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https://hdl.handle.net/1822/67941
Título: | Ghrelin as a novel locally produced relaxing peptide of the iris sphincter and dilator muscles |
Autor(es): | Rocha-Sousa, A. Saraiva, J. Henriques-Coelho, T. Falcão-Reis, F. Correia-Pinto, Jorge Leite-Moreira, A. F. |
Palavras-chave: | Animals Anterior Eye Segment Carbachol Cholinergic Agonists Dose-Response Relationship, Drug Epinephrine Ghrelin In Situ Hybridization Iris Male Muscle Contraction Muscle Relaxation Oculomotor Muscles Oligopeptides Peptide Hormones Potassium Channels Prostaglandin-Endoperoxide Synthases RNA, Messenger Rabbits Rats Rats, Wistar Receptors, G-Protein-Coupled Receptors, Ghrelin Peptide hormones Iris Ciliary epithelium Muscle fibers |
Data: | Nov-2006 |
Editora: | Academic Press |
Revista: | Experimental Eye Research |
Citação: | Rocha-Sousa, A., Saraiva, J., Henriques-Coelho, T., Falcao-Reis, F., Correia-Pinto, J., & Leite-Moreira, A. F. (2006). Ghrelin as a novel locally produced relaxing peptide of the iris sphincter and dilator muscles. Experimental eye research, 83(5), 1179-1187 |
Resumo(s): | Ghrelin is a recently described acylated peptide, which works as a somatosecretagogue and has described effects on the smooth, skeletal and cardiac muscle. We examined the production and effects of ghrelin on relaxation of the iris muscles. Contractile effects of 1-5 human ghrelin (frGhr, 10(-9)-6 x 10(-5)M) and 1-5 human des-octanoyl-ghrelin (d-frGhr; 10(-9)-6 x 10(-5)M) were tested on iris rabbit sphincter (n=11 frGhr; n=7 d-frGhr), dilator (n=6 frGhr; n=6 d-frGhr) and rat sphincter (n=6 frGhr; n=8 d-frGhr) precontracted muscles. On rabbit sphincter the effect of frGhr was also tested in presence of: i) L-NA (10(-5)M; n=7); ii) indomethacin (10(-5)M; n=7); iii) DLys(3)GHRP6 (10(-4)M; n=6); and iv) apamin+carybdotoxin (10(-6)M; n=6). Furthermore, on rabbit dilator the effect of frGhr was tested in presence of DLys(3)GHRP6 (10(-4)M; n=7). Finally, ghrelin mRNA production was assessed by "in situ" hybridization in Wistar rat eyes (n=8). In all muscles, frGhr promoted a concentration-dependent relaxation, maximal at 6 x 10(-5)M, 1.5-3 min after its addition, decreasing tension by 34.1+/-12.1%, 25.8+/-4.8% and 52.1+/-10.3% in the rabbit sphincter, dilator and rat sphincter, respectively. In the rabbit sphincter the relaxing effects of frGhr were: (i) enhanced in presence of DLys(3)GHRP6 (118.1+/-21.1%); (ii) blunted by indomethacin; and (iii) not altered by apamin+carybdotoxin (36.4+/-14.4%) or L-NA (52.4+/-11.4%). Relaxing effects of d-frGhr in rabbit (43.3+/-5.2%) and rat (77.1+/-15.3%) sphincter muscles were similar to those of frGhr. In rabbit dilator muscle, d-frGhr did not significantly alter active tension and the relaxing effect of frGhr was blunted by GHSR-1a blockage. Ghrelin mRNA was identified in iris posterior epithelium. In conclusion, ghrelin is a novel, locally produced, relaxing agent of iris dilator and sphincter muscles, an effect that is mediated by GHSR-1a in the former, but not in the latter. Furthermore, in the sphincter it seems to be mediated by prostaglandins, but not by NO or K(Ca) channels. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/67941 |
DOI: | 10.1016/j.exer.2006.06.005 |
ISSN: | 0014-4835 |
Versão da editora: | https://www.sciencedirect.com/science/article/pii/S0014483506002946 |
Arbitragem científica: | yes |
Acesso: | Acesso aberto |
Aparece nas coleções: | ICVS - Artigos em revistas internacionais / Papers in international journals |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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Rocha-sousa-2006-Ghrelin-as-a-novel-locally-produced.pdf | 274,97 kB | Adobe PDF | Ver/Abrir |