An Overview of Nicotinic Cholinergic System Signaling in Neurogenesis.

The production of new neurons continues in the adult mammalian brain because of the sustained proliferation and differentiation of neural stem cells (NSCs) in neurogenic regions. The subventricular zone (SVZ), lining the lateral ventricle, and the subgranular zone (SGZ), which is in the dentate gyrus (DG) of the hippocampus, are the central regions of neurogenesis in the brain. Neurogenesis brings great hope for repairing a damaged brain and motivates researchers to detect the controlling signals of this process. Neurogenesis is regulated by intracellular and extracellular mechanisms that are influenced by neurogenic microenvironments. Recent experimental evidence suggests that the cholinergic system and nicotinic acetylcholine receptors (nAChRs) can directly regulate postnatal neurogenesis via specific mechanisms in these regions. In this review, we outline the cholinergic projections to the neurogenic niches and explain how the cholinergic system may regulate the formation of new neurons. We also discuss the intrinsic signaling pathways by which this system affects neurogenesis.