Neuropeptide Y (NPY) and its receptors affect blood pressure, feeding behavior, and neurogenesis. In this study, the distribution of neurons expressing NPY Y5 receptor (Y5) was examined in adult mouse central nervous system by immunohistochemistry. Y5 protein localization was investigated using polyclonal anti-Y5 antibody, which was successfully preabsorbed with Y5 knockout brain tissues. The preabsorbed anti-Y5 antibody did not react with Y5 knockout brain tissues, thus meeting the "hard specificity criterion," which is the absence of staining in tissues genetically deficient for the antigen (Pradidarcheep et al., 2008). Y5-positive neurons were found in most brain areas. Most Y5 immunoreactivities were observed as dot-like structures adjacent to the plasma membrane, as expected for a cell membrane receptor. In situ hybridization showed that the Y5 mRNA expression was correlated with the Y5 protein level in each case and that it was probably controlled by the transcriptional regulation of the Y5 gene. In the nuclei where Y5 was expressed, Y5 immunoreactivities were found mainly in the somatic and dendritic areas. The distribution patterns of the Y5-positive cells that were broader than previously expected suggest important biological activities of the Y5 in many brain areas.
Keywords: G-protein coupled receptor; Knockout mouse, obesity; Specificity of antibody.
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