Nest Building Behavior of Mouse and Effect of Ovarian Hormones on the Behavior

The correlation between nest constructing behavior and stages of oestrus cycle and pregnancy and effect of ovarian hormone treatment on the behavior were studied in mice. Nest constructing behavior was sevearly affected by the circulating level of sexual hormones. Metoestrus animals displayed a significant increase of nest preparing activity compared with the activity of oestrus and proestrus animals. In pregnant mice, the nest weight started to increase markedly from day 4, reached a peak level on day 7 and decreased from day 14 of pregnancy. Nest preparation was evoked by exogenous administration of ovarian hormones in either intact or ovariectomized mice. The largest nest was observed in animals treated with 1 mg progesterone and 20 ng estradiol daily and the animal treated with progesterone alone followed. No induction of nest building was observed in animals treated with progesterone and 100 ng estradiol and estradiol along. Nest preparation in mouse may be facilitated by a synergim between small amount of estrogen and large amount of progesterone.Article信州大学農学部紀要. 32(1-2): 23-31 (1995)journal articl