Inhibition of High Glucose-induced Apoptosis of Pancreatic β-cells by Gallic Acid in Phyllanthus Emblica / 昆明医科大学学报

ABSTRACT

Objective To explore the protective effect of gallic acid in Phyllanthus emblica on high glucose－induced apoptosis of pancreatic islet β cells, and to provide a reference for the discovery of natural compounds for the treatment of diabetes. Methods In vivo experimental model, wistar male rats were used as in vivo subjects and 50 mg/kg STZ was injected intraperitoneally. After the model was successfully established, 25 mg/kg of gallic acid was given orally, and the positive drug was Sitagliptin. After 4 weeks of administration, the blood was taken and the pancreas was removed for HE staining. Western blot was used to measure the expression of NLRP3 and TXNIP in pancreatic tissue in high sugar state. In vitro model, insulinoma cell line INS－1 cells were used as in vitro targets to establish high levels. In sugar－induced apoptosis model, INS－1 cells were cultured in glucose－free RPMI 1640 complete medium supplemented with 25 mmol/L glucose. Gallic acid was used as the test sample. Experiments were divided into normal controls, high－sugar models, and low, medium and high levels of gallic acid groups. The cell viability was measured by MTT assay. The mRNA expression of NLRP3 and TXNIP in INS－1 cells was detected by QPCR and Western blot, and the expression of NLRP3 and TXNIP protein was detected.Results (1) INS－1 cells were cultured in a medium with glucose concentration of 25mmol/L for 48h, and the apoptosis rate was increased compared with the control group (P＜0.01), indicating that the apoptosis model was established successfully under high glucose conditions. (2) 10, 5, and 2.5 μmol/L GA were used to treat the control group and the high glucose model group cells respectively. The survival rate of the control group did not change significantly (P＞0.05) . Compared with the control group, the expression of NLRP3 and TXNIP in INS－1 cells in the high glucose model group was significantly different (P＜0.05);the protein expression level was significantly downregulated after GA treatment, and there was a statistical difference (P＜0.05) . Compared with the control group, the expression of NLRP3 protein in INS－1 cells in the high glucose model group was statistically different (P＜0.01), and the protein expression level was significantly downregulated after GA treatment (P＜0.01) ; The protein expression level was up－regulated (P＜0.05);the protein expression level after GA treatment was significantly down－regulated (P＜0.05); (4) The expression of NLRP3 and TXNIP mRNA in INS－1 cells was increased in the high glucose model group compared with the control group (P＜0.01) ; The expression of protein was significantly down－regulated after GA treatment (P＜0.01) . Conclusion The cells were cultured for 48 h in glucose－free RPMI 1640 complete medium supplemented with 25 mmol/L glucose. GA has no effect on the proliferation of normal INS－1 cells. GA protects INS－1 cells from apoptosis under high glucose conditions. The mechanism may be related to GA down－regulation of NLRP3 and TXNIP gene expression.