Behavioral effects in adolescence and early adulthood in two length models of maternal separation in male rats.

Maternal separation (MS) is an extensively used early life stress model. There is some variability in the MS lengths used. Maternal separation leads to emotional and behavioral alterations such as anxiety, despair, or memory problems. We performed MS in Wistar rats with two length models from postnatal day 1 until day 10 and from postnatal day 1 until day 21 during 4h per day in both groups. We performed a test battery of a wide range of behaviors to measure anxiety, despair, prepulse inhibition, recognition memory, and associative memory both in adolescent and adult subjects. We found that the longer model leads to anxious behavior and impairs recognition in adolescence and adulthood whereas the shorter one deteriorates associative/emotional learning only in adolescence and protects against anhedonic-like behaviors. In our opinion, these results can be explained by the fact that different lengths lead to different profiles: the longer one is an anxious profile, whereas the shorter one is more impulsive.