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Neural Plasticity
Volume 2015, Article ID 392591, 11 pages
http://dx.doi.org/10.1155/2015/392591
Research Article

Neuronal BDNF Signaling Is Necessary for the Effects of Treadmill Exercise on Synaptic Stripping of Axotomized Motoneurons

1Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Room 405P, Atlanta, GA 30322, USA
2Department of Plastic and Reconstructive Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China
3Department of Psychology, College of Charleston, 66 George Street, Charleston, SC 29424, USA

Received 1 February 2015; Revised 9 March 2015; Accepted 16 March 2015

Academic Editor: Manuel B. Graeber

Copyright © 2015 Joey Krakowiak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The withdrawal of synaptic inputs from the somata and proximal dendrites of spinal motoneurons following peripheral nerve injury could contribute to poor functional recovery. Decreased availability of neurotrophins to afferent terminals on axotomized motoneurons has been implicated as one cause of the withdrawal. No reduction in contacts made by synaptic inputs immunoreactive to the vesicular glutamate transporter 1 and glutamic acid decarboxylase 67 is noted on axotomized motoneurons if modest treadmill exercise, which stimulates the production of neurotrophins by spinal motoneurons, is applied after nerve injury. In conditional, neuron-specific brain-derived neurotrophic factor (BDNF) knockout mice, a reduction in synaptic contacts onto motoneurons was noted in intact animals which was similar in magnitude to that observed after nerve transection in wild-type controls. No further reduction in coverage was found if nerves were cut in knockout mice. Two weeks of moderate daily treadmill exercise following nerve injury in these BDNF knockout mice did not affect synaptic inputs onto motoneurons. Treadmill exercise has a profound effect on synaptic inputs to motoneurons after peripheral nerve injury which requires BDNF production by those postsynaptic cells.