Simple Summary
The gut-brain axis is a key communication system between the intestines and the brain, regulating stress responses, immunity and animal behavior. In pigs, its functioning is particularly important due to the relatively permeable intestinal barrier and the role of the gut microbiota in maintaining homeostasis. This review discusses the physiological and molecular mechanisms of the gut-brain axis, including neural, hormonal and immune signaling, as well as the involvement of microbiota-derived metabolites, such as neurotransmitters, short-chain fatty acids, bile acids and tryptophan derivatives. Nutritional interventions are also described, which, by modulating the microbiota, can help reduce stress, improve animal welfare and support sustainable pig production.
Abstract
The gut-brain axis is a complex communication network linking the gastrointestinal tract and the central nervous system, in which the gut microbiota plays a pivotal role in regulating intestinal homeostasis, immune responses and neuroendocrine functions. This review summarizes current knowledge on the role of the porcine gut microbiota in the functioning of the gut-brain axis and examines nutritional strategies aimed at its modulation. Key production-related stressors, such as weaning, transport and handling, disrupt microbiota composition, increase intestinal permeability and activate the hypothalamic-pituitary-adrenal (HPA) axis, leading to heightened stress responses, impaired immunity and behavioral disturbances. Evidence indicates that supplementation with probiotics, prebiotics, or postbiotics stabilizes the gut microbiota, enhances the production of bioactive metabolites, supports intestinal barrier integrity and alleviates oxidative stress. Such interventions improve adaptation to environmental stress, animal welfare and performance, while potentially reducing the need for antibiotics. Maintaining a balanced gut microbiota is therefore essential for the proper functioning of the neuroendocrine and immune systems in pigs. An integrated approach utilizing omics technologies (metagenomics, metabolomics, proteomics) may further elucidate microbiota-brain interactions and support the development of sustainable and ethical swine production strategies.