Characterisation of 11β-hydroxysteroid dehydrogenase (11βHSD) expression and activity in the pre- and post-pubertal porcine (sus scrofa) testis and male reproductive tract
V Sharp1, RC Fowkes1, LM Thurston1 & AE Michael2
Cortisol is metabolised by 11β-hydroxysteroid dehydrogenase enzymes (11βHSD1 and 11βHSD2). In immature rat Leydig cells, 11βHSD1 acts as an oxo-reductase whereas, after puberty, the dehydrogenase activity of 11βHSD1 predominates. In adult rats, 11βHSD1 is also highly expressed in caput epididymis, vas deferens and vesicular glands. Recently, 11βHSD1 mRNA and activities have been reported in post-pubertal pig testis. The objective of this study was to examine the expression and activity of 11βHSD enzymes in porcine testis and reproductive tract before and after puberty. Testis and reproductive tracts from pre- and post-pubertal pigs (n=3 and n=5, respectively) were collected prior to RNA and protein purification. 11βHSD expression and function were determined by RT-PCR, Western blotting and enzyme activity assays. 11βHSD1 and 11βHSD2 mRNA and protein were expressed in both pre- and post-pubertal testis and all reproductive tract tissues. 11βHSD2 activity was highest in pre-pubertal pig testis, caput epididymis, bulbourethral glands and penile urethra (13.5±2.5 pmol P<0.05, 0.8±0.6 pmol, 3.0±1.4 pmol and 1.7±0.8 pmol cortisone/mg protein.24 h, respectively) and remained predominant in post-pubertal penile urethra (1.4±0.3 pmol cortisone/mg protein.24 h). A switch to predominant 11βHSD1 dehydrogenase activity (3.4±1.1 pmol cortisone/mg protein.24 h) was observed in post-pubertal bulbourethral glands. In pre-pubertal pig testis, 11βHSD1 acted predominantly as an oxo-reductase (4.9±1.1 pmol cortisone/mg protein.24 h) but after puberty this enzyme only exhibited dehydrogenase action with comparable levels of NADP+- and NAD+-dependent cortisol oxidation (2.7±1.0 and 2.7±0.4 pmol cortisone/mg protein.24 h, respectively). In post-pubertal caput epididymis, a switch to predominant oxo-reductase activity was observed (0.5±0.1 pmol cortisol/mg protein.24 h P<0.05) suggesting a need for increased local concentrations of cortisol in the caput epididymis. 11βHSD enzymes predominantly inactivate cortisol in both pre- and post-pubertal testis, bulbourethral glands and penile urethra, suggesting that these enzymes may protect against the adverse effects of cortisol in these male reproductive tissues.