Changes in presynaptic proteins, SNAP-25 and synaptophysin, in the hippocampal CA1 area in ischemic gerbils.
A general consensus exists that the presynaptic terminals in the hippocampal CA1 area are resistant to ischemic stress in spite of the loss of their target cells (CA1 pyramidal neurons). We have verified this by immunostaining and Western immunoblotting using the antibodies for presynaptic proteins, synaptosomal-associated protein of 25 kDa (SNAP-25) and synaptophysin in gerbils after bilateral carotid artery ligature. In the immunohistochemical analysis, decreases in SNAP-25 and synaptophysin immunoreactivities in the strata radiatum and oriens, especially around the apical dendrite of CA1 neurons, and disappearance of SNAP-25 immunoreactivity in the alveus were observed on day 2 after ischemia. On days 7 and 14, SNAP-25-positive granular materials were expressed in the CA1 area, and intense synaptophysin immunoreactivity around surviving CA1 neurons was observed. Western immunoblot analysis revealed significant decreases of SNAP-25 and synaptophysin (about 60% of control levels) on day 2, and then increase of their proteins (130--140% of control levels) on day 14. These results indicate that presynaptic degeneration occurs in the hippocampal CA1 area after ischemia, and it precedes the delayed neuronal death of CA1 neurons. The presynaptic terminal damage may be responsible for some pathological changes in ischemic brains.
Ishimaru
H
H
Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy. ishimaru_hirohisa@mail.tsumura.co.jp
Casamenti
F
F
Uéda
K
K
Maruyama
Y
Y
Pepeu
G
G
D000818:Animals; D000906:Antibodies; D015153:Blotting, Western; D002545:Brain Ischemia / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D005849:Gerbillinae; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000737:chemistry / Q000378:metabolism*; D016708:Synaptophysin / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25
D000906:Antibodies; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D016708:Synaptophysin; D050825:Synaptosomal-Associated Protein 25