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Miniatura de curso rápido en el tiempo y corrientes excitadoras evocadas en las sinapsis cerebelares in situ
R A Silver1, S F Traynelis, S G Cull-Candy
1Department of Pharmacology, University College London, UK.
Nature
|January 9, 1992
Resumen
La neurotransmisión en el cerebelo utiliza principalmente el L-glutamato. Este estudio revela corrientes rápidas de receptores no-N-metil-D-aspartato y aberturas más lentas de canales de N-metil-D-aspartato en las células granulares cerebelares, desafiando teorías alternativas.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- Biología celular Biología celular.
- Neurofisiología La neurofisiología.
Sus antecedentes:
- Las células granulares cerebelares reciben la neurotransmisión de las terminales de las fibras musgosas.
- El L-glutamato es el presunto neurotransmisor que media en esta vía de señalización.
- Estudios anteriores propusieron diferentes mecanismos para las corrientes sinápticas en estas células.
Objetivo del estudio:
- Investigar los mecanismos precisos y la cinética de la neurotransmisión en las células granulares cerebelares.
- Para caracterizar los componentes de las corrientes postsinápticas excitadoras en miniatura (m.e.p.s.c.).
- Evaluar las hipótesis recientes con respecto a la participación del canal NMDA en las corrientes sinápticas de las células granulares.
Principales métodos:
- Registros electrofisiológicos de alta resolución de m.e.p.s.c. y corrientes evocadas.
- Se utilizaron finas rebanadas cerebelares para aprovechar las propiedades únicas de las células granulares (pequeño soma, procesos limitados, dendritas cortas).
- Analizó las distribuciones de curso de tiempo, farmacología y amplitud actuales.
Principales resultados:
- Se identificaron corrientes de receptores no N-metil-D-aspartato (no NMDA) excepcionalmente rápidas (tiempo de ascenso <100 μs, decaimiento τ = 1,0 ms).
- Se observaron aberturas de canales de N-metil-D-aspartato (NMDA) de 50 pS directamente resolubles después del componente no NMDA.
- No se encontraron pruebas que apoyen la única mediación de m.e.p.s.c. por los canales NMDA con un curso de tiempo novedoso.
- El componente no NMDA exhibió una distribución de amplitud sesgada, lo que afectó el análisis cuántico.
Conclusiones:
- La neurotransmisión hacia las células granulares cerebelares implica un rápido componente no NMDA seguido de aperturas de canales NMDA.
- Los hallazgos refutan la hipótesis de la única mediación del canal NMDA para estas corrientes sinápticas.
- Las diferencias en la cinética de la corriente sináptica pueden derivarse de distintas funciones sinápticas o efectos de filtrado electrotónico.
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