[Neurogenesis in the pathologies of the nervous system]

Neural stem cells (NSCs) are the self-renewing, multipotent cells that generate neurons, astrocytes, and oligodendrocytes in the nervous system. Contrary to the long-held dogma, neurogenesis occurs in discrete areas of the adult brain, the hippocampus and the subventricular zone, and NSCs reside in the adult central nervous system. Recent studies have shown that neurogenesis is increased in the diseased brains, after strokes and traumatic brain injuries, and that new neuronal cells are generated at the sites of injury, where they replace some of the degenerated nerve cells. Thus, the central nervous system has the capacity to regenerate after injury. The contribution and function of the increased neurogenesis in the pathologies of the nervous system remain to be understood. The increased hippocampal neurogenesis may play a role in neuroadaptation, such as in memory troubles and depression, associated with these pathologies. The increased neurogenesis at the sites of injury may represent an attempt by the central nervous system to regenerate itself after injury. Newly generated neuronal cells at the sites of injury originate from the subventricular zone. Hence, strategies that would promote neurogenesis in the subventricular zone may promote neuronal repair after injury of the nervous system. In this manuscript, we will review the studies on neurogenesis in the pathologies of the nervous system.