Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development

The size principle underlies the orderly recruitment of motor units; however, motoneuron size is a poor predictor of recruitment amongst functionally defined motoneuron subtypes. Whilst intrinsic properties are key regulators of motoneuron recruitment, the underlying currents involved are not well d...

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Autores principales:	Simon A Sharples, Gareth B Miles
Formato:	article
Lenguaje:	EN
Publicado:	eLife Sciences Publications Ltd 2021
Materias:	motoneuron recruitment size principle postnatal development spinal cord intrinsic properties Medicine R Science Q Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/4a3a71971e474a5dae760a339c442ef8
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spelling	oai:doaj.org-article:4a3a71971e474a5dae760a339c442ef82021-12-03T15:50:20ZMaturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development10.7554/eLife.713852050-084Xe71385https://doaj.org/article/4a3a71971e474a5dae760a339c442ef82021-11-01T00:00:00Zhttps://elifesciences.org/articles/71385https://doaj.org/toc/2050-084XThe size principle underlies the orderly recruitment of motor units; however, motoneuron size is a poor predictor of recruitment amongst functionally defined motoneuron subtypes. Whilst intrinsic properties are key regulators of motoneuron recruitment, the underlying currents involved are not well defined. Whole-cell patch-clamp electrophysiology was deployed to study intrinsic properties, and the underlying currents, that contribute to the differential activation of delayed and immediate firing motoneuron subtypes. Motoneurons were studied during the first three postnatal weeks in mice to identify key properties that contribute to rheobase and may be important to establish orderly recruitment. We find that delayed and immediate firing motoneurons are functionally homogeneous during the first postnatal week and are activated based on size, irrespective of subtype. The rheobase of motoneuron subtypes becomes staggered during the second postnatal week, which coincides with the differential maturation of passive and active properties, particularly persistent inward currents. Rheobase of delayed firing motoneurons increases further in the third postnatal week due to the development of a prominent resting hyperpolarization-activated inward current. Our results suggest that motoneuron recruitment is multifactorial, with recruitment order established during postnatal development through the differential maturation of passive properties and sequential integration of persistent and hyperpolarization-activated inward currents.Simon A SharplesGareth B MileseLife Sciences Publications Ltdarticlemotoneuronrecruitmentsize principlepostnatal developmentspinal cordintrinsic propertiesMedicineRScienceQBiology (General)QH301-705.5ENeLife, Vol 10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	motoneuron recruitment size principle postnatal development spinal cord intrinsic properties Medicine R Science Q Biology (General) QH301-705.5
spellingShingle	motoneuron recruitment size principle postnatal development spinal cord intrinsic properties Medicine R Science Q Biology (General) QH301-705.5 Simon A Sharples Gareth B Miles Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
description	The size principle underlies the orderly recruitment of motor units; however, motoneuron size is a poor predictor of recruitment amongst functionally defined motoneuron subtypes. Whilst intrinsic properties are key regulators of motoneuron recruitment, the underlying currents involved are not well defined. Whole-cell patch-clamp electrophysiology was deployed to study intrinsic properties, and the underlying currents, that contribute to the differential activation of delayed and immediate firing motoneuron subtypes. Motoneurons were studied during the first three postnatal weeks in mice to identify key properties that contribute to rheobase and may be important to establish orderly recruitment. We find that delayed and immediate firing motoneurons are functionally homogeneous during the first postnatal week and are activated based on size, irrespective of subtype. The rheobase of motoneuron subtypes becomes staggered during the second postnatal week, which coincides with the differential maturation of passive and active properties, particularly persistent inward currents. Rheobase of delayed firing motoneurons increases further in the third postnatal week due to the development of a prominent resting hyperpolarization-activated inward current. Our results suggest that motoneuron recruitment is multifactorial, with recruitment order established during postnatal development through the differential maturation of passive properties and sequential integration of persistent and hyperpolarization-activated inward currents.
format	article
author	Simon A Sharples Gareth B Miles
author_facet	Simon A Sharples Gareth B Miles
author_sort	Simon A Sharples
title	Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
title_short	Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
title_full	Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
title_fullStr	Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
title_full_unstemmed	Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
title_sort	maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development
publisher	eLife Sciences Publications Ltd
publishDate	2021
url	https://doaj.org/article/4a3a71971e474a5dae760a339c442ef8
work_keys_str_mv	AT simonasharples maturationofpersistentandhyperpolarizationactivatedinwardcurrentsshapesthedifferentialactivationofmotoneuronsubtypesduringpostnataldevelopment AT garethbmiles maturationofpersistentandhyperpolarizationactivatedinwardcurrentsshapesthedifferentialactivationofmotoneuronsubtypesduringpostnataldevelopment
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Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development

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