Abstract
The olfactory bulb (OB) is a highly plastic region of the adult mammalian brain characterized by continuous integration of inhibitory interneurons of the granule (GC) and periglomerular cell (PGC) types. Adult-generated OB interneurons are selected to survive in an experience-dependent way but the mechanisms that mediate the effects of experience on OB neurogenesis are unknown. Here we focus on the new-generated PGC population which is composed by multiple subtypes. Using paradigms of olfactory enrichment and/or deprivation combined to BrdU injections and quantitative confocal immunohistochemical analyses, we studied the effects of olfactory experience on adult-generated PGCs at different survival time and compared PGC to GC modulation. We show that olfactory enrichment similarly influences PGCs and GCs, increasing survival of newborn cells and transiently modulating GAD67 and plasticity-related molecules expression. However, PGC maturation appears to be delayed compared to GCs, reflecting a different temporal dynamic of adult generated olfactory interneuron integration. Moreover, olfactory enrichment or deprivation do not selectively modulate the survival of specific PGC phenotypes, supporting the idea that the integration rate of distinct PGC subtypes is independent from olfactory experience.
Highlights
Different forms of plasticity, ranging from molecular, synaptic or morphological changes in individual cells to neurogenesis persist in the adult mammalian brain
Most of the studies have been focused on granule cell (GC) integration, whereas few data are available on periglomerular cell (PGC) which incorporate into the glomerular layer (GL)
We initially investigated whether olfactory enrichment influences survival of new-generated PGCs at different time points
Summary
Different forms of plasticity, ranging from molecular, synaptic or morphological changes in individual cells to neurogenesis persist in the adult mammalian brain. The dentate gyrus of the hippocampus and the olfactory bulb (OB) represent the two main regions in which new neurons are continuously generated and integrated in adulthood [1,2]. Neurogenesis in these systems has been demonstrated to be modulated by experience and correlated to learning and memory functions, suggesting that continual addition of new neurons in adult might be crucial for the processing of new informations in response to a complex changing environment [3]. Experience influences the survival of newborn neurons in the OB, and a critical period when their survival is determined in an experience-dependent manner has been identified [13], but the mechanisms underlying this process are still largely unknown
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