[Tolvaptan attenuates atrial remodeling in rats undergoing chronic intermittent hypoxia via miRNA-21].

Objective: To investigate the effects and potential mechanisms of tolvaptan on chronic intermittent hypoxia (CIH)-induced atrial remodeling in rats. Methods: A total of 45 Sprague-Dawley rats were divided into 3 groups by the random number table: control group, CIH group (6 h/d for 30 days), CIH plus tolvaptan group (8 mg·kg(-1)·d(-1) per gavage for 30 days). Echocardiography examination was performed after 30 days. Thereafter, 5 rats were randomly chosen for histology evaluation, 5 for molecular biological examinations and another 5 rats underwent isolated heart electrophysiology study in each group. Protein and mRNA expression levels of miRNA-21, Spry1, PTEN, ERK/p-ERK, MMP-9, PI3K, AKT/p-AKT were detected. Results: Compared to the rats in control group, rats in the CIH group showed higher atrial interstitial collagen deposition (P<0.001), increased atrial fibrillation inducibility (P=0.022). The results of immunohistochemistry staining showed that the mean optical density (MOD) of ERK, p-ERK and MMP-9 were significantly increased (all P<0.05), the MOD of Spry1 and PTEN were significantly decreased (both P<0.05), above changes could be significantly reversed by cotreatment with tolvaptan. No significant differences were detected in PI3K and AKT among the three groups (P>0.05). In addition, compared with rats in control group, mRNA levels of miRNA-21, MMP-9, PI3K, AKT, and protein levels of ERK, p-ERK, MMP-9 were significantly increased in CIH group(all P<0.05), whereas protein levels of Spry1, PI3K, p-AKT were significantly decreased (all P<0.05). Above changes could be significantly attenuated. Conclusions: CIH induces significant atrial remodeling in this rat model, which can be attenuated by tolvaptan possibly through modulating miRNA-21/Spry1/ERK/MMP-9 and miRNA-21/PTEN/PI3K/AKT signaling pathways.目的： 探究托伐普坦能否改善慢性间歇缺氧所致大鼠心房重构及其机制。 方法： 雄性Sprague-Dawley大鼠45只，采用随机数字表法分为对照组、模型组和干预组，每组15只。对照组大鼠正常饲养，模型组大鼠每日接受慢性间歇缺氧6 h，干预组大鼠在此基础上给予托伐普坦进行干预，持续30 d。采用Masson染色观察大鼠心房组织纤维化程度（以胶原分数表示）。分别采用免疫组织化学染色、实时荧光定量PCR（RT-qPCR）和Western blot法检测细胞外信号调节激酶（ERK）、磷酸化细胞外信号调节激酶（p-ERK）、基质金属蛋白酶-9（MMP-9）、磷脂酰肌醇-3激酶（PI3K）、蛋白激酶B（AKT）、磷酸化蛋白激酶B（p-AKT）、微小（micro，mi）RNA-21及其靶基因侧支发芽因子同源物1（Spry1）、人第10号染色体缺失的磷酸酶及张力蛋白同源的基因（PTEN）的mRNA和蛋白表达水平。采用简单随机抽样法每组选取5只大鼠行离体心脏电生理实验，测量相关电生理参数和心房颤动（房颤）诱发率。 结果： 模型组大鼠心房组织胶原分数明显大于对照组（P<0.001），干预组胶原分数则明显小于模型组（P<0.05）。免疫组织化学染色结果显示，模型组大鼠心房组织中ERK、p-ERK和MMP-9蛋白的表达水平均明显高于对照组（P均<0.05），Spry1和PTEN的蛋白表达水平均明显低于对照组（P均<0.05）。干预组大鼠心房组织中p-ERK蛋白的表达水平明显低于模型组（P<0.05），Spry1的蛋白表达水平明显高于模型组（P<0.05）。三组大鼠心房组织中PI3K和AKT的蛋白表达水平差异均无统计学意义（P均>0.05）。模型组大鼠心房组织中miRNA-21、MMP-9、PI3K和AKT的mRNA表达水平均明显高于对照组（P均<0.01），Spry1和ERK的mRNA表达水平明显低于对照组（P均<0.05）。干预组大鼠心房组织中miRNA-21、MMP-9、PI3K和AKT的mRNA表达水平则均明显低于模型组（P均<0.05）。Western blot结果显示，模型组大鼠心房组织中ERK、p-ERK和MMP-9的蛋白表达水平均明显高于对照组（P均<0.05），而Spry1、PTEN、PI3K、AKT和p-AKT的蛋白表达水平均明显低于对照组（P均<0.05）。干预组大鼠心房组织中ERK、p-ERK和MMP-9的蛋白表达水平均明显低于模型组（P均<0.05），而Spry1、PI3K和p-AKT的蛋白表达水平均明显高于模型组（P均<0.05）。模型组大鼠房颤诱发率明显高于对照组（P=0.002），而干预组则明显低于模型组（P=0.046）。房间传导时间、高位右心房不应期及高位左心房不应期三组间差异均无统计学意义（P均>0.05）。 结论： 托伐普坦可改善慢性间歇缺氧所致的大鼠心房重构，其机制可能与调控miRNA-21/Spry1/ERK/MMP-9和miRNA-21/PTEN/PI3K/AKT信号通路有关。.