Immunohistochemical mapping of calcitonin receptors in the adult rat brain. 
Calcitonin receptors (CTR) have previously been identified in specific regions of the rat central nervous system using in situ hybridization or autoradiography with iodinated ligands.  In this study, the results of immunohistochemical mapping of CTR in the adult rat brain are reported, using a potent and recently developed antibody that recognizes an intracellular epitope of the rat CTR, and high-resolution immunofluorescence techniques.  Abundant expression was found in the brain, with highest densities in the nucleus accumbens, lateral arcuate nucleus, lateral substantia nigra, bed nucleus of the stria terminalis, locus coeruleus, area postrema, nucleus of the solitary tract, and some of the nuclei of the reticular formation.  These results are in close correspondence with previous mapping studies.  However, we detected CTR immunoreactivity in several additional brain areas, as the ventromedial, lateral and posterior hypothalamus, where CT binding has not yet been described.  Our detailed mapping of the CTR in the rat brain has identified CTR-positive cells that will be important for subsequent characterization of behavioral functions associated with the actions of CT-related peptides.