Exploring Role of Probiotic in Modulation of Depressive-Like Behavior: Unraveling Microbiome Gut-Brain Axis

Abstract

Background: Recently findings suggests that gut microbiota can influence cognitive health. In present study we have studied the effect oαf Bacillus coagulans (B. coagulans) on depression like phenotypes employing chronic unpredictable mild stress and maternal separation model in rats. Methods: Depression was induced by subjecting rats to maternal separation followed by chronic unpredictable mild stress. Bacillus coagulans treatment was given to rats for six weeks at the dose of 250mg/kg. The positive control fluoxetine was given at the dose of 10mg/kg. Depression were evaluated using sucrose preference test (SPT), forced-swimming test (FST), elevated-plus maze test (EPM), and open-field test (OFT). Animals were sacrificed and brain, intestine, and fecal samples were obtained for biochemical, molecular and histopathological studies. Results: B. coagulans reversed the effect of depressive behavior in sucrose preference test, forced swim test and elevated-plus maze test and open-field test suggests that B. coagulans ameliorates neurobehavioral abnormalities. B. coagulans treatment improved levels neurotransmitters like noradrenaline, dopamine serotonin and brain derived growth factor levels, as well as decreased levels of proinflammatory markers like C-reactive protein, TNF-α, IL-1β in brain. Administration of probiotic also restored levels of BDNF,doublecortin, GFAP, and zona occludens in brain indicates neuroprotective effect. Also increased ratio of firmicutes to Bacteroides in faecal samples indicates beneficial bacterial phylum. The histopathological analysis of brain and intestine shows normal architecture indicates maintenance of brain and gut integrity respectively. Conclusion- Thus results of present study indicates that antidepressant effects of B. coagulans mediated via remodelling of microbiota gut-brain axis.