Journal of Neuroscience, Vol 3, 915-923, Copyright © 1983 by Society for Neuroscience
Neuron-specific enolase as an index of neuronal regeneration and reinnervation
T Kirino, MW Brightman, WH Oertel, DE Schmechel and PJ Marangos
Neuron-specific enolase (NSE) is a glycolytic isoenzyme which is located in
central and peripheral neurons and neuroendocrine cells. Another enolase
isoenzyme, non-neuronal enolase (NNE), occurs in glial cells. The purpose
of this study was to follow any changes in NSE and/or NNE in cranial motor
neurons after separation of their cell bodies from their axon terminals.
One hypoglossal nerve in the rat and the cynomolgus monkey was thus crushed
or cut and, after a given period, the brains were perfusion fixed.
Immunocytochemistry, using anti-rat NSE and NNE or anti-human NSE and NNE,
was performed on Vibratome-sectioned specimens of the hypoglossal nuclei.
In the rat, NSE immunostaining decreased in the affected neurons 2 to 10
days following axonal injury. The change was greatest on the 10th day.
Twenty days following nerve crush. NSE staining began to recover on the
operated side and by the 45th day had returned to normal levels. NSE
changes in the monkey were similar to those in the rat. In rats, where the
nerve was cut and the proximal stump was translocated to a normally
innervated muscle to inhibit re-formation of synaptic contacts, the NSE
remained low for 60 days after nerve injury. As NSE levels fell during
degeneration, there was a slight increase in NNE in some of the monkey
specimens but not in others; the NNE alterations were, therefore,
equivocal. The results demonstrate that the content of NSE in neurons
serves as a molecular marker of axon injury, regeneration, and target
reinnervation.