Effects of pyruvate administration on mRNA expression of inflammatory cytokines in adipose tissue and whole-body glucose metabolism in male mice.

Pyruvate administration leads to the accumulation of intracellular lactate in adipocytes and affects inflammatory cytokine production and whole-body glucose metabolism. Therefore, the purpose of this study was to determine whether pyruvate administration improves the dysfunction of glucose metabolism induced by high-fat diet (HFD) intake. In an acute experiment, intraperitoneal injection of male mice with sodium pyruvate (1 g/kg body weight) increased pyruvate and lactate concentrations in blood and epididymal white adipose tissue (eWAT). In a chronic experiment, male mice were divided into three groups: normal diet, HFD with saline administration (HFD + SAL), and HFD with sodium pyruvate administration (HFD + PYR); the HFD + PYR group was injected with pyruvate five times a week for 8 weeks. Insulin concentrations in the basal state and during an oral glucose tolerance test were significantly lower in the HFD + PYR group than in the HFD + SAL group. The mRNA expression of inflammatory cytokines (tumor necrosis factor-alpha and interleukin 6) and a M2 macrophage polarity marker in eWAT was significantly higher in the HFD + PYR group than in the other groups. These results suggest that chronic pyruvate administration partially improves whole-body glucose metabolic dysfunction in HFD-fed mice, accompanied by increased mRNA expression of inflammatory cytokines and a M2 macrophage marker in the eWAT.