Science

Jessica Arseneault-Breard, Isabelle Rondeau, Kim Gilbert, Stephanie-Anne Girard, Thomas A. Tompkins, Roger Godbout, and Guy Rousseau

Myocardial infarction (MI) in rats is accompanied by apoptosis in the limbic system and a behavioural syndrome similar to models of depression. We have already shown that probiotics can reduce post-MI apoptosis and designed the present study to determine if probiotics can also prevent post-MI depressive behaviour. We also tested the hypothesis that probiotics achieve their central effects through changes in the intestinal barrier. MI was induced in anaesthetised rats via 40-min transient occlusion of the left anterior coronary artery. Sham rats underwent the same surgical procedure without actual coronary occlusion. For 7 d before MI and between the seventh post-MI day and euthanasia, half the MI and sham rats were given one billion live bacterial cells of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 per d dissolved in water, while the remaining animals received only the vehicle (maltodextrin). Depressive behaviour was evaluated 2 weeks post-MI in social interaction, forced swimming and passive avoidance step-down tests. Intestinal permeability was evaluated by oral administration with fluorescein isothiocyanate–dextran, 4h before euthanasia. MI rats displayed less social interaction and impaired performance in the forced swimming and passive avoidance step-down tests compared to the sham controls (P,0·05). Probiotics reversed the behavioural effects of MI (P,0·05), but did not alter the behaviour of sham rats. Intestinal permeability was increased in MI rats and reversed by probiotics. In conclusion, L. helveticus R0052 and B. longum R0175 combination interferes with the development of post-MI depressive behaviour and restores intestinal barrier integrity in MI rats.