Gut–brain communication: Do sensory fibres in the vagus nerve innervate the lower gastrointestinal tract?

Over the past few years, there has been considerable interest in the role of the vagus nerve in health and disease, particularly regarding communication between the gastrointestinal (GI) tract and the brain; the so-called ‘gut–brain axis’. Accumulating evidence suggests that health and disease might be modified significantly by activity within vagal sensory fibres along the gut–brain axis (Doenyas et al., 2025; Ma et al., 2025). In this dynamic era of gut–brain research, we must have a clear understanding of which regions of the GI tract are innervated by the vagal and/or spinal afferent neurons (Spencer et al., 2025). The latest research from different research groups reveals non-trivial inconsistencies regarding the sensory innervation provided by the vagus nerve to the lower GI tract (distal colon and rectum). This region of the GI tract, defined as within 30 mm of the anal sphincter in mice, is commonly studied at a functional level in gut–brain research and visceral pain models. Hence, to advance the field of gut–brain research, it is essential that we have a clear understanding of which sensory pathways underlie gut–brain communication.