Early life chronic stress causes anxiety, aggression in adulthood

Hostile environment -- chronic stress -- in adolescence disturbs psycho-emotional state and social behaviors of animals in adult life.
By Alex Cukan  |  March 27, 2014 at 2:45 PM
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COLD SPRING HARBOR, N.Y., March 27 (UPI) -- A hostile environment in adolescence disturbs the psycho-emotional state and social behaviors of animals in adult life.

Grigori Enikolopov of Cold Spring Harbor Laboratory said his experiments were designed to assess the impacts of social stress upon adolescent mice, both at the time they are experienced and during adulthood.

The tests began with 1-month-old male mice -- the equivalent of human adolescents -- each placed for two weeks in a cage shared with an aggressive adult male. The animals were separated by a transparent perforated partition, but the young males were exposed daily to short attacks by the adult males, which create social-defeat stress in young mice.

The study, published in the journal Plos One, found chronic social defeat in young mice induced high levels of anxiety, helplessness, diminished social interaction and diminished ability to communicate with other young animals.

However, another group of young mice also exposed to social stress was then placed for several weeks in an unstressful environment. Following this respite these mice -- now old enough to be considered adults -- were tested. In this group, most of the behaviors impacted by social defeat returned to normal.

"This shows that young mice, exposed to adult aggressors, were largely resilient biologically and behaviorally," Enikolopov said in a statement.
But in these resilient mice, the researchers measured two latent impacts. These adult mice were abnormally anxious and were observed to be more aggressive in their social interactions.

"The exposure to a hostile environment during their adolescence had profound consequences in terms of emotional state and the ability to interact with peers," Enikolopov observed.

[Cold Spring Harbor Laboratory]

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