The role of eicosanoids in the process of adaptation following massive bowel resection in the rat

Background: Long chain polyunsaturated fatty acids (LCPUFAs) such as arachi donic acid (AA) and eicosapentaenoic acid (EPA) stimulate intestinal adapta tion. Prostaglandins also enhance intestinal adaptation. The purpose of thi s study was to determine by which eicosanoid pathway dietary arachidonic ac id enhances intestinal adaptation. Cyclo-oxygenase or lipoxygenase were sel ectively inhibited to determine whether either of them enhanced or inhibite d adaptation. Methods: Sixty Sprague-Dawley rats were divided into 2 groups , one receiving an 80% small bowel resection and the other receiving a sham operation. Rats were further divided into groups receiving either a placeb o, a general lipoxygenase inhibitor (nordihydroguaiaretic acid [NDGA] at 40 mg/kg per day), or a cyclo-oxygenase-2 inhibitor (Etodolac at 3 mg/kg per day). Rats were pair-fed a diet containing 30% kcal from fat, primarily con sisting of AA. Results: After 14 days, mucosal mass, protein, DNA, and disa ccharidase activity were measured in the remaining small intestine. There w as a significant decrease in ileal mucosal mass in rats receiving Etodolac and a significant increase in mucosal mass in the duodenum in rats receivin g NDGA (both p < .001). Mucosal DNA, protein, and disaccharidase data showe d similar trends. Conclusions: These findings suggest that after small bowe l resection, dietary arachidonic acid may facilitate the adaptation process by acting as a substrate for the synthesis of prostaglandins, and not thro ugh the derivatives of lipoxygenase such as leukotrienes or thromboxanes.