Endocrine Abstracts

The enzymatic inactivation of cortisol is catalysed by isoforms of 11βHSD. 11βHSD1 is a bi-directional, NADP(H)-dependent enzyme whereas11βHSD2 is an NAD⁺-dependent dehydrogenase that inactivates cortisol. In the male rat, 11βHSD1 is highly expressed in the testis, epididymis, vas deferens and vesicular glands. Although 11βHSD activities have recently been reported in boar testicular tissue, cortisol metabolism in the boar reproductive tract has not yet been investigated. The objective of this study was therefore to assess cortisol oxidation by 11βHSD enzymes in boar testis and specific regions of the reproductive tract. Boar liver, kidney, testis and reproductive tracts were obtained from slaughterhouse material from 5 animals. Sperm samples were collected from fertile boars undergoing regular semen collection. Rat kidney homogenates +/−10 μM carbenoxolone served as negative and positive controls, respectively, in each assay. All tissue and sperm homogenates were incubated in triplicate with 0.5 μCi (7.25 pmol) ³H-cortisol plus nucleotide cofactors (4 μmol) in a final assay volume of 1 ml for 24 hrs. ³H-steroids were then extracted, resolved by TLC and quantified using a radiochromatogramme scanner. 11βHSD activities were highest in porcine liver and kidney incubated with NADP⁺ and NAD⁺ respectively. Testis exhibited high rates of cortisol oxidation in the presence of both NADP⁺ and NAD⁺(0.93+/−0.25 and 1.39+/− 0.15 pmol/mg.24 h respectively). Moderate rates of cortisol oxidation were observed in bulbourethral glands incubated with NADP⁺(0.38+/−0.07 pmol/mg.24 h) and in penile urethra incubated with NAD⁺(0.41+/−0.06 pmol/mg.24 h). However, levels of cortisol metabolism were low (<0.1 pmol/mg.24 h) in all regions of the epididymis, vas deferens, vesicular glands, prostate gland and in ejaculated sperm, irrespective of the nucleotide cofactor. We conclude that NADP⁺- and NAD⁺-dependent 11βHSD enzymes can inactivate cortisol in the boar testis, bulbourethral glands and penile urethra, but may have limited impact on the cortisol concentration in other regions of the boar reproductive tract or in boar sperm.