雷帕霉素对大鼠心房纤维化的影响

Effects of rapamycin on atrial fibrosis in rats

目的:探讨雷帕霉素(rapamycin,RAPA)对盐酸异丙肾上腺素(isoproterenol,ISO)诱导的大鼠心房纤维化的影响及其可能的机制。方法:雄性Wistar大鼠27只,随机分为空白对照组(对照组)、ISO组和ISO+RAPA组,每组9只(n=9)。皮下注射ISO建立大鼠心房纤维化模型,给予RAPA干预。实验的第15天,处死大鼠并取心房组织,用放射免疫测定法检测AngⅡ的含量,用免疫组化染色法及Western blot法检测缺氧诱导因子-1α(hypoxia-in-ducible factor-1alpha,HIF-1α)和转化生长因子-β1(transforming growth factor-beta 1,TGF-β1)的表达。将心房组织切片经Masson染色后,观察心房纤维化程度即胶原容积分数(CVF)。结果:①AngⅡ含量,与对照组(36.452±3.262)ng/L相比,ISO组(147.328±6.889)ng/L及ISO+RAPA组(142.252±4.968)ng/L明显升高(P<0.01)。对照组的CVF为(16.334±1.447)%,无心房纤维化,ISO组心房纤维化的程度明显(P<0.01),ISO+RAPA组(17.021±1.341)%较ISO组(85.692±2.430)%心房纤维化的程度明显减轻(P<0.01)。②免疫组化染色法及Western blot的结果显示,ISO组HIF-1α(0.264±0.017)A和TGF-β1(0.343±0.018)A的表达较对照组[分别为(0.160±0.012)A和(0.129±0.012)A]均明显升高(P<0.01),ISO+RAPA组[分别为(0.174±0.013)A和(0.139±0.014)A]较ISO组明显降低(P<0.01),且与纤维化的程度呈正相关(r值分别0.949和0.987,P<0.01);HIF-1α与TGF-β1的表达亦呈正相关(r值为0.945,P<0.01)。结论:RAPA可能通过抑制HIF-1α、TGF-β1的表达而使ISO诱导的大鼠心房纤维化减轻。

AIM： To explore the effects of rapamycin （RAPA） on atrial fibrosis in rats treated with high isoproterenol （ISO）. METHODS： Twenty-seven male Wistar rats were randomly divided into control group, ISO group [ 5 mg/（ kg· day） for 7 days ] and ISO ＋ RAP group [ 3 mg/（ kg. day） for 2 weeks ]. Mice were sacrificed after 15 days. Angiotensin II （Ang II） content in myocardial tissue was measured by radioimmunoassay, HIF-1α and TGF-β1 were detected by immunohistochemistry and Western blot, and atrial fibrosis was determined on H-E and Masson stained heart sections. RESULTS： Compared with the control group, Ang II content increased in ISO group and ISO ＋ RAP group （ P 〈 0. 01 ）. The degree of atrial fibrosis in ISO ＋ RAP group was significantly lower than that in ISO group （ P 〈 0. 01 ） and no atrial fibrosis was seen in control group. HIF-1α and TGF-β1 expressions of myocardium increased in ISO group compared with those in control group （ P 〈 0. 01 ） and decreased in ISO ＋ RAP group compared with those in ISO group （P 〈0.01 ）. CONCLUSION： HIF-1α may be involved in atrial fibrosis and RAPA can efficiently improve atrial fibrosis by repressing the expressions of HIF-1α and TGF-β1.