Pathological changes of distal motor neurons after complete spinal cord injury.
Traumatic spinal cord injury (SCI) causes serious disruption of neuronal circuits that leads to motor functional deficits. Regeneration of disrupted circuits back to their original target is necessary for the restoration of function after SCI, but the pathophysiological condition of the caudal spinal cord has not been sufficiently studied. Here we investigated the histological and biological changes in the distal part of the injured spinal cord, using a mice model of complete thoracic SCI in the chronic stage (3 months after injury). Atrophic changes were widely observed in the injured spinal cord both rostral and caudal to the lesion, but the decrease in area was mainly in the white matter in the rostral spinal cord while both the white and gray matter decreased in the caudal spinal cord. The number of the motor neurons was maintained in the chronic phase of injury, but the number of presynaptic boutons decreased in the lumbar motor neurons caudal to the lesion. Using laser microdissection, to investigate gene expressions in motor neurons caudal to the lesion, we observed a decrease in the expressions of neuronal activity markers. However, we found that the synaptogenic potential of postsynapse molecules was maintained in the motor neurons after SCI with the expression of acetylcholine-related molecules actually higher after SCI. Collectively, our results show that the potential of synaptogenesis is maintained in the motor neurons caudal to the lesion, even though presynaptic input is decreased. Although researches into SCI concentrate their effort on the lesion epicenter, our findings suggest that the area caudal to the lesion could be an original therapeutic target for the chronically injured spinal cord.
['Yokota|Kazuya|K|', 'Kubota|Kensuke|K|', 'Kobayakawa|Kazu|K|', 'Saito|Takeyuki|T|', 'Hara|Masamitsu|M|', 'Kijima|Ken|K|', 'Maeda|Takeshi|T|', 'Katoh|Hiroyuki|H|', 'Ohkawa|Yasuyuki|Y|', 'Nakashima|Yasuharu|Y|', 'Okada|Seiji|S|']
D000109:Acetylcholine D000818:Animals D001284:Atrophy D000071437:Axon Guidance D059329:Cholinergic Neurons D002908:Chronic Disease D005260:Female D005786:Gene Expression Regulation D061346:Laser Capture Microdissection D008159:Lumbar Vertebrae D008810:Mice, Inbred C57BL D009046:Motor Neurons D018377:Neurotransmitter Agents D017729:Presynaptic Terminals D013116:Spinal Cord D013119:Spinal Cord Injuries D013569:Synapses
Motor neurons Spinal cord injury Chronic phase Laser microdissection Synaptogenic potential Cell-selective gene expression