Objective: To explore the effect of niacin on the serum adiponectin concentration in hypercholesterolemia rabbit and the adiponectin concentration secreted by adipocytes in normal rabbits.
Methods: Ten male New Zealand white rabbits fed with high cholesterol diet for 8 weeks were randomly divided into 2 groups: (1) The high cholesterol group maintained a high cholesterol diet for 8 weeks. (2) The same cholesterol diet plus niacin (0.4g/kg*d ) were administrated for 6 weeks in the niacin group. A control group was fed with normal diet for 14 weeks. Subcutaneous adipose from the control group was collected for adipocyte culture. Matured adipocytes were incubated with various concentrations of niacin (0, 0.25, 0.5, 1.0, and 2.0micromol/L). Adiponectin concentrations in the serum and adipocyte culture supernatant were measured by enzyme-linked-immunosorbent assay.
Results: Compared with the control group, rabbits in the high cholesterol group showed higher serum levels of total cholesterol, and low density lipoprotein cholesterol (LDL-C), all of which were significantly reduced by niacin treatment (P<0.01),and serum high density lipoprotein-cholesterol (HDL-C) significantly increased (P<0.01). At 8th week, the mean adiponectin concentration of rabbits fed with high cholesterol diet was significantly lower than that of the control group[(1.268+/-0.039)mg/L vs.(1.449+/-0.107)mg/L,P<0.01]. Niacin treatment significantly elevated the serum adiponectin level which was positively related to HDL-C,and negatively related to TC and LDL-C. Cell experiment in vitro indicated that niacin could significantly induce the adiponectin secretion of adipocytes in a dose-dependent manner.
Conclusion: Niacin can significantly promote the adiponectin secretion of adipocytes, suggesting that niacin probably has an ability of elevating the serum adiponectin level in addition to lipid-lowering effect.