Growth hormone secretagogue receptor expression in the cells of the stomach-projected afferent nerve in the rat nodose ganglion.

Growth hormone secretagogue receptor (GHS-R) is widely expressed in various regions of the body, such as the brain, pituitary gland, heart and gastrointestinal tract. Recently, ghrelin, an endogenous ligand for GHS-R, was found in the rat stomach, and several studies have suggested that ghrelin acts via the vagal afferent nerve. In this study, we studied the expression of GHS-R mRNA in the rat nodose ganglion by reverse transcriptase-polymerase chain reaction and in situ hybridization, the results of which clearly demonstrated the presence of GHS-R mRNA and GHS-R producing cells in the rat nodose ganglion. We also studied the retrograde tracing of nodose ganglion cells to the stomach and found that some GHS-R mRNA-expressing cells contain the retrograde rebelling. Our results provide direct morphological evidence that GHS-R is produced in afferent neurons of the nodose ganglion and suggest that ghrelin signals from the stomach are transmitted to the brain via vagal afferent nerves.