ENZYME-SPECIFIC AND SEX-SPECIFIC DIFFERENCES IN THE INTRALOBULAR LOCALIZATIONS AND DISTRIBUTIONS OF ARYL SULFOTRANSFERASE-IV (TYROSINE-ESTER SULFOTRANSFERASE) AND ALCOHOL (HYDROXYSTEROID) SULFOTRANSFERASE-A INRAT-LIVER

Aryl sulfotransferase (AST) IV and alcohol (hydroxysteroid) sulfotrans ferase a (STa) catalyze the formation of sulfuric acid esters from a d iverse array of xenobiotic and endogenous molecules in the liver, Desp ite the fact that many studies have addressed the metabolic importance and catalytic characteristics of these two sulfotransferases, relativ ely little is known about their comparative in situ localizations and intralobular distributions in liver. The present investigation utilize d specific rabbit antisera prepared against AST IV and STa for immunop eroxidase staining of serial sections from livers of male and female S prague-Dawley rats and computer-assisted image analysis of immunohisto chemical staining intensity by means of microdensitometry. The overall concentration of AST IV was greater in males than in females, althoug h the intralobular distribution of the enzyme was similar in the liver s of both male and female rats, wherein centrilobular hepatocytes cont ained a greater level of AST IV than did midzonal cells, and midzonal hepatocytes had a greater concentration of AST IV than did periportal hepatocytes. In marked contrast, STa was present in livers of female r ats at a much greater overall concentration than in livers of male rat s, Furthermore, whereas the intralobular distribution of the enzyme wa s similar in both males and females, STa was present at greater concen trations in periportal hepatocytes than in midzonal hepatocytes and at greater concentrations in midzonal cells than in centrilobular hepato cytes. Significant intrazonal heterogeneity in STa levels within hepat ocytes was also observed, particularly in livers of female rats. These results indicate that, whereas the overall hepatic concentrations of these enzymes are clearly sex-dependent, the intralobular distribution s of AST IV and STa are characteristic of each particular sulfotransfe rase.