LTC4/LTB4 alterations in rat forebrain ischemia and reperfusion and effects of AA-861, CV-3988

LTC4, which enhances vascular permeability and promotes tissue edema, and LTB4, which is a potent chemotactic and activating factor for leukocytes, were measured in rat brain after ischemia and several time periods of reperfusion. Forebrain ischemia was induced by 4-vessel occlusion. LTC4/LTB4 in the brain were measured by RIA. We also studied the effects of a 5-lipoxygenase inhibitor, AA-861 and a PAF antagonist, CV-3988 on LTC4/LTB4 concentrations. LTC4 in brain tissue increased during 30 min forebrain ischemia (p < 0.001). After reperfusion, LTC4 increased further, but at 15 min reperfusion LTC4 returned to the control level. Tissue levels of LTB4 in the brain increased during 30 min ischemia and remained high until 5 min after reperfusion (p < 0.01) returning at 15 min reperfusion to the control level. AA-861 inhibited elevation of LTC4/LTB4 in the reperfusion phase, but was not effective during ischemia. CV-3988 had a similar effect. LTC4 and LTB4 may be involved in the pathogenesis of ischemia brain edema and leukocyte infiltration. Further, PAF and LTs have many similarities of their pathophysiological properties, and may interact therefore in pathologic process.