[Subcutaneous Metabolites Involving Acupoint Sensitization Induced by Myocardial Ischemia and Acupuncture Stimulation in Rabbits].

OBJECTIVE: The present study aimed at observing the profile of metabolites in sensitized acupoints induced by myocardial ischemia (MI) and the effect of acupuncture intervention on the changes of the metabolites so as to explore the material basis of acupoint sensitization. METHODS: A total of 20 New Zealand rabbits were randomly and equally divided into a control group and a model group. The MI model was established by occlusion of the anterior descending branch of the left coronary artery with a controllable air balloon inflation method for 5 min/time, twice a day (4-hours' interval) for continuous 5 days (the first stage of MI). After one day's rest, another 5 days' occlusion was conducted again (the second stage of MI) in the same way. The rabbits of the control group were treated with the same procedures but without occlusion. Subcutaneous microdialysis fluid samples were collected from "Neiguan" (PC 6), "Shenmen" (HT 7), "Xinshu" (BL 15), and "Taixi" (KI 3) regions on day 8(after recovery from operation), 14 (the first stage of MI), and 20 (the second stage of MI), as well as collected from PC 6 region during and post-acupuncture stimulation of PC 6, respectively. Manual acupuncture stimulation was applied to the right PC 6 for 30 min. Partial least squares -linear discriminant analysis (PLS-DA) was used to identify different metabolism patterns of the microdialysis fluid sample between groups and at different time-points in the same one group, and the distinct metabolites as the potential markers between groups were weighted via the values of variable importance in the projection (VIP) in combination with t-test analysis. An area under the curve (AUC) >1.0 indicated a test exhibiting good discrimination between groups. RESULTS: Six metabolites identified to be significantly different between the control and model groups were L-glutamic acid, phenylalanine and 3-hydroxyisobutyric acid (which were significantly increased relevant to the control group), and L-histidine, octadecanedioic acid and 9-keto palmitic acid (significantly decreased relevant to the control group) in the microdialysate of PC 6, HT 7 and BL 15 regions. In the microdialysate of PC 6, 4 metabolites including L-glutamic acid, octadecanedioic acid and 8-isohydroxy PGF 2 α (significantly increased), as well as L-histidine (markedly decreased) were identified to be considerably different between the model and control groups. After acupuncture for 30 min, the AUC level of L-glutamic acid was further significantly increased (P<0.05), that of L-histidine obviously decreased, and those of octadecanedioic acid and 8-isohydroxy PGF 2 α turned back nearly to the level of pre-MI. CONCLUSION: L-glutamic acid, phenylalanine, 3-hydroxyisobutyric acid, L-histidine, octadecanedioic acid and 9-keto palmitic acid from PC 6, HT 7 and BL 15 regions may be used as the material biomarker for MI-induced sensitization of these acupoints. Manual acupuncture intervention of PC 6 induces a significant change of L-histidine and L-glutamic acid in the local subcutaneous tissues.

[Observation on Acupoint Sensitization Phenomenon in Experimental Myocardial Ischemia Rabbits].

OBJECTIVE: To develop an animal model suitable for the study of acupoint sensitization in myocardial ischemia(MI) animals by observing changes of the mechanical withdrawal threshold (pain threshold, PT). METHODS: Twenty New Zea-land rabbits were randomly divided into control and model groups (n=10 in each group). The controllable MI model was set up by installing a balloon occluder at the left anterior descending branch of the left coronary artery. Air inflation of the balloon was given for 5 min/time, twice a day (4-hours' interval) for continuous 5 days (the first stage of MI), with one day's rest, then, another 5 days' air inflation was conducted again (2nd stage of MI). Electrocardiogram (ECG) of the standard limb lead Ⅱ was recorded for assessing MI, and myocardial 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to verify the degree of ischemic myocardium. The PT of the skin areas of "Neiguan" (PC 6), "Shenmen" (HT 7),"Taixi"(KI 3),hind paw(HP)was detected under conscious conditions,before MI, on day 8(after recovery from MI), day 14 (the first stage of MI), and day 20 (the second stage of MI), respectively. RESULTS: The controllable MI model was successful due to a marked elevation of ECG ST Ⅱ after inflation of the implanted balloon and a distinct recovery after balloon deflation (P<0.05). The myocardial TTC staining showed that the area of the myocardial necrosis was about 10%. The PT values were significantly decreased in PC 6 area at the first stage of MI and in both PC 6 and HT 7 regions at the 2nd stage of MI (P<0.01), suggesting a close relationship between the acupoints of the Pericardium and Heart meridians and the heart in terms of the basic theory of Chinese medicine. CONCLUSIONS: MI may induce a reduction of PT of some related acupoints in MI rabbits, and the controllable MI model of the present study is helpful to the study of acupoint sensitization phenomenon after occurrence of visceral diseases.