Pre-weaning paternal deprivation impairs social recognition and alters hippocampal neurogenesis and spine density in adult mandarin voles

Disruption of the early social environment, such as maternal separation or early deprivation, can impair cognitive function, alter offspring neurogenesis and restrict dendritic architecture in the hippocampus. However, whether paternal deprivation during the pre-weaning period affects adult neurogenesis, synaptogenesis and social recognition remains unclear in monogamous species. In the present study, mandarin vole (Microtus mandarinus) pups were deprived of fathers during postnatal day 14-21. Then social recognition, hippocampal neurogenesis and spine density, basal levels of corticosterone (CORT) and oxytocin (OT) were examined at adulthood. We found that paternal deprivation impaired social recognition at adulthood. In addition, paternal deprivation significantly reduced 5-bromo-2-deoxyuidine (BrdU) immunoreactive cells (p < 0.01) and Brdu/Neun-labeled cells (p < 0.05) in the dentate gyrus compared to those of biparental care group in females, but not in males (p > 0.05). Meanwhile, paternal deprivation group had fewer double-staining cells with BrdU and the immature neuron marker doublecortin than biparental care group both in male (p < 0.01) and female (p < 0.05) voles. Paternal deprivation also decreased the number of dendritic spines in the dentate gyrus at adulthood. Paternal deprivation reduced circulating levels of OT and increased CORT only in females. These results demonstrated that impaired social recognition induced by paternal deprivation may be linked with alterations in neurogenesis and spine density of the dentate gyrus and levels of OT and CORT, especially in females.