Identification of proteins regulated by estradiol in focal cerebral ischemic injury--a proteomics approach.

Estradiol protects neuronal cells against permanent and focal ischemic brain damage. We identified the proteins that are expressed following estradiol administration during cerebral ischemia in an animal model. Adult female rats were ovariectomized and treated with oil or estradiol prior to middle cerebral artery occlusion (MCAO) to induce cerebral ischemia, and brains were collected 24h after MCAO. Protein analysis was performed on the cerebral cortex using two-dimensional gel electrophoresis. Protein spots with difference in intensity between oil- and estradiol-treated groups were identified by mass spectrometry. Among these proteins, levels of protein phosphatase 2A (PP2A) and astrocytic phosphoprotein PEA-15 were significantly decreased in the oil-treated group in comparison to the estradiol-treated group. Moreover, Western blot analysis demonstrated that estradiol treatment prevents injury-induced decrease of PP2A and PEA-15 levels during both MCAO-induced injury and glutamate exposure in HT22 cells. In contrast, levels of the 60kDa heat shock protein (Hsp 60) were significantly increased in oil-treated animals, while estradiol prevented the injury-induced increase of Hsp 60. The results of this study provide an evidence that estradiol protects neuronal cells against ischemic brain injury through the up- and down-modulation of specific proteins. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.