Expression and activities of 11βHSD enzymes in the testes and reproductive tracts of sexually immature male pigs

In light of studies implicating glucocorticoids in the control of testicular steroidogenesis and/or spermatogenesis, the objective of this study was to characterise the expression and activities of the 11β-hydroxysteroid dehydrogenase (11βHSD) enzymes in the testis and reproductive tract of the pre-pubertal pig. Although 11βHSD1 and 11βHSD2 mRNA transcripts and proteins were co-expressed in all regions of the reproductive tract, cortisol-cortisone inter-conversion was detectable in the testis, caput epididymidis and bulbourethral glands only. In homogenates of these 3 tissues, the apparent Km for NADP+- and NAD+-dependent 11β-dehydrogenase activities ranged between 152-883 and 47-479 nmol l−1, respectively. Irrespective of the pyridine nucleotide co-substrate, estimates of Vmax were consistently two orders of magnitude higher in the testis. Moreover, while, in each tissue, levels of cortisol oxidation were comparable in the presence of either NADP+ or NAD+, maximal rates of NAD(P)+-dependent cortisol oxidation were up to 33-fold greater than the Vmax for NADPH-dependent reduction of cortisone. We conclude that in the testis, caput epididymidis and bulbourethral gland of the immature pig, NADP+- and NAD+-dependent 11βHSD enzymes catalyse net inactivation of cortisol, suggesting a physiological role for these enzymes in limiting local actions of glucocorticoids within these male reproductive tissues prior to puberty.