Abstract: Abstract: Objective To investigate the change of HO-1 expression in adipose tissue of obese young SD rats as well as its relationship with macrophage infiltration and polarization. Methods Three-week old SD rats (n=24) were randomly divided into 2 groups, routine diet group (NC) and high fat diet group (FC). After feeding 4 weeks, triglyceride (TG), high den⁃ sity lipoprotein (HDL-C), fasting glucose and insulin were compared between these two groups and the insulin resistance in⁃ dex was calculated. The gene expressions of HO-1, IL-6, IL-10 and MCP-1 were assessed by quantitative PCR. Infiltration and polarization of macrophages and M2 macrophages in the visceral adipose tissue were examined by immunohistochemis⁃ try. Results The levels of FINS, FBG and HOMA-IR in rats of FC group were higher than those of rats in NC group after 4 weeks feeding (P < 0.05). The level of HO-1, IL-6, MCP-1 in rats from FC group were significantly higher while level of IL- 10 were lower compared with those in rats from NC group after 4 weeks of feeding (P < 0.05). In samples from FC groups, more macrophages were detected in adipose tissue by DAB staining than those from NC group. There was no significant dif⁃ ference (P > 0.05) in MOD value of F4/80 and CD206 between these two groups (P > 0.05). Conclusion The infiltration of macrophage in visceral adipose tissue of obese young SD rats significantly increased while HO-1 expression was reactively increased. This insinuated that HO-1 might play an important role in anti-inflammatory mechanism through regulating polar⁃ ization of macrophages.

Key words: heme oxygenase (decyclizing), adipose tissue, macrophages, obesity, rats, Sprague-Dawley