| Insulin resistance(IR)is a pathological condition characterized by reduced biological response to insulin caused by genetic and exogenous factors.Adipose tissue is essential for insulin-stimulated glucose intake and therefore play a major role in energy balance.In the past few decades,Chinese herbal medicine as a potential therapeutic drug for IR has received more and more attention.Based on the research results of predecessors,we use traditional Chinese medicine boiling method to extract Pogostemon cablin(PC).The purpose of this study is to determine the relief effect of Pogostemon cablin water extract on IR and explore its mechanism of action,in order to find a safe and effective,small side effects of prevention and improve IR drugs.In this study,we explore the preventive effect of PC on IR and its molecular mechanism through in vivo and in vitro experiments.1.In vivo experiments: We choosed to feed mice high-fat diet to establish IR model.we randomly divided healthy male C57BJ/6L mice into 5groups,namely the control group(CON),the model group(HFD),the PC treated group was fed with high-fat diets and treated with low-concentration(HFD+L),medium-concentration(HFD+M),and high-concentration(HFD+H)PC for 8 weeks by gavage.During the experiment,the weight of the mice was weighed weekly and the food intake of each group of mice was recorded.In order to determine the success of the IR model,we conducted OGTT and ITT experiments on each group of mice at the eighth week.And we analyzed PC intervention in mouse IR status though detecting HOMA-IR and ISI indices.HE staining makes pathological observations of mouse epididymal adipose tissue,the relavant biochemical indicators and adipocytokines in blood and epididymal adipose tissue were measured,and the key proteins and genes in the PPARγ,PI3-K/AKT and GLUT4 pathways were measured.2.In vitro experiments:We identified 3T3-L1 adipocyte differentiation and maturation by oil red staining.The experiment was divided into 6 groups according to different treatments: the blank control group(CON)cells were not treated;the induced differentiation group(MDI),0.5,1.0,2.5 and 5.0mg/m L PC treated group(MDI+PC).Cells were collected after the above treatment for oil red and TG content detection,and the protein PPARγ was detected.Then,the Mature 3T3-L1 adipocytes were stimulated by palmitic acid(PA)to establish IR cell model.According to different treatments,the experiments were divided into 6 groups: the control group(CON);the IR model group(PA),0.5,1.0,2.5 and 5.0 mg/m L PC treated group(PA+PC).The treatment was continued for 24 hours,and the glucose consumption of each group of cells and the secretion level of adipocytokines were detected,and the key proteins and genes in the PPARγ,PI3-K/AKT and GLUT4 pathways were detected.The results of in vivo experiments showed that: 1.Oral different concentrations of PC can improve the pathological changes of hypertrophy in the adipose tissue of mice caused by high-fat diet feeding.2.The oral administration of low,medium and high concentration PC significantly inhibited the increase of high-fat diet feeding mice fasting serum Fins(P < 0.01).And the HOMA-IR and ISI index showed that,compared with the HFD group,oral administration of PC at various concentrations significantly inhibited the formation of IR homeostasis(P < 0.01),and significantly increased the insulin sensitivity index of mice(P < 0.01).At the same time,the values of AUC below the OGTT and ITT curve of mice in the PC groups were significantly lower than that in HFD group(P < 0.05 or P < 0.01).3.oral administration of low,medium and high concentrations of PC significantly inhibited the increase in serum TC(P < 0.01),TG(P <0.01)and FFA(P < 0.01)levels of high-fat diet feeding mice.In addition,oral administration of PC at various concentrations can improve the changes in serum of adiponectin,resistin,leptin,TNF-α and IL-6 of high-fat diet feeding mice.Compared with the HFD group,the m RNA expression of adiponectin in the adipose tissue of mice in low concentration(P < 0.01),medium concentration(P < 0.01)and high concentration(P < 0.05)were increased significantly.4.Western blot results showed that compared with the HFD group,the relative expression level of PPARγ protein in adipose tissue of mice in the PC groups were significantly increased(P < 0.01).At the same time,the relative expression level of the genes of PPARγ and its subtype PPARγ2 in adipose tissue of mice in the PC groups were significantly increased compared to the HFD group(P < 0.01).5.PC can improve the insulin sensitivity of mice through increasing the protein and gene levels of the insulin signal transduction pathway.Western blot results showed that,compared with the HFD group,the relative expression levels of IRS-1 protein in adipose tissue of mice in HFD+L(P < 0.01)group were significantly increased;at the same time,the relative expression levels of PI3-K protein in the adipose tissue of mice in HFD+L(P < 0.01),HFD+M(P < 0.01)and HFD+H(P < 0.01)groups;the relative expression levels of AKT protein in the adipose tissue of mice in HFD+L(P < 0.01),HFD+M(P < 0.01)and HFD+H(P < 0.01)groups;the relative expression levels of GLUT4 protein in the adipose tissue of mice in HFD+L(P <0.01),HFD+M(P < 0.01)and HFD+H(P < 0.01)groups were significantly higher than that in HFD group.The PCR results showed that,treatment with high concentrations of PC can effectively increase the relative expression of IRS-1 gene in adipose tissue of high-fat diet feeding mice(P < 0.05);In addition,compared with the HFD group,treatment with different concentrations of PC can effectively increase the relative expression of GLUT4 gene in the adipose tissue of mice.In vitro experiment results show that PC treatment can promote differentiation of 3T3-L1 preadipocytes,and effectively prevent the reduction of PA-induced glucose consumption in the cell;at the same time,PC can significantly improve PA-induced FFA,adiponectin,resistin,leptin,TNF-α and IL-6 secretion factor level on cell culture supernatant.In addition,the PC significantly increased the expression of PPARγ protein and genes,effectively promoting changes in IRS-1,PI3-K,AKT and GLUT4 proteins and their relative expression.The final results of in vitro experiments are basically consistent with in vivo experiments.The results showed that Pogostemon cablin water extract has a certain preventive improvement effect on IR,and this effect may be achieved by the secretion of insulin-sensitive related adipocytokines,as well as the regulation of key proteins and genes in the PPARγ,PI3-K/AKT and GLUT4 pathways. |
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