Electroacupuncture Improves Baroreflex and γ-Aminobutyric Acid Type B Receptor-Mediated Responses in the Nucleus Tractus Solitarii of Hypertensive Rats.

Qi Zhang,Dong-Yuan Cao,Xiao-Hua Liu,Fan-Rong Yao,Ying-Ying Tan

doi:10.1155/2018/8919347

Abstract

Electroacupuncture (EA) has been reported to benefit hypertension, but the underlying mechanisms are still unclear. We hypothesized that EA attenuates hypertension, in part, through modulation of γ-aminobutyric acid (GABA) receptor function in the nucleus tractus solitarii (NTS). In the present study, the long-term effect of EA on GABA receptor function and expression was examined in the NTS of two-kidney, one-clip (2K1C) renovascular hypertensive rats. EA (0.1–0.4 mA, 2 and 15 Hz) was applied at Zusanli (ST36) acupoints overlying the deep fibular nerve for 30 min once a day for two weeks. The results showed that long-term EA treatment improved blood pressure (BP) and markedly restored the baroreflex response in 2K1C hypertensive rats. The increased pressor and depressor responses to microinjection of GABAB receptor agonist and antagonist into the NTS in the hypertensive rats were blunted by the EA treatment. Moreover, EA treatment attenuated the increased GABAB receptor expression in the NTS of hypertensive rats. In contrast, EA had no significant effect on the GABAA receptor function and expression in the NTS of 2K1C hypertensive rats. These findings suggest that the beneficial effects of EA on renovascular hypertension may be through modulation of functional GABAB receptors in the NTS.

Highlights

Acupuncture has been used for centuries in treatment of various disorders, including cardiovascular disease
Mean arterial blood pressure (BP) (MAP) and heart rate (HR) were measured via radiotelemetry
The main findings of our present study demonstrated that (1) long-term EA treatment at ST36 lowers the increased blood pressure and improves the depressed baroreflex response in 2K1C hypertensive rats, (2) the enhanced responses to a GABAB receptor antagonist or an agonist microinjected into the nucleus tractus solitarii (NTS) of hypertensive rats were significantly reversed by long-term EA treatment at ST36, and (3) EA treatment

Summary

Introduction

Acupuncture has been used for centuries in treatment of various disorders, including cardiovascular disease (for review, see [1, 2]). It is well known that elevated sympathetic outflow and impaired baroreflex function contribute to the development of hypertension [9]. The evidence suggests that EA could lower sympathetic activity and significantly inhibit the sympathoexcitatory reflex responses in rats [10,11,12]. Our previous studies and others showed that hypertensive rats exhibit enhanced GABAB receptor function and regulation within the NTS [18,19,20,21]. We tested the hypothesis that EA reduced BP and improved baroreflex response in renovascular hypertensive rats, as well as the beneficial antihypertensive effect of EA was associated with modulation of functional GABAB receptors within the NTS of hypertensive rats

Methods

Results

Discussion