Effects Of Guava Leaf Extract On Glucose Metabolism And Its Mechanism In Diabetic KK-Ay Mice

Objective:The study is to observe the effect of guava leaf extract on blood glucose,body weight and insulin signaling pathway in diabetic KK-Ay mice,and to explore the mechanism of guava leaf extract on glucose metabolism in diabetic KK-Ay mice.The results will provide experimental basis for the further development of guava leaves.Methods: 28 male diabetic KK-Ay mice aged 7-8 weeks were randomly divided into high dose guava leaf treatment group,medium dose guava leaf treatment group,metformin treatment group and control group after adaptive feeding for 2 weeks.All mice were given KK feed.The high-dose guava extract group was given 2184mg/Kg gavage,the medium-dose guava extract group was given 1638mg/Kg gavage,and the metformin treatment group was given227.5mg/Kg gavage.The control group was given the same volume of normal saline gavage for 8 weeks.Daily monitoring of food intake and water intake of KK-Ay mice;Blood glucose and body weight of KK-Ay mice were monitored weekly?After 8 weeks of treatment,the mice were sacrificed with orbital blood taken.Serum insulin level of KK-Ay mice was determined by ELISA.Totalcholesterol(TC),triglyceride(TG),low density lipoprotein cholesterol(LDL-C)and high density lipoprotein cholesterol(HDL-C)in KK-Ay mice were determined by biochemical assay.And insulin resistance index(HOMA-IR)and insulin sensitivity index(ISI)were calculated.The hepatic tissue was stored in the-80? refrigerator for later use.Western blot(WB)was used to detect the expression of insulin receptor substrate-1(IRS-1),phosphatidylinositol 3-kinase(PI3K),Protein kinase B(Akt),phosphorylated-phosphatidyl inositol 3-kinase(p-PI3K)and phosphorylated-Protein kinase B(p-Akt)in the hepatic tissue of KK-Ay mice.Real-time quantitative PCR(RT qPCR)was used to detect the gene expressions of IRS-1,PI3 K and Akt in the hepatic tissue of KK-Ay mice.Results:1.With the extension of treatment time,the weight of diabetic KK-Ay mice in the four groups all decreased to varying degrees(P<0.05).After 8 weeks of treatment,the weight loss effect of guava leaf extract in the medium-dose treatment group was more significant(P<0.05).2.There was no significant difference in TC,TG,LDL-C and HDL-C between the four groups of diabetic KK-Ay mice.HDL-C increased and LDL-C decreased in the high-dose guava extract group,but there was no statistical significance compared with the control group.HDL-C increased and LDL-C and TG decreased in the extract medium dose group,but there was no statistical significance compared with the control group.3.With the extension of treatment time,the blood glucose,fasting insulin and HOMA-IR index of diabetic KK-Ay mice in the high-dose treatment group,the medium-dose treatment group and the metformin treatment group all decreased to varying degrees compared with the control group(P<0.05),while the ISI increased to varying degrees compared with the control group(P<0.05).However,there was no significant difference between the high-dose guava extract group and the medium-dose guava extract group.There was no significant difference between the guava leaf extract treatment group and the metformin treatment group.4.The treatment group with guava leaf extract was able to up-regulate the gene expressions of IRS-1,PI3 K and Akt in the hepatic tissue of KK-Ay mice(P<0.05),and up-regulate the protein expressions of IRS-1,PI3 K,Akt,p-PI3 K and p-Akt in the hepatic tissue(P<0.05).However,there was no significant difference between the guava leaf extract treatment group and the metformin treatment group.Conclusion:1.With the extension of treatment time,guava leaf extract had the effect of reducing the weight of diabetic KK-Ay mice.However,the improvement of blood lipid in diabetic KK-Ay mice was not obvious.It may be related to the short duration of drug treatment.2.Guava leaf extract could reduce blood glucose,fasting insulin and HOMA-IR index of diabetic KK-Ay mice,and increase ISI,suggesting that guava leaf extract can alleviate insulin resistance and increase insulin sensitivity.However,there was no significant difference between the guava leaf extract treatment group and the metformin treatment group.The results suggested that guava leaf extract and metformin had the same effect on reducing glucose and improving insulin resistance.There was no significant difference between the high-dose and medium-dose treatment groups,indicating that increasing the drug dose could not increase the hypoglycemic effect,suggesting that there might be an optimal drug dose for the hypoglycemic effect of guava leaf extract.3.Guava leaf extract could increase the mRNA expression of IRS-1,PI3 K and Akt genes in the hepatic tissue of diabetic KK-Ay mice.Thus,the expression of IRS-1,PI3 K,Akt,p-PI3 K and p-Akt proteins were increased.This suggests that guava leaf extract may play a hypoglycemic role by up-regulating the PI3K/Akt signaling pathway,thereby improving insulin resistance.In addition,the therapeutic effect of guava leaf extract was similar to that of metformin.