Ghrelin relaxes the iris sphincter muscle through a GHSR-1a independent pathway.

• Tipo: Resumo de Comunicação em Conferência Internacional
• Data: 2004

Autores

Rocha-Sousa A (Autor) FMUP; Saraiva I (Autor) Outra; Gonzaga S (Autor) Outra; Correia-Pinto J (Autor) FMUP; Falcão-Reis F (Autor) FMUP; Leite-Moreira AF (Autor) FMUP

Ata de Conferência Internacional

Título: Ophthalmic Research

Página Inicial: 156

European Association for Vision and Eye research (EVER).

Vilamoura, Portugal, 24 27 de Setembro de 2004

Classificação Científica

FOS: Ciências médicas e da saúde > Outras ciências médicas

CORDIS: Ciências da Saúde > Ciências Médicas > Medicina > Oftalmologia

Outras Informações

Resumo (PT): To characterize production and contractile effects of Ghrelin on iris sphincter muscle and the role of GHSR-1a in its mediation. Methods Cumulative doses of Des-octanoil 1-5 Ghrelin (Des-Ghr, 10e-9 to 6*10e-5M; n=10) or 1-5-Ghrelin (Ghr, 10e-9 to 6*10e-5M; n=54) to generate concentration-response curves were tested on precontracted (Carbacol; 10e-4M) rabbit iris sphincter muscles. Ghr was added in the absence (n=14) or presence of i) L-nitro-arginine (L-NA, 10e-4M; n=14); ii) indomethacin (10e-5M; n=14); iii) D-Lys-GHRP6, a selective GHSR-1a inhibitor (10e-4M; n=12). Results are expressed as % changes from control. Ghrelin production was assessed by “in situ” hybridization for detection of Ghrelin mRNA in Wistar rat eyes (n=7). Results Ghr and Des-Ghr promoted a concentration-dependent relaxation of the muscle maximal at 10e-5M, which relaxation of 34.1±12.1 % and 37.1±2.6 %. This was recorded 1.5-3 minutes after its addition to the bath and disappeared 10 minutes later. Although not statistically significant, there was a trend for L-NA to exacerbate and for indomethacin to attenuate Ghr’s relaxing effect (muscular tension decreased 58.0±10.5% and 20.3±12.1%, respectively). D-Lys3-GHRP6 significantly increased the relaxing effect of Ghr (118.1±21.1%). Ghrelin mRNA was identified in the posterior epithelium of the iris. Conclusions Ghrelin therefore is a novel, locally produced, relaxing agent of iris sphincter muscle. This effect has rapid onset, is transient and seems, to some extent, to be modulated by NO and prostaglandins. Its potentiation when GHSR-1a is inhibited and the similar effect of des-octanoil-ghrelin suggest a mediation through another type of GHS receptor.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Notas: European Association for Vision and Eye research (EVER), published in journal, Ophthalmic Research. 2004; 36(Suppl.1):156.