Effects Of High-fat And High-protein Diet On Growth And Hepatic Steatosis And Their Responses To Long-term Lowfat Diet Intervention

Background/Objective In recent decades, with the rapid development of economy, the improvement of residents’ living standard, the intake of fat and protein also increases greatly, diet gradually shift to high fat and protein diet pattern(HFP). In the meantime, the prevalence of obesity, metabolic diseases and NAFLD are increasing year by year in Chinese population, it has become a major public health problems in China. Diet has been considered as an important pathogenic factor of NAFLD. Although previous studies reported the associations between the intakes of individual foods or nutrients and the risk of NAFLD, the relationship between dietary patterns and NAFLD is rare.Low-fat diets have achieved weight loss and benefits in patients with NAFLD. However, when be low fat diet tended to company by high intake of carbohydrate, and whether such diets(Low-fat high- carbohydrate, LFHC) can improve NAFLD has not been studied. The objective of the study was to assess the effects of HFP on growth and NAFLD and LFHC is beneficial for improving the NAFLD in adult SD rat.Purpose Imitate the residents high-protein and high-fat diets to establish animal model of SD rats, research the effects of the dietary on growth and hepatic steatosis and their responses to long-term low-fat diet intervention.Methods 1 Sprague-Dawley(SD) rats were maintained on either standard rodent chow(Con) or HFP from pregnant to 12 weeks of age. And HFP group then given either Con, HFP or LFHC from 12 weeks to 36 weeks. Con and LFHC keep Con and LFHC diet. Five groups were analyzed, namely Con, HFP, HFP-Con and HFP-LFCH. 2 Body weight, food intake were assessed weekly. Offspring rats were sacrificed at 1th, 3th, 12 th and 36 th weeks respectively. Record and analyses weight of organs and abdominal fat. 3 The kit test serum TG and TC. Blood glucose assessed after fasting and re-feeding during an oral glucose tolerance test and intravenous glucose tolerance test. 4 Liver tissue was separated and weighed. One piece of liver was fixed with formaldehyde and used for the histology section. Liver triglyceride content was measured; protein levels of PPARα and FATP4 in liver were determined by Westernblotting.Results 1 The growth and development situation in different groups of newborn, 3w, 12 w and 36 w offspring,and their responses to low-fat diet intervention in adult of rats. 1.1 Con and HFP newborns at day p1 and 3 weeks had similar body weights. During the nursing period, offspring weight gain diverged into a rapid weight gain group among Con and HFP offspring by 12 weeks of age. HFP continued the divergent pattern through 36 weeks of age. Offspring weight loss diverged into a rapid weight loss among Con and LFHC by 3 weeks. HFP-Con demonstrated intermediate growth and HFPLFHC demonstrating weight gain similar to Con. Liver weight, abdominal fat and liver lipid were significantly higher in HFP compared to Con.1.2 At 12 weeks and 36 weeks of age, HFP had significant higher plasma TG and TC compare to Con. There were converse trend in LFHC group. At 12 weeks of age, HFP demonstrated the greatest area under the curve as compared to the other groups. When the glucose tolerance test was repeated at 36 weeks of age, HFP offspring again demonstrated the greatest areas under the curve. 2 Effects of diet on hepatic steatosis and their responses to long time low-fat diet intervention. At 12 weeks, HFP offspring exhibited hepatic steatosis that was confirmed by Oil Red O staining while Con livers showed normal morphology. At 36 weeks, HFP livers were filled with large droplets, and were accompanied with ballooning in hepatocytes. By contrast, in HFP-LFHC offspring, small lipid droplets were observed at 36 weeks only. Liver histology was normal in both Con and HFP-Con offspring during the experimental period. HFP diet FATP4 protein expression significantly higher than that of Con group, FATP4 protein expression has a downward trend compare to HFP diet after transfer to Con diet or LFHC diet in adult. PPAR alpha protein expression has a rising trend compare to HFP diet after transfer to Con diet or LFHC diet in adult.Conclusions The results of the present study demonstrate that HFP diet during early stage of life promotes offspring body weight, percent fat mass and organ mass, and continue to a HFP diet results in a further increase body weight, organ growth and fat mass in middleaged offspring. At the same time, cause glucolipid metabolism disorders and liver steatosis in adult. The effect of improvement of long-term LFHC intervention in weight,sugar, lipid metabolic disorder and liver steatosis were no significant.