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Refinamiento sináptico propioceptivo impulsado por la actividad en la médula espinal en desarrollo mediante
Chetan Nagaraja1, Serena Ortiz1, Akash R Murali1,2
1Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA.
bioRxiv : the preprint server for biology
|September 2, 2025
Resumen
Durante el desarrollo temprano, los aferentes de Ia propioceptivos se conectan inicialmente a través de segmentos espinales. Esta conectividad intersegmental es podada por el día postnatal 13, guiada por la actividad de los proprioceptores y la señalización del complemento C1qA.
Área de la Ciencia:
- La neurociencia
- Biología del desarrollo
- Circuitos de la médula espinal
Sus antecedentes:
- Los aferentes propioceptivos del grupo Ia son cruciales para el control del movimiento, formando conexiones monosinápticas con las neuronas motoras alfa espinales.
- Los mecanismos de desarrollo que establecen una segmentación precisa de estos aferentes siguen siendo en gran medida desconocidos.
- Comprender esta especificidad es clave para descifrar el desarrollo del control motor.
Objetivo del estudio:
- Investigar la línea de tiempo de desarrollo de la conectividad aferente propioceptiva a las neuronas motoras.
- Determinar el papel de la actividad de los propioceptores en el establecimiento de la especificidad segmentaria.
- Elucidar las vías moleculares implicadas en la eliminación de las conexiones intersegmentales excesivas.
Principales métodos:
- Electrofisiología ex vivo en preparados de médula espinal de ratón neonatal.
- Trazado anatómico para identificar las conexiones de las neuronas motoras aferentes.
- Análisis de NaV1.6 knockout condicional y C1qA knockout en modelos de ratón.
- Inmunohistoquímica para la expresión de C1qA.
Principales resultados:
- Los aferentes de Ia propioceptivos inicialmente forman conexiones monosinápticas tanto segmentarias como intersegmentales.
- Las conexiones intersegmentales son prominentes en el desarrollo posnatal temprano (P4-7) y en gran medida ausentes en P11-13.
- El deterioro de la señalización de los propioceptores (NaV1.6 cKO) o la deficiencia de C1qA prolonga la conectividad intersegmental.
- Se observó una reducción de la expresión de C1qA en ratones NaV1.6 cKO, lo que sugiere su participación.
Conclusiones:
- Existe una ventana postnatal crítica para el refinamiento de la conectividad aferente propioceptiva.
- La actividad de los propioceptores, mediada por C1qA, impulsa la eliminación de las conexiones intersegmentales excesivas.
- Este proceso establece la especificidad segmentaria precisa requerida para el control del motor maduro.
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