NEGR1 and major depressive disorder: In depression, oral treatment of A. muciniphila elicits anti-depressive effects from a mouse model subjected to either chronic restraint stress or antibiotic treatment.59–61 Postnatal supplementation of A. muciniphila ameliorates valproic acid-induced social deficits in mice.62 In contrast to these models, our study demonstrates that Akkermansia administration ameliorated depression-like behaviors in a genetically predisposed mouse model with NEGR1 deficiency.