Immunoreactive Akt, PI3-K and ERK protein kinase expression in ischemic rat brain

In order to clarify the role of protein kinases in ischemic brain injury, t he spatiotemporal expression of immunoreactive serine-threonine kinase AM, phosphatidylinositol 3-kinase (P13-K) and extracellular signal-regulated ki nase (ERK) were examined at 3, 8, or 24 h after permanent middle cerebral a rtery occlusion (MCAO) in rats. Weak staining for these protein kinases was found in both cortical and caudate neurons in sham controls. The staining for Akt-1 and P13-K was increased at 3-8 h in the ischemic penumbral region and declined at 24 h. A slight induction of these kinases was observed in the ischemic core region. Robust expression of ERK was noted at 3-8 h in mo st neurons in the area of ischemia. At 24 h, ERK continued to be expressed in the ischemic penumbra, but decreased in the ischemic core, These finding s suggest that the signaling for Akt and P13-K are different from the ERK d ependent signal transduction during ischemic brain injury. (C) 1999 Elsevie r Science Ireland Ltd. All rights reserved.