Selection of modeling time for type 2 diabetes mellitus mouse / 中国应用生理学杂志

OBJECTIVE@#To analyze the changes of blood biochemical index and the pathological changes of myocardium and kidney in type 2 diabetic mouse at different time points, which can provide the basis for the selection of type 2 diabetic modeling time for later research.@*METHODS@#After 6 weeks of feeding with high-fat diet, 24 healthy male ICR mice were injected with streptozocin (STZ, 30 mg/kg) intraperitoneally for 5 days to establish diabetic models. After 9 days, a random blood glucose ≥ 11.1 mmol / L was measured as diabetic mice. 4, 6 and 8 weeks after successfully preparing the diabetic mouse, 8 diabetic mice (a group)would be sacrificed each time. Then the biochemical and pathological conditions were analyzed: ① the indexes of heart and kidney were calculated. ②the serum levels of creatine kinase (CK), lactate dehydrogenase (LDH), creatinine (Cr) and blood urine nitrogen (BUN) were determined. ③ Histopathological changes of myocardium and renal tissues were observed by hematoxylin and eosin (HE) staining. Masson staining was used to observe the fibrosis of myocardium. PAS staining was adopted to observe the pathological changes of renal tissue. In addition, 8 ICR male mice were taken as the control group.@*RESULTS@#At the 4, 6 and 8 week, cardiac organ coefficient, the values of LDH and CK were all increased compared with the control group. Cardiomyocyte hypertrophy and myocardial fibrosis could be observed. Renal organ coefficient, the values of Cr and BUN were increased. Glomerular hypertrophy, basement membrane thickening and atrophy could be perceived.@*CONCLUSION@#At the 6 week, related biochemical and pathological changes in diabetic mice were comparatively obvious and breeding time was relatively short. Thus, 6 weeks after the preparation of the diabetic mice would be the optimal time for type 2 diabetes mellitus modeling, proper for inventions of drugs and other research purposes including pathology, physiology, biochemistry, etc.

Effect of ursolic acid on cardiomyopathy of mice with diabetes and its mechanism / 中国应用生理学杂志

OBJECTIVE@#To study the effect of ursolic acid on cardiomyopathy in mice with diabetes induced by high-fat diet combined with low dose streptozotocin, and to explore its possible mechanism.@*METHODS@#Thirty male ICR mice were randomly divided into control group (=10) and moulding group (=20), the mice in the two groups were fed with regular diet and high-fat diet respectively for 6 weeks, and then the mice in the moulding group were injected with streptozotocin (30 mg/kg) for 5 successive days to induce diabetes mellitus (DM). Fasting blood glucose (FBG) was measured after 9 days. Mice with FBG over 11.1 mmol/L were regarded as DM. Twenty DM mice were randomly divided into model group and ursolic acid group (=10). Mice in each group were continuously administrated ursolic acid (100 mg/kg) or corresponding solvent intragastrically for 8 weeks. After that, FBG was measured, body weight (BW), heart weight and left ventricular weight were weighed in order to calculate the heart mass index (HMI) and left ventricular mass index (LVMI). Levels of creatine kinase (CK), lactate dehydrogenase (LDH) in serum and the level of superoxide dismutase (SOD), malondialdehyde (MDA) in myocardial tissue were detected. HE staining was used to observe pathological changes of myocardial tissue. Immunohistochemistry was employed to determine the expression of NOD-like receptor protein 3 (NLRP3) and interleukin 1β (IL-1β).@*RESULTS@#Compared with the control group, HMI, LVMI were apparently enlarged, levels of FBG, CK, LDH in serum and MDA in myocardial tissue were extremely increased, while the activity of SOD in myocardial tissue were extraordinary decreased in diabetic group. HE staining of myocardium showed that arrangement disorder of myocardial fibers, edema and hypertrophy in myocardial cell, as well as inflammatory cell infiltration in model group. Immunohistochemistry showed that the expression of NLRP3 and IL-1β in myocardial tissue increased obviously in model group, the above changes inursolic acid group were significantly ameliorated.@*CONCLUSIONS@#Ursolic acid has a obvious protective effect on myocardial injury in mice with diabetes induced by high-fat diet combined with low dose streptozotocin, and its mechanism may be associated with inhibiting NLRP3 inflammasome activation, reducing IL-1β generation and alleviating myocardial inflammatory injury.