Neurons Co-Expressing GLP-1, CCK, and PYY Receptors Particularly in Right Nodose Ganglion and Innervating Entire GI Tract in Mice

Afferent vagal neurons convey gut-brain signals related to the mechanical and chemical sensing of nutrients, with the latter also mediated by gut hormones secreted from enteroendocrine cells. Cell bodies of these neurons are located in the nodose ganglia (NG), with the right NG playing a key role in metabolic regulation. Notably, glucagon-like peptide-1 receptor (GLP1R) neurons primarily innervate the muscle layer of the stomach, distant from glucagon-like peptide-1 (GLP-1)-secreting gut cells. However, the co-expression of gut hormone receptors in these NG neurons remains unclear. Using RNAscope combined with immunohistochemistry, we confirmed GLP1R expression in a large population of NG neurons, with <i>Glp1r</i>, <i>cholecystokinin A receptor (Cckar)</i>, and <i>Neuropeptide Y Y2 Receptor (Npy2r)</i> being more highly expressed in the right NG, while <i>neurotensin receptor 1 (Ntsr)</i>, G protein-coupled receptor (<i>Gpr65</i>), and <i>5-hydroxytryptamine receptor 3A (5ht3a)</i> showed equal expressions in the left and right NG. Co-expression analysis demonstrated the following: (i) most <i>Glp1r</i>, <i>Cckar</i>, and <i>Npy2r</i> neurons co-expressed all three receptors; (ii) nearly all <i>Ntsr1</i>- and <i>Gpr65</i>-positive neurons co-expressed both receptors; and (iii) <i>5ht3a</i> was expressed in subpopulations of all peptide-hormone-receptor-positive neurons. Retrograde labeling demonstrated that the anterior part of the stomach was preferentially innervated by the left NG, while the right NG innervated the posterior part. The entire gastrointestinal (GI) tract, including the distal colon, was strongly innervated by NG neurons. Most importantly, dual retrograde labeling with two distinct tracers identified a population of neurons co-expressing <i>Glp1r</i>, <i>Cckar</i>, and <i>Npy2r</i> that innervated both the stomach and the colon. Thus, neurons co-expressing GLP-1, cholecystokinin (CCK), and peptide YY (PYY) receptors, predominantly found in the right NG, sample chemical, nutrient-induced signals along the entire GI tract and likely integrate these with mechanical signals from the stomach.