Histidine supplementation alleviates inflammation in the adipose tissue of high-fat diet-induced obese rats via the NF-κB- and PPARγ-involved pathways.

Obesity is considered to be accompanied by a chronic low-grade inflammatory state that contributes to the occurrence of many chronic diseases. Our previous study has demonstrated that histidine supplementation significantly ameliorates inflammation and oxidative stress in obese women. However, the in vivo potential mechanisms are not known. The present study was conducted to investigate the mechanisms underlying the effects of histidine on inflammation in a high-fat diet (HFD)-induced female obese rat model. An obese model was established in female Sprague-Dawley rats by HFD feeding for 8 weeks and followed by histidine supplementation for another 4 weeks. The results revealed that HFD-increased body weight and HFD-lowered serum histidine concentrations were significantly reversed by histidine supplementation (P< 0·05). In addition, the serum concentrations of TNF-α, IL-6, C-reactive protein (CRP) and malondialdehyde were significantly reduced and those of superoxide dismutase (SOD) were significantly increased by histidine supplementation when compared with those in obese rats (P< 0·05). Correspondingly, the mRNA expressions of TNF-α, IL-6 and CRP in the adipose tissue were significantly down-regulated and that of CuZnSOD was significantly up-regulated by histidine supplementation (P< 0·05). Histidine supplementation significantly reduced the HFD-induced translocation of NF-κB p65 into the nucleus (P= 0·032) by reducing the phosphorylation of the inhibitor of κBα in the adipose tissue. The results also revealed that the expression of adiponectin was markedly increased both in the serum and in the adipose tissue after histidine supplementation, accompanied by the activation of PPARγ (P= 0·021). These findings indicate that histidine is an effective candidate for ameliorating inflammation and oxidative stress in obese individuals via the NF-κB- and PPARγ-involved pathways.