| Objective: To investigate the possible relationship between the genes related tohypothalamic fatty metabolism and differential susceptibility to high-fat diet-induced obesityand appetite regulation in Sprague-Dawkey rats and examined the effect of low fat dietintervention on hypothalamic fatty metabolism and insulin susceptibility.Method:55of Male Sprague-Dawley rats weighing120to140g were housed individually incages in pathogen-free animal rooms at (20±2)℃with a12/12h light/dark cycle. All ratswere free access to the food and water. According to their body weights, they were randomlydivided into two groups, which were respectively gave standard rat chow (control group,n=10) and high-fat diet (high-fat diet group, HF, n=45). After10weeks, the rats in HF groupwhose body weights surpass χ+1.96s of control group were classified as diet-inducedobesity (DIO) rats, and those less than χ+s of control group were considered as die-inducedobesity resistant (DIO-R) rats. Then the DIO and DIO-R rats were respectively allocated totwo groups (n=6), one group was kept on high-fat diet, and the other was switched to chowdiet for an additional8weeks. Daily food consumption was recorded and body weight wasmeasured weekly at fixed time. At the beginning, the tenth week and the end of the study, tailblood was collected after12h fasting overnight and then centrifuged. The serum was storedat-80℃for further use. Terminally, all rats were beheaded after12h fasting overnight. Trunkblood samples were collected and centrifuged, and the serum was stored at-80℃forsubsequent determination of blood glucose, insulin levels, triglyceride. Liver was remainedfor further determination of triglyceride. Adipose tissues around kidney and testis were dissected and weighed. Hypothalamus was quickly removed and snap-frozen in liquidnitrogen immediately. The tissues were then stored at-80℃for RNA extraction.Results: At the end of the10th week, there were18rats designated as DIO and12rats asDIO-R according to the body weight. The weight gains of DIO rats were more than DIO-Rand control rats, while DIO-R rats had the similar weights with control rats. The energyintake of DIO rats was higher than DIO-R and control rats. The average weight and energyintake of DIO-HF were both significantly more than those of the other groups includingDIO-CF, DIO-R-HF, DIO-R-CF and control rats after another8weeks chow intervention.At the end of study, FAT/CD36mRNA expression in DIO-HF rats’ hypothalamus wassignificantly increased compared to the other four groups. CPT1c mRNA expression inDIO-HF rats was significantly reduced compared to the other four groups, but shifting tochow food increased CPT1c expression of DIO-CF group. DIO-HF rats also had lowerACCβ expression compared with DIO-CF and DIO-R-CF group. GPR41expression wassignificantly reduced in DIO-CF group.Conclusion:1.The susceptibility to obesity in SD rats fed high-fat diet was differnt. DIO ratshad more body weight gain and energy intake, which can be reversed by chow food.2.Upregulated FAT/CD36mRNA expression may account to overeating and differentsusceptibility to obesity induced by high-fat diet. Hypothalamic FAT/CD36may be related tocontrolling food intake and energy homeostasis. Standard chow food may reverse increasedFAT/CD36mRNA to normalize in obese rats.3. High fat diet induced obesity andobesity-resistant rats continued to be gave diets whose energy densities were different,hypothalamic fatty acid metabolism-related genes CPT1c, ACCβ, GPR41expression weredifferent. That hypothalamic fatty acid metabolism may be associated with food intake andenergy homeostasis regulation. |
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