Altered AOB neurogenesis and pheromonal induced response in Semaphorin7A knockout male mice.

In rodents, adult neurogenesis in the main (MOB) and accessory olfactory bulb (AOB) is modulated by experience and plays a critical role in odor learning and pheromonal induced social/sexual behaviour. New interneurons originate in the subventricular zone (SVZ) and in the rostral migratory stream (RMS), from stem/progenitor cells whose activity is controlled by a complex network of cellular/molecular interactions still largely unknown. By in situ hybridization and RT-PCR analysis on SVZ-derived selected progenitors, we demonstrate that Semaphorin7A (Sema7A) and its receptors plexinC1 and beta1-integrin are expressed by adult SVZ progenitors. Analysis of adult neurogenesis in Semaphorin7A knockout male mice revealed that the lack of Sema7A enhances progenitor proliferation and induces a transient increase in newborn cell integration in the AOB. PlexinC1 knock out elicited similar effects suggesting this receptor as the main candidate to mediate Sema7A function on adult neurogenesis. Interestingly, Sema7A ko male mice showed an altered response to male pheromones, both in term of neurogenesis and c-fos expression in adult generated interneurons, and in term of sexual preference behaviour. Overall, these data suggest Sema7A plays a role in the complex network of mechanisms underlying social/sexual interaction.