Novelty-seeking behavior predicts vulnerability in a rodent model of depression

Physiol Behav. 2011 May 3;103(2):210-6. doi: 10.1016/j.physbeh.2011.02.001. Epub 2011 Feb 12.


Background: The onset of major depressive disorder is likely precipitated by a combination of heredity and life stress. The present study tested the hypothesis that rats selectively bred on a trait related to emotional reactivity would show differential susceptibility or resilience to the development of depression-like signs in response to chronic mild variable intermittent stress (CMS).

Methods: Male Sprague-Dawley rats that were bred based on the trait of either high or low locomotor activity in response to a novel environment were exposed to 4 weeks of CMS or control conditions. Changes in hedonic behavior were assessed using weekly sucrose preference tests and anxiety-like behavior was evaluated using the novelty-suppressed feeding test.

Results: During 4 weeks of CMS, bred low responder (bLR) rats became anhedonic at a faster rate and to a larger degree than bred high responder (bHR) rats, based on weekly sucrose preference tests. Measures of anxiety-like behavior in the novelty-suppressed feeding test were also significantly increased in the CMS-exposed bLR rats, though no differences were observed between CMS-exposed bHR rats and their unstressed controls.

Conclusions: These findings present further evidence that increased emotional reactivity is an important factor in stress susceptibility and the etiology of mood disorders, and that bHR and bLR rats provide a model of resistance or vulnerability to stress-induced depression. Furthermore, exposing bHR and bLR rats to CMS provides an excellent way to study the interaction of genetic and environmental factors in the development of depression-like behavior.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anxiety / complications
  • Anxiety / genetics
  • Anxiety / psychology
  • Depression / complications
  • Depression / genetics
  • Depression / psychology*
  • Disease Models, Animal*
  • Exploratory Behavior*
  • Feeding Behavior / psychology
  • Food Preferences / psychology*
  • Genetic Predisposition to Disease / genetics
  • Genetic Predisposition to Disease / psychology*
  • Male
  • Motor Activity / genetics*
  • Phenotype
  • Quantitative Trait, Heritable
  • Rats
  • Rats, Sprague-Dawley
  • Stress, Psychological / complications
  • Stress, Psychological / genetics
  • Stress, Psychological / psychology*