| The theory that "meridian points are pertinent to internal organs" reflects a two-way link between the points of external meridians and the internal organs of the body. Stimulation of points of external meridians has a therapeutic effect on related internal organs. On the contrary, disease of internal organs could be manifested in the external meridian points.Studies have shown that the pericardium meridian (or points) has a specific contact with the heart and the heart disease can be relatively specific reflected in pericardium meridian which locates at the external of the body. Meanwhile, needling points of pericardium meridian can regulate the function of cardiovascular system. Further studies showed that there were abundant sympathetic nerve endings and their transmitters in the skin tissue of the meridian line, so this specific contact is related with somatic sympathetic reflex activity. In recent years, study the relationship between points and internal organs from the aspect of the sympathetic nerve and its transmitters had attracted the attention of scholars, but there were not sufficient systematic and in-depth researches.Objective:To observe the skin low resistance value of different point area and content changes of NE and cGMP of skin tissue in pericardium, triple burner and stomach meridians in myocardial ischemia rats, as well as influence of EA with different frequency on them. To explore the internal mechanism of the correlation between the pericardium meridian and the heart from the aspect of sympathetic nerve related factors and provide experimental evidence to the theory that "meridian points are pertinent to internal organs" and optimized parameters for clinical treatment of myocardial ischemia by acupuncture.Methods:The myocardial ischemia rats were prepared by left anterior descending artery ligation. Skin low resistance value of different point areas in pericardium, triple burner and stomach meridians were recorded and content of NE and cGMP of related skin tissue were measured by enzyme-linked immunosorbent assay so as to observe the specific reaction of related points after myocardial ischemic injury and after the treatment of high-frequency and low-frequency electro-acupuncture. In order to explore the internal mechanism of the correlation between the pericardium meridian and the heart from the aspect of sympathetic nerves we further studied the impact of electro-acupuncture on sympathetic nerve related factors and compared the effects of high-frequency and low-frequency electro-acupuncture.Results:1. The ECG J point difference value J-point difference in the model group significantly increased immediately after modeling and10mins,30mins after that (P<0.05, P<0.05, P<0.001). Compared to the model group, J-point difference decreased significantly immediately after Low-frequency acupuncture and10mins,30mins after that (P<0.001, P<0.05, P<0.001). Compared to the model group immediately after high-frequency acupuncture and10mins after that there were no significant difference, and at the30min after modeling the J point difference value was significantly decreased (P <0.001).2. In normal group, myocardial cells packed tightly, stripes were clear, nuclear was in the center, and no inflammatory cells have been found; In model group myocardial cells packed sparsely and manifested as a wave sharp, stripes were not clear, some dilated blood vessels and infiltrated inflammatory cells were seen in the intercellular substance. In low-frequency electro-acupuncture group, myocardial cells packed almost tightly, stripes were clear and nuclear was in the center, some dilated blood vessels could be seen in the intercellular substance and infiltrated inflammatory cells significantly decreased. The condition in high-frequency electro-acupuncture group was similar to that in the low-frequency electro-acupuncture group.3. Skin resistance value of meridian pointsCompared with normal group, skin resistance value of Neiguan(PC6), Ximen(PC4)and tianquan(PC2)point in pericardium meridian in model group were significantly reduced (P <0.05, P<0.001, P<0.05), and no significant changes have been found in Waiguan(TE5) point of triple burner meridian and Zusanli(ST36) point of stomach meridian (P>0.05).Compared with model group, skin resistance value of Neiguan and Ximen were significantly increased immediately after the low-frequency acupuncture and no significant changes have been found in tianquan, Waiguan and Zusanli point (P>0.05);10mins after low-frequency acupuncture the skin resistance value of Waiguan point significantly reduced(P<0.05), and the rest of the points had no significant changes (P>0.05);30mins after low-frequency acupuncture the skin resistance value of all points had no significant changes (P>0.05). There were no significant changes in the skin resistance value of three pericardium meridian points at each time point after high-frequency acupuncture (P>0.05); there were no significant changes in skin resistance value of Waiguan point immediately and10mins after high-frequency acupuncture (P>0.05),but it significantly decreased at30mins after high-frequency acupuncture (P<0.05); immediately after the high-frequency acupuncture the skin resistance value of Zusanli point significantly increased but didn’t change significantly at10mins and30mins after high-frequency acupuncture.4. Content of NE in skin tissue of meridian points Compared with normal group, NE level of Neiguan, Tianquan, Ximen, Waiguan and Zusanli point in model group were significantly higher (p<0.001, p<0.001, p<0.05, P<0.001, P<0.001). Compared with model group, NE level of Neiguan point had no significant change in low-frequency electro-acupuncture group but NE level of Tianquan, Ximen, Waiguan and Zusanli point were significantly reduced (P<0.001, P<0.05, P<0.001, P<0.05); NE level of Neiguan, Tianquan, Ximen, Waiguan and Zusanli point in high-frequency electro-acupuncture group were significantly reduced (P<0.05, P<0.001, P<0.05, P<0.001, P<0.001).5. Content of cGMP in skin tissue of meridian pointsCompared with normal group, cGMP content of Neiguan, Tianquan, Waiguan and Zusanli point in model group were significantly higher (p<0.001, p<0.05, p<0.001, P<0.001) but no significant change were found at Ximen point; compared with model group, cGMP content of Neiguan, Tianquan, Waiguan and Zusanli point in low-frequency electro-acupuncture group were significantly reduced (P<0.05, P<0.001, P<0.001, P<0.001) but no significant change were found at Ximen point. The condition in high-frequency electro-acupuncture group was similar to that in the low-frequency electro-acupuncture group.Conclusion:1Neiguan electro-acupuncture can significantly improve the ECG J point difference value and the abnormal myocardial tissue morphology caused by myocardial ischemia The ECG J point difference value and the myocardial tissue of HE staining are not only important indicators for detection of myocardial ischemia, but also an evaluation for the effect of different treatment methods.2contrast the change of skin resistance value of pericardium, triple burner and stomach meridian we found that pericardium meridian is more responsive to myocardial ischemia state and high and low frequency acupuncture, suggesting a close and specific correlation of the heart and pericardium meridian.3myocardial ischemic injury increased the sympathetic nerve activity, synthesis and release of NE and impacted the synthesis of second messenger cGMP. High and low frequency electro-acupuncture treatment can antagonize sympathetic nerve activity, reduce NE synthesis and release, and regulate the function of the second messenger to protect the ischemic myocardium. Sympathetic nerves that widely distributed in the skin and visceral may be related with the formation of specific reaction of meridians points and the changes of its effect material. Meanwhile, it is related with the regulation effect of meridian points and can partly reveal the inner mechanism of the heart-pericardium meridian connection and provide new thoughts for study of the theory that "meridian points are pertinent to internal organs". 4Contrast the change of skin resistance value and NE and cGMP levels of pericardium, triple burner and stomach meridian we found that the heart and pericardium meridian is closely related, the triple burner and stomach meridian also had some relevance with the heart. It indicated that different meridians points have different biochemical and physical characteristics. Besides, there were also differences among different points on the same meridian. This may be related to characteristics of points and tissue structure. The specific mechanism needs further study.5low-frequency and high-frequency electro-acupuncture can improve myocardial ischemia state to some extent. Low-frequency electro-acupuncture had a better effect of improving ECG and skin low resistance value of meridian points than the high-frequency group. There were no significant difference between two groups in improving the myocardial tissue morphology and regulating the levels of NE and cGMP. It indicates that different EA frequency may produce different effects through different pathway. The specific mechanism needs further study. |
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