Antidepressive Mechanisms of Probiotics and Their Therapeutic Potential

Abstract

The accumulating knowledge of the host-microbiota interplay gives rise to the microbiota-gut-brain (MGB) axis. The MGB axis depicts the interkingdom communication between the gut microbiota and the brain. This communication process involves the endocrine, immune and neurotransmitters systems. Dysfunction of these systems, along with the presence of gut dysbiosis, have been detected among clinically depressed patients. This implicates the involvement of a maladaptive MGB axis in the pathophysiology of depression. Depression refers to symptoms that characterize major depressive disorder (MDD), a mood disorder with a disease burden that rivals that of heart diseases. The use of probiotics to treat depression has gained attention in recent years, as evidenced by increasing numbers of animal and human studies that have supported the antidepressive efficacy of probiotics. Physiological changes observed in these studies allow for the elucidation of probiotics antidepressive mechanisms, which ultimately aim to restore proper functioning of the MGB axis. However, the understanding of mechanisms does not yet complete the endeavor in applying probiotics to treat MDD. Other challenges remain which include the heterogeneous nature of both the gut microbiota composition and depressive symptoms in the clinical setting. Nevertheless, probiotics offer some advantages over standard pharmaceutical antidepressants, in terms of residual symptoms, side effects and stigma involved. This review outlines antidepressive mechanisms of probiotics based on the currently available literature and discusses therapeutic potentials of probiotics for depression.

Metagenome gene prediction of naturally fermented milk products of India using PICRUSt2 and Piphillin

“…These predictive functional hits were related to cognitive function. Probiotics are well-known for enhancing brain function and have been demonstrated to have various mechanisms in alleviating depression and enhancing brain function [37,38]. Lactobacillus is one of the main LAB genera reported from NFM products of India (Shangpliang et al 2018) and we also observed a signi cant positive correlation of this genus with glutamatergic synapse as per our ndings.…”

The Gut-Brain Axis and Its Role in Depression

“…The mixture of NK41 and NK46 also significantly reduced immobilization stress-induced anxiety-like/depressive behaviors [15]. Decreased expression of depressive-like behavior through the presence of Lactobacillus rhamnosus in chronically stressed mice was observed in work by Yong et al [16]. These studies support the concept of the benefits of specific Lactobacillus in treating MDD through anti-inflammatory mechanisms or through encouraging serotonin production.…”

Updated Review and Meta-Analysis of Probiotics for the Treatment of Clinical Depression: Adjunctive vs. Stand-Alone Treatment

“…For example, SSRIs have been found to be less effective for the treatment of anhedonia [ 47 , 48 ] and somatic presentations [ 49 ], while both SSRIs and SNRIs have shown limited efficacy for cognitive impairment [ 47 , 50 ] and anxious depression [ 51 ]. Simultaneously, animal models have identified various probiotics from the Lactobacilli and Bifidobacteria genera to be effective against each of these symptoms/sub-types (for a recent review, see [ 52 ]). Indeed, one of the RCTs included in this review, which applied a multi-strain probiotic as stand-alone treatment, reported significantly reduced cognitive reactivity to a sad mood, while overall depression was not improved [ 34 ].…”

“…In terms of optimal probiotic supplement content and dosage, there is little consensus at present, as reflected by the trials captured in this review. As extensively discussed elsewhere, different probiotics may be more beneficial for certain depressive symptoms or subtypes [ 52 ]; however, RCTs in depression usually do not report symptom-level data, thus making it difficult to establish strain-specific effects in clinical populations. While efforts to delineate the contributions and function of individual probiotics in single-strain, pre-clinical studies have been made, multistrain formulations have shown higher potency in humans, and are suggested to exhibit synergistic effects, with an expanded benefit on host physiology [ 52 ].…”