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La señalización de la melanopsina en el iris y la retina de los mamíferos

T Xue¹, M T H Do, A Riccio

¹Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. txue77@gmail.com

|November 5, 2011

Resumen

Los mamíferos poseen un reflejo de luz pupillar intrínseco (PLR) independiente del cerebro, que involucra a la melanopsina y el PLCβ4. Esta vía es crucial para la respuesta a la luz en las células ganglionares de la retina intrínsecamente fotosensibles.

Área de la Ciencia:

Oftalmología Oftalmología.
La neurociencia es la neurociencia.
Biología celular Biología celular.

Sus antecedentes:

Los vertebrados no mamíferos exhiben un iris intrínsecamente fotosensible y un reflejo de luz pupillar (PLR, por sus siglas en inglés).
Se cree generalmente que la PLR de mamíferos requiere conexiones neuronales entre el ojo y el cerebro.

Objetivo del estudio:

Investigar la presencia y los mecanismos de una PLR intrínseca en los mamíferos.
Para dilucidar los componentes moleculares involucrados en la PLR intrínseca de los mamíferos y las respuestas a la luz de la retina.

Principales métodos:

Investigó el PLR intrínseco en ratones.
Se utilizaron modelos de knockout genético (Plcb4(-/-)) para evaluar el papel de la PLCβ4.4.
Examinó la respuesta a la luz de las células ganglionares de la retina intrínsecamente fotosensibles que expresan melanopsina (M1-ipRGCs).
Estudió los efectos de la ablación de la expresión de TRPC6 y TRPC7.

Principales resultados:

Un componente intrínseco de la PLR está muy extendido en mamíferos nocturnos y crepusculares.
En ratones, este PLR intrínseco depende de la melanopsina y el PLCβ4.
La deficiencia de Plcb4 eliminó la PLR intrínseca y la respuesta a la luz de las M1-ipRGCs.
TRPC6 y TRPC7 no son esenciales para la PLR intrínseca, pero están involucrados en las respuestas a la luz M1-ipRGC.
Las vías de señalización de la melanopsina divergen entre el iris y la retina.

Conclusiones:

Los mamíferos poseen un PLR intrínseco mediado por melanopsina y PLCβ4 en el iris.
La vía dependiente de PLCβ4 es crítica tanto para la sensibilidad a la luz intrínseca de PLR como para la de M1-ipRGC.
Diferentes mecanismos de señalización de la melanopsina operan en el iris y la retina.

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