Cellular Localization of Prepro-Orexin and Orexin Receptors (Ox1R and Ox2R) in Merkel Cells
Orexins (A and B) were first demonstrated in neurons of the lateral hypothalamus, both peptides derived from a common precursor called prepro-orexin. Orexins act through previously orphan G-protein receptors named orexin receptor 1 (Ox1R) and orexin receptor 2 (Ox2R). Up to the present, various neuropeptides have been detected in neuroendocrine cells of the skin (Merkel cells). The aim of our study was to investigate the presence of orexin receptors and prepro-orexins in Merkel cells. Immunohistochemical techniques were performed to detect preproorexin and orexin receptors (Ox1R and Ox2R) in human and porcine Merkel cells. Prepro-orexin was expressed in the cytoplasm of Merkel cells of pig snout skin and human fingertip. Immunoreactivity for prepro-orexin was more intense in the mature side of the Merkel cell. Epidermal nerve terminals associated with Merkel cells and dermal nerve fibers showed no immunostaining. Orexin receptors were also demonstrated in the Merkel cells of pig snout skin. Further studies must be followed to ascertain the role that orexins play in cutaneous neuroendocrine cells.
KeywordsCitrate Cortisol Serotonin Polypeptide Paraffin
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