Doublecortin-immunoreactive immature neurons in the olfactory system across pregnancy and lactation in female mice
Motherhood is a critical period modulating behavioural changes to favour survival in mammals. In mice, olfaction is a key driver of social behaviours, and adult neurogenesis in the olfactory bulb is modulated at this stage, contributing to pup recognition. However, whether motherhood would also promote changes in the population of immature neurons of the piriform cortex is unknown. To investigate this question, we analysed the expression of doublecortin (DCX), a marker of immature neurons, in prepubescent vs young adults, in virgin vs pregnant and in pup-sensitized virgins vs lactating female mice. We found that the density of DCX cells sharply decreased in the piriform cortex with age, but pregnancy and lactation failed to significantly alter the density of these cells. To further analyse how motherhood could affect DCX-ir cells, we co-labelled DCX cells with NeuN, an archetypical marker of mature neurons. We did not find significant differences in the percentage of double-labelled cells nor in features related to maturation like number of neurites or main diameter in lactating dams as compared to pup-sensitized virgin females. Our results suggest that the first pregnancy does not significantly affect the differentiation of immature neurons of the piriform cortex.