Subcellular localization of thyrotropin-releasing hormone (TRH)- and Neuropeptide Y (NPY)-like immunoreactivity in the neurointermediate lobe of the frog pituitary |
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Authors: | G Morel E Leneveu MC Tonon G Pelletier H Vaudry PM Dubois |
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Institution: | 1. CNRS UA 559, Laboratoire d''Histologie et d''Embryologie Faculté de Médecine de Lyon Sud, 69600 Oullins, France;2. Groupe de Recherche en Endocrinologie Moléculaire, UA CNRS 650, Unité Alliée à l''INSERM Faculté des Sciences, Université de Rouen, 76130 Mont-Saint-Aignan, France;3. Groupe de Recherches du CRM en Endocrinologie Moléculaire, Centre Hospitalier de l''Université Laval Québec G1V 4G2, Canada |
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Abstract: | The presence of thyrotropin-releasing hormone (TRH) and neuropeptide Y (NPY) has been demonstrated in the neural lobe and in the intermediate lobe of the frog pituitary by immunocytochemistry on ultrathin sections of neurointermediate lobes obtained by cryoultramicrotomy. In the neural lobe, separate populations of TRH- or NPY-immunoreactive nerve fibers were observed. Both neuropeptides were contained in dense-core secretory vesicles about 200 nm in diameter. In intermediate lobe cells, TRH- and NPY-like immunoreactivities were observed in the cytoplasmic matrix and more sparsely in secretory granules. Occasionally, immunoreactive TRH could be visualized at the plasma membrane level. In the nucleus, both peptides were detected in the euchromatin, in the vicinity of the heterochromatin and in the nucleolus. Conversely, gonadotropin-releasing hormone-like immunoreactivity could not be detected. These results provide immunocytological evidence for the presence of endogenous TRH and NPY in frog melanotrophs indicating that these peptides may participate in the regulation of intermediate lobe secretion. |
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Keywords: | Thyrotropin-releasing hormone Neuropeptide Y α -Melanotropin Gonadotropin-releasing hormone Intermediate lobe Amphibian Cryoultramicrotomy Immunocytochemistry |
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