Influence of High Blood Glucose Fluctuation on Endothelial Function of Type 2 Diabetes Mellitus Rats and Effects of Panax Quinquefolius Saponin of Stem and Leaf

Objective： To observe the influence of high blood glucose fluctuation on the endothelial function of type 2 diabetes mellitus （T2DM） rats and the effects of Panax Quinquefolius Saponin （PQS） of stem and leaf. Methods： The T2DM model was induced by intraperitoneal injection of a small dose of streptozotocin （STZ, 35 mg/kg） plus high fat and high caloric laboratory chow. Then, diabetic rats were divided into steady high blood glucose （SHG） group and fluctuant high blood glucose （FHG） group according to fasting blood glucose coefficient of variation （FBG-CV）, and then, the FHG group rats were divided into 4 groups according to the level of FBG-CV and fasting blood glucose： PQS 30 mg/（kg·d） group, PQS 60 mg/（kg·d） group, metformin hydrochloride control （MHC） group, and FHG control group, 10 in each group. Meanwhile, 10 rats without any treatment were used as normal control （NOR） group. Eight weeks later, the aortic arteries histology, plasma hepatocyte growth factor （HGF）, and serum nitric oxide （NO）, endothelin-1 （ET-1）, tumor necrosis factor α （TNF-α）, and soluble intercellular adhesion molecule 1 （slCAM-1） were measured. Results： In comparison with the NOR group, the level of plasma HGF and serum NO, ET-1 and TNF-α, and slCAM-1 in SHG and FHG control groups were all significantly increased （P〈0.01）; in comparison with the SHG group, plasma HGF and serum NO, ET-1, TNF-α, and slCAM-1 in FHG group were all significantly increased further （P〈0.01 or P〈0.05）; meanwhile, in comparison with the FHG control group, the level of plasma HGF and serum NO, ET-1, TNF- α, and slCAM-1 in PQS and MHC groups were all decreased significantly （P〈0.01）. However, comparison of the aortic arteries histology among groups showed no significant differences either before or after treatment. Conclusion： Blood glucose fluctuation could facilitate the development of vascular endothelial dysfunction in T2DM rats, while PQS could improve the endothelial function of T2DM rats with high blood glucose fluctuation, which may be related to its effects of relieving vessel stress, decreasing vasoconstrictor ET-1 production, preventing compensated increase of NO, and reducing inflammatory reaction.

Hypoglycemic effects of black brick tea with fungal growth in hyperglycemic mice model

Dark tea(containing Eurotium cristatum)and black tea have hypoglycemic effects.The black brick tea with fungal growth is obtained from black tea by adding E.cristatum,followed by steaming,pressing,fungal growth,and drying.However,the hypoglycemic effects of black brick tea are still unexplored.Here,we used black brick tea with fungal growth and black tea as raw materials to study their hypoglycemic effects in a hyperglycemic mice model.Both these types of black tea could lower the content of blood glucose and increase the content of hepatic glycogen by upregulating the proteins and m RNA expression of phosphatidylinositol-4,5-bisphosphate3-kinase,glycogen synthase,protein kinase B and phosphoinositidedependent protein kinase-1 and downregulating the protein and m RNA expression of glycogen synthase kinase 3β.These regulatory steps were followed by high activities of glutathione peroxidase and superoxide dismutase and low content of malondialdehyde.These teas can promote blood glucose transport and absorption by upregulating the protein and m RNA expression of insulin receptor substrate-1 and glucose transporter-2 and stimulate glycolysis by upregulating the protein and m RNA expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2.Our study suggests that the black brick tea was more effective than the black tea in terms of hypoglycemic.