Effects of small molecules on neurogenesis:Neuronal proliferation and differentiation

Neurons are believed to be non-proliferating cells.However,neuronal stem cells are still present in certain areas of the adult brain,although their proliferation diminishes with age.Just as with other cells,their proliferation and differentiation are modulated by various mechanisms.These mechanisms are foundational to the strategies developed to induce neuronal proliferation and differentiation,with potential therapeutic applications for neurodegenerative diseases.The most common among these diseases are Parkinson's disease and Alzheimer's disease,associated with the formation ofβ-amyloid(Aβ)aggregates which cause a reduction in the number of neurons.Compounds such as LiCl,4-aminothiazoles,Pregnenolone,ACEA,harmine,D2AAK1,methyl 3,4-dihydroxybenzoate,and shikonin may induce neuronal proliferation/differentiation through the activation of pathways:MAPK ERK,PI3K/AKT,NFκB,Wnt,BDNF,and NPAS3.Moreover,combinations of these compounds can potentially transform somatic cells into neurons.This transformation process involves the activation of neuron-specific transcription factors such as NEUROD1,NGN2,ASCL1,and SOX2,which subsequently leads to the transcription of downstream genes,culminating in the transformation of somatic cells into neurons.Neurodegenerative diseases are not the only conditions where inducing neuronal proliferation could be beneficial.Consequently,the impact of pro-proliferative compounds on neurons has also been researched in mouse models of Alzheimer's disease.