Background: The aim of this study was to determine the level of lipid peroxidation and tissue protein after superior mesenteric artery occlusion tissue damage. The effect of melatonin as anti oxidant and free radical scavenger in prevention of tissue damage, were also evaluated.

Methods: Thity six young male Wisatr-Albino rats (weight: 80-120 gr), were divided equally in 6 group with different concentrations of melatonin (10,20,30 mg/kg) treatment. Group 1was control, group 2 the sham that surgical process was applied until superior mesenteric artery dissection and received vehicle solution only in equally volume by intra muscular route. Group 3 was ischemia- reperfusion (I/R), group 4 was I/R plus melatonin 10 mg/kg, group 5 I/R plus melatonin 20 mg/kg and finally group 6 I/R plus melatonin 30 mg/kg. After laparatomy, a microvascular atraumatic clip was placed across the superior mesenteric artery under general anaesthesia and itbremoved after ischemia for 30 minutes. The first dose of melatonin was applied just beforereperfusion, second dose, after reperfusion and third dose on the second day .On third day rats were killed and their bowels were removed. The level of tissue melandialdehyde (MDA) as index of lipid peroxidation and tissue protein was determined.

Results: The level of tissue MDA were significantly lower in group 4, 5, 6 than group 3 (p<0.05). Tissue protein levels were significantly upper in group 4 than group 3. (p<0.001). There was no significant difference tissue protein level in group 5, 6 than group 3(p>0, 05).

Conclusion: These results suggest that melatonin 10 mg/kg has antioxidant effect in prevention of inducing tissue damage during SMA occlusion in rat intestine.