BACKGROUND: Researches indicate that inducible nitric oxide synthase(iNOS) plays an important role in relieving destruction of blood brain barrier and protecting vascular endothelium and brain tissue in cerebral ischemia-reperfusion injury.OBJECTIVE: To observe the effect of Shuigou (DU26), Neiguan (PC6)and Zusanli (ST36) on the expression of inducible nitric oxide synthase messenger ribonucleic acid (iNOS mRNA) in hippocampus of the rats with cerebral ischemia-reperfusion.DESIGN: Randomized controlled study.SETTING: Shanghai University of Traditional Chinese Medicine, Shanghai Institute of Acupuncture and Meridian and Huashan Hospital Affiliated to Fudan University.METHODS: The experiment was completed at the Experimental Animal Center in Shanghai University of Traditional Chinese Medicine, Threegrade Acupuncture Immunological Laboratory of Shanghai Research Institute of Acupuncture and Meridian and Huashan Hospital Affiliated to Fudan University from December 2003 to December 2004. Totally 40 SD rats were randomly divided as normal group, sham operation group, model group and electroacupuncture group with 10 in each group. The hypertension model rats were induced with bi-kidney-bi-clip method, then the focal cerebral ischemia-reperfusion rat model was induced by reversible occlusion for a middle cerebral artery with a thread on the stroke prone renovascular hypertensive model rat. While the rats in sham operation group were operated without thread insertion. Shuigou (Du 26), bilateral Neiguan(PC 6) and bilateral Housanli (Zusanli, ST 36) were located according to"Atlas of Experimental Animal Acupoints" made by Hua's. Shuigou (Du26): 1 mm below nasal apex right on the Labium leporinum, be punctured 1 mm obliquely upward; Neiguan (PC 6): at the lateral palm of the forearm3 mm above wrist joint, between ulna and radius, be punctured 1 mm perpendicularly; Housanli (Zusanli, ST 36): under knee joint, 5 mm below the capitulum of fibula, be punctured 7 mm perpendicularly. The skin of Shuigou (Du 26) and the root of right ear, Neiguan (PC 6) and Housanli (Zusanli, ST 36) were connected with electroacupuncture Therapeutic Instrument G6805 with the parameters of continuous wave, 120 times/minute in frequency, 1 mA in intensity for 30 minutes. The treatment was applied once immediately after ischemia operation and again 12 hours after reperfusion. Being killed on 24 hours after reperfusion, the hippocampus of the rats were rapidly picked out. The effect of electroacupuncture on the expression of iNOS mRNA in hippocampus of the rats with cerebral ischemia-reperfusion was detected with fluorescence quantitative reverse transcription polymerase chain reaction (FQ-RT-PCR).MAIN OUTCOME MEASURES: The expression of iNOS mRNA in hippocampus.RESULTS: All 40 SD rats entered the final analysis. Expression of iNOS mRNA in hippocampus: [1] That in model group was significant higher than that in electroacupuncture group {[(4.85±1.29) ×1 000, (3.19±1.38) ×1 000] copy, (t=2.77, P ＜ 0.05)}; [2] That in model group was significant higher than that in sham operation group {[(4.85±1.29) ×1 000, (4.93±2.17)×10] copy, (t=97.38, P ＜ 0.01)}; [3] That in model group was significant higher than that in normal group {[(4.85±1.29) ×1 000, (3.13±1.68) ×10]copy, (t=11.81, P ＜ 0.01)}.CONCLUSION: Electroacupuncture may significantly inhibit the expression of iNOS mRNA in hippocampus and reduce the synthesis of NO to relieve the cerebral ischemia-reperfusion injury.