[Involvement of melatonin in the adjusting effect of electroacupuncture in resisting oxygen stress in cerebral ischemia-reperfusion injury rats].

OBJECTIVE

To explore the effect of electroacupuncture (EA) in resisting acute cerebral ischemia-reperfusion injury (CI-RI) via anti-oxidation of melatonin (MT).

METHODS

A total of 52 male SD rats were randomized into Sham-operation (sham, n=8), CI-RI (model, n=8), EA (n=8), MT (3.2 mg/Kg, i.p., n=8), EA+MT (n=8), EA+Luzindole (L, a blocker of MT, 1 mg/100 microl/rat, n=6), EA+PD 98059 (a blocker of mitogen-activated protein kinase, MAPK, 1 mg 100 microl/rat, n=6) groups. EA (3 Hz,1-3 mA, continuous waves) was applied to "Dazhui" (GV 14) and "Baihui" (GV 20) for 30 min. CI-RI model was induced by right middle cerebral artery occlusion (MCAO) for 60 min and reperfusion for 24 h except sham-operation group. MT content of pineal gland tissue was determined by high performance liquid chromatography (HPLC) and neuroethological scores of the rats were evaluated by Kuluz's and Julio's methods. Bax and Bcl-2 gene protein expression of the striate body was detected by immunohistochemistry.

RESULTS

In comparison with sham group, the number of Bax immunoreactive (IR) positive cells and Bax/Bcl-2 in striate body increased significantly (P<0.001), and neuroethological score and Bcl-2 IR-positive cells decreased considerably in model group (P<0.01). Compared with model group, pineal MT content, neuroethological score and Bcl-2 IR-positive cells in EA group, neuroethological scores in EA+L and EA+P groups, and Bcl-2 expression in MT and EA+MT groups increased considerably (P<0.01, 0.001); while Bax IR-positive cells and Bax/Bcl-2 in EA, MT and EA+MT groups decreased very significantly (P<0.001). It showed that EA could obviously increase pineal MT content, improve CI-RI rats' activity score, upregulate Bcl-2 expression and down-regulate Bax expression in striate body. In comparison with simple EA group, neuroethological scores of EA+L and EA+P groups, Bax IR-positive cells and Bax/Bcl-2 of EA+MT group were significant lower (P<0.05, 0.01). No significant differences were found between EA+L and EA+P groups in behavior scores, and between MT and EA+MT groups in Bax and Bcl-2 IR-positive cell number and Bax/Bcl-2 (P>0.05).

CONCLUSION

EA has a good effect of anti-oxygen stress, protecting the brain from ischemic damage directly or indirectly, which may be related to its effect in upregulating the synthesis and release of MT.