Abstract:

Objective To study the effect of Echinococcus multilocularis infection on the activities of drug-metabolizing enzymes in gerbil liver. Methods Ten gerbils （Meriones unguiculatus） were randomly divided into 2 groups, the experimental group in which each animal was intraperitoneally injected with 300 μl E. multilocularis cyst homogenates （containing about 600 protoscoleces）, and the control group in which each animal received 300 μl saline（i.p.）. Five months after infection, the animals were sacrificed by cervical dislocation, and livers were collected. The liver microsomal and cytosolic fractions were obtained by differential centrifugation. Protein concentration was measured by the BCA method. CYP450 and Cyt b5 contents in the microsomal fraction were measured with differential spectroscopy. Activities of 7-ethoxyresorufin（EROD） and 7-methoxyresorufin（MROD） were measured by fluorescence spectrometry. The activities of NADPH-cytochrome C reductase（NCR）, glutathione-S-transferase （GST）, and flavine monooxygenases （FMO） were measured by UV-visible spectrophotometry. Results The protein content of cytosolic fractions and liver microsomes in experimental group was （11.089±1.277） and （3.212±0.924） mg/ml， those in control group was （12.459±1.625） and （3.894±0.395） mg/ml， respectively. The contents of CYP450 and Cyt b5 in the experimental group [（0.508±0.142）, （0.515±0.077） nmol/mg protein, respectively] were both significantly lower than those in the control [（0.647±0.090）, （0.596±0.051） nmol/mg protein]（P<0.05）. The GST activity decreased significantly in the experimental group ［（1.766±0.339）×103 nmol/（mg·min）］ compared with the control ［（2.001±0.160）×103 nmol/（mg·min）］（P<0.05）. But the FMO and NCR activities increased significantly in the experimental group ［（1.142±0.327） nmol/（mg·min） and （0.602±0.162）×103 nmol/（mg·min）, respectively］ compared with the control ［（0.882±0.150） nmol/（mg·min） and （0.442±0.082）×103 nmol/（mg·min）］（P<0.05）. However, there were no significant differences in EROD and MROD activities between the two groups（P>0.05）. Conclusion The activities of FMO and NCR markedly increase, while that of GST significantly decreases in the gerbil liver after E. multilocularis infection.

Key words: Echinococcus multilocularis, Meriones unguiculatus, Drug-metabolizing enzyme, Colorimetry