Reconceptualizing Adult Neurogenesis: Role for Sphingosine-1-Phosphate and Fibroblast Growth Factor-1 in Co-Ordinating Astrocyte-Neuronal Precursor Interactions

Despite the powerful induction of neurogenesis by sphingosine-1-phosphate (S1P), its study in the role of adult neurogenesis has been relatively neglected. S1P, via its differential effects at different S1P receptor subtypes, is a significant determinant of neuronal precursor/stem cell and astrocyte cellular organization. The variations in neurogenesis, classically modelled via the interactions of phosphatase and tensin homolog and Notch, are intimately associated with the co-ordinated regulation of S1P and fibroblast growth factor-1. Incorporating S1P better explains the plasticity and cellular variations in astrocytes and progenitors as well as their interactions. This has treatment implications for both inducing and inhibiting neurogenesis, in conditions such as depression and macrocephaly associated autistic spectrum disorders respectively. Incorporating S1P and fibroblast growth factor-1 also provides a framework for conceptualizing the impact of peripheral inflammation, central inflammation, redox status and medication effects on neurogenesis, as well as future treatment targets.