Adipose Tissue Inflammation and Oxidative Stress: the Ameliorative Effects of Vitamin D

Obesity is a low-grade inflammatory disease and is associated with numerous comorbidities. The current study was aimed to evaluate the effects of vitamin D administrations on markers of inflammation and oxidative stress in adipose tissue of high-fat diet-induced obese rats. In the beginning of the study, 40 rats were divided into two groups: normal diet and high-fat diet (HFD) for 16 weeks; then, each group was subdivided into two groups including ND, ND + vitamin D, HFD, and HFD + vitamin D. Vitamin D supplementation was done for 5 weeks at 500 IU/kg dosage. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, monocyte chemoattractant protein (MCP)-1, transforming growth factor (TGF)-beta and IL-6 concentrations and markers of oxidative stress including glutathione peroxidase (GPx), superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) concentrations in adipose tissue of rats were determined using ELISA kits and spectrophotometry methods, respectively. Vitamin D treatment led to a significant reduction in adipose tissue TNF-alpha concentrations in both ND + vitamin D and HFD + vitamin D groups (P < 0.05). Adipose tissue MCP-1 concentration also reduced in HFD + vitamin D group compared with HFD group. Among markers of oxidative stress in adipose tissue, SOD and GPx concentrations significantly increased in adipose tissue of HFD + vitamin D treated group compared with other groups (P < 0.05). Reduced food intake and weight gain was also occurred after vitamin D treatment. Vitamin D improved adipose tissue oxidative stress and inflammatory parameters in obese rats. Vitamin D treatment was also associated with decreased food intake and decreased weight gain in animals under a high-fat diet. Further studies are needed to better clarify the underlying mechanisms.