Influence of electroacupuncture on stress-induced hypertension and its mechanism

Abstract

Background: Electroacupuncture (EA) and activation of the sympathetic inhibitory system in the brain, i.e. nucleus arcuatus–ventral periaqueductal gray matter–nucleus raphe obscurus (ARC–vPAG–NRO) system, can lower blood pressure (BP). This study was to observe the effect of EA on stressed-induced hypertensive rats and whether nitric oxide in vPAG can be involved in the effect of EA. Methods: On the anesthetized stress-induced hypertensive rats blood pressure, heart rate (HR), cardiac functions and electrocardiogram were recorded synchronously. EA of “zusanli” acupoints with microinjections of saline (NS) and N ω-nitro- l-arginine ( LNNA) into vPAG in brain was applied. Results: EA+NS resulted in a depressor, bradycardic response and an attenuation in the maximum of left ventricular pressure, and diastolic pressure and ±d p/d t, as well as an increase of total variance, very low frequency (VLF), low frequency (LF) and the LF–high frequency (HF) ratio (LF/HF). In the EA+ LNNA group, the above effects of EA were abolished or reduced significantly. Conclusions: The results suggest that the depressor effect of EA on stress-induced hypertensive rats might be mediated by NO in the vPAG due to activation of the sympathetic inhibitory system in the brain and by attenuated cardiac activities.