Evidence for apoptotic cell death in the choroid plexus following focal cerebral ischemia

Focal cerebral ischemia in rats subjected to middle cerebral artery (MCA) occlusion results in apoptotic DNA fragmentation and activation of putative cell death effector genes in neurons and functional impairment of the plexus choroideus. In the present study we investigated whether cerebral ischemia may induce apoptotic cell death in the choroid plexus. Using in situ end-labeling by terminal transferase and fluorescein-dUTP, nuclear DNA breaks were detected in the choroid plexus of the lateral ventricle of the ischemic hemisphere after 6 h but not after 1.5 h of MCA occlusion. Intense cytoplasmic immunostaining for pro-apoptotic Fax protein and moderate immunolabeling for Bcl-X was observed in the epithelium of the choroid plexus of the lateral and third ventricles. However, constitutive expression of Bax and Bcl-X proteins in the plexus choroideus did not change significantly following focal ischemia. Thus, cells of the choroid plexus may die by apoptosis after several hours of cerebral ischemia. Modulation of cell death effector genes of the bcl-2 family however, may not be required for apoptotic cell death to occur.