Natural variations in postpartum maternal care in inbred and outbred mice

Abstract

The role of maternal care in mediating variation in offspring phenotype has been examined in the rat and demonstrates that mother-infant interactions are critical for inducing long-term changes in behavior. Though phenotypic differences between mice strains are often attributed to genetic factors, the influence of early maternal environment has not been extensively explored. To understand maternal influence on phenotype in mice, we must first explore the nature of differences in behavior. In the present study, we examine aspects of maternal care differentiating mice strains and explore the relationship between postpartum behavior and measures obtained by a standard test of maternal responsivity (Retrieval Test). We compared inbred 129Sv (n = 25), C57BL/6J (n = 23), and outbred Swiss (n = 23) lactating female mice. Swiss females had shorter latencies to retrieve and crouch over pups (P < .01), whereas 129Sv females had shorter latencies to nestbuild (P