Bacteria Infection Causes stress induced memory dysfunction in mice

Glynis Steele

Senior Member
Newcastle upon Tyne UK
Bacterial infection causes stress-induced memory dysfunction in mice

This was in Gut magazine, an international journal of gastroentorology

Mlanie G Gareau1, Eytan Wine1,2, David M Rodrigues1, Joon Ho Cho3, Mark T Whary4, Dana J Philpott3, Glenda MacQueen5, Philip M Sherman1
+ Author Affiliations

1Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Canada
2Department of Pediatrics, Division of Gastroenterology and Nutrition, University of Alberta, Alberta, Canada
3Department of Immunology, University of Toronto, Toronto, Ontario, Canada
4Division of Comparative Medicine, Massachusetts Institute of Technology, Massachusetts, USA
5Department of Psychiatry, University of Calgary, Alberta, Canada
Correspondence to
Philip M Sherman, Cell Biology Program, Research Institute, Hospital for Sick Children, 555 University Ave, Rm 8409, Toronto, ON M5G 1X8, Canada;
Revised 1 September 2010
Accepted 3 September 2010
Published Online First 21 October 2010
Background The braingut axis is a key regulator of normal intestinal physiology; for example, psychological stress is linked to altered gut barrier function, development of food allergies and changes in behaviour. Whether intestinal events, such as enteric bacterial infections and bacterial colonisation, exert a reciprocal effect on stress-associated behaviour is not well established.

Objective To determine the effects of either acute enteric infection or absence of gut microbiota on behaviour, including anxiety and non-spatial memory formation.

Methods Behaviour was assessed following infection with the non-invasive enteric pathogen, Citrobacter rodentium in both C57BL/6 mice and germ-free Swiss-Webster mice, in the presence or absence of acute water avoidance stress. Whether daily treatment with probiotics normalised behaviour was assessed, and potential mechanisms of action evaluated.

Results No behavioural abnormalities were observed, either at the height of infection (10 days) or following bacterial clearance (30 days), in C rodentium-infected C57BL/6 mice. When infected mice were exposed to acute stress, however, memory dysfunction was apparent after infection (10 days and 30 days). Memory dysfunction was prevented by daily treatment of infected mice with probiotics. Memory was impaired in germ-free mice, with or without exposure to stress, in contrast to conventionally reared, control Swiss-Webster mice with an intact intestinal microbiota.

Conclusions The intestinal microbiota influences the ability to form memory. Memory dysfunction occurs in infected mice exposed to acute stress, while in the germ-free setting memory is altered at baseline.