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KMID : 0811720070110060249
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Korean Journal of Physiology & Pharmacology
2007 Volume.11 No. 6 p.249 ~ p.252
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Post-ischemic Time-dependent Activity Changes of Hippocampal CA1 cells of the Mongolian Gerbils
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Won Moo-Ho
Shin Hyung-Cheul
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Abstract
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Changes of single unit activity of CA1 hippocampus region were investigated in anesthetized Mongolian gerbils for six days following transient ischemia. Ischemia was produced immediately before the implantation of micro-wire recording electrodes. In control animals receiving pseudo-ischemic surgery, neither spontaneous neuronal activities (5.70±0.4 Hz) nor the number of recorded neurons per animal changed significantly for six days. Correlative firings among simultaneously recorded neurons were weak (correlation coefficient ＞0.6) in the control animals. Animals subjected to ischemia exhibited a significant elevation of neural firing at post-ischemic 12 hr (9.95±0.9 Hz) and day 1 (8.48± 0.8 Hz), but a significant depression of activity at post-ischemic day 6 (1.84±0.3 Hz) when compared to the activities of non-ischemic control animal. Ischemia significantly (correlation coefficient ＜0.6) increased correlative firings among simultaneously recorded neurons, which were prominent especially during post-ischemic days 1, 2 and 6. Although the numbers of spontaneously active neurons recorded from control group varied within normal range during the experimental period, those from ischemic group changed in post-ischemic time-dependent manner. Temporal changes of the number of cells recorded per animal between control group and ischemic group were also significantly different (p = 0.0084, t = 3.271, df = 10). Cresyl violet staining indicated significant loss of CA1 cells at post-ischemic day 7. Overall, we showed post-ischemic time-dependent, differential changes of three characteristics, including spontaneous activity, network relationship and excitability of CA1 cells, suggesting sustained neural functions. Thus, histological observation of CA1 cell death till post-ischemic day 7 may not represent actual neuronal death.
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KEYWORD
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Transient ischemia, Hippocampal CA1 cells, Temporal activity change, Correlative firing
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