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.

Testicular Gonadotropin Receptors, Testicular Testosterone, Dihydrotestosterone and Androstenedione in the Developing Bull

“…That bovine testicular membranes possess a ten times higher binding capacity for hFSH than for hLH confirms a previous report [4]. This is probably not due to differences in purities or biological activities of the hormones used, since in the rat the binding of hFSH is some five times lower than that of LH [2,8,211. The fact that the prepubertal bulls exhibited high binding capacity with regard to both gonadotropins implies that they have already at this stage achieved receptors required for responsiveness to gonadotropins.…”

Extracellular Androgen Binding Proteins

“…Nonetheless, it has been used to study Sertoli cell physiology (11,18). Decreased ABP activity in cryptorchidism (17), inher ited seminiferous tubular failure (37), and other disorders (15,19) suggests this protein may also be used as an index of testicular pathophysiology.…”

Temporal Relationship Between hCG Induced Desensitization of LH/hCG Responsive Adenylyl Cyclase and Down regulation of LH/hCG Receptors in the Rat Testis

“…Nonspecific binding was assessed by incubating parallel tubes with an excess of unlabeled hCG (10 IU). Details of the LH binding assay and iodination technique have been described previously [9].…”