Distribution of the Parathyroid Hormone 2 Receptor in Rat: Immunolocalization Reveals Expression by Several Endocrine Cells*

The PTH2 receptor is a G protein-coupled receptor selectively activated by PTH. We are studying the receptors distribution to guide the investigation of its physiological function. We have now generated an antibody from a C-terminal peptide sequence of the PTH2 receptor and used this to study its cellular distribution. Labeling with the antibody identified a number of endocrine cells expressing the PTH2 receptor, including thyroid parafollicular cells, pancreatic islet D cells, and some gastrointestinal peptide synthesizing cells. There was complete overlap of PTH2 receptor labeling with somatostatin in pancreatic islets, and partial overlap with somatostatin in thyroid parafollicular cells and in the gastrointestinal tract. Furthermore, observations made previously by in situ hybridization histochemistry, including expression throughout the cardiovascular system, as well as by discrete populations of cells within the gastrointestinal tract and reproductive system were confirmed. These data suggest a broad role for the PTH2 receptor, especially within the endocrine system, and provide a basis for experimental exploration of its physiology.