<i>Lactobacillus rhamnosus</i> zz-1 exerts preventive effects on chronic unpredictable mild stress-induced depression in mice <i>via</i> regulating the intestinal microenvironment

Abstract

Depression remains one of the most prevalent psychiatric disorders, and it has been confirmed that it is related to the dysfunction of the microbiota-gut-brain axis. Manipulation of the gut microenvironment by probiotics might improve mental health and prevent stress-related psychiatric disorders. The present study aimed to determine whether <i>Lactobacillus rhamnosus</i> (<i>L. rhamnosus</i>) zz-1 could prevent the occurrence of depression and its potential mechanisms using a mouse model with chronic unpredictable mild stress (CUMS). The results indicated that <i>L. rhamnosus</i> zz-1 intervention ameliorated CUMS-induced depression-like behaviors of mice with reduced body growth rate, lowered sucrose preference, increased immobility time, as well as decreased curiosity and mobility. Moreover, <i>L. rhamnosus</i> zz-1 significantly inhibited hormones released due to hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, alleviated CUMS-induced deficits of monoamine neurotransmitters, and increased the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB). These benefits were partially linked to the regulation of the intestinal microenvironment. <i>L. rhamnosus</i> zz-1 alleviated intestinal damage and reduced intestinal inflammation of the depressed mice. Meanwhile, <i>L. rhamnosus</i> zz-1 effectively adjusted the dysbiosis of mouse gut microbiota induced by CUMS, such as changes in the abundance of the <i>Lachnospiraceae</i> NK4A136 group, <i>Bacteroides</i>, and <i>Muribaculum</i>. Taken together, these results demonstrated that <i>L. rhamnosus</i> zz-1 was effective in preventing depression from chronic stress, adding new evidence to support the mental benefits of probiotics.