Synaptic mechanisms underlying modulation of locomotor-related motoneuron output by premotor cholinergic interneurons
Abstract
Spinal motor networks are formed by diverse populations of interneurons that set the strength and rhythmicity of behaviors such as locomotion. A small cluster of cholinergic interneurons, expressing the transcription factor Pitx2, modulates the intensity of muscle activation via ‘C-bouton’ inputs to motoneurons. However, the synaptic mechanisms underlying this neuromodulation remain unclear. Here, we confirm in mice that Pitx2+ interneurons are active during fictive locomotion and that their chemogenetic inhibition reduces the amplitude of motor output. Furthermore, after genetic ablation of cholinergic Pitx2+ interneurons, M2 receptor-dependent regulation of the intensity of locomotor output is lost. Conversely, chemogenetic stimulation of Pitx2+ interneurons leads to activation of M2 receptors on motoneurons, regulation of Kv2.1 channels and greater motoneuron output due to an increase in the inter-spike afterhyperpolarization and a reduction in spike half-width. Our findings elucidate synaptic mechanisms by which cholinergic spinal interneurons modulate the final common pathway for motor output.
Citation
Nascimento , F , Broadhead , M J , Tetringa , E , Tsape , E , Zagoraiou , L & Miles , G B 2020 , ' Synaptic mechanisms underlying modulation of locomotor-related motoneuron output by premotor cholinergic interneurons ' , eLife , vol. 9 , e54170 . https://doi.org/10.7554/eLife.54170
Publication
eLife
Status
Peer reviewed
ISSN
2050-084XType
Journal article
Description
F Nascimento was supported by The Alfred Dunhill Links Foundation. G B Miles and M J Broadhead received support from Biotechnology and Biological Sciences Research Council Grant BB/M021793/1. L Zagoraiou and E Tsape were supported by Fondation Santé.Collections
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