Immunohistochemical localization of the neuropeptide S receptor in the rat central nervous system.

The neuropeptide S receptor (NPSR) is a G-protein coupled receptor that is potently activated by the linear 20 amino acid peptide, neuropeptide S (NPS). Central administration of NPS promotes arousal and anxiolytic-like effects in rodents, and fails to promote such effects in NPSR knockout animals or in the presence of NPSR-selective antagonists. In situ hybridization (ISH) studies in rat brain have revealed that the mRNAs encoding the NPS precursor and the NPS receptor are expressed at high levels in discrete regions of the rat CNS. The distribution of the NPSR protein in brain has not been reported due to a lack of available antibodies. We have generated and validated a NPSR-specific antibody and used it to determine the distribution of the NPSR in male Sprague-Dawley (SD) rat brain. The anti-NPSR antibody identified a single protein by Western blot with an estimated molecular weight of 65 kD, which was prevented by pre-incubation of the antibody with the immunizing peptide. The protein distribution identified with this antibody in rat brain was consistent both with the mRNA distribution identified by in situ hybridization, and to the localization pattern identified by a second NPSR-specific antibody against a distinct NPSR epitope. NPSR protein was identified in the medial amygdala (MeA), substantia nigra pars compacta, subiculum, dorsal raphe, and several hypothalamic and thalamic regions. Additionally, NPSR protein was localized in the pyramidal cell layer of the ventral hippocampus, the medial habenula (MHb), and was widely distributed in the cortex. The distribution of NPSR protein provides further insight into the organization of the NPS system and may guide future studies on the role of the NPSR in brain.