1. ^*Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, Michigan, U.S.A.
2. ^†Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, U.S.A.
3. ^‡Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, U.S.A.

Correspondence: Gary S Krause, Wayne State University School of Medicine, Room 51.2 Lande Medical Research Building, 550 E. Canfield, Detroit, MI 48201 U.S.A.

Received 30 May 1997; Revised 21 July 1997; Accepted 24 July 1997.

Abstract

Postischemic brain reperfusion is associated with a substantial and long-lasting reduction of protein synthesis in selectively vulnerable neurons. Because the overall translation initiation rate is typically regulated by altering the phosphorylation of serine 51 on the -subunit of eukaryotic initiation factor 2 (eIF-2), we used an antibody specific to phosphorylated eIF-2 [eIF-2(P)] to study the regional and cellular distribution of eIF-2(P) in normal, ischemic, and reperfused rat brains. Western blots of brain postmitochondrial supernatants revealed that 1% of all eIF-2 is phosphorylated in controls, eIF-2(P) is not reduced by up to 30 minutes of ischemia, and eIF-2(P) is increased 20-fold after 10 and 90 minutes of reperfusion. Immunohistochemistry shows localization of eIF-2(P) to astrocytes in normal brains, a massive increase in eIF-2(P) in the cytoplasm of neurons within the first 10 minutes of reperfusion, accumulation of eIF-2(P) in the nuclei of selectively vulnerable neurons after I hour of reperfusion, and morphology suggesting pyknosis or apoptosis in neuronal nuclei that continue to display eIF-2(P) after 4 hours of reperfusion. These observations, together with the fact that eIF-2(P) inhibits translation initiation, make a compelling case that eIF-2(P) is responsible for reperfusion-induced inhibition of protein synthesis in vulnerable neurons.