Qualitative and quantitative estimates of apoptosis from birth to senescence in the rat brain

Apoptosis is crucial for proper development of the CNS, wherein a significa nt percentage of all central neurons produced during early ontogeny die by apoptosis. To characterize the pattern of developmental programmed cell dea th, we assayed rat brainstem, neocortex, hippocampus, and cerebellum from b irth through senescence. Quantitatively, using an ELISA for oligonucleosoma l DNA fragments, we demonstrated that PND1 brainstem, neocortex, and hippoc ampus have the highest levels of fragmented DNA compared to older ages. Cer ebellum displayed a large peak at PND10 and a smaller peak at PND21, Low le vels were observed throughout adulthood and into senescence, which was corr oborated qualitatively by agarose gel and TUNEL data. These data provide a temporal and regional baseline for further studies of the effects of pertur bations of cell death during neural development. Quantitative and qualitati ve changes in these regional profiles of apoptosis due to environmental ins ults during early ontogeny may alter neuron number and function later in li fe.