MATERNAL INFLUENCE ON THE EARLY POSTNATAL DEVELOPMENT IN OXYS RATS

Maternal environment is critically important for offspring health. Mother can contribute to offspring development during gestation and suckling periods. Variations in maternal environment may affect the developing brain, hippocampus in particular. This study addresses relative contribution of the maternal environment to neonatal growth and neurodevelopment, as well as to the neuronal density in hippocampus and prefrontal cortex in senescence-accelerated OXYS rats. Preimplantation embryos were transferred from OXYS rats to different recipient dams: either Wistar rats or F1 hybrids of the Sprague-Dawley and tame gray rats. Our results showed that neonatal development in OXYS offspring was accelerated if embryo transfer was performed, but the effects depended on the genotype of foster mother. OXYS pups born and fostered by the hybrid mothers were heavier, opened their eyes earlier, and demonstrated faster neurodevelopment during neonatal period, as was confirmed by higher percentage of successfully performed cliff avoidance and negative geotactic reactions. Moreover, these pups exhibited a reduced neuronal density in CA1, CA3, and the DG hippocampal areas as compared with naturally born OXYS rats. OXYS rat pups born and fostered by Wistar mothers showed faster posture maturation, opened their eyes earlier and exhibited lower neuronal density in CA3 area of hippocampus compared with controls. Moreover, these pups demonstrated a higher percentage of successfully performed negative geotactic reaction on day 10 of their life. To conclude, the replacement of senescence-accelerated OXYS mothers with any nonsenescence-accelerated recipient mothers led to faster neurodevelopment and hippocampus maturation in offspring.