Vaspin improves insulin sensitivity in type 2 diabetes rats by regulating the polarization of adipose tissue macrophages / 中华内分泌代谢杂志

ABSTRACT

Objective:This study aimed to explore the effect of Vaspin on adipose tissue macrophage polarization and its underlying mechanism.Methods:Fifty male SD rats, aged 8 weeks, were chosen and randomly allocated into three groups: the normal control(NC), the type 2 diabetes(T2DM), and various concentrations of Vaspin intervention(V1: 480 ng/kg, V2: 960 ng/kg, V3: 1 440 ng/kg). Vaspin was administered via intraperitoneal injection for 8 weeks. Glucose tolerance and insulin sensitivity were evaluated via intraperitoneal glucose tolerance test(IPGTT), intraperitoneal insulin tolerance test(IPITT) and hyperinsulinemic-euglycemic clamp. Adipose tissue inflammation and macrophage polarization were assessed using immunofluorescence, RT-PCR and western blotting.Results:After 8 weeks of intervention, there were no statistically significant differences in body weight and blood lipid levels among groups. IPGTT, IPITT, and hyperinsulinemic-euglycemic clamp experiments demonstrated that Vaspin intervention improved blood glucose and insulin sensitivity, exhibiting a dose-dependent manner( P<0.05). IF and RT-PCR showed that Vaspin downregulated the expression of CD11c, IL-1β, and TNF-α in eWAT, while upregulating the expression of CD206, IL-10, and PPARγ, which correlated with Vaspin concentration( P<0.05). ELISA revealed that Vaspin intervention reduced the concentrations of IL-1β and TNF-α in serum, while increasing the concentration of IL-10( P<0.05). Western blotting demonstrated that Vaspin downregulated iNOS protein expression, while upregulating Arg1, p-Akt, and PPARγ expression in a dose-dependent manner( P<0.05). Conclusion:Vaspin promotes M2 polarization of adipose tissue macrophages via PPARγ pathway, leading to reduced inflammation and improved insulin sensitivity in T2DM rats.