Microtubule-associated protein 2 as an early indicator of ischemia-induced neurodegeneration in the gerbil forebrain.
Microtubule-associated protein 2 (MAP-2) was studied in the gerbil hippocampus and striatum after transient ischemia. Western immunoblot analysis shows that there is a significant decrease of MAP-2 in the dorsolateral sector of the striatum and a slight decrease of MAP-2 in the CA1 region of the hippocampus 6-12 h after ischemia in the gerbil forebrain. The immunohistochemical staining pattern of MAP-2 in these two regions also shows a loss of immunostaining of MAP-2. In particular, a beaded MAP-2 immunostaining pattern at the apical dendritic region of the CA1 neurons of the hippocampus was found within 12 h after ischemia compared with the smooth dendritic immunostaining of MAP-2 in normal CA1 neurons. In vitro assays of MAP-2 degradation suggest that dendritic loss of immunoreactivity after ischemia seen on western blots may be due to calpain I degradation of MAP-2. Loss of MAP-2 in both the striatum and hippocampus was found to occur earlier than spectrin degradation by western blot analysis. These results suggest that loss of MAP-2 may participate in the initial phase of neuronal dysfunction and that dendritic breakdown may be a first sign of neurodegeneration.
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Department of Physiology and Biophysics, Hahnemann University, Philadelphia, Pennsylvania 19102.
Lin
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D000818:Animals; D002154:Calpain / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D005849:Gerbillinae; D006624:Hippocampus / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D007700:Kinetics; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009410:Nerve Degeneration; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D016548:Prosencephalon / Q000378:metabolism; D013049:Spectrin / Q000378:metabolism
D008869:Microtubule-Associated Proteins; D013049:Spectrin; D004533:Egtazic Acid; D002154:Calpain