ИСТИНА

Maternal care during early life influences physiology and behavior of adult animals via epigenetic mechanisms. In particular, maternal deprivation of neonatal mice and rats has long-term dramatic impact on offspring development. Previously we revealed immediate and long-lasting adverse effects of repeated maternal deprivation (45 min daily on postnatal days (PND) 3–6) on physiology and behavior of 129Sv mice. In the present work, we investigated hormonal and behavioral factors which could cause these changes. We analyzed two early-life stress markers: pup ultrasonic vocalizations (USVs) rates on PND 3 & 6, and the levels of corticosterone in pups on PND 7. In addition, we examined maternal behavior in the home cage for 30 min before deprivation and for 30 min immediately after the reunion with the pups on PND 3 and 6. This allowed us to reveal the correspondence between distinct acoustic properties of different signal types and the types of maternal behavior. Maternal deprivation for 45 min/day from PND 3 to PND 6 resulted in changes in maternal behavior, which was accompanied by hormonal and behavioral stress response in 129Sv pups. Specifically, we found an increase in corticosterone levels and USV rates during deprivation in comparison with baseline levels and with non-deprived pups. It is important to emphasize that the elevation of corticosterone levels and USV rates showed no recovery to the baseline levels for 30 min after the reunion. In addition, the increase in USV rates from PND 3 to PND 6 was revealed in deprived pups, but not in non-deprived pups. Our results suggest that hormonal and behavioral responses described above might be the early-life predictors of the long-term adverse effects of repeated 45-min maternal deprivation on the development of 129Sv mice. Supported by RFBR Grant 16-34-00253