The effect of testosterone propionate on the concentration of testicular and epididymal androgen binding activity in the hypophysectomised rat

Abstract

The effect of testosterone propionate on the level of androgen binding activity in both testis and epididymis was investigated by both a dextran coated charcoal (DCC) method and by equilibrium polyacrylamide gel electrophoresis (PAGE) which measures specifically androgen binding protein. There was a decrease in androgen binding activity in both testis and epididymis after hypophysectomy. Testosterone propionate treatment (1 mg/day), begun at one day posthypophysectomy, maintained androgen binding activity above the level in testes from hypophysectomised rats for 30 days (PAGE) or 60 days (DCC) and 60 days in epididymides (PAGE). The ability of testosterone propionate treatment (250, 500 and 750 μg/day) to restore androgen binding activity in testis and epididymis of chronically hypophysectomised rats (30 days) was tested using a 3-day treatment period. These doses restored testicular androgen binding activity to 60, 36 and 75% of the levels in control animals, respectively. The degree of restoration of androgen binding activity in epididymis in this time interval was inferior to that in the testis at all doses. Prolonged treatment with testosterone propionate (1 mg/day for 10, 30 and 60 days) resulted in complete restoration of androgen binding activity in testis, expressed per mg protein (PAGE and DCC), and over 50% restoration in the epididymis (PAGE). It was concluded that testosterone propionate is able to maintain and restore testicular and epididymal androgen binding activity and, in particular, androgen binding protein, after hypophysectomy and that this hormone may, in the short term, influence testicular rather than epididymal levels of binding activity.