Effects of curcumin pretreatment on iNOS activity during lung injury induced by intestinal ischemia-reperfusion in rats

Objective To evaluate the effects of curcumin pretreatment on the activity of inducible nitric oxide synthase (iNOS) during lung injury induced by intestinal ischemia-reperfusion (I/R) in rats. Methods Twenty-four pathogen-free female Sprague-Dawley rats, weighing 180-220 g, were randomly divided into 3 groups (n= 8 each) using a random number table: sham operation group (group Sham); intestinal I/R group (group II/R); curcumin pretreatment group (group Cur). A rat model of lung injury induced by intestinal I/R which was produced by occlusion of superior mesenteric artery for 75 min followed by reperfusion was established.At 5 days before I/R, curcumin 200 mg/kg (in 20 mg/ml of normal saline) was given through a gastric tube in group Cur, while the equal volume of normal saline was given instead in Sham and II/R groups.The rats were sacrificed at 4 h of reperfusion, and the pulmonary specimens were obtained for determination of wet/dry lung weight ratio (W/D ratio), NO content (by using nitrate reductase method) and iNOS activity (using colorimetric method) and for examination of pathological changes (with light microscope). The pathological changes of the lung were scored. Results Compared with group Sham, the pathological scores, W/D ratio, NO content and iNOS activity were significantly increased in II/R and Cur groups.Compared with II/R group, the pathological scores, W/D ratio, NO content and iNOS activity were significantly decreased in group Cur.The pathological changes of lungs were significantly attenuated in group Cur as compared with II/R group. Conclusion The mechanism by which curcumin pretreatment attenuates lung injury induced by intestinal I/R is related to decrease in iNOS activity in rats. Key words: Curcumin; Reperfusion injury; Intestines; Respiratory distress syndrome, adult; Nitric oxide synthase type Ⅱ