替米沙坦改善肥胖大鼠瘦素的促血管重构作用

Telmisartan inhibited leptin-induced vascular remodeling in obese rats

目的 探讨替米沙坦能否抑制肥胖大鼠血管周围脂肪组织中血管紧张素Ⅱ(AngⅡ)诱导的瘦素合成及瘦素的促血管重构作用。方法给予20只8周龄雄性Wistar大鼠高脂喂食12周,另取体质量、周龄匹配雄性Wistar大鼠20只,给予普通喂食12周。高脂喂食大鼠中肥胖大鼠造模成功14只,随机分为高脂组(n=7)和高脂治疗组(n=7),分别给予高脂喂食和高脂+替米沙坦8mg/(kg·d),普通喂食的Wistar大鼠中抽取14只随机分为普食组(给予标准大鼠饲料,n=7)和普食治疗组[标准大鼠饲料+替米沙坦8mg/(kg·d),n=7]。替米沙坦干预20周后,比较各组大鼠体质量、生化指标、主动脉Masson染色、血浆胶原代谢指标;酶联免疫吸附试验及放免法检测各组大鼠血浆及血管周围脂肪组织中AngⅡ、瘦素水平;同时用Western blot法检测AngⅡ1型受体(AT1R)、瘦素蛋白表达水平,主动脉瘦素、瘦素受体、Ⅰ型胶原蛋白表达水平;体外实验利用AngⅡ、替米沙坦干预成熟脂肪细胞,利用Western blot及酶联免疫吸附试验检测其瘦素表达水平;利用瘦素、替米沙坦、吡格列酮、过氧化物酶体增殖物激活受体γ(PPAR-γ)抑制剂干预血管平滑肌细胞,检测Ⅰ型胶原表达,并用四甲基偶氮唑盐比色法检测细胞增殖情况。结果 32周后,与普食组相比,高脂组主动脉胶原容积分数升高、血浆及血管周围脂肪组织中AngⅡ及瘦素水平均较高(均P<0.05),血管周围脂肪组织AT1R、瘦素蛋白表达水平升高(均P<0.05),主动脉中瘦素、瘦素受体、Ⅰ型胶原蛋白表达水平升高(均P<0.05);与高脂组相比,高脂治疗组主动脉胶原容积分数降低,血浆及血管周围脂肪组织中AngⅡ及瘦素水平减少(均P<0.05),血管周围脂肪组织AT1R、瘦素蛋白表达水平降低(均P<0.05),主动脉中瘦素、瘦素受体、Ⅰ型胶原蛋白表达水平下降(均P<0.05)。体外实验发现,AngⅡ促进成熟脂肪细胞的瘦素表达,替米沙坦可以抑制AngⅡ的促瘦素合成作用(均P<0.05);瘦素可促进血管平滑肌细胞Ⅰ型胶原的表达及细胞增殖,替米沙坦可以改善此现象,加入PPAR-γ抑制剂后,替米沙坦的抑制作用消除。结论替米沙坦抑制AngⅡ诱导的瘦素合成并通过部分激动PPAR-γ抑制瘦素的促血管重构作用。

Objective To determine whether telmisartan can inhibit leptin synthesis induced by angiotensin Ⅱ（AngⅡ）and inhibit leptin-induced vascular remodeling in perivascular adipose tissue of obese rats. Methods Twenty 8-week-old male Wistar rats were fed with a high fat diet for 12 weeks to establish the obese rat model.Age and weight-matched male Wistar rats（n=20）were fed with a standard diet for 12 weeks as controls. A total of 14 obese rat models were established and were randomly divided into high fat diet group（n=7）and high fat diet plus treatment group[high fat diet＋telmisartan 8 mg/（kg·d）,n=7];14 male Wistar rats fed with a standard diet were also randomly divided into standard diet group（n=7）and standard diet plus treatment group [standard diet＋telmisartan 8 mg/（kg·d）,n=7]. These rats were treated with telmisartan for 20 weeks,and then the body mass,biochemical indexes,aorta Masson staining and plasma collagen metabolic index were detected. The levels of AngⅡand leptin in plasma and perivascular adipose tissue in all groups were measured by enzyme-linked immunosorbent assay and radioimmunoassay. The levels of AngⅡ type 1 receptor（AT1 R）,leptin protein,leptin receptor and typeⅠcollagen in the aorta were detected by Western blotting. In vitro,after intervention of AngⅡand telmisartan,the expression of leptin in mature adipocytes was detected by Western blotting and enzyme-linked immunosorbent assay. After intervention of leptin,telmisartan,pioglitazone and peroxisome proliferator-activated receptor gamma（PPAR-γ）inhibitor in vascular smooth muscle cells,the expression of typeⅠcollagen was detected and the proliferation of cells was detected by methyl thiazolyl tetrazolium（MTT）assay. Results After 32 weeks,compared to the standard diet group,collagen volume fraction of the aorta,the levels of AngⅡ and leptin in the plasma and perivascular adipose tissue,the expression levels of AT1 R and leptin protein in perivascular adipose tissue,and the expression levels of leptin,leptin receptor and type Ⅰ collagen of the aorta were increased in the high fat diet group（all P〈0.05）;compared to the high fat diet group,collagen volume fraction of the aorta,the levels of AngⅡand leptin in the plasma and perivascular adipose tissue,the expression levels of AT1 R and leptin protein in perivascular adipose tissue,and the expression levels of leptin,leptin receptor and type Ⅰ collagen of the aorta were decreased in the high fat diet plus treatment group（all P〈0.05）. Experiments in vitro showed that the expression of leptin in mature adipocytes was promoted by Ang Ⅱ,and telmisartan could inhibit the expression of leptin induced by AngⅡ（all P〈0.05）. The expression of typeⅠ collagen and cell proliferation in vascular smooth muscle cells were promoted by leptin,which could be inhibited by telmisartan,and the inhibitory effect of telmisartan was eliminated by PPAR-γinhibitor. Conclusion Telmisartan inhibited AngⅡ-induced leptin synthesis,and inhibited leptin-induced vascular remodeling by partial agitation of PPAR-γ.