替米沙坦上调内脏脂肪组织的脂联素表达并改善胰岛素抵抗

目的 探讨替米沙坦对体外原代培养的人前脂肪细胞和OLETF大鼠脂肪组织中脂联素表达以及胰岛素敏感性的影响.方法 提取人腹部皮下和内脏的前脂肪细胞,原代培养并传代后接种于无血清培养基,分为对照组（H-N）、吡格列酮组（H-P）和替米沙坦（H-T）组.葡萄糖消耗试验测定细胞的胰岛素敏感性,实时荧光定量PCR（RT-PCR）技术测定细胞脂联素mRNA的表达,放射免疫法测定培养基上清脂联素的分泌量.4周龄雄性OLETF大鼠28只,初始体重150～180 g.高脂喂养,分为对照组（O-HFD组,10只）、吡格列酮组（O-P组,8只）和替米沙坦组（O-T组,10只）.口服葡萄糖耐量实验和高胰岛素-正糖钳夹实验检测胰岛素抵抗指数和60 ～ 120 min葡萄糖输注速度以测定大鼠胰岛素抵抗水平,RT-PCR和Western blotting技术检测大鼠皮下和内脏脂肪组织脂联素的mRNA和蛋白表达.计量资料均数比较应用单因素方差分析.结果 H-T组和H-P组内脏前脂肪细胞的葡萄糖消耗量较之H-N组明显升高[分别为（5.6±1.6）、（4.4±1.6）、（2.0±0.8）mmol/L,F=20.240,P＜0.05].O-T和O-P组大鼠高胰岛素-正糖钳夹实验得到的60 ～ 120 min葡萄糖输注速度明显高于O-HFD组大鼠[分别为（18±5）、（20±4）、（10±3） mg·kg-1·min-1,F=8.136,P＜0.05].O-T和O-P组大鼠的HOMA胰岛素抵抗指数也显著低于O-HFD组大鼠（分别为10.0±8.6、5.5±2.0、17.8±10.1,F=5.784,P＜0.05）.替米沙坦可降低高脂饲养OLETF大鼠升高的腹围、内脏脂肪系数和血清游离脂肪酸水平,并改善大鼠的空腹高血糖,差别有统计学意义[分别为（24.0±2.0）比（26.5±2.7） cm、5.8％±2.4％比8.6％±2.4％、（2.8±0.7）比（5.3±1.8）μg/L、（10±6）比（15±7） mmoL/L,均P＜0.05].H-T较之H-N组原代培养人前脂肪细胞和O-T较之O-HFD组大鼠脂肪组织脂联素的mRNA表达和蛋白分泌量均明显上调（均P＜0.05）.H-T较之H-P组人内脏脂肪细胞和O-T较之O-P组大鼠内脏脂肪组织脂联素mRNA和蛋白表达水平均升高或有上升的趋势（分别为59.9±2.0比6.0±1.6、1.807±0.297比1.332±0.112、4.43±2.57比1.71±0.57、2.6±0.9比1.9±0.5,均P＜0.05）.结论 替米沙坦具有提高OLETF大鼠与人前脂肪细胞胰岛素敏感性、缓解大鼠的内脏性肥胖和改善大鼠糖脂代谢功能紊乱的作用,并很可能通过上调脂肪尤其是内脏脂肪的脂联素表达来完成.

Telmisartan upregulates the expression of adiponectin in visceral fat and decreases insulin resistance

Objective To investigate the effects of telmisartan on insulin sensitivity and adiponectinexpression in primary cultured human preadipocytes and adipose tissue of spontaneously type 2 diabetic OLETF rats fed with high-fat diet. Methods Human subcutaneous and visceral preadipocytes were differentiated for 14 days in serum-free medium, in the presence of 10 μmol/L telmisartan （ group H-T）, or pioglitazone （group H-P）, or vehicle （group H-N ）. Insulin sensitivity of preadipocytes was detected by glucose consumption test. Radioimmunoassay was employed to determine the concentration of adiponectin in the culture medium. The mRNA expression of adiponectin was measured by real-time fluorescence quantitative polymerase chain reaction（real-time PCR） with TaqMan probe. From 22 weeks of age, the pre- diabetic OLETF rats, which were fed with high-fat diet from 8 weeks old, were divided into group O-HFD, O-T （treated with telmisartan 5 mg · kg-1·day-1）, or O-P （treated with pioglitazone 10 mg·kg-1· day-1 ）. The insulin resistance of OLETF rats were determined by euglycaemic-hyperinsulinaemic clamp test and oral glucose tolerance test （OGTr）. The mRNA and protein expression of adiponectin in the subcutaneous and visceral adipose tissue were measured by real-time PCR and Western blot. The statistical analyses were performed using the SPSS 13.0 software package, and the significance of differences between groups was analyzed by one-way ANOVA. Results The glucose consumption of human visceral preadipocytes in group H-T （ （5.6± 1.6） mmol/L） and H-P （ （4. 4 ± 1.6） retool/L） were higher than that in group H-N （（2.0 ±0. 8） mmol/L）. The 60 - 120 rain glucose infusion rates in euglycaemic- hyperinsulinaemic clamp test were （18 ± 5 ） and （20 ± 4 ）mg·kg-1·min-1 in group O-T and O-P, Prespectively, which were both higher than that of group O-HFD（ （10±3） mg·kg-1·min-1 ,F = 8. 136, P 〈 0. 05）. That improvement was also manifested with the HOMA index of insulin resistance in OGTr of OLETF rats （ F = 5. 784, P 〈 0. 05 ）. Telmisartan reduced the abdominal circumference （ （24. 0 ±2.0） vs （26.5 ± 2.7） cm）, visceral fat tissue coefficient （5.8% ±2.4% vs 8.6% ±2.4%）, serum free fatty acids （ （ 2. 8 ± 0. 7 ） vs （ 5.3 ± 1.8 ） μg/L） and the fasting plasma glucose （ （ 10 ± 6 ） vs （ 15 ± 7 ） mmol/L） in high-fat-diet OLETF rats （ P 〈 0. 05 ） . The mRNA and proteinexpression of adiponeetin in human preadipoeytes and the adipose tissue in OLETF rats were up-regulated significantly by telmisartan （P 〈 0. 05 ）. The especially important result was that the mRNA and protein expression of adiponectin in the human visceral preadipoeytes and the OLEFT rats visceral adipose tissue were higher in group H-T and group O-T than those in group H-P and O-P（59. 9 ±2. 0 vs 6. 0 ± 1.6,1. 807±0. 297 vs 1. 332 ±0. 112,4. 43 ± 2.57 vs 1. 71 ± 0.57,2.6 ± 0.9 vs 1.9 ＋- 0.5, with all P 〈 0.05 ）. Conclusions Telmisartan can increase the insulin sensitivity in the high-fat-diet OLETF rats and the human preadipocytes, ameliorate the visceral obesity and improve the glucose and lipid metabolism in the OLETF rats Those effects might via the upregulation of adiponeetin expression in the adipose tissue, especially in the visceral adipose tissue.