Expression Of Toll-like Receptor4and Relative Inflammatory Factors In Obese Rats Fed By High-fat Diet

Objective：To investigate the expression of Toll-like receptor4in hypothalamus and liver ofobese rats fed by high-fat diet and and the change of TNF-α、IL-6in Serum.Methods：Thirty Sprague-Dawley male rats,4weeks old, weighs about80g, purchased fromSPF laboratory animal center of Dalian Medical University. The animals were randomlydivided into two groups: high-fat diet group (n=20) and normal diet control group (n=10).Both groups are fed for8weeks.To duplicate the obese rat model fed with high-fatdiet (diet-induced-obesity rats,DIO group). The TLR4expression of Hypothalamus andliver by immunohistochemical staining and Real Time PCR. The analysis of seruminflammatory factors TNF-α, IL-6changes by ELISA. Hypothalamus and liverimmunohistochemical staining and Real Time PCR of TLR4expression.Results：1．The daily food intake of DIO group feeding on the8th day was higher than thecontrol group, the difference was statistically significant (P<0.05); From12days to the36th day, the DIO group daily food intake was significantly higher than the controlgroup (P<0.01);44days later, the daily food intake of control group began higher thanobese rats.48days later, the daily food intake of control group was higher than obeserats(P<0.05).The energy intake of DIO group was higher than the control group; thedifference of food energy intake between two groups was significant (P<0.01). After8weeks, the average weight of DIO group (456.38±19.20) g was higher than the averageweight of normal diet control group (372.10±22.47) g; the difference between twogroups was significant (P<0.01).2．Real-Time PCR shows the fold of hypothalamus TLR4mRNA (0.56±0.16) inDIO group was higher than that in control group(0.39±0.10). The difference between two groups was significant (P<0.05).The fold of liver TLR4mRNA (0.87±0.24) in DIOgroup was higher than that in control group(0.54±0.16). The difference between twogroups was significant (P<0.01).3．Immunohistochemical staining showed that DIO rats hypothalamus and livercell cytoplasm was stained in yellow, and brown granules can be observed whichindicated targeted expression was strongly positive; control group expressed weakly.4．ELISA shows the fold of TNF-α in DIO group（300.36±27.17）pg/ml was higherthan that in control group（164.15±30.22）pg/ml. The difference between two groupswas significant (P<0.01).The fold of IL-6in DIO group（231.50±17.01）pg/ml washigher than that in control group（155.36±19.63）pg/ml. The difference between twogroups was significant (P<0.01).Conclusion：The increased TLR4expressions in hypothalamus and liver of obese rat indicatedthat inflammatory response in those two regions involved in the mechanism of high-fatdiet-induced obesity. The increased TNF-α and IL-6expressions in serum of obese ratindicated that TNF-α and IL-6were important cytokine involved in the high-fatdiet-induced inflammation.