Effect of Vitamin D on monocyte/macrophage chemoattractant protein and macrophage infiltration in adipose tissue of infantile rats with obesity / 中华实用儿科临床杂志

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 wcighted after 6 weeks.The levels of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1 α (MIP-1 α) 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-1 α 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 ofMCP-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).The adipose cells ranged orderly in group N and group VitD;the structure was disordered in group OB with various shapes and sizes of adipose cells and the excessively expanded adipose cells existed with many small newborn adipose cells.Immunohistochemistry showed that the protein expressions of MCP-1,MIP-1α and F4/80 in adipose tissue in group OB(130 944.5 ±10 706.1,174 354.8 ±65 267.8,51 701.9 ± 50 105.1) significantly increased compared with those of group N (47 394.5 ± 9 261.9,54 376.7 ± 36 436.9,23 370.3 ± 16 613.1),and the differences were significant (all P ＜ 0.01);the protein expressions of MCP-1,MIP-1α and F4/80 in adipose tissue in group VitD (102 967.2 ± 9 329.3,48 659.8 ± 43 553.8,25 604.9 ± 11 411.6) significantly decreased compared with those of group OB,and the differences were significant (all P ＜ 0.01).The qPCR showed that mRNA expressions of MCP-1,MIP-1 α and NF-κB in adipose tissue in group OB (2.78 ± O.90,7.10 ± 1.85,1.50 ± 0.16) significantly increased compared with those of group N (0.88 ± 0.18,0.99 ± 0.80,1.00 ± 0.28),and the differences were significant (all P ＜ 0.05);the mRNA expressions of MCP-1,MIP-1α and NF-κB in adipose tissue in group VitD(1.73 ±0.51,1.59 ± 1.09,0.72 ±0.30) significantly decreased compared with those of group OB,and the differences were significant (all P ＜0.05).There was no significant difference in Lee's indexes among the 3 groups (F =0.351,P =0.711).At the age of 9 months age,the mRNA expression levels of MCP-1,MIP-1α and NF-κB in adipose tissue of infantile rats were positively correlated with body weight and intra-peritoneal fat coefficient(r =0.738,0.517,0.762,0.693,0.519,0.557,all P ＜ 0.05),but there was no correlation with the Lee's index(r =0.322,0.317,-0.023,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.