Cognitive deficits in the rat chronic mild stress model for depression: relation to anhedonic-like responses

Behav Brain Res. 2009 Mar 2;198(1):136-41. doi: 10.1016/j.bbr.2008.10.039. Epub 2008 Nov 8.

Abstract

The chronic mild stress (CMS) protocol is widely used to evoke depressive-like behaviours in laboratory rats. The aim of the present study was to examine the effects of chronic stress on cognitive performance. About 70% of rats exposed to 7 weeks of chronic mild stress showed a gradual reduction in consumption of a sucrose solution, indicating an anhedonic-like state. The remaining rats did not reduce their sucrose intake, but appeared resilient to the stress-induced effects on sucrose intake. Cognitive profiling of the CMS rats revealed that chronic stress had a negative effect on performance in the spontaneous alternation test, possibly reflecting a deficit in working memory. This effect was independent of whether the stressed rats were anhedonic-like or stress-resilient as measured by their sucrose intake. CMS did not influence performance in passive avoidance and auditory cued fear conditioning, however, in rats displaying an anhedonic-like profile, CMS increased freezing behaviour in contextual fear conditioning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Analysis of Variance
  • Animals
  • Avoidance Learning / physiology
  • Body Weight / physiology
  • Cognition / physiology*
  • Conditioning, Classical / physiology
  • Cues
  • Depression / physiopathology*
  • Disease Models, Animal
  • Exploratory Behavior / physiology
  • Fear / physiology
  • Fear / psychology
  • Feeding Behavior / physiology
  • Feeding Behavior / psychology*
  • Freezing Reaction, Cataleptic / physiology
  • Male
  • Memory / physiology*
  • Movement / physiology
  • Rats
  • Rats, Wistar
  • Stress, Physiological*
  • Sucrose / administration & dosage

Substances

  • Sucrose