Axotomy induces nerve growth factor receptor immunoreactivity in spinal motor neurons.
Expression of the nerve growth factor receptor (NGF-R) mRNA in adult motor neurons is increased by axonal injury. The present study was designed to examine, by immunocytochemistry, the onset, course, and specificity of NGF-R up-regulation following distal or proximal crush of the sciatic nerve. Lesions at both levels induced the appearance of NGF-R-like immunoreactivity in motor neurons beginning on day two postaxotomy. NGF-R-like immunoreactivity was present exclusively in axotomized neurons, as verified by the near complete colocalization of immunoreactive NGF-R with a fluorescent retrograde tracer injected at the crush site. NGF-R expression was closely linked with disconnection of cells from the target; one week after muscle reinnervation, NGF-R immunoreactivity was no longer detectable in animals with distal injuries. These results extend the previous findings of axotomy-induced expression of NGF-R mRNA to the level of the receptor. Furthermore, our observations are consistent with the hypothesis that target-derived factors participate in the regulation of NGF-R gene expression in adult motor neurons.
Koliatsos
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Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2181.
Crawford
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Price
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D000818:Animals; D001369:Axons / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D008297:Male; D009046:Motor Neurons / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor; D012584:Sciatic Nerve / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017475:Receptors, Nerve Growth Factor