Communication of gut microbiota and brain via immune and neuroendocrine signaling

Abstract

The gastrointestinal tract of the human is inhabited by about 5 × 1013 bacteria (of about 1,000 species) as well as archaea, fungi, and viruses. Gut microbiota is known to influence the host organism, but the host may also affect the functioning of the microbiota. This bidirectional cooperation occurs in three main inter-organ signaling: immune, neural, and endocrine. Immune communication relies mostly on the cytokines released by the immune cells into circulation. Also, pathogen-associated or damage-associated molecular patterns (PAMPs or DAMPs) may enter circulation and affect the functioning of the internal organs and gut microbiota. Neural communication relies mostly on the direct anatomical connections made by the vagus nerve, or indirect connections via the enteric nervous system. The third pathway, endocrine communication, is the broadest one and includes the hypothalamic-pituitary-adrenal axis. This review focuses on presenting the latest data on the role of the gut microbiota in inter-organ communication with particular emphasis on the role of neurotransmitters (catecholamines, serotonin, gamma-aminobutyric acid), intestinal peptides (cholecystokinin, peptide YY, and glucagon-like peptide 1), and bacterial metabolites (short-chain fatty acids).

Probiotics: Bridging the interplay of a healthy gut and psychoneurological well‐being

“…The efficacy of a probiotic is contingent upon its ability to withstand the harsh strains that have been scientifically demonstrated to survive and reach the gastrointestinal tract in a viable state is of significant importance (Kaźmierczak-Siedlecka et al, 2020). There is a prevailing belief that the administration of probiotics necessitates the use of enteric-coated capsules to safeguard the probiotic cultures during their transit through the digestive tract, before their release into the gastrointestinal tract.…”

“…Prolonged exposure to stressors induces persistent release of norepinephrine, leading to modifications in the gut microbiota and increased permeability of the gastrointestinal tract to bacteria and toxins. Subsequently, these alterations trigger stress‐related responses within the HPA axis (Kasarello et al, 2023). The present study proved the impact of the probiotic strain B. breve CCFM1025 on the composition of fecal microbiota and neurological changes in the brain (Ansari et al, 2023).…”

Glymphatic System Pathology and Neuroinflammation as Two Risk Factors of Neurodegeneration

“…There are many pathways for bidirectional communication that are mediated by microorganisms. Communication pathways can be distinguished as immune, including immune cells and the cytokines secreted by them; neural, made by the vagus nerve and enteric nervous system; and communication paths relying on neurotransmitters, intestinal peptides, and bacterial metabolites [99]. Dysbiosis refers to compositional and functional alterations in the microbiome, increasing proinflammatory species, or the loss of beneficial organisms [100,101].…”

Inhibitory Synaptic Influences on Developmental Motor Disorders

“…GABA (γ amino butyric acid) has a wide variety of synaptic (i.e., hyperpolarization) and extrasynaptic metabotropic effects on neurons [ 39 , 40 , 41 , 42 , 43 , 44 , 45 ], in addition to having influences on the immune system, the gastroenteric tract and in particular, pancreatic cells [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. Ionotropic synaptic inhibition is predominantly mediated by transmembrane GABA-A receptors, with some GABA-C receptors present in certain brain regions.…”