Chronic mild stress paradigm as a rat model of depression: facts, artifacts, and future perspectives

T. Strekalova*, Y.Z. Liu, D. Kiselev, S. Khairuddin, J.L.Y. Chiu, J. Lam*, Y.S. Chan, D. Pavlov, A. Proshin, K.P. Lesch, D.C. Anthony, L.W. Lim*

*Corresponding author for this work

Research output: Contribution to journal(Systematic) Review article peer-review

Abstract

Rationale The chronic mild stress (CMS) paradigm was first described almost 40 years ago and has become a widely used model in the search for antidepressant drugs for major depression disorder (MDD). It has resulted in the publication of almost 1700 studies in rats alone. Under the original CMS procedure, the expression of an anhedonic response, a key symptom of depression, was seen as an essential feature of both the model and a depressive state. The prolonged exposure of rodents to unpredictable/uncontrollable mild stressors leads to a reduction in the intake of palatable liquids, behavioral despair, locomotor inhibition, anxiety-like changes, and vegetative (somatic) abnormalities. Many of the CMS studies do not report these patterns of behaviors, and they often fail to include consistent molecular, neuroanatomical, and physiological phenotypes of CMS-exposed animals. Objectives To critically review the CMS studies in rats so that conceptual and methodological flaws can be avoided in future studies. Results Analysis of the literature supports the validity of the CMS model and its impact on the field. However, further improvements could be achieved by (i) the stratification of animals into 'resilient' and 'susceptible' cohorts within the CMS animals, (ii) the use of more refined protocols in the sucrose test to mitigate physiological and physical artifacts, and (iii) the systematic evaluation of the non-specific effects of CMS and implementation of appropriate adjustments within the behavioral tests. Conclusions We propose methodological revisions and the use of more advanced behavioral tests to refine the rat CMS paradigm, which offers a valuable tool for developing new antidepressant medications.
Original languageEnglish
Pages (from-to)663-693
Number of pages31
JournalPsychopharmacology
Volume239
Issue number3
Early online date24 Jan 2022
DOIs
Publication statusPublished - Mar 2022

Keywords

  • Chronic mild stress (CMS)
  • Depression
  • Sucrose test
  • Anhedonia
  • Forced swimming
  • Open field
  • Inter-individual variability
  • Stress resilience
  • Rat
  • ANXIETY-LIKE BEHAVIOR
  • ANTIDEPRESSANT-LIKE ACTIVITY
  • MALE WISTAR RATS
  • FORCED-SWIM TEST
  • ANIMAL-MODELS
  • INDUCED ANHEDONIA
  • UNPREDICTABLE STRESS
  • SUCROSE CONSUMPTION
  • HEART-RATE
  • PREFRONTAL CORTEX

Fingerprint

Dive into the research topics of 'Chronic mild stress paradigm as a rat model of depression: facts, artifacts, and future perspectives'. Together they form a unique fingerprint.

Cite this