The Effect Of RS4-type Sweet Potato Resistant Starch On Inflammatory Cytokines And PPAR-α MRNA In Mice Fed A High-fat Diet

Background:Obesity and associated comorbidities are worldwide health problems. Obesity is mainly caused by the disequilibrium between energy intake and metabolism. It is widely accepted that obesity is a kind of mild inflammatory state and the secretion of inflammation-related cytokines rises as adipose tissue expands, including tumor necrosis factor-α(TNF-α), interlukin6(IL-6) and monocyte-chemoattractant protein1(MCP-1), which play an important role in obesity related disorders. Inflammatory cytokines in the obese is greater than normal people, while presence of systemic inflammation has been linked to the increased risk of development of insulin resistance, type Ⅱ diabetes, cardiovascular disease and other metabolic disorders associated with obesity.Objective:This thesis mainly analyses the effects of three kinds of RS4-type sweet potato resistant starch on inflammatory cytokines and PPAR-a mRNA level in liver in C57/BL6J mice fed a high fat diet, and provides some corresponding theoretical basis for RS4resistant starch to prevent obesity and related metabolic disorders.Methods:Male C57BL/6J were divided into six groups:control group (CL, n=12), high-fat group(HF, n=12) and fed a high fat diet containing15%sweet potato starch (SPS, n=12), hydroxypropyl cross-linked sweet-potato modified starch(HPCL-SPS, n=12),cross-linked octenyl succinic anhydride sweet-potato modified starch(CLOSA-SPS, n=12), Citric acid acetylated sweet-potato modified starch(CAAC-SPS, n=12)for12weeks, the serum total cholesterol, triglyceride, lipoprotein and free fatty acid(FFA) were determined, necrosis factor-α(TNF-α), interlukin6(IL-6) and monocyte-chemoattractant protein1(MCP-1) were measured by ELISA; PPAR-α mRNA level in liver were determined by RT-PCR.Results:l.The body weight and adipose tissue weight in the HF-CLOSA-SPS, HF-HPCL-SPS and HF-CAAC-SPS group were significantly lower than those in the HF group(P<0.05).2.The serum TG,VLDL lever were reduced by CLOSA-SPS, HPCL-SPS and CAAC-SPS treatments in high fat diet(P<0.05), no significant effect on TC,HDL-C and LDL-C lever was observed; and the serum FFA was decreased compared to the HF group(P<0.05).3.Mice fed a high fat diet induce epididymal adipocyte hypertrophy and distribution were improved by HPCL-SPS,CAAC-SPS treatments, the result shows the area of adipocyte in HP-HPCL-SPS and HF-CAAC-SPS were less than those in the HF group by Image Pro-Plus6.0measurement.4.The serum TNF-a lever of HF-CLOSA-SPS,HF-HPCL-SPS and HF-CAAC-SPSHF group were significantly different than that in the HF group(P<0.05); the serum IL-6and MCP-1level were significantly reduced by HPCL-SPS, CAAC-SPS treatments in high fat diet compared to the HF group(P<0.05).5.The gene expression of PPAR-a in liver was detected, the result shows HPCL-SPS and CAAC-SPS added to the high fat diet up-regulation of PPAR-a mRNA level in the liver, were significantly different than those in the HF group(P<0.05).Conclusion:HPCL-SPS, CAAC-SPS may improve lipid metabolism circulation and bring down the serum FFA and inflammatory cytokines level by increasing PPAR-a mRNA expression level, to reduce the occurrence of the obesity caused by high fat diet and related metabolic diseases. Therefore, they have a potential effect in preventing obesity and metabolic syndrome.