| Objective: In this study, we will observe the effects of the flavonoids and saponins extract from Boussingaultia gracilis Miers var.pseudobaselloides Bailey leaves on Insulin resistance of ICR mouse which was treated by using high fructose diet, and investigate the hypoglycemic mechanism.Methods: Seventy two male ICR mice were bought in laboratory animal center of Dalian medical university, and divided randomly into six groups, named normal control group, model group, low dose flavonoids group, high dose flavonoids group,low dose saponins and high dose saponins group(n=12). The mice of normal control group were feed the normal diet and water; the mice of model group were feed high-fructose diet(60%) and water; the mice of low dose flavonoids group were feed high-fructose diet(60%) and the water included flavonoids extract(1%); the mice of high dose flavonoids group were feed high-fructose diet(60%) and the water included flavonoids extract(2%); the mice of low dose saponins group were feed high-fructose diet(60%) and the water included saponins extract(1%); the mice of high dose saponins group were feed high-fructose diet(60%) and the water included saponins extract(2%).Oral glucose tolerance test(OGTT) was conducted after completion of 19 weeks of the experiment. After a 12 h fasting, the mice were orally gavaged with glucose(2g/kg),and blood glucose concentrations were measured using blood samples was taken from tail vein at 0, 30, 60 and 120 minutes. At the time of 20 weeks, mice were weighted and fasted for 12 h and blood samples were collected by ocular puncture and serum was isolated. Then, the mice were sacrificed by cervical dislocation. Then the liver were excised and weighed. The liver injury in mice was evaluated by calculating the viscera coefficient though the weight of body an liver. The concentration of glucose,triglyceride, total cholesterol, LDL-C and HDL-C in mice fasting serum were tested by a automatic biochemical analyzer; The expression of PPARγ protein in liver tissues of mice was examined by Western Blot. The expression level of PPARγ mRNA in liver tissues of mice was determined by qRT-PCR. After the liver tissues of mice were treated by HE straining, the pathological changes of liver tissues were observed by a microscopic. The experimental results are all analyzed by using SPSS 17.0 statistical package.Results: The viscera coefficient of liver showed that the liver injury in mice of model group changed obviously than the control group, the difference was statistically significant(P<0.05); there was no significant difference of the viscera coefficient in mice liver between low dose flavonoids group, high dose flavonoids group and model group. Compared with model group, high dose saponins group dramatically improve the liver injury in mice(P<0.05). The oral glucose tolerance test showed that the mice of the model group apparently occurred abnormal glucose tolerance by comparing with the control group, the difference was statistically significant(P<0.05). There were no statistically significant difference of the glucose tolerant in mice between low dose flavonoids group, high dose falvonoids group and model group(P>0.05). Compared with the model group, the low dose saponins group and high dose saponins group significantly improve the abnormal glucose tolerant, the difference was statistically significant(P < 0.05) with the dose-effect relationship. Compared with the control group, the concentration of glucose, insulin, triglyceride, total cholesterol and LDL-C in fasting serum of the mice of the model group increased significantly and the concentration of HDL-C decreased, the difference was statistically significant(P <0.05); There was no statistically significant difference of low dose flavonoids group and high dose flavonoids group, compared with model group(P > 0.05). Compared with the model group, the difference was significant between low dose saponins group an high dose saponins group(P < 0.05), showing the dose-effect relationship. The qRT-PCR results show that the expression of PPARγ mRNA of the liver tissue of model group mice decreased significantly(P < 0.05); There was no statistically significant difference of the expression of PPARγ m RNA between low dose flavonoids group and high dose flavonoids group by comparing with model group(P>0.05);Compared with model group, the expression of PPARγ mRNA of low dose saponins group and high dose saponins group was higher, the difference was statistically significant(P<0.05), showing the dose-effect relationship. Western Blot showed that compared with control group, the expression of PPARγ protein of model group mice decreased significantly, the difference was statistically significant(P<0.05);Flavonoids low dose group and high dose of flavonoids group compared with model group had no statistical significance(P > 0.05);Low doses of saponins group and high dose saponins group compared with model group, PPARγ protein expression in liver tissue increased significantly, the difference was statistically significant(P < 0.05), and showing the dose-effect relationship. After HE staining, observing by the microscopic,the liver cells of the control group mice was in good condition, the liver tissue structure is clearly visible, no obvious pathological changes. In the liver cells of model group,low dose flavonoids group and high dose flavonoids group, there were apparent in the group of liver steatosis, inflammation cells infiltration and formation of fibrous connective tissue, etc; Compared with model group, pathological state of low doses saponins group and high dose saponins group are obviously improved.Conclusion: The saponins extract of Boussingaultia gracilis Miers var.pseudo baselloides Bailey leaves can promote the expression of PPARγ in mice, improv e the metabolism of lipid and glucose in the body, and inhibit the occurrence o f insulin resistance developing effectively with dose-effect relationship. |
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