5-HT_(2B)受体阻断剂对去甲肾上腺素诱导的肥厚心肌组织中心肌细胞凋亡的影响

Impact of 5-HT_(2B) receptor antagonist on cardiomyocyte apoptosis in cardiac hypertrophy induced by norepinephrine in rats

目的观察5-HT2B受体阻断剂对去甲肾上腺素(NE)诱导的肥厚心肌组织中心肌细胞凋亡的影响。方法雄性SD大鼠24只,随机分为3组,每组8只,分别为对照组,肥厚组、实验组。采用腹腔注射NE(1.5 mg/kg,2次/d,28 d)的方法建立心肌肥厚动物模型,自第15天起实验组腹腔注射SB204741(5-HT2B受体阻断剂)2 mg/kg,2次/d,连续注射14 d。对照组腹腔注射相同体积的生理盐水2次/d,28 d。采用TUNEL法检测各组心肌组织中心肌细胞的凋亡情况,Western blot方法分析Bcl-2、Bax、Caspase-3的表达情况。结果对照组的心肌组织中几乎看不到凋亡的心肌细胞,肥厚组心肌组织中凋亡心肌细胞数量显著增多,同时Bcl-2/Bax表达比例显著降低,Caspase-3的表达显著升高;与肥厚组相比,实验组心肌组织中凋亡心肌细胞的数量显著减少,Bcl-2/Bax表达比例显著升高,Caspase-3的表达显著降低。结论应用5-HT2B受体阻断剂不仅可减轻NE诱导的心肌肥厚的程度,还可通过上调Bcl-2/Bax表达比率、降低Caspase-3的活性抑制心肌细胞的凋亡。

Objecive To observe the anti-apoptotic activity of 5-HT receptor antagonist in cardiac hypertrophy induced by norepinephrine in rats. Methods Experiments were performed on Sprague-Dawley rats （weighing 180-220 g）. To induce ventricular hypertrophy, rats were injected with norepinephrine （i.p.,1.5 mg/kg） twice daily for 28 days. Starting on the Day 15, 5-HT2s receptor antagonist SB 204741 （i.p.,2 mg/kg,in study group,n=8） was injected twice daily for another 14 days in the norepinephrine-injected rats. In control group, normal saline （n=8） was injected twice daily for 28 days. Ratios of left ventricular weight to body weight （LVW/ BW） were measured after rats had been decapitated. And then authors applied TUNEL assay to detect cardiomyocyte apoptosis,Western blot method to detect the levels of Bcl-2,Bax and Caspase-3 protein. Results Apoptotic cardiomyocytes were rarely seen in the hearts of saline-treated rats,but TUNEL-positive nuclear staining increased significantly in the left ventricles of rats treated with NE. The number of TUNEL-positive nuclei in left ventricles of NE-treated rats decreased significantly following treatment with SB 204741. Following chronic NE treatment of rats,cardiac Bcl-2 protein levels decreased significantly,whereas Bax and caspase 3 protein levels increased. Blockade of 5-HT receptors with SB 204741 resulted in an increase in the Bcl-2/Bax ratio and decreased caspase-3 expression. Conclusion In the process of cardiac hypertrophy induced by norepinephrine, blockade of 5-HT2s receptor with SB204741 resulted in anti-apoptotic activity,as evidenced by an increase in the Bcl-2/Bax ratio and decreased caspase-3 expression.