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期刊论文

Electrophysiological changes of CA3 neurons and dentate granule cells following transient forebrain ischemia

高天明Eugene M. Howard a Tian-Ming Gao ab William A. Pulsinelli a Zao C. Xu a*

Brain Research 798 (1998) 109-118,-0001,():

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摘要/描述

The electrophysiological responses of CA3 pyramidal neurons and dentate granule (DG) cells in rat hippocampus were studied after transient forebrain ischemia using intracellular recording and staining techniques in vivo. Approximately 5 min of ischemic depolarization was induced using 4-vessel occlusion method. The spike threshold and rheobase of CA3 neurons remained unchanged up to 12h following reperfusion. No significant change in spike threshold was observed in DG cells but the rheobase transiently increased 6-9h after ischemia. The input resistance and time constant of CA3 neurons increased 0-3h after ischemia and returned to control ranges at later time periods. The spontaneous firing rate in CA3 neurons transiently decreased shortly following reperfusion, while that of DG cells progressively decreased after ischemia. In CA3 neurons, the amplitude and slope of excitatory postsynaptic potentials (EPSPs) transiently decreased 0-3h after reperfusion, and the stimulus intensity threshold for EPSPs transiently increased at the same time. No significant changes in amplitude and slope of EPSPs were observed in DG cells, but the stimulus intensity threshold for EPSPs slightly increased shortly after reperfusion. The present study demonstrates that the excitability of CA3 pyramidal neurons and DG cells after 5min ischemic depolarization is about the same as control levels, whereas the synaptic transmission to these cells was transiently suppressed after the ischemic insult. These results suggest that synaptic transmission is more sensitive to ischemia than membrane properties, and the depression of synaptic transmission may be a protective mechanism against ischemic insults.

版权说明:以下全部内容由高天明上传于   2006年06月17日 01时16分00秒,版权归本人所有。

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