Effects of forced, passive, and voluntary exercise on spinal motoneurons changes after peripheral nerve injury

Abstract

After peripheral nerve injury, there are important changes at the spinal level that can lead to disorganization of the central circuitry and thus compromise functional recovery even if axons are able to successfully regenerate and reinnervate their target organs. Physical rehabilitation is a promising strategy to modulate these plastic changes and thus to improve functional recovery after the damage of the nervous system. Forced exercise in a treadmill is able to partially reverse the synaptic stripping and the loss of perineuronal nets that motoneurons suffer after peripheral nerve injury in animal models. The aim of this study was to investigate whether passive exercise, by means of cycling in a motorized bicycle, or voluntary free running in a wheel is able to mimic the effects induced by forced exercise on the changes that axotomized motoneurons suffer after peripheral nerve injury. Partial preservation of synapses and perineuronal nets was observed only in axotomized motoneurons from animals subjected to high-intensity cycling and the ones that freely ran long distances, but not when low-intensity exercise protocols were applied. Therefore, the intensity but not the type of exercise used is the key element to prevent synaptic stripping and loss of perineuronal nets in motoneurons after axotomy.

Effects of exercise on muscle reinnervation and plasticity of spinal circuits in rat sciatic nerve crush injury models with different numbers of crushes

“…SYN is a synaptic marker that labels almost all axon terminals. A previous study 29 reported that many axon terminals, except of primary afferent neurons, recover from withdrawal of synaptic input, which is also consistent with our results.…”

“…[17][18][19][20][21][22][23][24][25] Promoting axonal regeneration facilitates reinnervation of the NMJ, 26 and enhancing afferent input to motor neurons via exercise reconnects primary afferents and motor neurons that have withdrawn because of the modulation of spinal cord changes, reestablishing synaptic function. [27][28][29] A planned peripheral nerve insult (conditioning lesion [CL]) promotes the axonal regeneration of peripheral nerves in response to subsequent nerve damage. 30 It has been reported that after repeated peripheral nerve injury by CL, the time from injury to the onset of regeneration is shortened, 31 and the rate of axonal outgrowth 32,33 and the number of regenerating axons 34 are increased.…”

Effects of Two Training Programs on Transcriptional Levels of Neurotrophins and Glial Cells Population in Hippocampus of Experimental Multiple Sclerosis

“…Conversely, the LICT also could not promote significant changes in microglia morphology, indicating that HIIT rather than LICT is a highly effective strategy to improve neuroinflammation in the brain compared to CT [62]. Additionally, Arbat-Plana observed that higher intensity protocols reduced microglia reactivity to modulate the spinal changes after nerve damage [5]. Therefore, the differences in neuroinflammation response can be explained by differences in the amount of stress induced by the different protocols of physical activity.…”

GDNF to the rescue: GDNF delivery effects on motor neurons and nerves, and muscle re-innervation after peripheral nerve injuries

“…There is increasing evidence of exercise having beneficial regenerative, rehabilitative, and neuro-plasticity-associated effects in central and peripheral nervous systems (Park and Höke, 2014;Arbat-Plana et al, 2017;Theisen et al, 2017). Additionally, exercise has been linked with possible neurotrophic factor signaling regulation, as reviewed by Cobianchi et al (2017) and Cintrón-Colón et al (2020).…”