The effect of melatonin on functional responses of isolated ileal smooth muscle in ischemia-reperfusion injury in rats

ABSTRACT THE EFFECT OF MELATONIN ON FUNCTIONAL RESPONSES OF ISOLATED ILEAL SMOOTH MUSCLE IN ISCHEMIA- REPERFUSION INJURY IN RATS Zerrin ÖZCELİK. Purposes: The aim of this study was to determine the effect of melatonin, a hormone that is known as an antioxidant, on functional responses of isolated ileal smooth muscle in rat intestinal ischemia-reperfusion Materials and Methods: A total of 48 Sprague-Dawley rats were divided equally into 6 groups: Group 1 was control, Group 2 was sham-operated, Group 3 was ischemia, Group 4 was ischemia-reperfusion, Group 5 was ischemia plus melatonin, and Group 6 was ischemia- reperfusion plus melatonin. A dose of 10 mg/kg melatonin was administered intraperitoneally. 30 minutes before intestinal ischemia was followed by 90 minutes of reperfusion. Rats were sacrified after removal of ileal segments. Ileal segments were placed in isolated organ baths and contraction responses for acetylcholine and relaxation responses for adrenaline were recorded. Additionally, ileal segments were examined histopathologically. Results : By t he c ontraction r esponses of a cetylcholine, w hile G roup 2 w as c ompared t o Group 3 and Group 4, the differences between these groups were found significant (p<0.05, p< 0.01). Also the differences between Group 3 and Group 4, Group 5 were found significant (p<0.01). The comparison of Group 4 and Group 6 was found significant (pO.Ol). Comparison of relaxation adrenaline responses of Group 2 with Group 3 and Group 4 was found significant (respectively p<0.05, p< 0.01). The comparison of Group 3 and Group 5 was also found significant (p<0.05, pO.Ol). The comparison of Group 4 and Group 6 was found significant (p<0.05). The histopathologic results were consistent with responses of contraction and relaxation. Conclusions: The results of this study showed that the contraction and relaxation responses of rat ileal tissue exposed to ischemia-reperfusion were lower than those of control and sham- operated group. Treatment with melatonin before ischemia-reperfusion improved the responses of ileal tissues. Key words: ischemia-reperfusion, melatonin, isolated ileum, rat. xm