Short‐term fasting promotes insulin expression in rat hypothalamus |
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| Authors: | Tamara B. Dakic Tanja V. Jevdjovic Mina I. Peric Ivana M. Bjelobaba Milica B. Markelic Bojana S. Milutinovic Iva V. Lakic Nebojsa I. Jasnic Jelena D. Djordjevic Predrag Z. Vujovic |
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| Affiliation: | 1. Department for Comparative Physiology and Ecophysiology, Faculty of Biology, Institute for Physiology and Biochemistry, University of Belgrade, Belgrade, Serbia;2. Centre for Laser Microscopy, Faculty of Biology, Institute for Physiology and Biochemistry, University of Belgrade, Belgrade, Serbia;3. Institute for Biological Research ‘Sinisa Stankovic’, University of Belgrade, Belgrade, Serbia;4. Chair for Cell and Tissue Biology, Faculty of Biology, Institute for Zoology, University of Belgrade, Belgrade, Serbia;5. Institute for the Application of Nuclear Energy, University of Belgrade, Belgrade, Serbia |
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| Abstract: | In the hypothalamus, insulin takes on many roles involved in energy homoeostasis. Therefore, the aim of this study was to examine hypothalamic insulin expression during the initial phase of the metabolic response to fasting. Hypothalamic insulin content was assessed by both radioimmunoassay and Western blot. The relative expression of insulin mRNA was examined by qPCR. Immunofluorescence and immunohistochemistry were used to determine the distribution of insulin immunopositivity in the hypothalamus. After 6‐h fasting, both glucose and insulin levels were decreased in serum but not in the cerebrospinal fluid. Our study showed for the first time that, while the concentration of circulating glucose and insulin decreased, both insulin mRNA expression and insulin content in the hypothalamic parenchyma were increased after short‐term fasting. Increased insulin immunopositivity was detected specifically in the neurons of the hypothalamic periventricular nucleus and in the ependymal cells of fasting animals. These novel findings point to the complexity of mechanisms regulating insulin expression in the CNS in general and in the hypothalamus in particular. |
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| Keywords: | fasting glucose hypothalamus insulin rat |
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