Effects of acute maternal-filial separation on posterior maternal behavior in mice

Abstract

Maternal behavior ensures offspring’s survival, until the progeny arrives to sexual maturity. This behavior is regulated by the socio-sexual brain, an interconnected neural network that regulates social behaviors. Different factors, like sensorial stimuli, hormones, experience or environmental factors can influence in the activity of this neural network to induce performance of maternal behavior. Among environmental factors, stress might have important effects in several physiological factors as well in behavior. Maternal-filial separation is known to cause an intense stress in pups which is the cause of severe neuropsychiatric problems. However, the effects of maternalfilial separation on the mother have not been properly studied, even if it might also be a stressful event for her. The goal of the present study is to analyze the effect of a 3-hour episode of acute maternal-filial separation (postpartum day 2) on three relevant aspects (experiments 1- 3) of maternal behavior: maternal aggression, maternal motivation and maternal care. In all three experiments we compare the behavioral performance of two groups of dams, separated and non-separated controls. Separated mothers attack faster to castrated males than non-separated controls, thus suggesting that separation stress increases maternal aggression. However, separation from pups shows no effect on maternal motivation. Concerning maternal care, our results indicate that separated mothers spend less time “on nest” and retrieve the pups before as compared to non-separated controls. These results suggest that mothers undergoing pup separation-induced stress are more anxious and consequently exhibit a more protective maternal style and an increased aggressiveness.