इस नई विधि में एक एकल वयस्क माउस motoneuron और अपनी मांसपेशी फाइबर द्वारा उत्पादित बल की माप के साथ – साथ intracellular रिकॉर्डिंग परमिट. सामान्य और आनुवंशिक रूप से संशोधित पशुओं में मोटर इकाइयों के विद्युत और यांत्रिक गुणों की संयुक्त जांच neuromuscular प्रणाली के अध्ययन के लिए एक सफलता है.
The spinal motoneuron has long been a good model system for studying neural function because it is a neuron of the central nervous system with the unique properties of (1) having readily identifiable targets (the muscle fibers) and therefore having a very well-known function (to control muscle contraction); (2) being the convergent target of many spinal and descending networks, hence the name of “final common pathway”; and (3) having a large soma which makes it possible to penetrate them with sharp intracellular electrodes. Furthermore, when studied in vivo, it is possible to record simultaneously the electrical activity of the motoneurons and the force developed by their muscle targets. Performing intracellular recordings of motoneurons in vivo therefore put the experimentalist in the unique position of being able to study, at the same time, all the compartments of the “motor unit” (the name given to the motoneuron, its axon, and the muscle fibers it innervates1): the inputs impinging on the motoneuron, the electrophysiological properties of the motoneuron, and the impact of these properties on the physiological function of the motoneurons, i.e. the force produced by its motor unit. However, this approach is very challenging because the preparation cannot be paralyzed and thus the mechanical stability for the intracellular recording is reduced. Thus, this kind of experiments has only been achieved in cats and in rats. However, the study of spinal motor systems could make a formidable leap if it was possible to perform similar experiments in normal and genetically modified mice.
For technical reasons, the study of the spinal networks in mice has mostly been limited to neonatal in vitro preparations, where the motoneurons and the spinal networks are immature, the motoneurons are separated from their targets, and when studied in slices, the motoneurons are separated from most of their inputs. Until recently, only a few groups had managed to perform intracellular recordings of motoneurons in vivo2-4 , including our team who published a new preparation which allowed us to obtain very stable recordings of motoneurons in vivo in adult mice5,6. However, these recordings were obtained in paralyzed animals, i.e. without the possibility to record the force output of these motoneurons. Here we present an extension of this original preparation in which we were able to obtain simultaneous recordings of the electrophysiological properties of the motoneurons and of the force developed by their motor unit. This is an important achievement, as it allows us to identify the different types of motoneurons based on their force profile, and thereby revealing their function. Coupled with genetic models disturbing spinal segmental circuitry7-9, or reproducting human disease10,11, we expect this technique to be an essential tool for the study of spinal motor system.
यहाँ वर्णित तैयारी पहली बार है कि वयस्क माउस, एक काठ motoneuron और पेशी अपने अक्षतंतु द्वारा innervated फाइबर द्वारा उत्पादित बल की माप के साथ – साथ intracellular रिकॉर्डिंग की अनुमति देता है, है.
जानवर के छोटे आकार …
The authors have nothing to disclose.
यह काम Fondation डालना ला Recherche MEDICALE (एफ आर एम), ALS अनुसंधान (ALS एसोसिएशन), NIH NINDS NS05462 और NS034382 अनुदान, और ANR अनुदान HyperMND के लिए मिल्टन Safenowitz Postdoctoral फैलोशिप से वित्तीय सहायता के लिए संभव धन्यवाद किया गया था.
Name of the reagent | Company | Catalogue number | Comments (optional) |
Atropine sulfate | Aguettant | ||
Methylprenidsolone | Pfizer | Solu-Medrol | |
Sodium pentobarbitone | Sanofi-Aventis | Pentobarbital | |
Ketamine | |||
Xylazine | |||
Glucose | |||
Plasma expander | Roger Bellon | Plasmagel | |
Blunt scissors | FST | 14079-10 | |
Blunt fine scissors | FST | 15025-10 | |
Vannas Spring Scissors | FST | 15002-08 | |
Fine forceps serrated | FST | 11370-32 | |
Fine forceps serrated | FST | 11370-31 | |
Cunningham Spinal Adaptor | Stoelting Co. | ||
Kwik-Cast sealant | WPI | #KWIK-CAST | |
Ventilator | CWE Inc | SAR-830/AP | |
Capnograph | CWE Inc | μcapstar | |
Heating blanket | Harvard Apparatus | 507221F | |
Intracellular amplifier | Axon Instruments | Axoclamp 2B | |
Pipette puller | Sutter Instruments | P-97 | |
KCl | Sigma-Aldrich | P9333-500G |