Ischemia-induced inhibition of the initiation factor 2α phosphatase activity in the rat brain

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Abstract
Rats were subjected to the standard four-vessel occlusion model of brain transient ischemia for 30 min. Following different recirculation periods, the level of phosphorylation of the initiation factor 2 subunit α (eIF2α) and the eIF2α kinase/s and phosphatase/s activity were determined. eIF2α phosphorylation significantly increased very early during reperfusion (10–30 min), recovering at 4 h of reperfusion. Activation of any eIF2α kinases studied during ischemia or reperfusion was not noted. Conversely, eIF2α phosphatase activity significantly decreased at 10–15 min of reperfusion, reaching values even higher than in controls at 2–4 h of reperfusion. Our results support the hypothesis that the reperfusion-induced phosphorylated eIF2α changes are at least a result of the transiently eIF2α phosphatase inhibition.