GCH1通过BH4通路对快速心房起搏犬自主神经重构的影响

Effects of GCH1 on atrial autonomic nerve remodeling by regulating tetrahydrobiopterin in A-TP canines

目的探讨磷酸鸟苷环化水解酶1(GCH1)基因对房颤犬心房自主神经重构的作用。方法健康成年杂种犬24只随机分为右心房快速起搏组(A-TP组)、对照组、GCH1过表达组和GCH1沉默组,每组6只。A-TP组以400次/min持续右心房起搏4周。GCH1过表达组在右上脂肪垫(RSFP)内注射含GCH1过表达的慢病毒。GCH1沉默组在RSFP内注射含GCH1沉默的慢病毒。感染2周后处死动物,剪取RSFP周围小于0.5 cm的心房组织。分别采用qRT-PCR法检测mRNA的表达,Western blotting法检测蛋白的表达,免疫组化法检测神经密度以及Elisa法检测四氢生物喋呤(BH4)含量。结果 4周后,A-TP组较对照组GCH1表达明显下降(P<0.05)。与对照组相比,GCH1过表达组心房有效不应期明显延长,RSFP中PGP9.5表达下降明显,BH4含量增加。与对照组相比,GCH1沉默组RSFP中PGP9.5表达明显上升,BH4含量减少。结论右房快速起搏导致GCH1基因表达下调,GCH1可能通过增加BH4含量抑制房颤自主神经重构。

Objective To investigate the expression of guanosine triphosphate cyclohydrolase I （ GCH1 ） on atrial auto- nomic nerve remodeling （ANR） in atrial-tachypacing （A-TP） canines. Methods A total of 24 mongrel dogs were randomly divided into 4 groups： atrial tachypacing group （A-TP）, control group, GCH1 over-expression group and lenti-anti-GCH1 group. Each group had 6 dogs. Canines in the A-TP group had continuous right A-TP （400 beats/ min） for 4 weeks, and then atrial tissue samples were harvested from right superior fat pad （RSFP）. Canines in the GCH1 over-expression group were injected with lenti-GCH1 into RSFPs. Canines in the lenti-anti-GCH1 group were in- jected with lenti-anti-GCH1 into RSFPs. After 2 weeks, canines were anesthetized and atrial samples were collected. The mRNA expression was detected with qRT-PCR, the protein expression was detected with Western blotting, nerve density was evaluated with immunohistochemical staining, and Tetrahydrobiopterin（BH4） content was determined with Elisa analysis. Results GCH1 expression in the A-TP group was obviously lower than that in the control group （P 〈 0.05 ）. Compared with the control group, GCH1 over-expression group had longer atrial effective refractory period, de- creased PGP9.5 expression, but increased BH4 content. Compared with the control group, the lenti-anti-GCH1 group had increased PGP9.5 expression and decreased BH4 content. Conclusion Rapid pacing of right atrium can lead to downregulation of GCHI. GCH1 may inhibit ANR during atrial fibrillation by regulating BH4 content.