[FR] Étude des mécanismes de coordination des activités rythmiques locomotrice et sympathique au sein d’un réseau spinal activé par l’acétylcholine chez le rat nouveau-né.
Defended on December 15, 2017
Supervisor: Jean-René Cazalets. INCIA, CNRS UMR 5287.
Équipe Coordination et plasticité des générateurs spinaux (Sandrine Bertrand).
Locomotion, as any other forms of physical activity, mobilizes the autonomic nervous system to match the increasing physiological demand. These autonomic responses mostly rely on the coupling between sympathetic and somatic motor activities. The propriospinal cholinergic system plays an important role in the control of locomotor networks, and several lines of evidences suggest that it may also activate sympathetic preganglionic neurons from the intermediolateral nucleus (IMLs).
The aim of my doctoral thesis was to investigate the role of the cholinergic propriospinal system in the coordination between these two systems. Using the in vitro isolated spinal cord from new born rat, we showed that application of acetylcholine synchronized the locomotor and sympathetic networks, via the activation of muscarinic receptors. Indeed, the non-selective agonist oxotremorine induced slow rhythmic activity blocked by muscarinic receptor antagonists. In addition, oxotremorine revealed endogenous rhythmogenic capabilities of the thoracic segments.
This slow oscillatory activity propagated from thoracic ventral roots to lumbar ones, but not the reverse. We observed that thoracic MNs were rhythmically activated during both locomotor-like activity and oxotremorine-induced rhythm. In contrast, IMLs were rhythmically activated solely in the presence of oxotremorine. This study provides new light on the origin of the coupling between the somatic and the sympathetic systems. We propose that synchronizing mechanisms are achieved in part by an intraspinal network which may be activated under the control of the cholinergic propriospinal system.
Keywords: spinal cord, electrophysiology, somatic system, sympathetic system, acetylcholine.
– Sourioux M*, Bestaven E*, Guillaud E, Bertrand SS, Cabanas M, Milan L, Mayo W, Garret M & Cazalets JR. 3-D motion capture for long-term tracking of spontaneous locomotor behaviors and circadian sleep/wake rhythms in mouse. Journal of Neuroscience Methods (2017). In press. *contributed equally
– Sourioux M, Bertrand SS & Cazalets JR. A cholinergic-activated thoracic spinal network for coupling of locomotor and sympathetic activities. Submitted.