Gastrointestinal nutrient sensing and vagal nerve function: A clinical perspective

Abstract

The gastrointestinal tract is connected with the central nervous system by autonomic nerves, which transmit information from digested substances at the luminal side. Afferent fibers constitute between 80% and 90% of the vagus nerve and play an important role in conveying sensory information evoked by the gastrointestinal luminal substances to the central nervous system. The luminal substances consist of digested food, bacterial metabolites, and endogenous digestive juice, which can modulate the function of the afferent vagal nerve with the epithelial cells acting as intermediaries. In this process, epithelial cells receive luminal substances and promptly release a series of peptide hormones, so-called food-related hormones, which act directly on the receptors of the afferent vagal nerve, thereby controlling signals to the central nervous system. Recently, the gastrointestinal nutrient sensing exerted by food-related hormones and the afferent vagal nerve have been recognized as regulators of hypothalamic autonomic functions. In this session, current knowledge about gastrointestinal nutrient sensing and the function of the afferent vagal nerve is summarized from the clinical perspective, and their clinical relevance to the symptoms of autonomic disorders including Parkinson’s disease is discussed.