Abstract
The effect of melatonin on morphological changes after ischemia-reperfusion injury was investigated in rat skeletal muscle. Dimethyl-sulfoxide(DMSO) was also tested for comparison. Muscle injury was evaluated in 4 groups as a single laparotomy group(control), ischemia-reperfusion group, DMSO group, melatonin group. Left hind limb ischemia was induced for 4 hours by vascular clamping of the common femoral artery and followed by 24 hours of reperfusion. The midportion of gastrocnemius muscle was taken for histological evaluation. In light microscopic study, ischemia-reperfusion group showed severe neutrophil infiltration, interstitial edema, and partial loss or degeneration of muscle fibers. The muscle tissue of melatonin group showed relatively normal architecture with mild inflammatory cell infiltration. In electron microscopic study, dilated cisternae of sarcoplasmic reticulum, dilated mitochondria with electron loose matrix and dilated cristae, disordered or loss of myofilament, indistinct A-band and I-band, intracytoplasmic vacuoles, and markedly decreased glycogen granules were observed in ischemia-reperfusion group. But relatively well maintained A-band, I-band, Z-line, M-line, and mildly dilated mitochondria with well preserved cristae were observed in melatonin group. The DMSO group showed intermediately attenuated ultrastructural changes. The results show that melatonin improves morphologically ischemia-reperfusion injury more effectively than DMSO. In conclusion, melatonin seems to be a promising agent that can salvage the skeletal muscle from severe ischemia-reperfusion injury.