LOBULAR DISTRIBUTION OF HUMAN LIVER PHENOL AND BILIRUBIN URIDINE 5-DIPHOSPHATE GLUCURONOSYLTRANSFERASE MESSENGER-RNAS

Background & Aims: Heterogeneity in uridine 5'-diphosphate (UDP) glucu ronosyltransferase expression across the human hepatic acinus may be i mportant in the manifestation of certain zone-specific chemical hepato toxicities. Previous immunohistochemical studies suggested that a phen ol transferase induced by polycyclic aromatic hydrocarbons may be diff erentially expressed in centrilobular hepatocytes of rats. The aim of this study was to assess the distribution of the phenol and bilirubin transferases in human liver at the RNA level. Methods: In situ RNA hyb ridization was used with two human liver samples and specific probes f or the phenol transferase RNA, HLUG P1, and the bilirubin transferase RNAs, HUG-Br1 and HUG-Br2. Results: The highest density signals were o bserved for the bilirubin transferase RNAs, both appearing to be evenl y expressed in hepatocytes across the liver lobule. Slightly higher de nsity of HUG-Brl message was observed in some centrilobular hepatocyte s surrounding larger central vein structures. HLUG P1 RNA was expresse d at low levels (approximate to fivefold greater than background signa l) and was evenly distributed. Conclusions: The data suggest that a sp ecies difference exists in the distribution of the human and rat pheno l transferase. No evidence was found for significant zonation in the p attern of expression of either the phenol or bilirubin transferase gen es in human liver.