Zhang Qi, Li Fang-Fang, Wen Xin, Tan Ying-Ying
Shaanxi Provincial Key Laboratory of Encephalology of Traditional Chinese Medicine, Shaanxi University of Chinese Medicine, Xianyang 712046, Shaanxi Province, China.
Zhen Ci Yan Jiu. 2021 Mar 25;46(3):187-93. doi: 10.13702/j.1000-0607.200488.
To investigate the effect of electroacupuncture (EA) at "Taichong"(LR3) on blood pressure, sympathetic nerve activity, baroreflex sensitivity, and α 2-adrenergic receptor (α2AR) expression in nucleus tractus solitarii (NTS) in hypertensive rats, so as to reveal its mechanisms underlying improvement of hypertension.
Male Sprague Dawley rats were randomly divided into 4 groups: sham-operation, model, EA, and sham-EA (non-acupoint) groups, with 12 rats in each group. The hypertension model was established by occlusion of the right renal aorta (two-kidney-one clip method). Rats of the sham-operation group received the same surgery but without occlusion of the renal artery. EA (2 Hz/15 Hz, 2 mA) was applied to bilateral LR3 for 30 min, once a day for 28 days, and sham EA was applied to the skin of the rat tail near the buttock on both sides. The mean arterial pressure (MAP) of the abdominal aorta and heart rate (HR) were recorded. The autonomic nerve function was assessed by using frequency domain analysis of heart rate variability (HRV), and the baroreflex sensitivity detected by sequential method. Plasma norepinephrine (NE) level was measured by ELISA, and the α2AR positive neurons and α2AR protein expression in NTS were detected by using fluorescence immunohistochemistry and Western blot, respectively. The functions of α2AR within the NTS in modulating MBP and HR were verified by microinjection of its agonist (clonidine) and antagonist (yohimbine) separately.
Compared to the sham operation rats, the hypertension rats displayed significant increases in the MAP (<0.01), plasma norepinephrine content (<0.01), ratios of low frequency/total power (LF/TP) and low frequency/high frequency (LF/HF) (<0.01), and significant reduction in the overall gain, uplink sequence gain and downlink sequence gain of baroreflex (<0.01), the number α2AR positive neurons and α2AR protein expression level in NTS (<0.01). The rats in the EA group (rather than in the sham-EA group) showed significant reduction in MAP at the 3rd and 4th week, plasma NE content, LF/TP and LF/HF (<0.01), and obvious increase in the overall gain, uplink sequence gain and downlink sequence gain of baroreflex (<0.01), and the number of α2AR positive neurons and α2AR protein expression in comparison (<0.05) with those of the model group. Microinjection of clonidine into NTS induced an evident decrease in both MAP and HR in the model group relevant to the sham operation group (<0.01), while the MAP and HR changes of the EA (not sham EA) group were considerably bigger than those of the model group (<0.05), being similar to those of the sham-operation group (>0.05), which suggested an elimination of the BP-lowering effect of clonidine after EA.
EA at LR3 can reduce MBP, sympathetic activities, improve baroreflex sensitivity in renovascular hypertensive rats, which may be associated with its effects in up-regulating the decreased NTS α2AR expression and functional activities.
观察电针“太冲”（LR3）对高血压大鼠血压、交感神经活动、压力反射敏感性及孤束核（NTS）α2-肾上腺素能受体（α2AR）表达的影响，以揭示其改善高血压的机制。
雄性Sprague Dawley大鼠随机分为假手术组、模型组、电针组和假电针（非穴位）组，每组12只。采用右肾动脉缩窄法（两肾一夹法）建立高血压模型。假手术组大鼠接受相同手术但不结扎肾动脉。电针组采用2Hz/15Hz、2mA电针双侧LR3 30min，每日1次，共28天；假电针组针刺大鼠双侧臀部尾根部皮肤。记录腹主动脉平均动脉压（MAP）和心率（HR）。采用心率变异性（HRV）频域分析评估自主神经功能，采用序贯法检测压力反射敏感性。采用酶联免疫吸附测定（ELISA）法检测血浆去甲肾上腺素（NE）水平，分别采用荧光免疫组织化学法和蛋白质免疫印迹法检测NTS中α2AR阳性神经元及α2AR蛋白表达。分别向NTS微量注射α2AR激动剂（可乐定）和拮抗剂（育亨宾），验证NTS内α2AR对平均动脉压（MBP）和HR的调节作用。
与假手术组大鼠相比，高血压大鼠MAP（P<0.01）、血浆NE含量（P<0.01）、低频功率/总功率（LF/TP）及低频功率/高频功率（LF/HF）比值（P<0.01）显著升高，压力反射总增益、上行序列增益及下行序列增益（P<0.01）、NTS中α2AR阳性神经元数量及α2AR蛋白表达水平（P<0.01）显著降低。电针组大鼠在第3、4周MAP、血浆NE含量、LF/TP及LF/HF（P<0.01）较模型组显著降低，压力反射总增益、上行序列增益及下行序列增益（P<0.01）、NTS中α2AR阳性神经元数量及α2AR蛋白表达（P<0.05）较模型组明显增加。向NTS微量注射可乐定后，模型组大鼠MAP和HR较假手术组明显降低（P<0.01），电针组大鼠MAP和HR变化幅度明显大于模型组（P<0.05），与假手术组相似（P>0.05），提示电针后可乐定降压作用消失。
电针LR3可降低肾血管性高血压大鼠MBP，抑制交感神经活动，提高压力反射敏感性，其机制可能与上调NTS中降低的α2AR表达及功能活动有关。
