An adverse rearing environment alters maternal responsiveness to infant ultrasonic vocalizations

Abstract

Rodent pups use a variety of ultrasonic vocalizations (USVs) to facilitate maternal care. Importantly, infant USV repertoires are dependent on both the age and early life experiences of the pups. We have shown that an adverse rearing environment modeled with the maternal separation (MS) paradigm alters caregiving behavior, but little is known about how pup USVs differentially elicit maternal attention. In the present study, maternal approach towards a vocalizing pup over a non-vocalizing pup was tested in a Y-maze apparatus at two developmental time points over the course of MS. At the postnatal day (P) 10, dams engaged in longer interaction times with the vocalizing pup compared to the non-vocalizing pup. This effect was modulated by rearing environment and the sex of the pup, with only MS dams spending more time with vocalizing male pups. As expected at P20, dams did not show a preference for either the vocalizing or non-vocalizing pups regardless of rearing environment, however, MS dams spent a greater amount of time in the center of the apparatus as compared to control dams, which can be interpreted as a measure of uncertainty and indecision. These effects are important considering the sex specific effects of MS exposure across all developmental stages. Our novel findings support the hypothesis that sex-specific pup-dam interactions may drive later life outcomes following adversity.