Melatonin Binding Sites in Senegal Sole: Day/Night Changes in Density and Location in Different Regions of the Brain |
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Authors: | Catarina Oliveira José Fernando López‐Olmeda María Jesus Delgado Angel Luis Alonso‐Gómez |
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Affiliation: | 1. Faculty of Biology, Department of Physiology, Murcia University, Murcia, Spain;2. Faculty of Biology, Department of Physiology (Animal Physiology II), Complutense University, Madrid, Spain |
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Abstract: | We localized melatonin binding sites in different brain regions (optic tectum, telencephalon, cerebellum, hypothalamus, olfactory bulbs, and medulla oblongata) of Senegal sole, a species of aquaculture interest, and checked day/night changes in density (Bmax) at mid‐light (ZT06) and mid‐dark (ZT18). Plasma melatonin was measured using a radioimmunoassay, while binding assays were performed using 2‐[125I]iodomelatonin as a radioligand. Plasma melatonin concentrations were significantly lower at mid‐light (189.5±46 pg/ml) than mid‐dark (455.5±163 pg/ml). Values of Bmax were statistically significantly higher in the optic tectum (5.6±0.6 and 12.3±1 fmol/mg prot, at mid‐light and mid‐dark, respectively) and in the cerebellum (7.7±1.1 and 10.6±1.3 fmol/mg prot, at mid‐light and mid‐dark, respectively). Significant day/night differences were only observed in these two tissues. These results show for the first time the distribution of melatonin binding sites within the brain of a flatfish species and their lack of down‐regulation. |
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Keywords: | Fish Melatonin binding sites Plasma melatonin Solea senegalensis Diurnal variation |
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