Microtubule-associated protein 2 expressing COS7 cells are resistant to argyrophilia under oxygen- and glucose-free condition

Argyrophil III silver impregnation is a very sensitive method to detec t the early damage to neurons following brain ischemia. The argyrophil III staining and microtubule-associated protein 2 (MAP2) immunocytochemistry were performed on PC12D cells and MAP2C cDNA-transfected COS7 cells to detect the changes cytoskeletal proteins (microtubules/MAP2). After exposing these cells to simulated ischemic condition (oxygen and/or glucose free), the correlation between the appearance of the argyrophilia and the disappearance of MAP2 was investigated. The PC12D cells expressed very low MAP2 and became argyrophilic very easily depending on the degree of the ischmeia-like insult, whereas MAP2C cDNA-transfected COS7 cells expressed a higher level of MAP2C and were resistant to argyrophilia, although the diameter of their immunoreactive processes became thinner. Thus, when MAP2C is expressed at a higher level, cells became resistant to argyrophilia, suggesting a correlation between the argyrophilia and the damage on microtubules and MAPs.