Effects of the Maternal Environment on Early Postnatal Development in OXYS Rats

Changes in the environment of the embryo during intrauterine development can affect the postnatal ontogeny of offspring. We report here studies using OXYS rats, which provide a model of premature aging, addressing the influence of the maternal environment on the growth of neonates and the development of their reflexes, as well as prefrontal cortex and hippocampus neuron density. Preimplantation embryos were transferred from OXYS rats to different female recipients: either Wistar rats or F1 hybrids between Sprague–Dawley females and tame gray rats. Our results showed that, in general, the neonatal development of OXYS offspring obtained by embryo transfer (ET) was accelerated, though this was influenced by the genotype of the recipient female. OXYS rat pups born to and reared by hybrid mothers had greater body weight, opened their eyes earlier, and demonstrated accelerated maturation of neonatal reflexes as demonstrated in the cliff avoidance and negative geotaxis reactions. Moreover, these offspring had lower neuron densities in the hippocampal fields CA1 and CA3 and the dentate gyrus (DG) as compared with the OXYS control group (no ET). OXYS rats born to and raised by Wistar mothers showed earlier mature posture and eye opening, and also had lower neuron density in the CA3 region of the hippocampus than controls. In addition, these offspring displayed negative geotaxis reactions at an earlier stage of neonatal ontogeny than controls. In conclusion, it should be noted that the replacement of OXYS mothers with recipient mothers without a genetic predisposition to premature aging led to faster maturation of neonatal reflexes and a change in the density of neurons in the hippocampus in the offspring.