ABSTRACT
Objective To investigate the roles of tumor necrosisfactor-α(TNF-α) and nuclear factor-κB (NF-κB) in cerebral ischemia-reperfusion injury in rats w ith diabetes mel itus. Methods Thirty-six healthy male Sprague-Daw ley rats w ere divided into a euglycemic sham operation group, a euglycemic isc hemia-reperfusion group, and a diabetes ischemia-reperfusion group (n=12 in each group) according to a random number table. A diabetes model w as induced by intraperitoneal injection of streptozotocin, and then a focal cerebral ischemia-reperfusion model w as induced by the suture method. The neurological deficit score was performed at 24 h after reperfusion. 2,3,5 triphenyl tetrazolium staining was used to measure the cerebral infarction area. Western blotting w as used to detect the expression levels of NF-κB and TNF-αon the ischemic sides. Results The neurological function scores w ere 0.00 ±0.00, 2.50 ±1.08, and 3.20 ± 1.03, respectively in the euglycemic sham operation, euglycemic cerebral ischemia-reperfusion and diabetes cerebral ischemia-reperfusion groups, and there w ere significant differences (F=38.015, P<0.001). The neurological deficit scores of the diabetes cerebral ischemia-reperfusion group w ere significantly aggravated compared with the euglycemic cerebral ischemia-reperfusion group (P<0.05). The infarct areas of the euglycemic sham operation, euglycemic cerebral ischemia-reperfusion and diabetes cerebral ischemia-reperfusion groups w ere 0.00% ±0.00%, 33.09% ±5.17%, and 55.45% ±9.29%, respectively, and there w ere significant differences among the groups (F=206.614, P<0.001), in w hich the infarct area in the diabetes cerebral ischemia-reperfusion group w as enlarged significantly compared w ith the euglycemic cerebral ischemia-reperfusion group ( P< 0.05 ). At 24 h after reperfusion, there w ere no significant differences in the expression levels of the cortical NF-κB (F=29.993, P<0.001) and TNF-α(F=28.722, P<0.001) on the ischemic sides in each group, in w hich the expression levels of NF-κB and TNF-αin the diabetes cerebral ischemia-reperfusion group w ere increased significantly compared w ith the euglycemic cerebral ischemia-reperfusion group (al P<0.05). Conclusions Diabetes may aggravate cerebral ischemia reperfusion injury. The upregulated expression of TNF-αand NF-κB may be one of the mechanisms of diabetes aggravating cerebral ischemia-reperfusion injury.
ABSTRACT
Objective To study the potential role of tumor necrosis factor-α (TNF-α) 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-α (TNF-α 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-α 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-αmRNA 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-α 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-α level was measured at 0.5 hr after clamp release ( P ＜ 0.01); however, prophylactic treatment with TNF-α MoAb completely annulled the increase of local TNF-α levels seen in the control animals. Similarly, after anti-TNF-α MoAb administration, intestinal TNF-α 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-α 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-α appears to be involved in the development of local damage associated with intestinal ischemic injury. Moreover, prophylactic treatment with TNF-α MoAb exerts preventive effects on ischemia/ reperfusion-induced circulating D (-)-lactate elevation and gut injury. ( J Geriatr Cardiol 2004;1(2):119-124. )