Abstract: Objective To explore the effect of angiogenesis on protecting young mice obesity by cytochrome(CYP1B1) deletion.Methods Sixteen male CYP1B1 deficient mice and sixteen wild type(WT) mice(C57/BL,3-week-old,right after weaning) were randomly divided into low-fat-diet(LFD,10% fat) and high-fat-diet(HFD,60% fat) groups for 11 weeks feeding.The body weight and food consumption were recorded every 3 days.The mice were sacrificed at the age of 12 weeks by decapitation and epididymal fat pad was quickly removed.Part of tissue was snap frozen in liquid nitrogen to extract total RNA for real time-PCR(RT-PCR) and another part of tissue was fixed in 4% parafomaldehyde(PFA) for sectioning and immunofluorescence detecting.Results HFD significantly downregulated WT mice CD31 expression in both transcription and translation levels,while CYP1B1 deletion rescured this inhibiton.Knockout(KO) mice exhibited higher level of angiopoietin-1 than that in WT mice on basal condition,and HFD supressed its expression in both WT and KO mice while kept angoipoietin-2 unchanged.Pro-angiogenic factor-leptin was greatly increased by HFD in mice of the two groups and CYP1B1 deletion suppressed this action.Conclusion Modulation of angiogenic factors expression and endothelial cell density by CYP1B1 deletion might play an important role in protecting the mice from HFD induced obesity,however,the detail and its mechanism need further investigation.