Electroacupuncture Decreases Chronic Inflammation, Sympathetic Activities, and Blood Pressure in Dahl Salt‐Sensitive Hypertensive Rats

Low grade chronic inflammation is detected in hypertensive patients. The dahl salt-sensitive hypertensive (DSS HTNive) rat model has been investigated on different pathways how excessive salt intake induces elevation in blood pressure (BP). Previous studies have demonstrated low grade chronic inflammation and elevated sympathetic outflow in DSS HTNive rats. We have shown in series of studies that sympathoinhibitory electroacupuncture (SI-EA) at acupoints ST36-37 suppresses sympathoexcitatory cardiovascular responses and reduces BP in HTNive rats and patients. Other researchers reported that EA at acupoints SP6-7 as well as ST 36-37 decreases inflammation. Therefore, we hypothesized that combined EA (cEA) at ST36-37 and SP6-7 induces greater reduction in BP than SI-EA through the modification of chronic inflammation and elevated sympathetic activity in DSS HTNive rats. DSS rats (n=36) were fed with 4% salt diet and treated with SI-EA, cEA or Sham-EA (without electrical stimulation) twice weekly for five weeks once the rats developed moderate HTN (SBP 160±5 mmHg). Systolic/diastolic BP (SBP/DBP) and heart rate (HR) were measured by weekly tail-cuff non-invasively. Upon completion of different treatments, cardiac perfusion was performed under anesthesia, and plasma samples were collected to measure the concentration of high-sensitivity c-reactive protein (hs-CRP), an indicator of low-grade chronic inflammation, and norepinephrine (NE) by ELISA. We observed that DSS rats fed with 4% salt diet developed moderate HTN (SBP 163±3.8 mmHg) in five weeks compared to those fed with standard rat chow (SBP 129±5.4 mmHg). After five weeks of treatments, the EA treated rats displayed significantly lowered SBP (138±4.7 mmHg for cEA group, 147±4.2 mmHg for SI-EA group) compared to the Sham-EA treated rats (SBP 191±6.8 mmHg). The cEA group showed greater reduction in SBP by 28% than the SI-EA group (23%) compared to Sham-EA group. The DBP but not HR among the groups exhibited similar trends. Furthermore, we observed that plasma NE concentrations showed greater reduction in the cEA group by 24.5% than the SI-EA group (11.4% decrease) compared to the Sham-EA group. In addition, the rats treated with cEA displayed lowest concentration of plasma hs-CRP (225 ug/mL) in the three hypertensive groups. As such, our findings suggest that cEA at ST36-37 and SP6-7 induces larger BP-lowering effect than SI-EA in DSS HTNive rats and was associated with reduction of biomarkers of chronic inflammation and sympathetic outflow.