A new target of electroacupuncture pretreatment mediated sympathetic nervous to improve MIRI: glutamatergic neurons in fastigial nucleus of the cerebellum

Ischemic heart disease is a fatal cardiovascular disease that irreversibly impairs the function of the heart, followed by reperfusion leading to a further increase in infarct size. Clinically, we call it myocardial ischemia-reperfusion injury (MIRI). A growing number of clinical observations and experimental studies have found electroacupuncture (EA) to be effective in alleviating MIRI. This study attempts to investigate whether glutamatergic neurons in fastigial nucleus (FN) of the cerebellum are involved in EA pretreatment to alleviate MIRI via sympathetic nerves, and the potential mechanisms of EA pretreatment process. A MIRI model was established by ligating the coronary artery of the left anterior descending branch of the heart for 30 minutes, followed by 2 hours of reperfusion. Multichannel physiological recordings, electrocardiogram, cardiac ultrasound, chemical genetics, enzyme-linked immunosorbent assay and immunofluorescence staining methods were combined to demonstrate that EA pretreatment inhibited neuronal firing and c-Fos expression in FN of the cerebellum and reduced cardiac sympathetic firing. Meanwhile, EA pretreatment significantly reduced cardiac ejection fraction (EF), shortening fraction (SF), percentage infarct area, decreased myocardial norepinephrine (NE), creatine kinase isoenzyme (CK-MB) concentrations, and improved MIRI-induced myocardial tissue morphology. The results were similar to the inhibition of glutamatergic neurons in FN. However, the activation of glutamatergic neurons in FN diminished the aforementioned effects of EA pretreatment. This study revealed that glutamatergic neurons in FN of the cerebellum is involved in EA pretreatment mediated sympathetic nervous and may be a potential mediator for improving MIRI.

缺血性心脏病是一类可不可逆损害心脏功能的致命性心血管疾病，而再灌注会进一步扩大梗死面积，临床上将其称为心肌缺血再灌注损伤（MIRI）。越来越多的临床观察与实验研究证实，电针（EA）可有效缓解心肌缺血再灌注损伤。本研究旨在探讨小脑顶核（FN）内的谷氨酸能神经元（glutamatergic neurons）是否通过交感神经（sympathetic nerves）参与电针预处理缓解心肌缺血再灌注损伤的过程，并解析电针预处理的潜在作用机制。本研究通过结扎心脏左冠状动脉前降支30分钟、随后再灌注2小时的方法构建心肌缺血再灌注损伤模型。研究联合采用多通道生理记录、心电图、心脏超声、化学遗传学、酶联免疫吸附试验及免疫荧光染色等技术，证实电针预处理可抑制小脑顶核内的神经元放电与c-Fos表达，并降低心脏交感放电活性。同时，电针预处理可显著改善心肌射血分数（EF）与短轴缩短率（SF），降低梗死面积百分比，下调心肌去甲肾上腺素（NE）与肌酸激酶同工酶（CK-MB）水平，并缓解心肌缺血再灌注损伤诱导的心肌组织形态学损伤。上述效应与抑制小脑顶核内谷氨酸能神经元的效果一致。然而，激活小脑顶核内的谷氨酸能神经元会抵消电针预处理的上述保护作用。本研究揭示，小脑顶核内的谷氨酸能神经元参与了电针预处理介导的交感神经调控通路，或可作为改善心肌缺血再灌注损伤的潜在介导靶点。