| Currently,the overweight or obese is more than one billion around the world. Among them about 20% of which come from China. World Health Organization (WHO) has put obesity and diabetes, cardiovascular disease, cancer and other diseases into chronic diseases. Diet adjustment combined with exercise is recognized as the most effective method to keep healthy. Adipose tissue can secrete hormones and cytokines. Leptin is one of the cytokines. Leptin which can inhibits appetite and reduce energy intake, increase energy consumption and inhibit fat synthesis. However, the serum leptin level in most obese animal models and human beings is significant higher than commons. Leptin resistance is recognized as one of the important mechanism which caused obese.The biological effect of leptin is mediated by its long form receptor OB-Rb, and high-fat diet down regulates hypothalamic OB-R gene expression which may cause the leptin resistance. JAK/STAT signaling pathway is the major leptin signaling pathway. SOCS-3 is the major inhibitory factor regulating in this pathway after receptor. High-fat diet up regulates expression of SOCS-3 mRNA of hypothalamic. The changes have a significant impact on leptin resistance.Purpose: After observing 12 weeks high fat diet and swimming training,the changes of OB-Rb mRNA, SOCS-3 mRNA of hypothalamus, and serum leptin level. Explore the role which swimming training on different state of central leptin resistance. Fully understand the reasons which cause overweight and put forward reliable theoretical basis on exercise for weight lose.Methods: Thirty six 12-week-old SD rats were randomly assigned to three groups: control group (CC); high-fat diet group (CH); high fat diet combined with swimming-trained (HE) group. The rats in CH and HE groups were fed by high fat diet, and the rats in CC group were fed with standard rodent chow ad libitum. Animals in the HE group were trained by swimming exercise for 12 weeks (specific exercise program, see Experimental Methods). Body weight and food intake of every rat were measured every week. At the end of experiment,all rats were killed. And the blood, epididymal fat as well as perirenal fat were obtained. Serum GLU was tested by competitive radioimmunoassay, TC was tested by COD-PAD. TG was tested by GPO-PAD. Serum leptin was tested by enzyme-linked ELISA. OB-Rb and SOCS-3 mRNA in hypothalamus were tested by Real Time PCR.Results:①The body weitht of rats in CH group were significantly higher than that of CC group (641.33±65.03 VS 581.09±67.29, p<0.05) the pididymal and perirenal fat weight of CH was significantly higher than that of CC group (29.62±5.89 VS 21.16±7.10, p<0.05). Suggest that high-fat diet increases visceral fat accumulation and weight gain. After 12 weeks of swimming training, HE group of rats weighing less than CC group (486.27±51.97 VS 581.09±67.29,p<0.05). Visceral fat pad weight of rats in HE group was less than the CH group (8.26±1.11 VS 21.16±7.10, p<0.05), suggest that 12 weeks of swimming training reduce the accumulation of visceral fat to maintain normal growth in weight.②Serum GLU,INS,TC,TG of CH were higher than CC group, indicating that high-fat diet for 12 weeks increased serum INS,TC,TG.③During the experiment, differences of total food intake in each group rats were not statistically significant, CH group and the HE group, the total caloric intake were higher than CC group (P <0.05).④Serum leptin of CH group was higher than CC group (3.93±1.86 VS 1.99±0.83,p<0.05), and the serum leptin of HE was lower than CH group, (1.01±0.33 VS 3.93±1.86,p<0.05), suggest high-fat diet increased serum leptin level, while swimming exercise down graduate serum leptin levels.⑤The OB-Rb mRNA in hypothalamus of CH group was lower than CC group(0.59±0.24 VS 1,p<0.01). The OB-Rb mRNA in hypothalamus of HE group was higher than CH group (1.02±0.38 VS 0.59±0.24,p<0.05).Suggest high-fat diet reduced the hypothalamus in the OB-Rb mRNA expression, and 12 weeks swimming training increased hypothalamic expression of OB-Rb mRNA.⑥The SOCS-3 mRNA in hypothalamus of CH group was higher than CC group (1.19±0.15 VS 1,P<0.05), HE group and CH group of SOCS-3 mRNA expression were not significant. Suggest that the the high-fat diet increased SOCS-3 mRNA expression.Conclusions:①High fat diet induced weight gain, visceral fat accumulation, higher serum leptin levels. 12 weeks of swimming training reduced serum leptin levels and maintain normal body weight increase.②High fat diet reduced the expression of hypothalamic OB-Rb mRNA, swimming training within 12 weeks increased hypothalamic expression of OB-Rb mRNA, which may improve leptin resistance movement and an important mechanism for obesity.③High-fat diet increased the hypothalamic expression of SOCS-3 mRNA may be produced leptin resistance mechanisms.
|
PDF Full Text Request