Repetitive electroacupuncture attenuates cold‐induced hypertension is associated with opioid precursors in hypothalamic paraventricular and arcuate nuclei (686.2)

Acupuncture lowers elevated blood pressure in clinical and experimental hypertension, possibly through an opioid mechanism. To mimic human studies, we performed repeated electroacupuncture (EA) on unanesthetized male SD rats exposed to cold (5°C) for 11 weeks. Systolic blood pressures (SBP) were measured weekly. Rats were randomly divided into EA (n=9), sham (n=6) and untreated hypertension groups (n=6) after 6 weeks of cold exposure when elevated SBP had stabilized. EA and sham groups then received either repetitive EA (1‐4 mA, 2 Hz, 0.5 ms) at ST36‐37 acupoints bilaterally (overlying deep peroneal nerve) or sham (needle placement without electrical stimulation) 30 min twice weekly for 5 weeks. The elevated SBP in the EA group was reduced after 6 sessions and remained low throughout treatment (139 ± 3 vs. 175 ± 3 mmHg, EA vs. sham) and 72 hr after termination of EA (155 ± 4 vs. 187 ± 3 mmHg, after EA vs. sham). Both preproenkephalin (PPE) and proopiomelanocortin (POMC) mRNA in PVN 72 hr after EA were increased in the EA (0.43±0.001 and 85±1.2, respectively) compared to the sham group (0.30±0.001 and 44±1.1) and the untreated hypertensive rats (0.31±0.012 and 42±1.2). POMC mRNA also was increased in the arcuate nucleus of the EA group (100± 3.2 vs. 82± 3.8, EA vs. sham). Thus, prolonged inhibition of elevated blood pressure by action of EA is associated with prolonged increases of opioid mRNA expression in the PVN and ARC. Grant Funding Source : Supported by NIH HL‐63313 and HL‐072125