About this Research Topic
The complex mechanisms of food intake, behavior and energy balance are controlled by several molecular and structural pathways and the gut microbial community (microbiota), which mediate one form of bidirectional signaling between the gastrointestinal tract and the brain, the so-called gut-brain axis. The communication pathways of this axis include interactions between peptides, lipids, microbial metabolites and the host. Biologically active peptides are produced by central and peripheral neurons alongside with endocrine cells in the gastrointestinal tract, as well as by species of gut microbiota. Neuropeptides share transduction mechanisms with gut hormones, and their release is influenced also by neurotransmitters. Other than gut hormones, species of gut microbiota produce many neurotransmitters including gamma-aminobutyric acid, serotonin, and dopamine. Gut-brain communication is bidirectional. Afferent signaling can take place via vagal and spinal afferent neurons, immune mediators, gut hormones, and microbiota-derived molecules. Efferent signals from the brain to the gut are carried by sympathetic and parasympathetic neurons, and include neuroendocrine factors involving the adrenal medulla and the adrenal cortex.
The gut microbiota depend fully on nutrients and water provided by their host. However, the intrinsic ability of bacteria to regulate their growth and to maintain their population within the gut are also controlled through molecular pathways controlling energy balance in the host. Increasing evidence suggests that regulation of food intake is based on bacteria–host communication, and not just on intrinsic gut–brain or brain-gut signaling. Bacterial components and metabolites, can stimulate intestinal satiety pathways and be released into the systemic circulation, acting on hypothalamic neurons. Therefore, the short-term bacterial growth-linked modulation of intestinal satiety can be coupled with long-term regulation of appetite, controlled by the neuropeptidergic circuitry in the hypothalamus. Many examples exist of the multiple roles that the gut microbiome may play in the regulation of brain development and function, including the modulation of satiety and appetite, behavior, perception of pain, and inflammatory processes. The gut-brain axis is thus interlinked through symbiotic mutualistic relationships existing between the gut microbiota and the host. Involved in these are a wide array of neural and endocrine messengers and interactions which underlie a body’s homeostasis in health and disease, and depend on genetic makeup, birth mode, diet, and environmental factors such as cultural considerations and antibiotic use.
In this Research Topic we welcome Original Articles, Mini-Reviews, Full Reviews, Commentaries, and Perspectives. Manuscripts must focus on any aspects of:
- Nutrition and microbiota-gut-brain axis;
- Gut bacteria in short and long-term control of appetite, satiety, eating disorders, obesity;
- Food-derived energy balance between the host and gut bacteria;
- Microbiota-gut-brain axis and endocrine system; and
- Modulation of gut microbiota (use of probiotics, antibiotics, germ-free animals and fecal microbiota).
Keywords: Neuropeptides, Satiety, Appetite, Eating disorders, Obesity, Gut bacteria, Energy homeostasis, Gut-brain axis
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