be an effect of the LH contamination of the FSH preparations. To examine this question, 3 FSH preparations of different potencies and degrees of LH contamination or their neuraminidase-treated derivatives were administered to hypophysectomized immature rats for 5 days. The capacity of the testes to produce androgens in vitro was assessed at the end of the treatment period. Neuraminidase treatment reduces the in vivo activity of ovine and bovine FSH but does not alter the activity of ovine or bovine LH. Neuraminidase treatment of one FSH preparation (NH-bFSH-B1) did not reduce the ability of this FSH preparation to increase the response of the testis to LH stimulation in vitro. This suggests that the considerable LH contamination of the NIH-bFSH-B1 may be responsible for its effect. However, neuraminidase treatment of 2 more highly purified FSH preparations (bFSH-199C and NIH-oFSH-S13) abolished or greatly reduced the ability of these preparations to increase testicular weight and the response to LH in vitro. It is concluded that the ability of highly-purified FSH preparations to increase the amount of androgen produced by the testis is due to FSH activity and not the contaminating LH.