Poster Presentation The International Congress of Neuroendocrinology 2014

Mouse pup retrieval and crouching behavior following social isolation in virgin male mice (#140)

Chitose Orikasa 1 , Kentaro Nagaoka 2 , Yasuhiko Kondo 3 , Yasuo Sakuma 4
  1. Nippon Medical School, Tokyo, Japan
  2. Tokyo Univ. Agri. Tech., Tokyo, Japan
  3. Teikyo Univ. of Sci., Tokyo, Japan
  4. Univ. Tokyo Health Sci., Tokyo, Japan

Maternal care is an indispensable element of reproduction in mammalian species that feed offspring by lactation. When pups are present, lactating females immediately initiate maternal cares, such as licking around anogenital area, pup retrieving to the nest, and crouching over pups. These behaviors are female specific and are considered as one of sexually dimorphic behavior. In male mammals, parental care was not so spontaneous. Indifference or overt aggression towards pups is mostly common in most strains of laboratory male mice. It has been reported in males that experience of mating followed by cohabitation with the gestated females suppresses infanticide and provokes males to be parental similar to lactating mother. Here, we report that sexually naïve male mice show parental behavior toward pups after social isolation. The isolation for 3 weeks, but not sufficient for a week, made male mice parental. The effect of social isolation was not restricted to adolescence of the aged 5 – 8 weeks old. It was also induced by that of postpubertal 8 – 11 weeks old. The effect of social isolation was blocked by social odors derived from an adjacent chamber, suggesting that olfactory cues of male conspecifics plays a key role in isolation-induced parental behavior in male mice. When virgin male mice encountered with pups at first sight, the males occasionally showed infanticide, no matter whether they were parental. Thus, such social isolation does not affect incidence of infanticide. This is the first demonstration of the facilitatory effect of social isolation on parental paternal behavior in sexually inexperienced male mice. We also showed a key role of olfactory cues that may develop a disinhibition of brain circuits regulating parental care in the male mice.