Sertoli Cell Function in the Androgen Insensitive (TFM) Rat

Abstract

The Sertoli cells of the androgen insensitive (tfm) rat are capable of producing androgen binding protein (ABP) both in vivo and in vitro. ABP levels in the tfm testis are significantly higher (P < 0.01) than that in normal littermates (NL); 2.9 ± 0.5 (SD) pmoles/mg protein and 63.7 ± 15 (SD) pmoles/testis in the tfm compared to 0.41 ± 0.07 pmoles/mg protein and 34.3 ± 6.7 pmoles/testis in the NL. However, ABP secretion rate in vitro is significantly lower in the tfm testis than that in the NL testis; 0.12 ± 0.02 (SD) pmol/testis per h and 0.31 ± 0.06 pmol/testis per h respectively. Thus, the increased levels of ABP in the tfm testis does not reflect increased ABP secretion, but is due to the atresia of the excurrent ducts and accumulation of seminiterous tubular secretion. The tfm testes show a higher concentration of FSH receptors than that in NL (171 fmoles/mg protein and 57 fmoles/mg protein respectively). However, when FSH binding is calculated per testis, binding capacities in tfm and NL testis are very similar (632 fmoles/testis and 798 fmoles/testis respectively). The present study shows that normal induction of FSH receptors is not dependent on the presence of an androgen receptor and that production and secretion of ABP is taking place in a situation where the target cells are insensitive to physiological doses of androgen.The reduction in ABP secretion rate in vitro in the tfm rat testis supports previous studies showing that both FSH and androgens are important for normal Sertoli cell function.