TRPV1和NaV1.8在食管高敏感中的作用和机制研究

Role and Mechanism of TRPV1 and NaV1.8 in Esophageal Hypersensitivity

背景:食管高敏感是胃食管反流病(GERD)患者烧心等症状产生的重要原因。瞬时受体电位香草酸亚型1(TRPV1)和电压门控钠离子通道1.8(NaV1.8)可能在食管高敏感的调控中发挥重要作用。目的:检测TRPV1、NaV1.8在GERD动物模型食管和迷走神经感觉神经元中的表达,探究其在食管高敏感中的作用。方法:12只雄性豚鼠随机分为对照组和GERD组,后者通过饮用盐酸胃蛋白酶溶液建立GERD模型。通过观察动物体质量变化、食管炎症组织学评分和炎症细胞因子表达验证造模成功与否。通过分析心率变异性(HRV)明确动物是否处于内脏高敏感状态。以免疫荧光法、qRT⁃PCR和蛋白质印迹法检测食管、迷走神经结状神经节和颈静脉神经节中的TRPV1、NaV1.8表达、分布和共表达情况。结果:GERD组食管炎症组织学评分显著高于对照组(0.85±0.43对0.22±0.45),促炎细胞因子表达增高,抗炎细胞因子表达降低,体质量增长缓慢(P均<0.05)。造模前两组HRV指标低频/高频(LF/HF)比值无明显差异(P>0.05),造模后GERD组LF/HF比值显著增高(P<0.05)。GERD组食管黏膜上皮和颈静脉神经节TRPV1、NaV1.8表达和共表达均显著上调(P均<0.05),结状神经节中两者表达无明显变化(P均>0.05)。结论:在食管酸暴露情况下,食管黏膜上皮TRPV1、NaV1.8表达增高,迷走神经颈静脉神经节中两者表达亦显著上调,促进迷走神经通路伤害性信号的传递,最终导致食管高敏感发生。

Background:Hypersensitivity of esophagus is an important cause of heartburn and other symptoms in patients with gastroesophageal reflux disease(GERD).It has been revealed that transient receptor potential vanilloid type 1(TRPV1)and voltage⁃gated sodium channel NaV1.8 might contribute to the regulation of esophageal hypersensitivity.Aims:To explore the expression levels of TRPV1 and NaV1.8 in esophagus and vagal sensory neurons in GERD animal model and their roles in mediating esophageal hypersensitivity.Methods:Twelve male guinea pigs were randomly allocated into control group and GERD group.Model of GERD was established by drinking hydrochloric⁃pepsinogen acid water and verified by body weight monitoring,esophageal inflammatory histological scoring and measurements of pro⁃and anti⁃inflammatory cytokines.Visceral hypersensitivity was determined by heart rate variability(HRV)analysis.Expressions,distribution,and co⁃expression of TRPV1 and NaV1.8 in esophagus and vagal nodose/jugular ganglia were quantified by immunofluorescence,qRT⁃PCR and Western blotting.Results:Compared with the control group,score of esophageal inflammatory histology in GERD group was increased(0.85±0.43 vs.0.22±0.45),accompanied by elevated proinflammatory cytokine expressions and reduced antiinflammatory cytokine expression(all P<0.05).The weight gain was also slower in GERD group than in control group(P<0.05).As an indicator of HRV analysis,the low frequency to high frequency(LF/HF)ratio had no significant difference between GERD group and control group before model construction(P>0.05),but increased significantly in GERD group after modeling(P<0.05).In GERD group,expressions and co⁃expression of TRPV1 and NaV1.8 were up⁃regulated in esophageal mucosal epithelium and jugular ganglion(all P<0.05),but not changed in nodose ganglion(all P>0.05).Conclusions:In the acid⁃exposed esophagus,expressions of TRPV1 and NaV1.8 were up⁃regulated in esophageal mucosal epithelium and vagal jugular ganglion,thus promoting the nociceptive transmission in vagus nerve pathway,and ultimately resulting in esophageal hypersensitivity.