Effects of prenatal stress on development in mice: maturation and learning

Female CD-1 mice were stressed during the final week of gestation. Beginning 3 days after birth, until weaning, their pups were examined for eye opening, startle response, tooth eruption, surface righting, ability to cling to and climb an incline, tail pull reflex, rotation, linear movement and exploration. At 3 months of age, they were tested in a Morris Water Maze. Stressed animals were significantly lighter and shorter than non-stressed animals the first week after birth. By 3 days after birth, significantly fewer stressed animals could rotate or right themselves. By 6 days after birth, significantly fewer stressed animals could cling to or climb an inclined screen, or show the tail pull reflex. By 9 days of age, significantly fewer stressed animals had teeth. In contrast, by day 12 of age, significantly more stressed animals demonstrated exploratory behavior than did non-stressed animals. There were no sex differences in the ability of animals to perform these tasks at the same age. Stressed animals were significantly slower than non-stressed animals to reach the hidden platform in the water maze on all trials, and this difference was due to stressed females being slower to find the platform than non-stressed females, with no main effect of stress on males. This study supports and expands previous findings in rodents that prenatal stress can cause deficiencies in some early indices of physical maturation and also that these deficiencies can be continued into adulthood.