Abstract:Objective To investigate the role of the hippocampal dentate gyrus (DG) in acupuncture at the heart meridian in the treatment of myocardial ischemia. Methods A total of 60 rats were randomly divided into sham-operation group, model group, acupuncture group, and damage group, with 15 rats in each group. A rat model of acute myocardial ischemia was established by thoracotomy and ligation of the left anterior descending branch of the coronary artery. The rats in the acupuncture group and the damage group were given electroacupuncture at the "Shenmen-Tongli" section of the Shaoyin heart meridian with an intensity of electric current of 1 mA and a frequency of 2 Hz for 3 consecutive days with 30 minutes per day. The rats in the sham-operation group and the model group were not given such treatment. All groups were observed in terms of the changes in electrocardiographic findings, cell morphology in the hippocampal DG, and neuronal discharge frequency. Results Compared with the sham-operation group, the model group had significant increases in heart rate and ST segment (P<0.05). Compared with the model group, the acupuncture group had significant reductions in heart rate and ST segment (P<0.05). Compared with the acupuncture group, the damage group had significant increases in heart rate and ST segment (P<0.05). In the sham-operation group, the neurons in the hippocampal DG were arranged closely with large and round nuclei, and the cytoplasm was uniform and light in color with rich Nissl bodies; in the model group, the neurons in the hippocampal DG were sparse with reductions in cell volume and Nissl bodies; in the acupuncture group, the neurons in the hippocampal DG were arranged closely with relative increases in cell volume and Nissl bodies. Compared with the sham-operation group, the model group had a significant increase in neuronal discharge frequency in the hippocampal DG (P<0.05); compared with the model group, the acupuncture group had a significant reduction in neuronal discharge frequency (P<0.05). Conclusion The hippocampal DG may be one of the key centers for improving acute myocardial ischemia by acupuncture.