Bacterial immunization prevents PTSD-like symptoms in mice

Injecting mice with a UCL-discovered bacterium can reduce stress and inflammation, preventing them from developing PTSD-like conditions, finds a new international study led by the University of Colorado Boulder. The research, published in Proceedings of the National Academy of Sciences, found that mice injected with the bacterium were more resilient to stress, showing less fear and anxiety in stressful situations. The immunization also changed serotonin activity in the brain, with similar beneficial effects to antidepressants or long-term exercise. Additionally, immunized mice were protected against colon inflammation which was caused or worsened by stress in unimmunized mice. The bacterium, Mycobacterium vaccae (M. vaccae) , is found naturally in soil and was first isolated and characterised at UCL by Professor John Stanford. Its immunological properties were investigated by Professor Graham Rook (UCL Infection & Immunity), a co-author on the new study.