Protective effect of estrogen on intestinal ischemia-reperfusion injury in pubertal rats.

PURPOSE: This study investigated the role of 17beta-estradiol (E(2)) in intestinal ischemia-reperfusion (I/R) injury and its possible mechanism.

METHODS

Rats of pubertal age were ovariectomized and injected subcutaneously with vehicle (vehicle group) or E(2) (100 or 500 mug/kg/every other day, E(2) or 5E(2) group) for 4 weeks. Other rats of the same age underwent sham ovariectomy as a control group. The rats in each group (n = 15) were subjected to superior mesenteric artery occlusion followed by 1 hour (n = 5), 6 hours (n = 5), or 24 hours (n = 5) reperfusion. Intestine specimens then were obtained for the determination of histopathologic score, inducible nitric oxide synthase (iNOS) mRNA expression, and iNOS activity.

RESULTS

In vehicle, control, E(2), and 5E(2) groups, the histopathologic scores were 3.31 +/- 0.12, 3.00 +/- 0.09, 2.57 +/- 0.12, and 2.98 +/- 0.08, respectively. The expression levels of iNOS mRNA were 3.85 +/- 0.42, 4.86 +/- 0.76, 5.17 +/- 0.34, and 4.25 +/- 0.41 log copies, respectively. Lower histopathologic score but higher iNOS mRNA expression were found in E(2) group than in the other groups (P < .01). The level of iNOS activity paralleled the expression of iNOS mRNA.

CONCLUSIONS

Estrogen may exert a protective effect on intestinal I/R injury in pubertal rats, probably by enhancing iNOS expression.