Aim To investigate the effect of niacin on serum leptin levels in hypercholesterolemic rabbits and the expression of leptin,peroxisome proliferator-activated receptor γ(PPARγ)and CD36 in adipocytes from hypercholesterolemic rabbits.Methods Twelve rabbits fed with high-cholesterol diet for 8 weeks were randomly divided into two groups:high cholesterol group(n=6)maintained on high cholesterol diet for 6 weeks,niacin group(n=6)fed with the same cholesterol diet plus niacin 0.2 g/(kg·d)for 6 weeks.Control group(n=6)was fed with normal diet for 14 weeks.Subcutaneous adipose was collected for RNA analysis.Leptin levels in serum and adipocytes culture supernatant were measured by enzyme linked immunosorbent assay(ELISA).Reverse transcription polymerase chain reaction(RT-PCR)was used to evaluate leptin,PPARγ and CD36 mRNA expressions in adipose and adipocytes.Results Compared with control group,rabbits fed with high cholesterol diets showed higher levels of serum and adipocyte leptin,all of which were significantly reduced by niacin treatment.Leptin mRNA expression of adipose was significantly lower in rabbits treated with niacin than those fed with high cholesterol diet.Leptin mRNA expression of hypercholesterolemic rabbits by niacin was negatively correlated with the mRNA expression of PPARγ and CD36 by niacin.Niacin dose-dependently inhibited leptin secretion and increased CD36 and PPARγ expression in cultured adipocytes.Conclusion Niacin can reduce serum level and adipose mRNA expression of leptin,and upregulate PPARγ and CD36 mRNA expression in hypercholesterolemic rabbits.