Effect of oral enprostil, a synthetic prostaglandin E2, on intestinal brush border membrane lipid composition following abdominal irradiation in the rat.

Previous studies have demonstrated that external abdominal irradiation alters intestinal nutrient transport and brush border membrane (BBM) phospholipid content. This study was undertaken to assess the possible protective effect of oral dosing of enprostil, a synthetic E2 prostaglandin, on the BBM marker enzyme and lipid composition of non-irradiated control (CONT) animals and of rats exposed seven days perviously to a single dose of 600 cGy external abdominal irradiation (RAD). Half the CONT and RAD animals were orally dosed with enprostil 5 mcg/kg body weight, two and one mornings before the day of irradiation, and one hour before 600 cGy; the remaining half were dosed with placebo according to the same schedule. BBM were isolated and purified from the animals seven days post-irradiation for analysis of marker enzymes and lipid composition. Radiation was associated with a decline in jejunal and ileal BBM activity of sucrase. Enprostil was associated with a decline in the ratio of alkaline phosphatase/sucrase in jejunal BBM from irradiated rats, despite its preventing a radiation-associated decline in BBM sucrase activity. Radiation was associated with changes in ileal BBM phospholipids, and these alterations were not prevented with enprostil. Furthermore, enprostil given to non-radiated control rats altered BBM composition, such as increased jejunal and ileal lysophosphatidylethanolamine, and lowered ileal BBM sphingomyelin and phosphatidylethanolamine. Thus, enprostil failed to protect the intestine from the effects of abdominal irradiation on BBM phospholipids, but did partially prevent the effect of abdominal irradiation on jejunal sucrase activity.