| Objective:This paper investigated the effects of exercise and2,3,7,8-TCDD on the hepatic lipid anabolic in the SD rats, and explored the mechanism of the effects. The aim is to develop a new knowledge of the pathogenesis of metabolic diseases, and provide a corresponding support for the hypothesis that exercise might prevent the metabolic deseases caused by dioxin-like environmental pollutants.Methods:SD rats (8weeks old) were divided into4different groups randomly:control group (C), exercise group (E), T group treated with2,3,7,8-TCDD, and ET group treated with exercise and2,3,7,8-TCDD. Rats in groups T and ET were intraperitoneally given2,3,7,8-TCDD in a first dose of6.4μg/kg·bw, and thereafter, they were administrated a mantenance dosage by21%of the first dose weekly for7weeks. Groups E and ET swam30min every day with a tail load of5%body weight for5days per week. The healthy status of the rats was daily observed. The blood samples were collected through the inner canthus vein at the end of1st,3rd,4th,6th,8th weekends, and then the serum lipid indicators were measured. Half groups of the rats were killed at the4th and8th weekends respectively, and the relative weights of the organs were calculated. The liver tissues were collected to conduct the biochemical parameter measurements and histopathological detections. ACC1, FAS, SCD1, LXRa, SREBP-1, ChREBP mRNA and protein expression were determined via real-time quantitative PCR and Western Blot methods.Results:(1) All rats were in good mental state and normal activity. And the body weights showed a growth trend, but there were differences between each group. The relative weights of the livers significantly increased in the rats of groups ET and T. The relative weights of epididymal fat greatly decreased at the4th weekend in the rats of group ET.(2)2,3,7,8-TCDD showed a significantly increasing effect on the TG concentrations in livers, while long-term exercise might have a deceasing effect. Rats in group E had the lowest serum TG and TC concentrations, while that of rats in groups ET and T showed a increasing trend. The serum concentrations of LDL-C significantly increased in rats of groups ET and T, but the serum HDL-C concentraions of rats in group E increased.(3) Results of HE and Oil Red0staining of the liver tissues demonstrated that2,3,7,8-TCDD may induce obvious pathological changes and lipid infiltration, which can be improved by long-term exercise.(4) Continuous exposure to2,3,7,8-TCDD may significantly increase mRNA and protein expression of enzymes (ACC1, FAS, SCD1) and transcription factors (LXRa, SREBP-1) related to the lipid synthesis. Long-term exercise may significantly decrease the above mRNA and protein expressions. The interactions in some indicators between2,3,7,8-TCDD exposure and exercise treatment showed an antagonistic effect.Conclusions:(1)2,3,7,8-TCDD may effect on the mRNA and protein expression of the hepatic lipid anabolic related enzymes and transcription factors, and consequently result in the lipid metabolism disorders.(2) The influences of exercise on hepatic lipid anabolic showed a time effect, indicated that only long-term exercise might have an evident effect. However, further studies should be conducted to investigate the mechanism.(3) Long-term exercise can improve the lipid metabolic disorders caused by2,3,7,8-TCDD. |
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