| Objective: Diabetes mellitus is one of the most important chronic non communicable diseases threatening human health today.Diabetes is a multi gene hereditary disease.The apoptosis of islet beta ? is the main pathological change in the pancreas of diabetic patients.The main causes of islet ? cell apoptosis are oxidative stress and mitochondrial damage,endoplasmic reticulum stress and so on.?-PGG(1,2,3,4,6-penta-O-galloyl-?-D-glucose)is one of water-soluble polyphenols in Galla Chinensis.It has multiple biological and pharmacological activities,such as antioxidation,anti-inflammatory and anti-tumor.In recent years,it has been found that ?-PGG has a certain role in the treatment of diabetes,such as improving insulin resistance and increasing insulin secretion.The anti-inflammatory and antioxidant effects of ?-PGG can inhibit the apoptosis of islet ? cells induced by inflammatory factors and oxidative stress,but there are few reports on whether ?-PGG can inhibit the apoptosis of islet ? cells induced by endoplasmic reticulum stress to improve diabetes.We designed experiments to explore whether ?-PGG can inhibit the apoptosis of pancreatic ? cells in diabetic rats by inhibiting the endoplasmic reticulum stress pathway.Methods:1.Optimization of Extraction Process of ?-PGG from Galla Chinensis by Response Surface Method.The ultrasonic time,solid-liquid ratio and volume fraction of methanol for the effects of ?-PGG extraction conditions,design response surface analysis the influence of ultrasonic time,solid-liquid ratio,volume fraction of methanol on ?-PGG was extracted with the combination design method Design-Expert Box-Behnken software center,and establish the mathematical model through the regression analysis of variance.2.The role of ?-PGG in improving diabetic rats and the mechanism of inhibiting apoptosis.After a week of adaptive feeding,70 male Wistar rats were divided into control group(n=10)and model group(n=60).The rats in the model group were fasted 12 h,and Streptozocin(STZ)50mg/kg were injected intraperitoneally.After 72 h,the diabetic rats were determined by fasting blood glucose(FBG)more than 11.1mmol/L.The diabetic rats were randomly divided into model group(n=10),positive group(n=10,Sitagliptin 10.5mg/kg*d),low dose group of ?-PGG(n=10,20 mg/kg*d),dose group of ?-PGG(n=10,40 mg/kg*d)and ?-PGG high dose group(n=10,80 mg/kg*d).Control group and model group gavage solvent liquid.All rats were covered 6 weeks of continuous administration.FBG and weight were measured at the end of the week.After the intervention,the damage and histomorphology of pancreatic islet cells were observed by Hematoxylin-Eosin staining.The apoptosis of islet ? cells was observed by Fuchsin-Orange G staining of islet ? cells,and the amount of Caspase-12,Caspase-3,JNK and TXNIP protein in pancreatic tissue was detected by Western Blot method.Results: 1.Optimization of Extraction Process of ?-PGG from Galla Chinensis by Response Surface Method.The extraction of ?-PGG reached 24.742 mg/g when the extraction conditions were ultrasonic time 22 min,the ratio of material to 1:42(g/m L),and the volume fraction of methanol was 49%.2.The role of ?-PGG in improving diabetic rats and the mechanism of inhibiting apoptosis.After 6 weeks of drug intervention,the weight of the control group rats increased continuously.The average weight of the model group was lighter.The average weight of the rats in the low,middle and high dose group of the ?-PGG group had different degrees of improvement compared with the model group.The positive group and the high dose group of ?-PGG were significantly different from those in the model group(P<0.05).The cell staining of pancreatic tissue showed that the high dose of ?-PGG could significantly improve the atrophy of islets and decrease the damage of pancreatic ? cells.Western Blot detection showed that the expression of Caspase-12 protein in pancreas tissue of model group increased significantly.The expression of protein in the positive group and the high dose group of the ?-PGG group was significantly lower than that in the model group(P<0.05).The expression of Caspase-3 protein in the pancreas tissue of the model rats increased and the expression of the protein in each group decreased in varying degrees,and the difference was significant compared with the model group(P<0.01),the difference between the high dose group of ?-PGG and the model group was significant(P<0.05).The expression of JNK protein in the model group was obviously increased.The protein expression level of the positive group and the low,middle and high dose group decreased,and the positive group and the high dose group of ?-PGG were significantly different from those in the model group(P<0.05).The expression level of TXNIP protein in the positive group and the high dose group of ?-PGG decreased significantly after 6 weeks of administration,and the difference was statistically significant compared with the model group(P<0.05).Conclusion: 1.Optimization of Extraction Process of ?-PGG from Galla Chinensis by Response Surface Method.Box-Behnken design response surface analysis can optimize the process of extraction of ?-PGG in Galla Chinensis.2.The role of ?-PGG in improving diabetic rats and the mechanism of inhibiting apoptosis.?-PGG can maintain the weight of diabetic rats,improve the symptoms of weight loss,reduce the fasting blood glucose of diabetic rats,reduce hyperglycemia,inhibit islet atrophy,increase the number of islet ? cells and inhibit the apoptosis of islet ? cells induced by endoplasmic reticulum stress. |
PDF Full Text Request