The conditioned stimulus elicits taste aversion but not sickness behavior in conditioned mice

Neuroimmunomodulation. 2010;17(5):325-32. doi: 10.1159/000292021. Epub 2010 Apr 17.


Objectives: This article extends previous reports on (i) elicitation of taste aversion after pairing a flavored beverage (saccharin solution) with a disease-provoking microbial product (lipopolysaccharide, LPS, or polyinosinic:polycytidylic acid, poly I:C); (ii) elicitation of sickness behavior (assessed as diminished ingestion of water and food) by the conditioned stimulus, and (iii) development of tolerance to those microbial products.

Methods: Mice of the CD1 strain were conditioned by pairing ingestion of 0.15% saccharin solution with injection of LPS (100 mug/mouse) or poly I:C (6 mg/kg). A few days later, some mice were offered saccharin solution and were injected with saline, whereas other mice were offered saccharin solution and were injected with the microbial product.

Results: Regardless of the nature of the unconditioned stimulus (LPS or poly I:C), (i) taste aversion to saccharin ensued, (ii) tolerance ensued to sickness elicitation by a second administration of the microbial component, and (iii) saccharin taste did not evoke sickness.

Conclusions: Symptoms of infectious sickness in the absence of infection are hardly explained by exposure to the conditioned stimulus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avoidance Learning / physiology*
  • Bacterial Infections / immunology
  • Bacterial Infections / physiopathology*
  • Bacterial Infections / psychology*
  • Conditioning, Psychological / physiology*
  • Female
  • Illness Behavior / physiology*
  • Male
  • Mice
  • Neuropsychological Tests
  • Taste / immunology
  • Taste / physiology*