Effects Of Taurine On The Apoptosis Of Pancreatic Beta Cells Mediated By Endoplasmic Reticulum Stress

Aim:Bad eating habits, especially large amounts intake of high fat diet are the main reasons of dysfunction of islet cell insulin resistance and give rise to the onset of type 2 diabetes. Endoplasmic reticulum stress is the main way to start beta cell apoptosis and the islet beta cell apoptosis is a key link to the development of the type 2 diabetes. Taurine is an important amino acid in the body, with a variety of biological functions. Many researches showed that taurine can reduce the blood glucose of diabetic rats, inhibit the apoptosis of pancreatic beta cells, but the mechanism of which is still unclear. This study eatablished pancreatic beta cells endoplasmic reticulum stress of rats caused by long time high fat and high glucose diet combined with streptozotocin (STZ), and aims to investigate the intervention effects of taurine on the endoplasmic reticulum stress mediated beta cell apoptosis, and to provide a theoretical basis for the application of taurine to prevent and treat human and pet diabetes.Methods:50 male SD rats were randomly divided into 3 groups, control group, high fat and high glucose diet group with normal drinking water, and high fat and high glucose diet group with taurine in the drinking water. After 8 weeks, high fat and high glucose diet with normal drinking water group and with taurine drinking water group were divided into two parts. Part of rats in each group were injected with 30 mg/kg STZ to damage the islet beta cells to induce type 2 diabetes mellitus. After two weeks, rats with fasting blood glucose more than 7.8 mmol/L and 2 h glucose tolerance between 11.0-32.0 mmol/L were identified as type 2 diabetes.8 weeks later, the serum insulin, total cholesterol, triglyceride, low density lipoprotein, high density lipoprotein cholesterol and insulin sensitivity, islet cell secretion and insulin resistance level were detected. The expressions of endoplasmic reticulum stress and apoptosis factor IRE1, XBP1, CHOP and Caspase-12 in pancreatic tail tissue were assayed. The apoptosis of islet cells was detected by in situ end labeling (TUNEL). The effect of taurine on endoplasmic reticulum stress caused by high fat, high glucose diet and streptozotocin (STZ) were investigated.Results:1) The results of the determination method of type 2 diabetes showed that STZ (30 mg/kg) combined with high fat and glucose diet can induce type 2 diabetes mellitus in rats.2) The fast glucose level, serum insulin resistance index, serum insulin level, total cholesterol, triglyceride, low density lipoprotein levels in the type 2 diatetes group and rats fed with high fat and high sugar feed were significantly higher than the control group(P<0.05), while the insulin sensitivity index decreased, insulin secretion index and high density lipoprotein content decreased significantly (p＜0.05). Fast glucose level, serum insulin resistance index, serum insulin level, total cholesterol, triglyceride, low density lipoprotein levels in rats drinking Taurine decreased significantly compared with rats with out Taurine treatment (P<0.05), while the insulin sensitivity index increased, insulin secretion index and high density lipoprotein content increased significantly (P＜0.05).3) The percentage of apoptosis of pancreatic islet cells, the gene and protein expressions of IRE1, XBP1 and gene expressions of CHOP, Caspase-12 increased significantly in high fat and high glucose diet combined with STZ group and high fat and glucose diet group compared with the control group (P<0.05), and the percentage of apoptosis of pancreatic islet cells, the gene and protein expressions of IRE1, XBP1 and gene expressions of CHOP, Caspase-12 decreased significantly (P＜0.05) in taurine treatment group than rats without taurine group.Conclusion:Taurine could delay the onset of type 2 diabetes and development by regulating lipid metabolism and improve insulin sensitivity, the function of islet cells, and alleviate the endoplasmic reticulum stress mediated beta cell apoptosis and delay the occurrence and development of type 2 diabetes mellitus..