Effects of perinatal stress on the emotion-related behavior of the adolescent mouse.

We examined the effects of perinatal stress on the emotion-related behavior of the mouse during their adolescent period. Firstly, we applied the sound noise and/or the forced swim stress to the maternal pregnant mice in the pregnant mice at 10 to 18 d gestation. The stress applied during the fetal period did affect neither the spontaneous locomotor activity of the offspring mice in a new environment at an age of 4 weeks, nor those sound-induced changes in the locomotor activity. Secondly, we applied the stress to the neonatal mouse during the late lactation period, 14 to 18 d after birth. The mice that underwent the forced swim stress accompanied by the sound noise stress showed a significant reduction of the locomotor activity. On the other hand, the mice that underwent the forced swim stress during the lactation period showed a significant increase in the locomotor activity after the stimulation by the sound noise. Lastly, we applied the stress to the neonatal mouse immediately after the weaning period, 21 to 25 d after birth. The spontaneous locomotor activity of the mice was not changed compared to that of the non-stressed group. Thus, it was found that the stress applied to the mice during the lactation period, thought to be the critical period of mouse brain development, selectively influenced the emotion-related behavior in the subsequent adolescent period. These results suggested that second postnatal week may be the critical period for establishing proper behavioral responses to emotional stress in the adolescent mouse.