Investigating Gut-Brain Communication: Which Chemosensory Cells in the Gut Connect with Vagal Sensory Afferents?

Recent research has shown that specialized populations of epithelial cells lining the lumen of the gut are chemosensors that act similar to taste receptor cells on the tongue, aiding in detection of chemicals within the digestive tract. These chemosensory cells are known to secrete various hormones in response to nutrient content. These hormones and secreted neurotransmitters are detected in part by sensory neurons of the vagus nerve that relay information to the brain about the contents of the gut. These signals prepare the body to "rest and digest" or to protect itself from harmful substances and toxins (through emesis or diarrhea). Based on previous research done by Kaelberer et al. 2018, we now have evidence that chemosensory cells communicate with the brain by forming synapses with vagal afferents. We are trying to answer what chemosensory cell populations form synapses with vagal neurons in the gut. Focusing on the stomach and duodenal region of the GI tract, we use immunohistochemistry to locate different chemosensory cells and the vagal fibers that innervate them. We also aim to identify and locate different cell populations of the vagus and obtain transcriptome profiles of the vagal neurons by using single cell RNA-sequencing. We hypothesize that there are distinct cell populations within the vagus that contribute to the detection specific nutrients and irritants in the gut. Our goal is to identify which specific chemosensory cell types communicate with vagal neurons to either promote digestion or satiety or trigger nausea and emesis.