The effects of adrenal steroids and excitatory input on neuronal birth and survival.

The dentate gyrus of the rat forms in three developmental phases, each of which is characterized by neuronal birth, migration and death. Recent evidence indicates that adrenal steroids regulate neuronal birth, death, and possibly migration throughout the life of the animal. However, the observation that very few neuroblasts in the developing or adult dentate gyrus express adrenal steroid receptors suggests that the effects of adrenal steroid manipulations on neurogenesis are indirect. Additional evidence indicates that NMDA receptor activation regulates neuronal birth and death in this brain region presenting the possibility that adrenal steroids influence these processes through direct actions on excitatory afferents. Future studies will address this possibility.