[Biochemical and pathological analysis of mice with type 2 diabetes mellitus induced by high-fat diet and low-dose streptozotocin injections].

Objective: To analyze the biochemical and pathological changes in mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet combined with low-dose streptozotocin (STZ) injections.

Methods: C57BL/6J mice were divided randomly into normal control group (NC group), high-fat diet group (HC group) and high-fat diet plus STZ group (HC+STZ group). The mice were fed on normal chow or a high-fat diet for 1 month before two introperitoneal injections of STZ (40 mg/kg) or citrate buffer with an interval of 24 h as appropriate. Fasting blood glucose (FBG) was detected every week for 4 weeks, and oral glucose tolerance test (OGTT) was performed one month after the injections, after which the biochemical profiles, islet and liver were evaluated by immunohistochemical and pathological analysis.

Results: In HC+STZ group, FBG was above the cutoff value (13.89 mmol/L) in 75% of the mice at 1 week after STZ injections and in all the mice at two weeks except for the death of 1 mouse, with a success rate of modeling of 91.3%. FBG in HC group, though slightly higher than that in NC group, remained normal (6.8 mmol/L). The body weight in HC+STZ and HC groups was significantly higher than that in NC group after feeding but without obvious increases after the injections (P<0.01). Blood glucose in HC+STZ group at 0.5 to 2 h after OGTT and the area under curve (AUC) were higher than those in NC and HC groups (P<0.01); the AUC in HC group was a also higher than that in NC group (P<0.05). Plasma creatinine was significantly higher in HC+STZ group than in NC (P<0.01) and HC (P<0.05) groups. Insulin secretion by the islets decreased obviously in HC+STZ and HC group. The mice in HC+STZ group showed atrophy, fibrosis, and vacuolization in the islets with mild fatty liver but no visible renal pathologies.

Conclusion: High-fat diet and low-dose STZ injections can induce T2DM in mice with very similar biochemical and pathological changes to human T2DM and with such complications as fatty liver.