Objective To examine the enzyme activities and protein expressions of liver CYP1A2 and CYP2E1 in rats exposed to organic extracts from drinking water, and to provide evidence for health risk assessment for local drinking water and elucidation of its hepatotoxicity.
Methods Organic pollutants in drinking water were extracted by solid-phase extraction method. A total of 40 SD rats were randomly divided into four groups. The control group was administered with corn oil. The exposed groups were administered respectively with the organic extracts at 5, 20, and 80 L/(kg· d). The exposure by gavage lasted 12 weeks. Fluorescence spectrophotometry and chromatometry were applied to evaluate the activities of CYP1A2 and CYP2E1 respectively. The protein levels of CYP1A2 and CYP2E1 were measured by Western blot method.
Results Compared with the control group, the enzyme activity of CYP1A2 in the 80 L/(kg· d) group increased remarkably (P<0.05); the enzyme activities of CYP2E1 in the 20 L/(kg· d) group and 80 L/(kg· d) group both increased significantly (P<0.05). With the rise of exposing dose, the expression of CYP1A2 protein significantly increased in the 80L/(kg· d) group (P<0.05). Compared with the control group, the expression of CYP2E1 protein obviously increased in the 20L/(kg· d) group and the 80 L/(kg· d) group (P<0.05).
Conclusion Exposed to high level of organic extracts from the local drinking water could result in the up-regulated expressions of CYP1A2 and CYP2E1 proteins, and then induce the rise of CYP1A2 and CYP2E1 enzyme activities. This might be one of the important mechanisms for liver damage.
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