CORTICOSTEROIDS DO NOT ALTER MUCOSAL PERMEABILITY AFTER SUBCLINICAL INTESTINAL ISCHEMIA-REPERFUSION INJURY IN THE RAT

Maternal administration of corticosteroids is thought to decrease the incidence of necrotizing enterocolitis in premature infants. To determ ine if this protection is mediated by mucosal stabilization, we tested the effect of prenatal and postnatal steroids in a model of subclinic al ischemia-reperfusion injury in immature rats. Ten-day and 6-week-ol d rats were subjected to superior mesenteric artery occlusion for 10 m in or to sham operation. Ileal mucosal permeability to labelled chromi um EDTA ((51)CrEDTA) was assessed 30 min after reperfusion. Animals re ceived 3 mg/kg betamethasone, 50 mg/kg hydrocortisone, 2 mg/kg dexamet hasone, or saline for 3 days prior to the experiment and at the time o f laparotomy. To test the effect of prenatal steroid administration, p regnant rats were treated with betamethasone, dexamethasone, or saline daily for 3 days prior to term delivery. Permeability was then tested in the newborns at 10 days of age. Ten-minute occlusion resulted in a significant increase in permeability to (51)CrEDTA in all animals. Th ere was no significant attenuation of the ischemia-reperfusion-induced permeability increase by any steroid at either age or by prenatally a dministered steroids. We conclude that protective mechanisms other tha n mucosal stabilization, such as decreased neutrophil infiltration or inhibition of inflammatory mediators, must therefore be postulated and tested.