EFFECTS OF SEX STEROIDS ON EXPRESSION OF ANDROSTENONE-METABOLISING ENZYMES IN ISOLATED PIG HEPATOCYTES

摘要

IntroductionBoar taint is a meat quality defect which occurs due to an excessive accumulation of two major compounds, skatole and androstenone, in pig adipose tissue (Bonneau, 1982). One of the reasons for high levels of skatole and androstenone is a low rate of degradation of these compounds in pig liver (Squires and Lundstrom, 1997; Doran et al., 2004). The pig hepatic skatole metabolism has been extensively studied, whilst metabolism of androstenone has received less attention. Androstenone metabolism involves two stages: oxidative and conjugative. Oxidative stage is catalysed by the enzyme 3 -hydroxysteroid dehydrogenase (3 -HSD), which reduces a keto-group at the 3-position to a hydroxyl-group in the -conformation (Doran et al., 2004; Sinclair et al., 2005). The second stage of androstenone metabolism is conjugation and involves sulfotransferases (SULTs). Sulfoconjugation increases the water solubility of steroids, facilitating their excretion (Sinclair et al. 2005). It has been previously established that pigs with high adipose tissue androstenone have a low hepatic 3 -HSD activity, mRNA and protein expression (Doran et al., 2004; Nicolau-Solano et al., 2006). The mechanism regulating expression of pig hepatic androstenone-metabolising enzymes is not clear. Since androstenone level is related to the hormonal status (Zamaratskaia et al., 2005), sex steroids might be one of the factors controlling expression of androstenone-metabolising enzymes, and hence the rate of androstenone degradation.The present study investigated effects of three sex steroids; testosterone, androstenone and estrone sulphate, on expression of pig hepatic 3 -HSD and SUL2B1 using primary cultured pig hepatocytes as a model system.