Effect of testosterone, estrone sulphate and androstenone on 3β-hydroxysteroid dehydrogenase protein expression in primary cultured hepatocytes

Androstenone (5 alpha-androst-16-en-3-one) is a steroid pheromone, excessive accumulation of which in pig adipose tissue contributes to the phenomenon of boar taint. The incidence of boar taint increases with age and weight of entire male pigs. One of the reasons for the excessive accumulation of androstenone in adipose tissue of some pigs is a low rate of androstenone degradation in pig liver, which is related to defective expression of the androstenone-metabolising enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD). The mechanism regulating 3 beta-HSD expression in pig liver remains unclear. The present study investigated the effects of the sex steroids testosterone, estrone sulphate and androstenone on the expression of 3 beta-HSD protein using primary cultured hepatocytes as a model system. The study was performed on hepatocytes from pigs of two weight/age groups: lighter weight (average carcass weight 70 kg, age 21 weeks) and heavier weight (average carcass weight 92 kg, age 26 weeks). Testosterone at the range of concentrations from 5 to 100 nM induced 3 beta-HSD expression in lighter weight pigs but not in heavier weight animals. In contrast, estrone sulphate (5 to 100 nM) and androstenone (5 to 500 nM) induced 3 beta-HSD expression only in heavier weight but not lighter weight pigs. Induction of 3 beta-HSD expression by the sex steroids was protein-synthesis-dependent. Overall this study demonstrates for the first time that sex steroids are involved in regulation of 3 beta-HSD protein expression in primary cultured pig hepatocytes and that the effect of sex steroids depends on age and weight of animals. The results of this work might contribute to understanding the mechanism controlling androstenone deposition in pigs. (C) 2007 Elsevier B.V. All rights reserved.