Immunohistochemical analysis of cyclic AMP response element binding protein phosphorylation in focal cerebral ischemia in rats

Phosphorylation of cyclic AMP response element binding protein (CREB) is on e of the most important mechanisms controlling various gene transcriptions. In the present study, the phosphorylation of CREB was examined immunohisto chemically at 24 h of recirculation following 1.5 h of middle cerebral arte ry occlusion (MCAO) in rats. MCAO was induced by the intraluminal suture me thod. The infarct core revealed a significant reduction in the number of im munoreactive cells with the anti-phosphorylated CREB and with the anti-CREB antibody, which binds to both unphosphorylated and phosphorylated CREB. In contrast, the peri-infarct area exhibited a marked increase in the number of immunopositive cells as well as in the intensity of nuclear staining wit h each antibody, so that almost all of the cells expressing CREB demonstrat ed phosphorylation of CREB. On the other hand, about half of the CREB immun opositive cells reacted weakly with the anti-phosphorylated CREB antibody i n the sham group. These findings indicated that the expression as well as p hosphorylation of CREB protein was significantly activated in the regions s urrounding the infarct area. Since phosphorylation of CREB has recently bee n implicated in signal transductions that promote the survival and differen tiation of neurons, the present data suggest that tissue repair mechanisms may be markedly activated in the peri-infarct area. (C) 1999 Elsevier Scien ce B.V. All rights reserved.