Expression of c-fos and fos-B proteins following transient forebrain ischemia: effect of hypothermia.
Immediate early genes are induced by transient global ischemia. Using immunohistochemistry we studied the effect of intraischemic hypothermia (30 degrees C) on the expression of c-fos and fos-B proteins following 10 min forebrain ischemia in the gerbil. Postischemia (PI) periods of 1 hour (h), 6 h, 1 day (d) and 2 d and nonischemic controls were examined in normothermic and hypothermic brains. In normothermic ischemic brains, marked expression of c-fos occurred in the dentate gyrus after 1 h PI which extended to CA2-4 regions by 6 h. Hypothermia hastened the time course of c-fos expression as it was expressed simultaneously in the dentate gyrus as well as CA2-4 regions after only 1 h, and by 6 h the expression remained only in the CA2-4 regions and not the dentate gyrus in hypothermic ischemic brains. There was no difference in its expression between normothermic and hypothermic brains in the 1 d and 2 d PI animals. Somewhat similar changes were noted in fos-B expression. In normothermic ischemic brains fos-B was induced in the dentate gyrus by 1 h PI, and by 6 h it extended to involve CA1-4 cells. The hypothermic ischemic brains showed faster induction of fos-B so that the dentate gyrus as well as CA1-4 regions were immunopositive at 1 h PI. There was no difference in its expression between normothermic and hypothermic brains in the subsequent PI periods of 6 h, 1 d and 2 d. The shift towards faster sequential induction of these genes by hypothermia in ischemic brains may be indicative of preservation of or faster recovery of mechanisms involved in intracellular signalling.
Kumar
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Department of Pathology, Michigan State University, East Lansing 48824, USA. kumar@pathology.cvm.msu.edu
Wu
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Evans
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D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D004195:Disease Models, Animal; D017781:Genes, Immediate-Early / Q000276:immunology; D005849:Gerbillinae; D007035:Hypothermia / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*
D016760:Proto-Oncogene Proteins c-fos