Limosilactobacillus reuteri ameliorates maternal separation stress in newborn mice and alters subsequent adult behaviour

Maternal separation (MS) in mice results in behavioral deficits and gut microbiota dysbiosis that all persist into adulthood. Limosilactobacillus reuteri DSM 17938 modulates gut microbiota, alters systemic metabolites, and facilitates immune regulation. To assess the effect of DSM 17938 on biochemical and behavioural stress-associated changes, newborn mice were exposed to unpredictable MS (MSU) daily from day 7 to day 20 of life, with intragastric administration of DSM 17938 or PBS as control. Body weight, brain levels of cholecystokinin (CCK), glial fibrillary acidic protein (GFAP), corticosterone, and stool microbiota were assessed at day 21. Behaviour tests including Y-maze (YMT), Tail Suspension (TST), and Open Field (OFT) were evaluated in adult mice. MSU resulted in a decrease in early postnatal growth, which improved with DSM 17938. Reduced CCK and increased corticosterone brain levels due to MSU were reversed by DSM 17938. GFAP levels increased with MSU, indicating that the decreased brain CCK was likely secondary to neuronal damage. DSM 17938 treated offspring demonstrated better cognitive function and less anxious behaviour in adult behaviour tests. DSM 17398 corrected stress related gut microbial dysbiosis. In conclusion, early life modulation of gut microbiota by DSM 17938 had beneficial effects on stress-associated physical and biochemical changes caused by MS in neonates and on subsequent adult behaviour.