Emotional reactivity in mice, a case of nongenetic heredity?

Nongenetic heredity cases have been described in man, as well as in animals , and relationships between parents and offspring seem to play an important role in this transmission. In mice, mothering type could be nongenetically heritable by a latent learning close to mechanism. As mothering style clea rly influences emotional reactivity, this reactivity could be nongeneticall y transmitted over generations. To clarify this question, the mother's infl uence on adult offspring reactivity must be established (whatever its basis , genetic, social or other). Thus, two reciprocal F1 hybrids (CB6 from a BA LB/c mother and B6C from a C57BL/6 mother) have been compared using an etho logical analysis in animal tests of emotional reactivity such as the free e xploration paradigm and the light/dark box. First results show a sharp infl uence of the mother's strain and that suggests an effect of mothering style . The offspring from C57BL/6 mothers display less reactivity in the free ex ploration paradigm than the offspring from BALB/c mothers. In the light/dar k box, no difference has been found between the two hybrids. Moreover, the mother's influence is greater in males than in females. (C) 2001 Elsevier S cience Inc. All rights reserved.