Daily rhythms in the somatotropic axis of Senegalese sole (Solea senegalensis): The time of day influences the response to GH administration |
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Authors: | J. F. López-Olmeda I. M. Pujante L. S. Costa A. Galal-Khallaf J. M. Mancera F. J. Sánchez-Vázquez |
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Affiliation: | 1. Department of Physiology, Faculty of Biology, Regional Campus of International Excellence “Campus Mare Nostrum”, University of Murcia, Murcia, Spain;2. Department of Biology, Faculty of Marine and Environmental Sciences, Campus de Excelencia Internacional del Mar (CEI-MAR), University of Cádiz, Cádiz, Spain;3. Department of Animal Science, Federal University of Lavras, Minas Gerais, Brazil;4. Department of Marine Biology and Aquaculture, Instituto de Ciencias Marinas de Andalucia - CSIC, Cádiz, Spain |
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Abstract: | Growth factors in vertebrates display daily rhythms, which, while widely described in mammals, are still poorly understood in teleost fish. Here, we investigated the existence of daily rhythms in the somatotropic axis of the flatfish Solea senegalensis. In a first experiment, daily rhythms of the expression of pituitary adenylate cyclase–activating polypeptide (pacap), growth hormone (gh), insulin-like growth factor 1 (igf1) and its receptor (igf1r) were analyzed under a 12:12 h light:dark cycle. All genes displayed daily rhythms with the acrophases of pacap, gh and igf1 located in the second half of the dark phase (ZT 20:28–0:04 h), whereas the acrophase of igf1r was located around mid-light (ZT 5:33 h). In a second experiment, the influence of the time of day (mid-light, ML, versus mid-darkness, MD) of GH administration on the expression of these factors and on plasma glucose levels was tested. The response observed depended on the time of injection: the strongest effects were observed at MD, when GH administration significantly reduced pituitary gh and enhanced liver igf1 expression. These results provide the first evidence of daily rhythms and differential day/night effects in growth factors in S. senegalensis, suggesting new insights for investigating the physiology of growth and possible applications to improve fish aquaculture. |
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Keywords: | Flatfish GH chronopharmacology growth hormone insulin-like growth factor pituitary adenylate cyclase-activating polypeptide |
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