| Abstract No.: | A-A1017 |
| Country: | Canada |
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| Title: | CONSEQUENCIES OF IMPAIRED OLFACTORY BULB NEUROGENESIS IN THE ADULT MICE |
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| Authors/Affiliations: | 1 Vincent Breton*; 1 Morgane Lemasson; 1 Modesto Peralta; 1 Daniel Côté; 1 Armen Saghatelyan;
1 Centre de recherche de l’Université Laval à Robert-Giffard, Québec, QC, Canada
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| Content: | Newly born neurons are continuously renewed in the main olfactory bulb (OB) during the entire lifespan of mammals. Neuronal precursors are generated in the subventricular zone (SVZ) and migrate via the rostral migratory stream (RMS) to reach the OB where they differentiate into mature interneurons, granule and periglomerular cells. Despite extensive investigations of the molecular and cellular mechanisms orchestrating adult OB neurogenesis, we still know very little about functional implications of new neurons in the adult OB neuronal circuitry. To better understand the functional role of newly generated interneurons in the adult OB, we decided to ablate generation of neuronal precursors in the SVZ via infusion of an anti-mitotic drug (ARAc) into the lateral ventricle of adult mice. 28 days of AraC infusion drastically reduced the number of migrating cells (doublecortin+) arriving in the OB. Consequently, electrophysiological recordings from the mitral cells, the main target neurons receiving synaptic contacts from granule and periglomerular cells in the OB, showed a reduction in the frequency, but not the amplitude, of miniature inhibitory postsynaptic currents (mIPSCs). To elucidate the changes in the action potential- and glutamate-induced GABA release at the dendro-dendritic synapses between mitral and granule cells we analyzed the percentage of reduction of spontaneous postsynaptic currents (sPSCs) following application of TTX and kynurenic acid. Interestingly, this analysis revealed different contribution of action potential- and glutamate-induced GABA releases in the newly born as compared to the pre-established granule cells in the OB. Behavioral studies are in progress to demonstrate the role of adult neurogenesis in the olfactory functions. Together, our data suggest that newborn cells arriving on the olfactory bulb are essential for the normal functioning of the olfactory system.
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