Radiation-induced apoptosis of oligodendrocytes in vitro.

It has been suggested that glial cells and/or their progenitors are the primary target cells for radiation-induced demyelination. Cultures of terminally differentiated oligodendrocytes, immature oligodendrocytes, and O-2A progenitor cells were generated from the cerebral cortex and spinal cord of perinatal rat pups. Irradiation of cultures of terminally differentiated oligodendrocytes resulted in a significant increase in the percentage of apoptotic cells from 15% in control to 30% in irradiated samples, with the maximum increase induced by 10 Gy. This increase in apoptosis could be observed by 1 h after irradiation with the maximum level reached at 3-6 h. Apoptotic cells were not detected before or after irradiation of cultures of O-2A progenitor cells or immature oligodendrocytes. These data suggest that radiation-induced apoptosis of terminally differentiated oligodendrocytes may be involved in early demyelination.