Immunohistological markers for staging neurogenesis in adult hippocampus.

Neurogenesis in the adult dentate gyrus (DG) of the hippocampus occurs constitutively throughout postnatal life, and the rate of neurogenesis within the DG can be altered under various physiological and pathophysiological conditions. Adult neurogenesis includes the process in which the division of a precursor cell takes place and the multi-step process (proliferation, differentiation, migration, targeting, and synaptic integration) that ends with the formation of a postmitotic functionally integrated new neuron. During specific time-frames of adult neurogenesis, various markers are expressed that correlate with the differentiation steps along the pathway from early progenitor cells to newly generated postmitotic neurons within the DG. Markers that are currently widely used for the investigation of adult hippocampal neurogenesis are: glial fibrillary acidic protein, nestin, Pax6, NeuroD, PSA-NCAM, doublecortin, TUC-4, Tuj-1, and calretinin. The discovery and development of specific markers that allow the time-course and fate of neurons to be followed during adult neurogenesis in a detailed and precise fashion are not only helpful for gaining further insights into the genesis of new neurons in the hippocampus, but also might be applicable to the development of strategies for therapeutic interventions.