Intervention effect of transcutaneous auricular vagus nerve stimulation on myocardial structural remodeling, electrical remodeling and apoptosis in rat heart failure model with preserved ejection fraction / 中华老年医学杂志

ABSTRACT

Objective:To observe the effect of percutaneous auricular vagus nerve stimulation on myocardial structural remodeling, electrical remodeling and apoptosis in rats of heart failure with preserved ejection fraction, and to explore the relationship between this effect and oxidative stress.Methods:The arteriovenous fistula was closed by ligation two weeks after establishment in SD rat.By increasing cardiac volume load in the short term, a rat model of heart failure with preserved ejection fraction was constructed.Forty rats were randomly divided into four groups, with 10 rats in each group: sham operation group(S), abdominal aorta-inferior vena cava fistula + closure group(AVF+ L), abdominal aorta-inferior vena cava fistula + closure+ percutaneous auricular vagus nerve stimulation group(AVF+ L+ tVNS)and abdominal aorta-inferior vena cava fistula + closure+ percutaneous auricular vagus nerve stimulation + acetylcholine M 2 receptor antagonist group(AVF+ L+ tVNS+ M -). Rats in the AVF+ L+ tVNS group received percutaneous vagal nerve stimulation on the basis of those in the AVF+ L group.Rats in the AVF+ L+ tVNS+ M - group received daily injection of acetylcholine M 2 receptor antagonist mesotramine(0.5mg/Kg)into tail vein on the basis of those in the AVF+ L+ tVNS group.The parameters of cardiac structural remodeling and electrical remodeling in each group were obtained by cardiac ultrasound and cardiac electrophysiological stimulator.Enzyme-linked immunosorbent assay(ELISA)was used to detect the values of B-type natriuretic peptide precursor(NT-proBNP)and oxidative stress-related indicators in each group.hematoxylin-eosin(HE)staining was used to observe the damage of myocardial structure, disorder of cell arrangement and infiltration of inflammatory cells.Cardiomyocyte apoptosis was observed by TdT-mediated dUTP nick end labeling(TUNEL)staining and apoptosis index was calculated.reverse transcription-polymerase chain reaction(RT-PCR)and Western blotting were used to detect the mRNA and protein expression of B cell lymphoma / leukemia-2(BCL-2)and apoptosis promoting gene(BAX)in BCL-2 gene family. Results:The rats in the AVF + L group developed heart failure characterized by ventricular wall hypertrophy and diastolic dysfunction, and the left ventricular ejection fraction(LVEF)was >50 %.The rat heart failure model with preserved ejection fraction was successfully established.HE staining showed that the myocardial tissue structure damage, cell arrangement disorder and inflammatory cell infiltration were obvious in AVF+ L group, while the pathological changes of myocardial tissue in AVF+ L+ tVNs were significantly less than those in AVF+ L group.Compared with AVF+ L group, in the AVF+ L+ tVNs, the value of NT-proBNP decreased[(301.25 ± 16.07)ng/L vs.(79.33±5.63)ng/L, P<0.05], the value of E/A increased(1.28 ± 0.06 vs.1.66 ±0.05, P<0.05), the expression of BCL-2 mRNA[0.08(0.07, 0.08) vs.0.70(0.64, 0.76), P<0.05]and BCL-2 protein(0.19±0.03 vs.0.46±0.04, P<0.05)both increased, the expression of BAX mRNA(5.00±0.32 vs.2.14±0.36, P<0.05)and BAX protein(0.76±0.04 vs.0.43±0.05, P<0.05)both decreased, while the apoptotic index was also decreased(16.26±0.32 vs.7.04±0.24, P<0.05). Compared with AVF + L group, the indexes of myocardial structural remodeling, electrical remodeling and oxidative stress were decreased in AVF + L + tVNs group(P<0.05). Compared with AVF + L group, there was no significant difference in the above indexes in AVF + L + tVNS + M - group( P>0.05). Conclusions:tVNS can alleviate myocardial structural remodeling, electrical remodeling and apoptosis in HFpEF rats, which may be related to the reduction of oxidative stress response activity.