Probiotic effects on anxiety-like behavior in animal models

Gut microbiota have been shown to be useful in treating gastrointestinal diseases, cancer, obesity, infections, and, more recently, neuropsychiatric conditions such as degenerative diseases and depression. There has also been recent expansion in testing probiotics and prebiotics on anxiety-like behaviors in animals. Current results indicate that probiotic substances of the Lactobacillus and Bifidobacterium type are effective in reducing anxiety-like behaviors in mice or rats evaluated in the elevated plus-maze, the open-field, the light-dark box, and conditioned defensive burying. Probiotics are also effective in reducing serum or plasma corticosterone levels after acute stress. It is hypothesized that probiotics cause anxiolytic-like effects via vagal influences on caudal solitary nucleus, periaqueductal gray, central nucleus of the amygdala, and bed nucleus of the stria terminalis. Further experimentation is needed to trace the neurochemical anatomy underlying anxiolytic-like behaviors of gut microbiata exerting effects via vagal or nonvagal pathways.