In vivo evidence for accelerated generation of hydroxyl radicals in liver of Long-Evans Cinnamon (LEC) rats with acute hepatitis

Abstract

The Long-Evans Cinnamon (LEC) rats accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson’s disease (WD) and spontaneously develop acute hepatitis with severe jaundice. Although hydroxyl radicals ( OH) have been proposed to be a cause of hepatitis by the accumulation of Cu, it is not clear whether or not OH can be produced in the liver of hepatitic LEC rats in vivo and also can be involved in the onset of hepatitis. In the present study, OH production in plasma and liver of hepatitic LEC rats was quantified by trapping OH with salicylic acid (SA) as 2, 3-dihydroxybenzoic acid (2, 3-DHBA). The ratios of 2, 3-DHBA/SA were significantly higher in plasma and liver of hepatitic LEC rats than those of Wistar rats and LEC rats showing no signs of hepatitis. Furthermore, the ratios of 2, 3-DHBA/SA in plasma and liver of hepatitic LEC rats were almost the same as those of Wistar rats treated orally with CuSO 4 (0.5 mmol/kg) 2 h before acetylsalicylic acid (ASA) injection. We also evaluated the protective effects of D-mannitol (a OH scavenger) treatment against acute hepatitis in LEC rats. D-mannitol (500 mg/kg) was administered intraperitoneally to 10-week-old LEC rats for 3 weeks. D-mannitol treatment suppressed the increases in serum aspartate aminotransferase activity and total bilirubin concentration. In addition, D-mannitol treatment significantly reduced hepatic mitochondrial lipid peroxidation, which is thought to be important in the pathogenesis of Cu-induced hepatotoxicity. These observations suggest that accelerated generation of OH catalyzed by free Cu in the liver may, at least in part, play a role in the pathogenesis of acute hepatitis in LEC rats.