Transient oxygen-glucose deprivation induces rapid morphological changes in rat hippocampal dendrites.

Previous studies have revealed that pyramidal neurons in the CA1 region of the hippocampus are extremely susceptible to ischemia-induced cell damage and undergo selective degeneration 2-4 days after the insult. Little is known about early morphological changes in neurons occurring immediately after ischemic insult. Using two-photon laser scanning microscopy we monitored dendritic morphology of cells expressing enhanced green fluorescent protein in response to a transient hypoxic-ischemic episode in organotypic hippocampal slice preparations. This type of vital imaging provides direct evidence of dendritic rearrangements in rat CA1 pyramidal neurons occurring as soon as 20 min after oxygen-glucose deprivation. We propose that dendritic reorganization, resembling that occurring after tetanic stimulation, may be an early stage response to compensate the loss of synapses caused by ischemia-induced neuronal injury.