The Journal of Neuroscience, August 1, 1998, 18(15):5789-5803
Readiness of Zebrafish Brain Neurons to Regenerate a Spinal
Axon Correlates with Differential Expression of Specific Cell
Recognition Molecules
Thomas
Becker1,
Robert
R.
Bernhardt1,
Eva
Reinhard3,
Mario F.
Wullimann2,
Enrico
Tongiorgi1, and
Melitta
Schachner1, 4
1 Department of Neurobiology, Swiss Federal Institute
of Technology, Hönggerberg, CH-8093 Zürich, Switzerland,
2 Brain Research Institute, University of Bremen, D-28334
Bremen, Germany, 3 Department of Pharmacology, Biozentrum,
University of Basel, CH-4056 Basel, Switzerland, and
4 Zentrum für Molekulare Neurobiologie Hamburg,
Universität Hamburg, D-20246 Hamburg, Germany
We analyzed changes in the expression of mRNAs for the axonal
growth-promoting cell recognition molecules L1.1, L1.2, and neural cell
adhesion molecule (NCAM) after a rostral (proximal) or caudal (distal)
spinal cord transection in adult zebrafish. One class of cerebrospinal
projection nuclei (represented by the nucleus of the medial
longitudinal fascicle, the intermediate reticular formation, and the
magnocellular octaval nucleus) showed a robust regenerative response
after both types of lesions as determined by retrograde tracing and/or
in situ hybridization for GAP-43. A second class
(represented by the nucleus ruber, the nucleus of the lateral
lemniscus, and the tangential nucleus) showed a regenerative response
only after proximal lesion. After distal lesion, upregulation of L1.1
and L1.2 mRNAs, but not NCAM mRNA expression, was observed in the first
class of nuclei. The second class of nuclei did not show any changes in
their mRNA expression after distal lesion. After proximal lesion, both
classes of brain nuclei upregulated L1.1 mRNA expression (L1.2 and NCAM were not tested after proximal lesion). In the glial environment distal
to the spinal lesion, labeling for L1.2 mRNA but not L1.1 or NCAM mRNAs
was increased. These results, combined with findings in the lesioned
retinotectal system of zebrafish (), indicate
that the neuron-intrinsic regulation of cell recognition molecules
after axotomy depends on the cell type as well as on the proximity of
the lesion to the neuronal soma. Glial reactions differ for different
regions of the CNS.
Key words:
CNS regeneration; teleost; Mauthner cell; L1; NCAM; axotomy
Copyright © 1998 Society for Neuroscience 0270-6474/98/18155789-15$05.00/0
Previous Article | Next Article
