Tenascin-R restricts posttraumatic remodeling of motoneuron innervation and functional recovery after spinal cord injury in adult mice

TY - JOUR

T1 - Tenascin-R restricts posttraumatic remodeling of motoneuron innervation and functional recovery after spinal cord injury in adult mice

AU - Apostolova, Ivayla

AU - Irintchev, Andrey

AU - Schachner, Melitta

PY - 2006/7/26

Y1 - 2006/7/26

N2 - Tenascin-R (TNR) is an extracellular glycoprotein in the CNS implicated in neural development and plasticity. Its repellent properties for growing axons in a choice situation with a conducive substrate in vitro have indicated that TNR may impede regeneration in the adult mammalian CNS. Here we tested whether constitutive lack of TNR has beneficial impacts on recovery from spinal cord injury in adult mice. Using the Basso, Beattie, Bresnahan (BBB) locomotor rating scale, we found that open-field locomotion in TNR-deficient (TNR-/-) mice recovered better that in wild-type (TNR+/+) littermates after compression of the thoracic spinal cord. We also designed, validated, and applied a motion analysis approach allowing numerical assessment of motor functions. We found, in agreement with the BBB score, that functions requiring low levels of supraspinal control such as plantar stepping improved more in TNR-/- mice. This was not the case for motor tasks demanding precision such as ladder climbing. Morphological analyses revealed no evidence that improved recovery of some functions in the mutant mice were attributable to enhanced tissue sparing or axonal regrowth. Estimates of perisomatic puncta revealed reduced innervation by cholinergic and GABAergic terminals around motoneurons in intact TNR-/- compared with TNR+/+ mice. Relative to nonlesioned animals, spinal cord repair was associated with increase in GABAergic and decrease of glutamatergic puncta in TNR-/- but not in TNR+/+ mice. Our results suggest that TNR restricts functional recovery by limiting posttraumatic remodeling of synapses around motoneuronal cell bodies where TNR is normally expressed in perineuronal nets.

AB - Tenascin-R (TNR) is an extracellular glycoprotein in the CNS implicated in neural development and plasticity. Its repellent properties for growing axons in a choice situation with a conducive substrate in vitro have indicated that TNR may impede regeneration in the adult mammalian CNS. Here we tested whether constitutive lack of TNR has beneficial impacts on recovery from spinal cord injury in adult mice. Using the Basso, Beattie, Bresnahan (BBB) locomotor rating scale, we found that open-field locomotion in TNR-deficient (TNR-/-) mice recovered better that in wild-type (TNR+/+) littermates after compression of the thoracic spinal cord. We also designed, validated, and applied a motion analysis approach allowing numerical assessment of motor functions. We found, in agreement with the BBB score, that functions requiring low levels of supraspinal control such as plantar stepping improved more in TNR-/- mice. This was not the case for motor tasks demanding precision such as ladder climbing. Morphological analyses revealed no evidence that improved recovery of some functions in the mutant mice were attributable to enhanced tissue sparing or axonal regrowth. Estimates of perisomatic puncta revealed reduced innervation by cholinergic and GABAergic terminals around motoneurons in intact TNR-/- compared with TNR+/+ mice. Relative to nonlesioned animals, spinal cord repair was associated with increase in GABAergic and decrease of glutamatergic puncta in TNR-/- but not in TNR+/+ mice. Our results suggest that TNR restricts functional recovery by limiting posttraumatic remodeling of synapses around motoneuronal cell bodies where TNR is normally expressed in perineuronal nets.

KW - Animals

KW - Behavior, Animal

KW - Female

KW - Gait Disorders, Neurologic

KW - Mice

KW - Mice, Inbred C57BL

KW - Motor Neurons

KW - Nerve Regeneration

KW - Recovery of Function

KW - Spinal Cord Injuries

KW - Tenascin

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1523/JNEUROSCI.1526-06.2006

DO - 10.1523/JNEUROSCI.1526-06.2006

M3 - SCORING: Journal article

C2 - 16870730

VL - 26

SP - 7849

EP - 7859

JO - J NEUROSCI

JF - J NEUROSCI

SN - 0270-6474

IS - 30

M1 - 30

ER -