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ObjectiveTo investigate the medicinal effect of total flavonoids of mulberry leaves on regulating liver lipid metabolism disorder in diabetes mellitus type 2 （T2DM） rats， and the mechanism based on liver peroxidase proliferators activate receptors-α （PPAR-α） and carnitine palmityl transferase-1 （CPT-1） proteins. MethodTotal flavonoids of mulberry leaves were extracted and purified by ethanol extraction + macroporous resin purification and then identified. T2DM rat model was induced by high fat diet （HFD） + streptozocin（STZ）method. Rats with blood glucose ≥ 11.1 mmol·L-1 were divided into three administration groups with the high dose （300 mg·kg-1）， medium dose （150 mg·kg-1）， and low dose （75 mg·kg-1） of total flavonoids of mulberry leaves for 8 weeks， respectively， to observe the weight and blood glucose of the rats. The pathological changes of rat livers were observed by hematoxylin-eosin （HE） staining. Biochemical method was used to detect the levels of total cholesterol （TC）， triglyceride （TG）， low density lipoprotein-cholesterol （LDL-C）， and high density lipoprotein-cholesterol （HDL-C） of blood lipid metabolism in rats. The messenger ribonucleic acid （mRNA） and protein expressions of PPAR-α and CPT-1 were determined by real-time quantitative polymerase chain reaction （Real-time PCR） and Western blot. ResultAfter 8 weeks of intervention of total flavonoids of mulberry leaves， compared with the control group， the food intake， liver index， and fasting blood glucose of rats in the model group increased significantly （P<0.01）. Compared with the model group， the food intake， fasting blood glucose， and liver index of rats in the administration groups decreased significantly （P<0.01）. The results of HE staining showed that the liver tissue structure of rats in the control group was complete and there was no obvious abnormality. The model group showed vacuolar degeneration and inflammatory infiltration of hepatocytes of rats. There was no obvious abnormality in the liver structure of rats in the administration groups. The results of blood lipid showed that compared with the control group， the levels of TC， TG， and LDL-C increased significantly （P<0.01）， but the level of HDL-C decreased significantly （P<0.01） in the model group. Compared with the model group， the levels of TC， TG， and LDL-C decreased significantly （P<0.05， P<0.01）， whereas the level of HDL-C increased significantly （P<0.01） in the administration groups. The results of Real-time PCR showed that compared with the control group， the mRNA expression of PPAR-α and CPT-1 of rats in the model group decreased significantly （P<0.01）. Compared with the model group， the mRNA expressions of PPAR-α and CPT-1 of rats in the high-dose group increased significantly （P<0.01）. The results of Western blot showed that compared with the control group， the protein expressions of PPAR-α and CPT-1 of rats in the model group decreased significantly （P<0.01）. Compared with the model group， the protein expressions of PPAR-α and CPT-1 of rats in the high-dose group increased significantly （P<0.05， P<0.01）. ConclusionTotal flavonoids of mulberry leaves can effectively reduce blood glucose and improve liver lipid metabolism disorder in T2DM rats. The total flavonoids of mulberry leaves could regulate lipid metabolism and play a hypoglycemic role by activating and regulating PPAR-α and CPT-1 proteins and promoting oxidative decomposition of fatty acids.
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Objective: To investigate the effects of continuous exercise training (CT) and high-intensity interval exercise training (HIIT) on liver lipid metabolism and the correlation of the level of fibroblast growth factor 21(FGF21) in serum and liver tissues. Methods: Male SD rats were randomly divided into normal diet group (N) and obesity model group (H) after 1 week of adaptive feeding. Rats in the obesity model group were fed with 45% high-fat diet for about 8 weeks, and 20% weight increase compared with normal rats was considered as obesity. The rats were divided into normal diet control group (LC), normal diet HIIT group (LHI), normal diet CT group (LCT), High fat diet-induced obese control group (OC), obese HIIT group (OHI), and obese CT group (OCT) (n=10). Exercised rats were given weight-bearing swimming training intervention for 8 weeks. Blood samples were collected at least 24h after the last exercise intervention to detect the serum levels of inflammatory factors and FGF21. Liver tissue samples were collected to detect the lipid content, lipid metabolic enzyme content and FGF21 expression level. Results: Compared with LC group, the body weight, serum inflammatory factors levels and hepatic triglyceride content were increased significantly (P＜0.05). Hepatic triglyceride content was downregulated in LHI group and FGF21 expression level was enhanced in LCT group (P＜0.05). Compared with OC group, the body weight and hepatic triglyceride content were decreased significantly (P＜0.05), mitochondrial CPT-1β and β-HAD enzyme contents in liver were increased significantly (P＜0.05) in OHI group, the contents of LPL and FAT/CD36 enzyme in liver and the levels of FGF21 in serum and liver of OCT group were increased significantly (P＜0.05). Conclusion: Both exercise modes can reduce the body weight in normal and obese rats, and lipid deposition in the liver of obese rats. HIIT has a more significant effect on alleviating liver lipid deposition in obese rats by upregulating mitochondrial lipid oxidation level in normal and obese rats. CT improves the levels of FGF21 in serum and liver tissues of normal and obese rats, enhances enzyme contents that involved in fatty acids uptake to the liver, which has limited effect on alleviating lipid deposition in liver of obese rats.
Subject(s)
Animals , Male , Rats , Body Weight , Diet, High-Fat/adverse effects , Fatty Liver , Fibroblast Growth Factors , Obesity/metabolism , Rats, Sprague-Dawley , TriglyceridesABSTRACT
OBJECTIVE: To analyze the effects and the underlying mechanisms of photoperiodism and exposure to bisphenol A(BPA) on hepatic lipid metabolism in female mice. METHODS: A 2×2 factorial design was used. The photoperiod factor was set to fixed and shifted photoperiod, and the BPA factor was set to BPA exposure(BPA group) and non-exposure(control group). Specific pathogen free female C57 BL/6 J mice were randomly divided into four groups: fixed photoperiod control group, shifted photoperiod control group, fixed photoperiod BPA group, and shifted photoperiod BPA group, with eight rats in each group. The fixed photoperiod mice received a 12 ∶12 hours light-dark cycle, and the shifted photoperiod mice experienced reversed light-dark cycle once a week. Mice in BPA group were administered a dose of BPA 50 μg/kg body weigh by gavage, while mice in control group were given a equal volume of corn oil, once per day, five days per week for 12 weeks. The body weight of mice was measured during the experiment. After 12 weeks, all mice in each group were sacrificed. Plasma was collected and the levels of biochemical parameters were measured. Liver tissues were separated for examination of lipid deposition using oil red O and hematoxylin-eosin staining, and plasma triglyceride levels were measured. Real-time fluorescence quantitative polymerase chain reaction was used to detect the mRNA relative expression of genes of fat metabolism in liver tissues. RESULTS: At the end of the experiment, the body weights of mice were higher than that before the experiment(all P<0.05), but there was no statistically significant difference in body weights among the four groups(all P>0.05). The levels of plasma glucose, triglyceride and activity of alanine aminotransferase were higher in shifted photoperiod mice than that in the fixed photoperiod mice(all P<0.05). The plasma aspartate transaminase level was higher in BAP group than that in control group(P<0.01). The area of lipid staining in hepatic tissue was larger in the shifted photoperiod control group, fixed photoperiod BPA group and shifted photoperiod BPA group(all P<0.05), and hepatic lipid droplets aggregation was increased in these three groups compared with the fixed photoperiod control group. The mRNA relative expression of acetyl-coenzyme A carboxylase alpha(Acaca) was higher in the fixed photoperiod BPA and shifted photoperiod control groups(all P<0.05), compared with the fixed photoperiod control group. The relative expression of Acaca mRNA was lower in the shifted photoperiod BPA group than that in the fixed photoperiod BPA group(P<0.05). The mRNA relative expression of sterol regulatory element binding protein(Srebp) 1 and Srebp2 were significantly higher in the BPA group than that in the control group(all P<0.05). CONCLUSION: Both the single shifted photoperiod or BPA exposure can increase hepatic lipid deposition in female mice. The mechanism may be related to up-regulation of the mRNA expression of Acaca, Srebp1 and Srebp2. The shifted photoperiod in combination of BPA exposure has an antagonistic effect on the expression of Acaca mRNA in liver tissues of female mice.
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The prevalence of nonalcoholic fatty liver disease (NAFLD) worldwide has increased at an alarming rate, which will likely result in enormous medical and economic burden. NAFLD presents as a spectrum of liver diseases ranging from simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and even to hepatocellular carcinoma (HCC). A comprehensive understanding of the mechanism(s) of NAFLD-to-NASH transition remains elusive with various genetic and environmental susceptibility factors possibly involved. An understanding of the mechanism may provide novel strategies in the prevention and treatment to NASH. Abnormal regulation of bile acid homeostasis emerges as an important mechanism to liver injury. The bile acid homeostasis is critically regulated by the farnesoid X receptor (FXR) that is activated by bile acids. FXR has been known to exert tissue-specific effects in regulating bile acid synthesis and transport. Current investigations demonstrate FXR also plays a principle role in regulating lipid metabolism and suppressing inflammation in the liver. Therefore, the future determination of the molecular mechanism by which FXR protects the liver from developing NAFLD may shed light to the prevention and treatment of NAFLD.