Electron paramagnetic resonance analysis of liver and serum in Sprague-Dawley rats exposed subchronically to coplanar pentachlorobiphenyl-congener 3,3',4,4',5

Abstract

A unique electron paramagnetic resonance (EPR) signal was found at g = 2.49 at 77 K in the liver tissues or microsomes of Sprague–Dawley rats that were exposed to 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by the oral route. This unique EPR signal was not detected in the liver excised from rats treated with carbon tetrachloride or 3-methyl-cholanthrene. The EPR signal intensity increased in proportion to the dose; no gender-specific difference was noted and the EPR signal at g = 2.49 may have originated from heme-iron in cytochrome P450. Although, several serum parameters of the PCB126-treated rats were slightly higher than those of the control, PCB126 does not induce hepatic dysfunction at the dose range used in this study. 3,3′,4,4′,5-Pentachlorobiphenyl was given daily via the oral route to pregnant rats. The rats were reared until Day 22 of pregnancy, after which they were killed and EPR signals were obtained from the fetal livers. A signal at g = 2.49 was observed for each fetal liver. These results indicate that the EPR signal at g = 2.49 could be appropriate as a biomarker of exposure to PCB126 or TCDD in the situation where hepatic dysfunction is not detected.