Role of melatonin in electroacupuncture-induced reduction of lung injury induced by limb ischemia-reperfusion in rabbits / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of melatonin in electroacupuncture (EA)-induced reduction of lung injury induced by limb ischemia-reperfusion (I/R) in rabbits.Methods:Fifty clean-grade healthy male New Zealand white rabbits, weighing 2.0-2.5 kg, aged 3 months, were divided into 5 groups ( n=10 each) using a random number table method: sham operation group (group Sham), limb I/R group (group IR), EA group, sham EA group (group SEA) and EA plus melatonin receptor antagonist luzindele group (group EA+ L). The model of limb I/R injury was established by clamping the femoral artery for 3 h followed by 4-h reperfusion in anesthetized animals.In group EA and group EA + L, bilateral Zusanli and Feishu acupoints (4-6 mm depth) were stimulated with constant voltage (2/15 Hz, l-2 mA, disperse-dense waves) for 30 min once a day during 1-7 days before establishing the model and during establishment of the model.EA was performed at the points (3 mm depth) 0.5 cm lateral to the acupoints of Zusanli and Feishu instead in group SEA.Luzinole 30 mg/kg was intraperitoneally injected at 30 min before establishing the model in group EA+ L.Blood samples from the right internal jugular vein were collected before ischemia (T 0), at 3 h of ischemia (T 1) and 4 h of reperfusion (T 2) for determination of the serum melatonin concentrations by enzyme-linked immunosorbent assay.Bronchoalveolar lavage fluid (BALF) was collected at 4 h of reperfusion for measurement of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and IL-6 concentrations (by enzyme-linked immunosorbent assay), superoxide dismutase (SOD) activity (by xanthine oxidase method), and malondialdehyde (MDA) concentration (by thiobarbituric acid method). Then the rabbits were sacrificed, and the lung tissues were taken for determination of wet to dry weight ratio (W/D ratio) and for microscopic examination of the pathological changes (with a light microscope) which were scored and ultrastructure (with a transmission electron microscope). The number of mitochondria and relative cross-sectional area of mitochondria were calculated. Results:Compared with group Sham, lung injury scores and W/D ratio were significantly increased, the number of mitochondria was decreased, the relative cross-sectional area of mitochondria was increased, levels of TNF-α, IL-1β, IL-6 and MDA in BALF were increased, and activities of SOD in BALF were decreased in the other four groups, and the serum melatonin concentration was decreased at T 1 and T 2 in group I/R and increased at T 0 in EA and EA+ L groups ( P<0.05). Compared with group IR, the lung injury score and W/D ratio were significantly decreased, the number of mitochondria was increased, the relative cross-sectional area of mitochondria was decreased, levels of TNF-α, IL-1β, IL-6 and MDA in BALF were decreased, and activities of SOD in BALF were increased in group EA, the serum melatonin concentration was increased at each time point in EA and EA+ L groups ( P<0.05), and no significant change was found in the parameters mentioned above in group SEA ( P>0.05). Compared with group EA, lung injury scores and W/D ratio were significantly increased, the number of mitochondria was decreased, the relative cross-sectional area of mitochondria was increased, levels of TNF-α, IL-1β, IL-6 and MDA in BALF were increased, and activities of SOD in BALF were decreased in SEA and EA+ L groups, and the serum melatonin concentration was decreased at each time point in group SEA ( P<0.05). Conclusion:EA can reduce lung injury induced by limb I/R by increasing serum melatonin level in rabbits.