title: Temporal profiles of axon terminals, synapses and spines in the ischemic penumbra of the cerebral cortex: ultrastructure of neuronal remodeling.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Neuropathology, Tokyo Metropolitan Institute for Neuroscience, Tokyo, 2-6, Musashidai, Fuchu-shi, Tokyo 183-8526, Japan. umeo-ito@nn.iij4u.or.jp
authors.forename: Umeo
authors.initials: U
authors.lastname: Ito
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: Jun
authors.initials: J
authors.lastname: Nagasao
authors.forename: Emiko
authors.initials: E
authors.lastname: Kawakami
authors.forename: Kiyomitsu
authors.initials: K
authors.lastname: Oyanagi
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000473:pathology* / Q000503:physiopathology; D049229:Dendritic Spines / Q000648:ultrastructure*; D005849:Gerbillinae; D008297:Male; D008854:Microscopy, Electron; D019579:Neocortex / Q000473:pathology* / Q000503:physiopathology; D009473:Neuronal Plasticity; D017729:Presynaptic Terminals / Q000648:ultrastructure*; D013569:Synapses / Q000648:ultrastructure*; D013997:Time Factors