About this item:

459 Views | 0 Downloads

Author Notes:

Corresponding author: M. J. Pinter, Department of Physiology, Emory University, School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA. Email: mpinter@physio.emory.edu

We wish to thank Drs Robert Burgess, Kevin Seburn and Pete Wenner for comments on earlier versions of this manuscript.


Research Funding:

This work was supported by National Institute of Neurological Disorders and Stroke (NINDS) (Grant NS24707).

Rat motoneuron properties recover following reinnervation in the absence of muscle activity and evoked acetylcholine release


Journal Title:

Journal of Physiology


Volume 585, Number Pt 1


, Pages 47-56

Type of Work:

Article | Post-print: After Peer Review


Available evidence supports the idea that muscle fibres provide retrograde signals that enable the expression of adult motoneuron electrical properties but the mechanisms remain unknown. We showed recently that when acetylcholine receptors are blocked at motor endplates, the electrical properties of rat motoneurons change in a way that resembles changes observed after axotomy. This observation suggests that receptor blockade and axotomy interrupt the same signalling mechanisms but leaves open the possibility that the loss of muscle fibre activity underlies the observed effects. To address this issue, we examined the electrical properties of axotomized motoneurons following reinnervation. Ordinarily, these properties return to normal following reinnervation and re-activation of muscle, but in this study muscle fibre activity and evoked acetylcholine release were prevented during reinnervation by blocking axonal conduction. Under these conditions, the properties of motoneurons that successfully reinnervated muscle fibres recovered to normal despite the absence of muscle fibre activity and evoked release. We conclude that the expression of motoneuron electrical properties is not regulated by muscle fibre activity but rather by a retrograde signalling system coupled to activation of endplate acetylcholine receptors. Our results indicate that spontaneous release of acetylcholine from regenerated motor terminals is sufficient to operate the system.

Copyright information:

© 2007 The Authors, Journal compilation, The Physiological Society

Export to EndNote