Objective To investigate the effect of acupuncture at the heart meridian on the expression levels of IL-2,JunB protein,and c-fos in the medial septal nucleus of rats with acute myocardial ischemia (AMI),as well as the role and mechanism of the medial septal nucleus in acupuncture against AMI.Methods The rats were divided into sham-operation group,model group,and electroacupuncture group, with 6 rats in each group.Ligation of the left anterior descending coronary artery was performed to establish a rat model of AMI.The rats in the electroacupuncture group were given intervention at the "Shenmen-Tongli" segment of the heart meridian of hand-Shaoyin for 30 minutes each time,once a day for 3 consecutive days,with an intensity of 1 mA and a frequency of 2 Hz,while those in the sham-operation group and the model group were not treated with electroacupuncture.ELISA was used to measure the level of IL-2 in the medial septal nucleus of rats;Western blot was used to measure the protein expression level of JunB in the medial septal nucleus of rats;immune of luorescence assay was used to measure the expression of c-fos-positive neurons in the medial septal nucleus of rats.Results Compared with the sham-operation group,the model group had significant increases in the levels of IL-2 and JunB protein (P<0.05) and the number and average optical density (OD) of c-fos-positive neurons (P<0.05) in the medial septal nucleus of rats.Compared with the model group,the electroacupuncture group had significant reductions in the levels of IL-2 and JunB protein (P<0.05) and the number and average OD of c-fos-positive neurons (P<0.05) in the medial septal nucleus of rats. Conclusion The medial septal nucleus participates in the effect of electroacupuncture at the heart meridian in the treatment of AMI,possibly by reducing the expression levels of IL-2,JunB protein,and c-fos-positive neurons in the medial septum nucleus.