Effect of Vitamin D on monocyte/macrophage chemoattractant protein and macrophage infiltration in adipose tissue of infantile rats with obesity

Abstract

Objective To investigate the effect of Vitamin D (VitD) on intraperitoneal fat coefficient, monocyte/macrophage chemoattractant protein and macrophage infiltration in adipose tissue of infantile rats with obesity. Methods A total of 45 weanling female SD rats were randomly divided into control group(group N), obesity model group(group OB) and VitD intervention group(group VitD), and each group had 15 rats.The rats of group N were fed with basic diet, and the rats in group OB and group VitD were fed with high-fat diet.The rats of group VitD were administrated intragastrically with VitD 5 μg/(kg·d)(equivalent to 400 IU VitD for human infants) for 6 weeks, while the rats of group OB and group N were given plant oil [5 mL/(kg·d)] for 6 weeks instead.The body weight of rats were recorded once every week, and Lee′s indexes were calculated.The fat mass in enterocoelia were weighted after 6 weeks.The levels of monocyte chemoattractant protein-1(MCP-1) and macrophage inflammatory protein-1α(MIP-1α) in serum were detected by adopting enzyme-linked immunosorbent assay.The specimens of adipose tissue were observed and the number of adipocyte was counted through hematoxylin-eosin stain.The protein expressions of MCP-1, MIP-1α and F4/80 in adipose tissue were determined by immunohistochemistry, and the mRNA expressions of MCP-1, MIP-1α and nuclear factor (NF)-κB in adipose tissue were determined by real time quantitative polymerase chain reaction(qPCR), then the correlation analysis with body weight, Lee′s index and fat mass in enterocoelia were conducted. Results After 6 weeks with high-fat diet, the body weight, intraperitoneal fat coefficient, serum levels of MCP-1 and MIP-1α in group OB[(244.1±16.2) g, (3.25±0.63)%, (2 275.2±229.3) ng/L, (190.4±61.9) ng/L] significantly increased compared with those of group N[(224.2±10.9) g, (2.43±0.47)%, (1 522.1±577.1) ng/L, (63.6±31.6) ng/L] and group VitD[(214.0±12.5) g, (2.04±0.64)%, (1 863.4±477.0) ng/L, (120.3±29.5) ng/L], and the differences were significant (all P 0.05). Conclusions VitD supplement can suppress the obesity induced by high-fat-diet, and the possible mechanism is that VitD reduce the expression of monocyte/macrophage chemoattractant protein and macrophage infiltration in adipose tissue through regulating NF-κB signal pathway. Key words: Intraperitoneal adipose tissue; Monocyte chemoattractant protein-1; Macrophage inflammatory protein-1α; Macrophage; Vitamin D; Infantile rat