Fasting-induced reduction of intestinal reperfusion injury

Fasting is associated with significant structural, functional, and metabolic alterations in the intestinal mucosa. Before abdominal surgery, patients are usually fasted the night before surgery or for a longer period of time if chronic illness is present. The splanchnic organs may experience varying degrees of ischemia/reperfusion as blood vessels are occluded during the various manipulations.

To study whether fasting alters intestinal reperfusion injury, rats were fasted for 0 to 2 days, and the mesenteric artery was occluded for 30 minutes and then reperfused for 1 hour. Mucosal atrophy was quantitated by measuring jejunal villus height and crypt depth, and mucosal injury was quantitated by measuring jejunal villus width to villus height and mucosal integrity. To determine whether any effect of fasting on reperfusion injury was due to the absence of luminal nutrients or to a systemic nutrient deficiency, rats were fed parenterally for 7 days before ischemia/reperfusion.

A 1-day fast produced significant mucosal atrophy. Reperfusion in the 0-day and 1-day fasted animals produced mucosal injury and additional mucosal atrophy. After a 2-day fast, there was no mucosal injury or mucosal atrophy other than that produced by fasting alone. Parenteral feeding before ischemia/reperfusion did not prevent ischemia/reperfusion induced mucosal atrophy and injury.

The protective effect of a 2-day fast before intestinal ischemia/reperfusion cannot be attributed to the physical and chemical absence of food within the intestinal lumen.