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Progressive morphological abnormalities observed in rat spinal motor neurons at extended intervals after axonal regeneration
Author(s) -
Bowe Constance M.,
Evans Nyle H.,
Vlacha Vasoliki
Publication year - 1992
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903210406
Subject(s) - axotomy , motor neuron , spinal cord , dorsal root ganglion , biology , neuroscience , anatomy , sciatic nerve , axoplasmic transport , spinal cord injury , regeneration (biology) , sensory system , axon , central nervous system , microbiology and biotechnology
It is generally accepted that mammalian spinal motor neurons return to normal after axotomy if their regenerated axons successfully reinnervate appropriate peripheral targets. However, morphological abnormalities, recently observed in spinal motor neurons examined 1 year after nerve crush injury, raise the possibility that delayed perikaryal changes occur after regeneration is complete. In order to distinguish between chronic and progressive alterations in neurons with long‐term regenerated axons, rat spinal motor neurons and dorsal root ganglion cells were examined at 5 and 10 months following unilateral sciatic nerve crush. Neurons with regenerated axons were identified by retrograde labelling with horseradish peroxidase. The structural properties of neurons ipsilateral to nerve injury were compared to those of neurons from the spinal cord and dorsal root ganglia on the contralateral side and from age‐matched control rats. At 5 months postcrush, the morphology of motor and sensory neurons ipsilateral to injury was comparable to that of control cells. However, several features of the motor neurons with regenerated axons distinguished them from control motor neurons at 10 months postcrush. Mean perikaryal area of ipsilateral spinal motor neurons was larger than the means for control motor neurons (p < 0.001). Ipsilateral spinal motor neurons also appeared clustered within the spinal cord and had thicker dendrites. Dorsal root ganglion cells with regenerated axons were slightly larger than control cells at 10 months postcrush but they exhibited no other morphological changes. The present findings indicate that spinal motor neurons are progressively altered after their regenerated axons have reestablished functional synapses with their peripheral targets. © 1992 Wiley‐Liss, Inc.