TNF-a and plasma D(-)-lactate levels in rats after intestinal ischemia and reperfusion

Objective To study the potential role of tumor necrosis factor-a (TNF-a) induction in the development of mucosal barrier dysfunction in rats caused by acute intestinal ischemia-reperfusion injury, and to examine whether pretreatment with monoclonal antibody against TNF-a (TNF-a MoAb) would affect the release of D(-)-lactate after local gut ischemia followed by reperfusion. Methods Anesthetized Sprague-Dawley rats underwent superior mesenteric artery occlusion for 75 min followed by reperfusion for 6 hr. The rats were treated intravenously with either TNF-a MoAb (20 mg/kg) or albumin (20 mg/kg) 30 min prior to the onset of ischemia. Plasma D(-)-lactate levels were measured in both the portal and systemic blood by an enzymatic spectrophotometric assay. Intestinal TNF-a mRNA expression as well as protein levels were also measured at various intervals. In addition, a postmortem examination was performed together with a macropathological evaluation based on a four-grade scoring system. Results Intestinal ischemia resulted in a significant elevation in D(-)-lactate levels in the portal vein blood in both the control and treatment groups ( P < 0.05). However, animals pretreated with TNF-a MoAb at 6 hr after reperfusion showed significant attenuation of an increase in both portal and systemic D(-)-lactate levels when compared with those only receiving albumin (P < 0.05). In the control animals, a remarkable rise in intestinal TNF-a level was measured at 0.5 hr after clamp release ( P < 0.01), however, prophylactic treatment with TNF-a MoAb completely annulled the increase of local TNF-a levels seen in the control animals. Similarly, after anti-TNF-a MoAb administration, intestinal TNF-a mRNA expression was markedly inhibited, which showed significant differences when compared with the control group at 0. 5 hr, 2 hr and 6 hr after the release of occlusion ( P < 0. 05-0. 01). In addition, the pathological examination showed marked intestinal lesions that formed during ischemia, which were much worse upon reperfusion, particularly at the 6 hr time point. These acute injuries were obviously attenuated in animals receiving TNF-a MoAb. Conclusions It appeared that acute intestinal ischemia was associated with failure of the mucosal barrier, resulting in increased plasma D(-)-lactate levels in both portal and systemic blood. These results suggest that TNF-a appears to be involved in the development of local damage associated with intestinal ischemic injury. Moreover, prophylactic treatment with TNF-a MoAb exerts preventive effects on ischemia/ reperfusion-induced circulating D (-)-lactate elevation and gut injury.