Central,but not peripheral application of motilin increases c-Fos expression in hypothalamic nuclei in the rat brain |
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Authors: | Mei?Wu Ming?Tang Dirk?Adriaensen Inge?Depoortere Theo?L?Peeters Email author" target="_blank">Jean-Pierre?TimmermansEmail author |
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Institution: | (1) Laboratory of Cell Biology & Histology, Department of Biomedical Sciences, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium;(2) Medical College, University of Qingdao, 38 Dengzhou Road, 266021 Qingdao, People s Republic of China;(3) Gastrointestinal Hormone Lab, University of Leuven, Herestraat 49, box 701, 3000 Leuven, Belgium |
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Abstract: | Previous immunocytochemical studies have shown the presence of motilin-immunoreactive neurons in specific brain areas of rats and autoradiographic studies in rabbits demonstrated motilin-binding sites in the central nervous system as well. Therefore, the aim of this study was to determine the anatomical localisation and neurochemical features of neurons activated by central administration of motilin (Mo) in rats. One week after cannulation, an intracerebroventricular injection of Mo (ICV, 3 g/6 l 0.9% saline) was given. For comparative purposes, a group of animals received an intravenous injection of motilin (IV, 9 g/300 l 0.9% saline) or an equal volume of saline. Neuronal excitation was assessed by c-Fos immunocytochemistry and combined with immunostaining for neurotransmitter markers. In contrast to the IV motilin-treated animals, the ICV motilin-treated animals displayed a significant increase in c-Fos expression in the supraoptic nuclei (SO) and paraventricular nuclei of the hypothalamus (PVH). At the level of the dorsomedial, ventromedial and lateral hypothalamic nuclei, ICV administration of motilin did not induce changes in c-Fos expression. In addition, the cerebellum did not show c-Fos expression after ICV motilin administration either. These findings might suggest distinct pathways and actions of centrally released and systemic motilin, but, particularly in rodents, do not rule out the possibility that the effects seen in the SO and PVH after ICV application are aspecific in nature. At present, we cannot exclude the fact that the results observed with motilin in rodents are due to cross-interaction with other related (e.g. ghrelin) or not yet identified receptors. |
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Keywords: | Motilin Hypothalamus Cerebellum c-Fos immunoreactivity Rat |
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