谷氨酰胺与缬沙坦对大鼠心房纤维化及缝隙连接蛋白43重构的影响

Effects of glutamine and valsartan on atrial fibrosis and connexin 43 remodeling in rats

目的研究谷氨酰胺（Gln）与缬沙坦对大鼠心房纤维化及缝隙连接蛋白43（Cx43）重构的影响及其可能的作用机制。方法将SD雄性大鼠（160±20）g32只随机等分为对照组（A组）、盐酸异丙肾上腺素（ISO）（5mg·kg^-1·d^-1）（B组）、ISO（5mg·kg^-1·d^-1）＋丙氨酰谷酰胺注射液（Ala—Gln）（0．75mg·kg^-1·d^-1）（C组）和ISO（5mg·kg^-1·d^-1）＋缬沙坦（30mg·kg^-1·d^-1）（D组）。各组1次／d给予相关试剂，ISO连续给药7d，而后C、D两组大鼠继续给予相关试剂至28d后处死。心肌组织中血管紧张素Ⅱ（AngⅡ）含量采用放免法检测；通过H—E染色观察心肌纤维化情况；Masson染色计算胶原容积分数（CVF）并作为心肌纤维化程度的量化指标；免疫组化SP法半定量测定心肌组织中热休克蛋白70（HSP70）、磷酸化c—Jun氨基末端激酶1／2／3（p-JNK1／2／3）、c-Jun及Cx43蛋白的表达。结果AngⅡ在B、C、D组中含量较A组显著升高且差异有统计学意义（P〈0．01）；B组与A、C、D组相比出现明显的心房纤维化（P〈0．01）且心肌组织中p-JNK1／2／3和c—Jun的含量较高，差异有统计学意义（P〈0．01），C、D组与A组相比心房纤维化程度及心肌组织中p-JNK1／2／3和c—Jun的含量差异无统计学意义（P〉0．05）；与其他各组相比，C组中HSP70的含量明显升高，且差异有统计学意义（P〈0．01），A、B、D组中HSP70的含量相互间差异均无统计学意义（P〉0．05）；B组中Cx43含量较A组减少（P〈0．01）且分布无规律性，侧面化分布相对增多。而C、D组中Cx43含量与A组比较差异无统计学意义（P〉0．05）且部分呈线性分布于心肌细胞闰盘处；C、D两组中Cx43含量比较差异均无统计学意义（P〉0．05）。结论谷氨酰胺与缬沙坦均可减轻AngⅡ诱发的大鼠心房纤维化及Cx43重构，其机制可能与降低p-JNK1／2／3和c—Jun的表达，抑制JNK信号通路的不同位点有关，在改善大鼠心房纤维化程度和Cx43重构方面起到类似的作用。

Objective To study the effects of glutamine and valsartan on atrial fibrosis and connexin43 remodeling in rats induced by isoprenaline（ISO） and the possible mechanisms. Methods Thirty-two male SD rats（ 160＋20 ） g were randomly divided into four groups （ n = 8 ） ： control group （ A ） , ISO （ 5 mg·kg^-1·d^-1 ） group （B）,and ISO（5 mg·kg^-1·d^-1）＋Ala-Gln（0. 75 mg·kg^-1·d^-1） group （C）,ISO（5 mg·kg^-1·d^-1） ＋valsartan（30 mg·kg^-1·d^-1） group（D）. Each group was treated with the corresponding reagent once a day, ISO administration for seven days, group C and D continued to be treated with corresponding drugs for 28 days, all rats were killed after 28 days. The Ang Ⅱ content was measured by radioimmunoassay ; myocardial fibrosis was analyzed by H-E staining;Collagen volume fractions were quantified by Masson staining and as the indicators of atrial fibrosis; The expressions of HSP70, p-JNK1/2/3, c-Jun and Cx43 were semi-quantified with immunohistochemical method. Results Compared with the A group,the contents of Ang Ⅱ in group B ,C,and D were significantly increased（P〈0. 01,respectively）. No obvious atrial fibrosis was observed in group A, and there was evident atrial fibrosis in group B, and was much higher than that in group C ,group D （P〈0. 01, respectively）. The expressions of p-JNK1/2/3 and c-Jun in group B were significantly increased （ P〈0.01 ）, while the expressions of p-JNK1/2/3 and c-Jun in the group A , C and D were not obvious change （P〉0. 05）, The content of HSP70 in group C was significantly increased, and the difference was statistically was significant higher than that in other groups （P〈0.01, respectively）. There was no significant difference in contents of HSP70 among the groups of A,B and D. The content of Cx43 in group B was obvious reduced（ P〈0. 01 ） with irregular distribution, relatively increased in the side of the myocardial cells. While the content of Cx43 in group C and D had no obvious change compared with that in A group（P〉0. 05）. The Cx43 partly linearly distributed in myocardial cell intercalated disc, and the content of Cx43 in group C and D showed no significant difference （P〉0. 05 ）. Conclusion Glutamine and valsartan can reduce the atrial fibrosis and connexin 43 remodeling in rats induced by isoprenaline. The mechanism may be relate to inhibit JNK pathways at different levels.