Apoptotic neuron death in rat substantia nigra induced by striatal excitotoxic injury is developmentally dependent.

We have previously observed that an axon-sparing lesion of the striatum during development is associated with an induction of apoptotic cell death in the substantia nigra (SN). We have postulated that the induced death is due to a loss of striatum-derived trophic support. In other paradigms of neural development, it is often found that a need for trophic support is primarily observed only during a critical development period. We have therefore examined the time course for early striatal lesion to induce cell death in substantia nigra. We find that induction of apoptotic cell death is largely restricted to the first 2 postnatal weeks. After that time, induction of death in SN pars compacta abates. In SN pars reticulata, apoptotic death also abates, but by postnatal day 28, a non-apoptotic morphology of death appears. Thus, induced apoptotic death in SN is restricted to a critical developmental period.