Increased Activity and Involvement of Caspase-3 in Radiation-Induced Apoptosis in Neural Cells Precursors from Developing Rat Brain

Using primary cultures of neural precursor cells of cortex from developing rat brain, we demonstrated the involvement of caspase-3 in the apoptotic process induced by gamma irradiation. The precursor nature of cells was confirmed by nestin and GFAP immunoreactivity and by the capacity of differentiation in neuronal and glial cells after 5 days in culture. Neural precursors were irradiated with single doses ranging from 0.1 to 4 Gy. Cellular death, determined 24 h post-irradiation (pi) was dose-dependent and the induction of apoptosis was confirmed by nuclear condensation, DNA fragmentation and hypodiploid DNA peak represented by the “sub G1” region. For the higher doses, apoptosis was evident after 4–6 h pi and increased during 24 h. Caspase-3 activity increased with doses and was maximal at 4–6 h pi with 3 Gy and remained similar with 4 Gy. The protection from radiation-induced apoptosis by caspase-3 inhibitor, zDEVD-fmk, confirmed that this enzyme is involved in the apoptotic mechanism in this system. The possibility of using this tissue culture system for studying the effects of ionizing radiation on morphological and molecular differentiation was considered.