Study On The Hypoglycemic Effect And Mechanism Of The Leaves Of P. Chinensis

Purpose:To clarify the actions of lowering blood glucose and regulatiing blood lipids of the leaves of Exochorda serratifolia by studying the effect on glucose and lipid metabolism in T2 DM rats.To explore the relationship between the effect of Exochorda serratifolia and JNK signaling pathway by researching the effect on JNK,AKT,PDX-1,IRS-1 m RNA exression of Exochorda serratifolia in T2 DM rats.To clarify the mechanism of lowering blood glucose of Exochorda serratifolia from another point of view by studying inhibition effect of Exochorda serratifolia onα-glucosidase on Caco-2 cell model.Material and method:1.SD rats were randomly divided into normal control group(NC group)and diabetes mellitus group(DM group),the type 2 diabetes models in rats were made by feding high fat and sugar emulsion together with injecting the streptozotocin(STZ)of low dose,the successful models were random divided into 4 groups: diabetes mellitus model group(DM),the decoction of Exochorda serratifolia in high dose [9g·(kg·d)-1](ESD in high dose)and low dose [3g·(kg·d)-1](ESD in low dose),diabetes with Metformin hydrochloride[0.1g·(kg·d)-1] treatment group(MH),10 rats per group.The drug was administered by intragastric administration for 6 weeks,and the rats were measured for the fasting plasma glucose level weekly.Afterwards,the blood plasma of rats was collected and the levels of FINS,SOD,MDA,TG,TC,NEFA were measured.2.The islet tissues of above rats were rmoved and the RNA werw extracted,the expression of JNK,AKT,PDX-1,IRS-1 m RNA were measured by Q-PCR.3.The model of Caco-2 monolayer cells was established to study the inhibitory effect of Exochorda serratifolia on α-glucosidase,mainly the inhibitory effect on sucrose and maltase activity.Results:1.Compared with NC group rats,the DM group rats became polydipsia,excretion,hyperglycemia,hyperlipemia symptoms,and later lose weight,be consistent with the clinical features of T2 DM.After 6 weeks of treatment,the body weight of the NC group rats increased,the body weight of DM group rats decreased significantly(P<0.01).Compared with DM group,the body weight of MH,ESD in high dose and ESD in low dose group rats were heavier(P<0.01)or(P<0.05).Campared with DM group,after 3 weeks of treatment,the FBG level of rats in each drug-administration group decreased.The FBG level of MH group and ESD in high dose group in the 6th week decreased significantly(P<0.05),FBG in the ESD in low dose group decreased without significance.Compared with their own,the FBG level decreased significantly(P<0.05)after 6 weeks treatment.The levels of MDA,TC,TG,NEFA in increased significantly in the DM group(P<0.05),which is the manifestation of hyperlipidemia.The level of FINS significantly decreased,which showed abnormal function or structure of beta cells.After administration,the level of FINS in MH group and ESD in high dose group increased significantly(P<0.01),while the level of FINS in ESD in low dose group increased without significance.Compared with DM group,the level of SOD in ESD in low and high dose group increased significantly(P<0.01).Compared with DM group,the level of MDA in MH group and ESD in high dose group decreased significantly(P<0.01).Compared with DM group,the level of TG in MH group and ESD in high dose group decreased significantly(P<0.05 or P<0.01).Compared with DM group,the level of TC in MH group and ESD in high dose group decreased significantly(P<0.05),while the level of TC in ESD in low dose group increased without significance.Compared with DM group,the level of NEFA in MH group and ESD in high dose group and ESD in low dose group decreased significantly(P<0.01).2.Compared with NC group,the expression level of JNK m RNA in DM group rat islet significantly increased(P<0.01),and AKT,PDX-1,IRS-1 m RNA significantly decreased(P<0.01).Compared with DM group,ESD in high dose and ESD in low dose group down regulated the expression of JNK m RNA(P<0.05),up-regulated the expression of AKT,PDX-1,IRS-1 m RNA(P<0.05).Metformin Hydrochloride had a significant effect on down regulating JNK m RNA expression(P<0.05),and up regulating AKT,PDX-1 and IRS-1 m RNA expression(P<0.01).3.The decoction of Exochorda serratifolia(250,50μg/m L),luteolin(100,10μg/m L),rutin(150,20μg/m L),apigenin-7-O-β-D-neospheroside(200,50μg/m L)and apigenin-7-O-β-D-glucoside(100,10μg/m L)were chosen as the low and high concetration to investigate the inhibitary rate of α-glucosidase on the Caco-2monolayer cell model.Both the decoction of Exochorda serratifolia and flavonoid monomers showed inhibitory effects on sucrase and maltase activity,reduced the content of free glucose in AP side and BL side.The inhibitory rate of the decoction of Exochorda serratifolia was better than those of the flavonoid monomersion,there was no significant dose dependence.The inhibitary rates of flavonoid monomers on sucrase enzyme and maltose enzyme were different,the inhibitary rate of apigenin-7-O-β-D-neospheroside and luteolin was higher than that of the anther two flavonoid monomers.Conclusion:1.The established T2 DM rat model can meet the experimental requirements.The decoction of Exochorda serratifolia could reduce fasting blood glucose and improve the living condition,meanwhile,they had the effects of decreasing blood glucose and reducing the blood lipid at the same time.2.The decoction of Exochorda serratifolia in high dose and low dose affected the JNK,AKT,PDX-1,IRS-1 target of JNK signaling pathway,which showed the mechanism of hypoglycemic activity,protection of islet tissue and repaired effect of islet function of Exochorda serratifolia is related to JNK signaling pathway.3.The another mechanism of hypoglycemic activity of Exochorda serratifolia is that it can inhibite the activity of sucrose enzyme and maltase enzyme.