Radiation sensitivity of glial cells in primary culture

Primary cultures from newborn mouse brain were subjected to ionizing radiation to determine the sensitivity of galactocerebroside-positive oligodendrocytes and A2B5-positive progenitor cells during development. The radiosensitivity or D0 of the 2 cell populations was determined by measuring the fraction of surviving cells after various doses of x-rays. When the cultures were exposed to a single dose of x-rays at 6 days, oligodendrocytes showed a D0 of 1.4 Gy, and A2B5-positive cells a D0 of 4.5 Gy. When the cultures were exposed to a single dose of x-rays at 12 days, oligodendrocytes showed a D0 of 4.4 Gy, indicating that they have become more radioresistant. Cultures exposed to a dose of 1.5 Gy and monitored from 9 h to 2 weeks after irradiation showed a reduced but constant number of galactocerebroside-positive cells at all time points. Since galactocerebroside-positive oligodendrocytes are non-dividing or slowly dividing cells, the radiosensitivity of young oligodendrocytes was attributed to interphase cell death. These results indicate that young differentiated oligodendrocytes are more radiosensitive than other glial cell types, and that there is no significant replacement of lost oligodendrocytes either through proliferation or through differentiation of progenitors after irradiation in the culture system.