Biology Reference
In-Depth Information
Figure 6.1 Schematic illustration of hypothetical mechanisms supporting the effect of
physical exercise on nerve regeneration and functional recovery. Increased locomotion
by means of treadmill exercise gives rise to mechanosensory inputs that converge to
CNS and increase the input onto axotomized motoneurons, through regenerating sen-
sory neurons or propriospinal circuitry. Activation of descendent spinal pathways also
increases during treadmill running (not shown). Converging excitatory inputs enhance
the regenerative response of axotomized motoneurons and promote the increase in the
number of outgrowing axons into the distal nerve stump. Increased activity within neu-
ral pathways also stimulates axonal branching and raises the rate of axonal elongation.
Treadmill running might also increase the levels of neurotrophic factors in the ventral
horn of the spinal cord and in the regenerating nerve. The levels of proinflammatory
cytokines in the spinal cord and injured peripheral nerve are lowered by treadmill
exercise undertaken before and during the immediate days following PNS injury,
reflecting either lower neuroinflammatory response magnitude or faster resolution of
this response. Diminished levels of proinflammatory cytokines and of pronociceptive
neurotrophic factors in the dorsal horn of the spinal cord (e.g., GDNF and NT-3), as a
result of treadmill running, blunts glial activation, hyperreflexia, and prevents the devel-
opment of neuropathic pain. Mechanosensory inputs delivered by passive exercise trig-
ger a similar neuroprotective and neuroregenerative response.
manual mobilization in treating peripheral neuropathy in patients with
results only moderately positive.
ACKNOWLEDGMENT
This work was partially supported by grant PTDC/DES/104036/2008 from Funda¸˜o para a
Ciˆncia e a Tecnologia, Minist´rio da Educa¸
˜
o e Ciˆncia, Portugal.
