| Objective: To investigate the effect of peroxisome proliferator activated receptors α(PPARα) in rat hepatocytes on nonalcoholic fatty liver (NAFL) and to explore the mechanism in fatty acid metabolization.Methods: (1) 95 Wistar rats were randomly divided into basic diet-treated group (C group), high fat diet-treated group (H group), basic diet and gemfibrozil -treated group (BG group), high-fat diet and gemfibrozil -treated group (HG group) and high-fat diet for 8 weeks and gemfibrozil-treated after 4weeks (HG' group). Meanwhile each of the former four groups were divided into 4 subgroups (1 week, 2 week, 4 week, 8 week) respectively, and HG'group were divided into 3 subgroup (5 week, 6 week, 8 week ).Each subgroup has 5 rats. (2) The following parameters were observed dynamically in each group: ①changes of animal weight, liver weight, liver weight index, ② changes of liver pathology by HE staining with microscopy, ③ expression of PPARα of mRNA and protein with semi-quantitative method (RT-PCR) and Western blotting respectively; ④ distributions of PPARα in liver tissues with immunohistochemistry; ⑤ changes of mRNA expression of fatty acid oxidation related genes such as Long-chain acyl-CoA dehydrogenase (LCAD), Acyl-CoA oxidase (ACO), Cytochrome P450 A1 (CYP450A1) with RT-PCR and ⑥ levels of triglyceride (TG), malondialdehyde( MDA )in liver tissues and TG, alamine—aminotrasferase (ALT), free fatty acid (FFA) in serum. Results: ①After 8 weeks, animals'weight in H group increased significantly as compared with that in other groups (P<0.05),and no obvious difference of rats'weight in other groups was observed (P>0.05); For liver weight, the order was HG group >H group > BG group >C group, and the differences in every two groups were distinctive(P<0.05), while no difference was observed between HG′group and HG group(P>0.05). ② Results of HE staining showed that mild fatty liver appeared at 4 weeks, and moderate to severe fatty liver at 8 weeks. ③ In BG, HG, HG'groups, mRNA and protein expression of PPARα peaked at 1 week after using gemfibrozil (P<0.05), and decreased gradually, but still remained higher significantly compared with that in C group (P<0.05); in H group,they elevated remarkably at 1 week(P<0.05), peaked at 2 weeks,decreased gradually, but still remained higher significantly compared with that in C group (P<0.05); Compared with the subgroup at the same time point, mRNA and protein expression of PPARα in C, H, BG groups increased sequentially ; and the significant differences among groups were observed (P<0.05); No obvius difference was observed between HG and BG groups (P>0.05). ④ Compared with C group, the increasing positive brown staining in hepatocytes was observed in H group, BG group and HG group. But no difference was observed among H group, BG group and HG group. ⑤ Changes of mRNA expression of fatty acid oxidation related genes such as LACD, AOX and CYP450A1 were similar to changes of PPARα. ⑥ Levels of TG and MDA in liver tissues in H group were obviously higher than those in HG, BG and C groups at 2 weeks, and with time passing by ,they increased gradually and remarkably (P<0.05). Levels of TG, MDA in HG, BG and C groups were similar to those in H group; in HG'group, they decreased gradually (P<0.05) and restored to normal at 8 weeks (P>0.05); Changes of levels of ALT, TG and FFA in serum were similar to those in tissues , but in BG group, changes of levels of ALT were not obvious compared with those in C group. Conclusions: 1. PPARα in rat hepatocytes and fatty acid oxidation regulated by which have close relationship with NAFL, and fatty acid metabolism regulated by PPARα is an adapatable reaction to high fat diet. 2. Enhanced PPARα expression with gemfibrozil may decrease the levels of serm TG and FFA in high fat diet rats by regulating fatty acid metabolism related gene ; and that can not only prevent the occurrence of NAFL induced by high fat-diet, but also has therapeutic effect on the early stage of NAFL. 3. Enhanced PPARα expression...
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