Hormonal Influences on the Level of Testicular Androgen Binding Activity: Effect of FSH Following Hypophysectomy

Abstract

Concentrations of high affinity (Ka equals 5.5 plus or minus 0.83 times 10-8M-1) androgen binding activity in carbonextracted rat testicular supernatants have been determined by Scatchard plot analysis under a variety of hormonal situations: (a) 0-90 days following hypophysectomy; (b) 0-60 days of daily injection of NIH-FSH-P1 (150 mug) beginning 1 day after hypophysectomy; and (c) 0-60 days of daily FSH treatment beginning 30 days after hypophysectomy. The high affinity binding component declined from 0.32 pmoles/mg protein intact adults to 0.28, 0.17, and less than 0.08 (limit of detectability) pmoles/mg protein at 11, 16 and 31 days, respectively. FSH treatment beginning immediately after surgery slowed this decline, giving values of 0.30, 0.17, and 0.12 pmoles/mg protein after 11, 29, and 54 days of treatment, respectively. Expressed as pmoles per testis this represented 96, 61, and 40% of the intact control level. Similar effects on the level of androgen binding protein (Rf 0.54) were measured by steady-state polyacrylamide gel electrophoresis (PAGE). The concentration in both testis and epididymis declined gradually to nondetectable levels by 30 days after surgery. FSH treatment for 11, 29, and 54 days, respectively, resulted in 0.37, 0.38, and 0.03 pmoles of sites/mg protein in testis compared to 0.34 in intact controls and 5.7, 2.6, and 0.2 pmoles/mg protein in epididymis compared to 2.8 in intact controls. Doses of 80, 150, and 300 mug FSH/rat/day for 3 days beginning 30 days after hypophysectomy when postmeiotic elements of the germinal epithelium had degenerated caused graded increases in both testicular and epididymal levels of androgen binding protein. Prolonged FSH treatment (150 mug) under these conditions resulted in an increase in binding activity to a level of 0.12, 0.19, 0.17, and 0.20 pmoles/mg protein after 3, 11, 25, and 56 days of treatment. On a per testis basis this represented less than 20% of intact control levels. PAGE estimates were comparable except at the long treatment intervals. These results indicate that FSH treatment influences the level of androgen binding protein in adult testis and epididymis. This may reflect a direct influence on synthesis, degradation, and transport and/or indirect effects on general maintenance and responsiveness of the pertinent cell types.

Effect of streptozotocin-induced hyperglycaemia on androgen-binding protein in rat testis and epididymis

“…Slices were counted for radioactivity 48 h after addition of scintillation fluid (Quickszint 212; Zinsser, Frankfurt/Main, FRG) with an efficiency of 32% in a TriCarb model 2650 spectrometer (Packard, Frankfurt/Main, FRG). The ABP content was normally calculated from five fractions (Rf=0.46) with elevated radioactivity (in comparison to the basal activity) and could be clearly distinguished [8] from a small peak representing se-rum albumin (Rt = 0.67). A third peak of radioactivity reported to represent androgen receptor [15] could not be detected.…”

“…Although a specific androgen-binding protein (ABP) was shown several years ago to be a marker of Sertoli cell function [8][9][10][11][12][13], ABP measurements in diabetic rats have been reported in only one study [2]. A paradoxical increase of ABP content (expressed as lxl-equivalent of epididymal cytosol standard) of the testes (the site of production) but no change of ABP content of the epididymis (a possible site of action) has been found in rats 4 weeks after streptozotocin injection [2].…”

Rat androgen-binding protein: evidence for identical subunits and amino acid sequence homology with human sex hormone-binding globulin.

“…Immunochemical studies and studies utilizing a steady-state polyacrylamide gel electrophoresis binding assay have demonstrated that cellular ABP levels and secretion of ABP are regulated by follicle-stimulating hormone and androgens (11)(12)(13)(14)(15)(16). Studies with the purified epididymal protein have shown that the native protein has a molecular weight of 85,000-100,000 (9,10).…”

Sertoli cell ultrastructure. II. Morphological effects of hypophysectomy in pubescent pigs

“…Recent work has determined that the Sertoli cells of hypophysectomized rats continue to maintain an efficient blood-testis barrier (Hagenas et al, 1978) ; these data were obtained with a lanthanum-immersion technique (Neaves, 1973 ;Hagends et al, 1977). Testicular ABP production disappeared after hypophysectomy, but was reestablished by FSH administration (Hansson et al, 1973 ;Fritz et al, 1974 ;Hansson et al, 1974 ;Sanborn et al, 1974 ;Vernon et al, 1974 ;Sanborn et al, 1975 ;Tindall et al, 1975). This ABP production was maintained or restored in adult hypophysectomized rats given a testosterone treatment Aumüller et aI., 1978), but when only the androgen was used in prepuberal hypophysectomized animals, the function was not re-established.…”

“…The effects of hypophysectomy on Sertoli cells have been studied numerically and structurally by Courot (1970Courot ( , 1971, Bressler (1976), Aumiiller et al (1978) and Hochereau-de-Reviers and Courot (1978). These same effects have been reviewed from a functional viewpoint by Johnson (1970) and Hagends et al (1978), who reported on the blood-testis barrier, and by Fritz et al (1974), Vernon et al (1974), Sanborn et al (1974Sanborn et al ( ,1975, Weddi ngton et al (1975 and Aumiiller et al (1978) as concerns the production of androgen-binding protein (ABP). Recent work has determined that the Sertoli cells of hypophysectomized rats continue to maintain an efficient blood-testis barrier (Hagenas et al, 1978) ; these data were obtained with a lanthanum-immersion technique (Neaves, 1973 ;Hagends et al, 1977).…”