Plasma FSH, LH and testosterone levels in the male rat during degeneration of the germinal epithelium caused by severe heat treatment or ligation of the vasa efferentia

Effect on gonadotrophin secretion of blockage of the ductuli efferentes in the normal and androgen-deprived rat

“…Therefore blockage of the ductuli efferentes should retain the products of the seminiferous epithelium, including inhibin, within the testes, and a preferential rise of FSH could then be predicted if inhibin is absorbed by this route, especially if the steroid secretion from the Leydig cells was not impaired. This indeed was found in this study, both treatments resulting in a preferential rise in serum FSH with no change in LH and, possibly, androgen secretion, thus confirming the results of others (Collins, Collins, McNeilly & Tsang, 1978;Main et al, 1978;Morris & Jackson, 1978a). However, the question arises as to whether the increased FSH secretion is due to (a) denial of inhibin to its site of absorption, (b) subsequent degeneration of the seminiferous epithelium, (c) the impairment of Leydig cell function because of the dramatic changes in testicular weight and turgidity which may obstruct the lymphatic and venous drainage, or (d) a combination of these factors.…”

“…However, serum LH, androgen-dependent organ weights and serum androgens were not changed in this experiment or in those of others (Collins et al, 1978;Main et al, 1978) although Morris & Jackson (1978a) (Swerdloff & Walsh, 1973). Changes in Leydig cell function can occur in the aspermatogenic testes without any gross changes in the secondary sex organs.…”

“…While a gross correlation can be made that chronically FSH levels are raised in the presence of aspermia, acute increases in FSH may be detected at a time when the major components of spermatogenesis are still present (Collins et al, 1978;Main et al, 1978). Also the Sertoli cell, the possible source of inhibin, is still functioning which is reflected by the increase in testes weight (Rich & de Kretser, 1977).…”

Effect of scrotal insulation on the pituitary--testicular axis of the ram

“…The effects of high ambient temperature, local heating of the scrotum and cryptorchidism on spermatogenesis are well known and relatively consistent (VanDemark & Free, 1970;Blackshaw, 1977). However, the effects of these treatments on the endocrine status of the testis in vivo are not as clear (Collins, Collins, McNeilly & Tsang, 1978;Main, Davies & Setchell, 1978 ;Damber, Bergh & Janson, 1978). The purpose ofthe present study was to examine the effects of heat-induced testicular damage on plasma concentrations of hormones to clarify some of the relationships between gonadal hormones and the pituitary gonadotrophins.…”

“…Several earlier investigations into the hormonal changes that accompany injury to the testes have demonstrated considerable variation in the concentrations of LH and testosterone (Collins et al, 1978 ;Main et al, 1978). Because of this variation, quite large changes in mean values obtained for these hormones are sometimes dismissed as being insignificant.…”