Motor neurons are rich in non-phosphorylated neurofilaments: Cross- species comparison and alterations in ALS

Yee Man Tsang, Freddie Chiong, Daniel Kuznetsov, Edward Kasarskis, Changiz Geula

Research output: Contribution to journalArticlepeer-review

111 Scopus citations


The localization and distribution of non-phosphorylated neurofilaments (NP-NF) in the upper and lower motor neurons was investigated in the rat, the common marmoset, the rhesus monkey and man using the SMI-32 antibody. Within the spinal cord of all species studied, the most intense NP-NF immunoreactivity was observed within the ventral horn α-motor neurons. Concurrent staining for the cholinergic marker choline acetyltransferase (ChAT) demonstrated that virtually all of the ChAT-positive α-motor neurons contain NP-NF immunoreactivity. Although NP-NF staining was also observed in other neurons within the ventral and intermediate horns, these neurons were loosely scattered and contained a considerably lower staining intensity. The only other prominent NP-NF staining in the spinal cord occurred within the neurons of the dorsal nucleus of Clark and the intermediolateral cell column. Phosphorylated neurofilament (P-NF) immunoreactivity was found primarily in neuronal processes. Occasionally, a solitary motor neuron contained weak P-NF immunoreactivity. Within the brainstem, neurons in all cranial nerve motor nuclei contained intense NP-NF immunoreactivity. The distribution and apparent density of NP-NF immunoreactive neurons in these nuclei was virtually identical to that observed for neurons immunoreactive for ChAT. NP- NF immunoreactive neurons of relatively lower intensity were found in many other regions of the brainstem. All of the giant Betz cells of layer (L) V in the motor cortex contained dark NP-NF immunoreactivity. Within the spinal cord of amyotrophic lateral sclerosis (ALS) patients, both Nissl and NP-NF staining demonstrated the dramatic loss of α-motor neurons characteristic of this disorder. Some of the remaining motor neurons contained intense P-NF immunoreactivity. These observations suggest that NP-NF immunoreactivity is a good marker for motor neurons in health and disease and may be a useful tool for studies of motor neuron degeneration (MND). (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)45-58
Number of pages14
JournalBrain Research
Issue number1
StatePublished - Apr 7 2000

Bibliographical note

Funding Information:
We thank Nicholas Nagykery for expert technical assistance. This work is supported in part by the Milton Fund of the Harvard Medical School.


  • Brainstem
  • Choline acetyltransferase
  • Cholinergic
  • Motor cortex
  • Phosphorylated neurofilament
  • Spinal cord

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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