烟酸对兔脂肪细胞分泌脂联素的影响

目的:探讨烟酸对高胆固醇血症兔血清脂联素及正常兔脂肪细胞分泌脂联素的影响.方法:将10只新西兰大白兔饲以高胆固醇饲料8周后,随机分为高脂淀粉组(5只)和高脂烟酸组(5只),后者在高胆固醇饮食基础上给予烟酸缓释片0.4 g/(kg·d)共6周;另设普通饲料对照组(5只),于第14周末取皮下脂肪组织行脂肪细胞培养,以不同浓度烟酸孵育兔脂肪细胞24 h后提取上清液.采用ELISA方法分别测定兔血清及上清液中脂联素的浓度.结果:高脂淀粉组兔血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)明显高于对照组(P＜0.05),高密度脂蛋白胆固醇(HDL-C)轻度升高;烟酸干预后,血TC和LDL-C明显降低(P＜0.001),HDL-C明显升高(P＜0.001).8周时高脂组血清脂联素浓度为(1.268±0.039)mg/L,明显低于对照组的(1.449±0.107)mg/L(P＜0.01),经治疗后,脂联素水平明显升高至(1.444±0.057)mg/L,且与HDL-C呈正相关,与TC和LDL-C呈负相关.体外干预实验发现,烟酸促进正常脂肪细胞分泌脂联素,呈浓度依赖性.结论:高胆固醇血症兔脂肪细胞脂联素分泌明显减少,烟酸能显著促进脂联素的分泌,提示烟酸可能有独立于降脂外的升高脂联素的作用.

Effect of niacin on adiponectin levels in the adipocytes secretion in rabbits

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.