Chronic psychosocial stress induces visceral hyperalgesia in mice

Abstract

Experimental and clinical evidence has shown that chronic stress plays an important role in the onset and/or exacerbation of symptoms of functional gastrointestinal disorders. Here, we aimed to investigate whether exposure to a chronic and temporally unpredictable psychosocial stressor alters visceral and somatic nociception as well as anxiety-related behaviour. In male C57BL/6J mice, chronic stress was induced by repeated exposure to social defeat (SD, 2 h) and overcrowding (OC, 24 h) during 19 consecutive days. Visceral and somatic nociception was evaluated by colorectal distension and a hot plate, respectively. The social interaction test was used to assess social anxiety. Mice exposed to psychosocial stress developed visceral hyperalgesia and somatic hypoalgesia 24 h following the last stress session. SD/OC mice also exhibited social anxiety-like behaviour. All these changes were also associated with physiological alterations, measured as a decreased faecal pellet output and hypothalamic-pituitary-adrenal (HPA) axis disruption. Taken together, these data confirm that this mouse model of chronic psychosocial stress may be useful for studies on the pathophysiological mechanisms underlying such stress-associated disorders and to further test potential therapies.

Keywords::

• Brain–gut axis
• chronic stress
• colorectal distension
• social avoidance
• somatic analgesia
• visceral hypersensitivity

Acknowledgements

The authors would like to thank Dr Stefan Reber and Dr David Slattery (University of Regensburg, Germany) for information and advice on the stress protocol and also Dr Beate Finger for her helpful comments on this paper and assistance in establishing the stress protocol. We thank Dr Marcela Julio-Piper and Mr. Patrick Fitzgerald for their technical assistance.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.