The brain-gut-microbiome axis is a bidirectional communication pathway between the gut microbiota and the central nervous system. The growing interest in the gut microbiota and mechanisms of its interaction with the brain has contributed to the considerable attention given to the potential use of probiotics, prebiotics and postbiotics in the prevention and treatment of depressive disorders. This review discusses the up-to-date findings in preclinical and clinical trials regarding the use of pro-, pre- and postbiotics in depressive disorders. Studies in rodent models of depression show that some of them inhibit inflammation, decrease corticosterone level and change the level of neurometabolites, which consequently lead to mitigation of the symptoms of depression. Moreover, certain clinical studies have indicated improvement in mood as well as changes in biochemical parameters in patients suffering from depressive disorders.

Probiotics, Prebiotics and Postbiotics on Mitigation of Depression Symptoms: Modulation of the Brain–Gut–Microbiome Axis

Xiao-Chai-Hu-Tang ameliorates tumor growth in cancer comorbid depressive symptoms via modulating gut microbiota-mediated TLR4/MyD88/NF-κB signaling pathway

Chronic Kidney Disease (CKD) and neurodegenerative diseases are aging-related diseases. CKD with declined renal function is associated with an elevation of circulating indoxyl sulfate, a metabolite synthesized by gut microbes. We explored the roles of gut microbial metabolites in linking with Central Nervous System (CNS) diseases by administrating indoxyl sulfate intraperitoneally to male C57BL/6 mice with unilateral nephrectomy. Upon exposure, the accumulation of indoxyl sulfate was noted in the blood, prefrontal cortical tissues, and cerebrospinal fluid. Mice showed behavioral signs of mood disorders and neurodegeneration such as anxiety, depression, and cognitive impairment. Those behavioral changes were accompanied by disturbed neuronal survival, neural stem cell activity, expression of Brain-Derived Neurotrophic Factor, serotonin, corticosterone, and Repressor Element-1 Silencing Transcription Factor, and post-receptor intracellular signaling, as well as upregulated oxidative stress and neuroinflammation. Uremic toxin adsorbent AST-120 improved the above mentioned changes. Intriguingly, intracerebroventricular indoxyl sulfate administration only caused limited alterations in the normal mice and the alterations were reversed by aryl hydrocarbon receptor antagonism. The findings suggest pathogenic roles of indoxyl sulfate in the development of CNS diseases, and highlight gut microbiota as alternative targets for intervention with the aim of slowing down the progression of CKD and decreasing CNS complications.

Indoxyl sulfate caused behavioral abnormality and neurodegeneration in mice with unilateral nephrectomy.

Chamomile tea: Source of a glucuronoxylan with antinociceptive, sedative and anxiolytic-like effects.

The microbiome residing in the human gut performs a wide range of biological functions Recently, it has been elucidated that a change in dietary habits is associated with alteration in the gut microflora which results in increased health risks and vulnerability towards various diseases Falling in line with the same concept, depression has also been shown to increase its prevalence around the globe, especially in the western world Various research studies have suggested that changes in the gut microbiome profile further result in decreased tolerance of stress Although currently available medications help in relieving the symptoms of depressive disorders briefly, these drugs are not able to completely reverse the multifactorial pathology of depression The discovery of the communication pathway between gut microbes and the brain, ie the Gut-Brain Axis, has led to new areas of research to find more effective and safer alternatives to current antidepressants The use of probiotics and prebiotics has been suggested as being effective in various preclinical studies and clinical trials for depression Therefore, in the present review, we address the new antidepressant mechanisms via gut microbe alterations and provide insight into how these can provide an alternative to antidepressant therapy without the side effects and risk of adverse drug reactions

M.Y. Simon Lee

Papers

Fructo-oligosaccharides from Morinda officinalis remodeled gut microbiota and alleviated depression features in a stress rat model.