The role of gut microbiota in the gut-brain axis: current challenges and perspectives

Abstract

Brain and the gastrointestinal (GI) tract are intimately connected to form a bidirectional neurohumoral communication system. The communication between gut and brain, knows as the gut-brain axis, is so well established that the functional status of gut is always related to the condition of brain. The researches on the gut-brain axis were traditionally focused on the psychological status affecting the function of the GI tract. However, recent evidences showed that gut microbiota communicates with the brain via the gut-brain axis to modulate brain development and behavioral phenotypes. These recent fi ndings on the new role of gut microbiota in the gut-brain axis implicate that gut microbiota could associate with brain functions as well as neurological diseases via the gut-brain axis. To elucidate the role of gut microbiota in the gut-brain axis, precise identification of the composition of microbes constituting gut microbiota is an essential step. However, identifi cation of microbes constituting gut microbiota has been the main technological challenge currently due to massive amount of intestinal microbes and the diffi culties in culture of gut microbes. Current methods for identifi cation of microbes constituting gut microbiota are dependent on omics analysis methods by using advanced high tech equipment. Here, we review the association of gut microbiota with the gut-brain axis, including the pros and cons of the current high throughput methods for identifi cation of microbes constituting gut microbiota to elucidate the role of gut microbiota in the gut-brain axis.

Mechanisms underlying the effects of prenatal psychosocial stress on child outcomes: beyond the HPA axis

“…Importantly, the intestinal microbiota plays a pivotal role in the development of the child's immune system, and hence in the child's early and future health [82]. Also, it has recently become clear that the intestinal microbiota, by means of the gut-brain axis, influences brain development and behavior [83,84]. In mice, for example, chronic treatment with a lactic acid bacteria Lactobacillus rhamnosus induced region-dependent alterations in the brain in GABA receptor expression with increases in cortical regions and reductions in the hippocampus and amygdala.…”

“…Moreover, lower diversity and stability of infant microbiota during the first weeks of life, as well as specific bacterial signatures, have been related to excessive crying or colic [88,92]. To date, increasing importance is allocated to the role of intestinal microbiota in the development of health and behavior [83,84]. The fact that the links between maternal prenatal stress and infant microbiota have yet to be determined in humans, should not deter future researchers from investigating this promising area.…”

Neurochemicals, Behaviours and Psychiatric Perspectives of Neurological Diseases

“…ACTH with relation to the increased systematic pro-inflammatory cytokines along with environmental stress subsequently triggers cortisol release by the adrenal glands. A combination of neural, hormonal, and gut microbiota network helps the brain regulate the effector cells [129,130]. Oral administration of antibiotics in subjects showing symptoms of hepatic encephalopathy exhibited significant improvement in microbiota-brain interaction.…”

Commensal Bugs from the Gut-Shaping Human Health and Disease

“…External factors such as stress or depression influence the course of GI diseases such as irritable bowel syndrome and inflammatory bowel disease [153]. Furthermore, stress can alter the integrity of the GI epithelium modulate GI motility and induce the release of catecholamines and cortisol which has direct effect on intestinal immunity and cytokine production [154]. Bailey et al [155] demonstrated that exposure to a social stressor affects the gut microbiota and circulating levels of cytokines particularly IL-6 and MCP-1.…”