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Fototransducción por las células ganglionares de la retina que establecen el reloj circadiano
David M Berson1, Felice A Dunn, Motoharu Takao
1Department of Neuroscience, Brown University, Providence, RI, 02912 USA. David_Berson@brown.edu
Science (New York, N.Y.)
|February 9, 2002
Resumen
Los ritmos circadianos de los mamíferos están sincronizados por la luz, pero no a través de varillas o conos. Las células ganglionares retinianas intrínsecamente fotosensibles señalan directamente al núcleo supraquiasmático (SCN), actuando como fotorreceptores primarios para esta captura de luz.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- Cronobiología cronobiología.
- Oftalmología Oftalmología.
Sus antecedentes:
- Los ritmos circadianos en los mamíferos están sincronizados con los ciclos medioambientales de luz y oscuridad.
- Este proceso, conocido como arrastre fótico, involucra al núcleo supraquiasmático (SCN) en el hipotálamo.
- Se sabe que el arrastre fótico ocurre independientemente de los fotorreceptores de bastón y cono.
Objetivo del estudio:
- Para investigar el mecanismo fotorreceptor subyacente sincronización de la luz de los ritmos circadianos de los mamíferos.
- Para identificar las células específicas de la retina responsables de transmitir la información luminosa a la SCN.
- Para determinar si las células ganglionares de la retina poseen fotosensibilidad intrínseca relevante para el arrastre circadiano.
Principales métodos:
- Registros electrofisiológicos de las células ganglionares de la retina que se proyectan hacia el SCN.
- Bloqueo farmacológico de la entrada sináptica de las varillas y conos.
- Evaluación de la despolarización de las células ganglionares en respuesta a estímulos de luz.
- Análisis de la sensibilidad espectral y las propiedades cinéticas de la respuesta a la luz.
Principales resultados:
- Las células ganglionares de la retina que innervan el SCN demostraron fotosensibilidad intrínseca.
- Estas células se despolarizaron al exponerse a la luz, incluso cuando las vías de varilla y cono estaban bloqueadas.
- La sensibilidad a la luz medida, el ajuste espectral y la cinética lenta coincidían con los requisitos para el arrastre fotótico.
Conclusiones:
- Es probable que las células ganglionares retinianas intrínsecamente fotosensibles sean los fotorreceptores primarios para sincronizar los ritmos circadianos de los mamíferos.
- Estas células ganglionares especializadas proporcionan una entrada retiniana directa al SCN para el arrastre fótico.
- Los hallazgos desafían el papel exclusivo de las barras y conos en toda la percepción visual de la luz relevante para la regulación circadiana.
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