on June 29, 2006
Published online before print June 29, 2006, doi: 10.1161/01.STR.0000231875.96714.b1
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Submitted on February 15, 2006
From the Department of Neuropathology (U.I., J.N., E.K., K.O.), Tokyo Metropolitan Institute for Neuroscience, Tokyo, Japan; and the Department of Neuropathology (T.K.), Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan. * To whom correspondence should be addressed. E-mail: umeo-ito{at}nn.iij4u.or.jp.
Background and Purpose--Because the recovery process of axon terminals, synapses, and spine-dendrites in the ischemic penumbra of the cerebral cortex is obscure, we studied the temporal profile of these structures up to 12 weeks after the ischemic insult, using a gerbil model. Methods--Stroke-positive animals were selected according to their stroke index score during the first 10-minute left carotid occlusion done twice with 5-hour interval. The animals were euthanized at various times after the second ischemic insult. Ultra-thin sections including the 2nd to 4th cortical layers were obtained from the neocortex coronally sectioned at the infundibular level, in which the penumbra appeared. We counted the number of synapses, spines and multiple synapse boutons, measured neurite thickness, and determined the percent volume of the axon terminals and spines by Weibel point counting method. Results--The number of synapses, synaptic vesicles and spines and the total percent volume of the axon terminals and spines decreased until the 4th day. From 1 to 12 weeks after the ischemic insult, these values increased to or exceeded the control ones, and neuritic thickening and increase in number of multiple synapse boutons occurred. Conclusions--In the ischemic penumbra, the above structures degenerated, with a reduction in their number and size, until 4 days and then recovered from 1 to 12 weeks after the ischemic insult.
Revised on May 1, 2006
Accepted on May 24, 2006
Temporal Profiles of Axon Terminals, Synapses and Spines in the Ischemic Penumbra of the Cerebral Cortex. Ultrastructure of Neuronal Remodeling
Umeo Ito MD, PhD, FAHA*;
Key words: axon terminal • dendrites • spine • synapses • transient cerebral ischemia
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