Expression of stathmin and SCG10 proteins in the olfactory neurogenesis during development and after lesion in the adulthood

Stathmin and SCG10 belong to a family of phosphoproteins associated to cell proliferation and differentiation. In the present study, we have analyzed immunocytochemically the distribution of these proteins during neurogenesis in the mouse olfactory system, from midgestation to adulthood. Data show that already at embryonic day 12, stathmin and SCG10 immunoreactivities were present in the olfactory and vomeronasal neurons, and their number increased greatly, colocalizing with neuronal specific tubulin, a marker of immature neurons. Later on up to adulthood, the distribution of stathmin and SCG10 became progressively restricted to a few immature receptor and chemosensory neurons. Significantly, in the olfactory epithelium, stathmin was seen in immature neurons and also in basal cells representing precursors of neuronal elements. Interestingly, before birth stathmin and SCG10 immunopositive cells were seen outside the olfactory epithelium, seemingly migrating toward the olfactory bulb. After regeneration in the adult following peripheral lesion of the olfactory epithelium, stathmin and SCG10 were again strongly expressed and generally colocalized with neuronal specific tubulin immunoreactivity. Overall these results indicate that stathmin and SCG10 are expressed in immature olfactory neurons as well as in the migrating cells generated from the olfactory epithelium, supporting the role of these proteins in neurogenesis and cell migration.