In situ end-labeling detects of DNA strand breaks associated with apoptosis in X knife treating rat C6 glioma

To investigate apoptosis in X knife treating rat C6 glioma by way of a novel technique, in situ end labeling. We scored apoptotic cell which was detected by this technique as positive nuclei by microscopic examination of paraffin sections made from the tumor specimens under the assistance of computer image handling and SAS statistical systems and observed as a classical “Ladder pattern” of oligonucleosome sized fragments character by DNA agarose gel electrophoresis. Microscopic analysis results showed that 15, 20 or 30 Gy groups displayed significantly apoptosis at 4 hour and 1 day after radiosurgery treatment compared to control and 40 Gy groups （P ＜0.01）. This result corresponds completely to DNA agarose gel electrophoresis, showing the “Ladder pattern” clearly within 1 day after SRS treatment in 15, 20 or 30 Gy groups, whereas the 40 Gy group was vaguely. The later group showed more necrosis than apoptosis. We find that this new technique has its unique preciseness to identify apoptotic cells and that it makes it easy to distinguish apoptotic cells from other cells. These results confirm that the apoptotic mode of cell death and necrosis may represent the response in this X knife treated rat C6 glioma model.