Ischemia-related changes in galanin expression in the dentate hilar region after transient forebrain ischemia in gerbils

초록

Although galanin (GAL) protects hippocampal neurons from ischemic damage, no study has examined ischemia-related changes in endogenous GAL in the hippocampal dentate gyrus. We investigated the chronological changes of GAL, well-known as the potassium channel opener, expression in the dentate gyrus at various times after 5 min of transient forebrain ischemia in gerbils. A few GAL-immunoreactive (IR) neurons were found in the polymorphic layer of the sham-operated group. Three hours after ischemia-reperfusion, the pattern of GAL immunoreactivity was similar to that of the sham-operated group and the number of GAL-IR neurons and immunoreactivity were highest 12 h after ischemic insult. At this time, GAL-IR neurons in the polymorphic layer showed strong GAL immunoreactivity. Thereafter, GAL-IR neurons and immunoreactivity significantly decreased in the dentate hilar region. Four days after ischemic insult, GAL-IR neurons were not detectable. In addition, the results of a Western blot study showed a pattern of GAL expression similar to the immunohistochemical changes. GAL protein content also was highest 12 h after ischemia. In conclusion, the increased expression of endogenous GAL in the dentate gyrus after ischemia is related to response to the ischemic damage.

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