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A.C. S. Alvaro, A. Santiago, A.P. Silva, J.O. Malva, E. Grouzmann, A.L. Carvalho, A.F. Ambrósio, C. Cavadas; The Role of Neuropeptide Y (NPY) and NPY Receptors on the [Ca2+]i Changes in Retinal Neural Cells . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4012.
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Purpose: Neuropeptide Y (NPY) is a 36 amino acid peptide, and its effects are mediated through the activation of six G–protein–coupled receptors named NPY Y1, Y2, Y3, Y4, Y5, and y6. The aim of the present study was to investigate the role of NPY and NPY receptors on the [Ca2+]i changes in rat retinal cell cultures. Methods: Rat retinal cells were obtained from newborn Wistar rats and cultured for 9 days. NPY–producing cells were identified by immunocytochemistry and the content of amidated–NPY was quantified by a sandwich–ELISA assay. The expression of NPY and its receptors was determined by RT–PCR. Single cell [Ca2+]i measurements were carried out with fura–2–AM fluorescence imaging. Results: The intracellular content of amidated–NPY in retinal cells was 1.4+0.1 fmoles NPY/million cells, and NPY was localised both in neurons and in glial cells. Retinal cells expressed mRNA for both NPY and NPY Y1, Y2, Y4 and Y5 receptors. NPY inhibited heterogeneously the increase in [Ca2+]i evoked by 30 mM KCl in a concentration–dependent manner. The [Ca2+]i increase was also inhibited by [Leu31Pro34]NPY (Y1/Y4/Y5 agonist), but not by NPY13–36 (Y2 agonist). Conclusions:These results indicate that rat retinal cells synthesize NPY and express NPY Y1, Y2, Y4 and Y5 receptors. Also, NPY inhibits [Ca2+]i changes in some cells through the activation of NPY Y1, Y4 or Y5 receptor subtypes, thus modulating visual information processing in the retina.
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