Puberty and motherhood promote region-specific maturation of doublecortin cells in olfactory circuits of mice

Abstract In mammalian females, both adolescence and motherhood are critical periods modulating behavioural changes to favour evolutionary survival. In mice, olfaction is a key driver of social behaviours, and adult neurogenesis in the olfactory bulb is an important form of neural plasticity underlying adequate behavioural responses towards conspecifics. In this study, we sought to investigate whether transition to adulthood and motherhood would affect the populations of immature neurons described in other areas of the olfactory system. To do so, we analysed the expression of doublecortin (DCX), a marker of immature neurons, and Ki67, a marker of proliferation, in the olfactory tubercle and piriform cortex of pre-pubertal and adult CD1 female mice. Our results revealed sustained proliferation of neuroblasts in the olfactory tubercle in both pre-pubertal and adult females, with Ki67 nuclei located in close apposition to clusters of DCX-immunoreactive cells. However, the density of DCX-immunoreactive cells in this area was not affected by either puberty, pregnancy, or lactation. In contrast, lactating females had significantly less DCX-immunoreactive cells than pup-sensitised virgin females at the piriform cortex, with a similar non-significant tendency observed in the group of pregnancy alone. This suggests that lactation can act on top of pregnancy to promote the maturation of these embryonically generated DCX-immunoreactive neurons at the piriform cortex. Our results expand our current knowledge on how motherhood remodels the brain and reveal the olfactory tubercle as an unexplored niche for adult neurogenesis.