Ultrastructural changes in the hippocampal CA1 region following transient cerebral ischemia: evidence against programmed cell death

Research output: Contribution to journalArticle

Abstract

The ultrastructural changes in the pyramidal neurons of the CA1 region of the hippocampus were studied 6 h, 24 h, 48 h, and 72 h following a transient 10 min period of cerebral ischemia induced by common carotid occlusion combined with hypotension. The pyramidal neurons showed delayed neuronal death (DND), i.e. at 24 h and 48 h postischemia few structural alterations were noted in the light microscope, while at 72 h extensive neuronal degeneration was apparent. The most prominent early ultrastructural changes were polysome disaggregation, and the appearance of electron-dense fluffy dark material associated with tubular saccules. Mitochondria and nuclear elements appeared intact until frank neuronal degeneration. The dark material accumulated with extended periods of recirculation in soma and in the main trunks of proximal dendrites, often beneath the plasma membrane, less frequently in the distal dendrites and seldom in spines. Protein synthesis inhibitors (anisomycin, cycloheximide) and an RNA synthesis inhibitor (actinomycin D), administered by intrahippocampal injections or subcutanously, did not mitigate neuronal damage. Therefore, DND is probably not apoptosis or a form of programmed cell death. We propose that the dark material accumulating in the postischemic period represents protein complexes, possibly aggregates of proteins or internalized plasma membrane fragments, which may disrupt vital cellular structure and functions, leading to cell death.

Details

Authors
Organisations
External organisations
  • Johns Hopkins Hospital
  • Skåne University Hospital
  • Sahlgrenska University Hospital
  • University of Turku
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurosciences

Keywords

  • Cerebral ischemia, Glutamate, Heat shock protein, Hippocampus, Programmed cell death, Rat, Ubiquitin
Original languageEnglish
Pages (from-to)91-105
Number of pages15
JournalExperimental Brain Research
Volume88
Issue number1
Publication statusPublished - 1992 Jan 1
Publication categoryResearch
Peer-reviewedYes