| Objective:To investigate the protective effects of electro-acupuncture (EA) at ST36 points on the intestine and remote organ injury after intestinal ischemia and reperfusion injury in rats, and study if the protective effect is related to the excitement or blocking of dopamine or its receptors. To explore the anti-inflammatory and shock resistance effects of EA at ST36 through dopamine mechanism, and provide theoretical foundation for the electric acupuncture to treat ischemic and inflammatory diseases.Methods:84 SD rats, were randomly divided into seven groups:sham group, intestinal ischemia-reperfusion (IR) group, I/R+EA (EA) group, I/R+EA+vagotomy (VX) group, I/R+EA+sciatic surgical neurectomy (SSX) group, I/R+EA+ butaclamol (BC) group, I/R+EA+ spiperone (SP) group. According to different observation time, each group was divided into two subgroups:1h and 4h after injury(n=6) for detection. The intestinal ischemia-reperfusion (I/R) model was established by superior mesenteric artery (SMA) occlusion for 30min, followed by reperfusion for 1h or 4h. The stimulation of EA at the bilateral ST36 points was performed for 30min using an electric current with the intensity of 2mA and 2-100Hz after ischemia. Rats in sham group just be opened stomach and receive no SMA occlusion or other operation. Rats in EA group received EA immediately after ischemia, and those in model group received no treatment. Rats in the VX group underwent vagotomy of the dorsal and ventral vagus nerve on the distal esophagus prior to electro-acupuncture at ST36 points immediately after the ischemia. Rats in the SSX group underwent sciatic surgical neurectomy prior to electro-acupuncture at ST36 points immediately after the ischemia. Rats in the BC group underwent intraperitoneal administration of Butaclamol (1μg/kg, IP, Sigma; a standard D1 receptor antagonist) before ischemia 1h. Rats in the SP group underwent intraperitoneal administration of Spiperone hydrochloride (1mg/kg, IP, Sigma; a D2 receptor antagonist) before ischemia 1h. At 1h and 4h after I/R, the blood samples were taken for measurement of DA, TNF-a, CK-MB, LDH, ALT, Cr and DAO. The samples of myocardium, lung and intestine tissues were harvest for levels of MPO and MDA. The pathologic lesions of myocardium, lung and intestine tissues were also observed.Results:1. The plasma level of DA was significantly decreased in IR1 and IR4 groups compared with sham group. Meanwhile, compared with IR group, electro-acupuncture at ST36 obviously elevated the level of DA, and significantly attenuated the release of tumor necrosis factor-a (TNF-a) in plasma (all P<0.05). However, the role of EA was disappeared in VX, SSX and BC groups.2. Compared with IR group, EA at ST36 inhibited the activity of MPO and MDA of myocardium, lung and intestine tissue after I/R injury, and the effect was more obvious at 4h than at 1h. The percentage of EA inhibiting the activity of MDA of heart, lung and intestinal respectively is 9%,18%, 8.9% after I/R injury 1 h, and is 30%,30%,39.2% after I/R injury 4 h; The percentage of EA inhibiting the activity of MPO of heart, lung and intestinal respectively is 13.4%, 41.5%,27% after I/R injury 1 h, and is 15.1%,26.1%,37% after I/R injury 4 h. These results indicated that EA could inhabited the activity of MDA or MPO, and the protective effect of EA was obvious in the early implementation.3. Compared with IR group, EA at ST36 significantly attenuated the activity of DAO in plasma (EA1: 33.76ng/mL±6.37 ng/mL, IR,:45.47ng/mL±9.46 ng/mL; EA4:42.46ng/mL± 9.21ng/mL, IR4:65.53ng/mL±10.72 ng/mL; all P<0.05), and it shows EA could protect the intestine tissue.4. After I/R injury 4h, the plasma levels of CK-MB, LDH and ALT in EA4 were significantly reduced than in IR4 (all P<0.05). Meanwhile, these indicators had no obvious difference between the groups of VX, SSX, BC and IR, and had statistical differences between SP group and IR group. This phenomenon demonstrated EA at ST36 protected the function of multiple organs via D1 receptor instead of D2 receptor. EA had no influence on the plasma level of Cr.5. After I/R injury 4h, edema, hemorrhage, inflammatory cells infiltration and tissue disorder were observed at pathological section of myocardium, lung and intestine tissue. Compared to the model group, the injury of EA group was much milder. The effect of EA in VX, SSX and BC groups was weakened, and pathological section in SP group had no obvious difference compared with EA group.Conclusion:These findings suggest that electro-acupuncture ST36 could attenuate the injury of myocardium, lung and intestine after intestinal ischemia and reperfusion injury, and the protective mechanism may be related to the increase level of DA after EA, the attenuate release of TNF-a, MPO and MDA, the removal of the oxygen free radicals, and reduced inflammation reaction. After vagotomy or sciatic surgical neurectomy, the protective effect of EA weakened or disappeared, it prompted that EA at ST36 played the role of anti-inflammatory by activating sciatic nerve-vagus nerve-adrenal axis, and releasing DA. After intraperitoneal administration of butaclamol, a standard D1 receptor antagonist, the role above became weakened or disappeared, so we considered the protective effect of EA may be through D1 receptor. |
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