Risk assessment of environmental oxidative chemicals using catalase mutant primary cultured hepatocytes

More and more chemicals are synthesized for industrial and consumer use, it is impossible to finish long-term rodent bioassay for identification of environmental hazards in all chemicals because it involves large numbers of animals and is extremely expensive. Therefore, simple and efficient pre-screening alternatives to animal experimentation are desirable. This study attempted to develop a risk assessment method to accurately identify environmental oxidative chemicals and assess their potential toxic effect at low doses on biological systems. Primary cultured hepatocytes from catalase-mutant mice (Csb) and wild type (Csa) were isolated using collagenase perfusion techniques. The catalase level of Csb was 73% of Csa. We preliminarily examined hydroquinone, a widely used chemical in clinical situations and cosmetics industry because of its inhibitive effect of melanin formation. We found that even low dose of hydroquinone exposure reduced the cell viability significantly and increased cytochrome P450 CYP2E1 mRNA expression with negative correlation to catalase levels. The mRNA level of CYP2E1 was increased about 1.5-fold after 24hr exposure to 0.4mM hydroquinone in Csb relative to Csa. Pretreatment of resveratrol markedly suppressed hydroquinone toxicity, particularly in Csb. Oxidized glutathione (GSSG) levels in Csb was significantly increased by hydroquinone in comparison with Csa. Hydroquinone-induced cell apoptosis was also observed in both Csa and Csb. The present results suggest a possibility of this test system for environmental hazard assessment of oxidative chemicals.