Journal of Neuroscience, Vol 9, 1481-1489, Copyright © 1989 by Society for Neuroscience
The noradrenergic neurotoxin DSP-4 eliminates the coeruleospinal projection but spares projections of the A5 and A7 groups to the ventral horn of the rat spinal cord
WE Lyons, JM Fritschy and R Grzanna
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Systemic administration of the noradrenergic neurotoxin DSP-4 results in a
complete loss of staining of noradrenergic (NA) axons in the dorsal horn
and intermediate zone of the rat spinal cord. NA axon staining in the
ventral horn and in the intermediolateral cell column is only slightly
decreased by the drug treatment. We have taken advantage of this
differential effect of DSP-4 on NA axons to determine the location and
number of cells that give rise to NA axons in the ventral horn and the
intermediolateral cell column. Retrograde transport of the fluorescent
tracer True blue was combined with dopamine-beta-hydroxylase
immunohistochemistry 2 weeks after treatment of rats with 50 mg/kg of
DSP-4. Compared with controls, the drug treatment resulted in a more than
90% decrease in the number of retrogradely labeled NA neurons in the locus
coeruleus and an only 30- 50% reduction in the number of retrogradely
labeled NA cells in the A5 and A7 groups. The results reveal different
sites of termination in the spinal cord of NA axons originating in the LC
and in NA cells of the A5 and A7 groups: the LC distributes fibers mainly
to the dorsal horn and the intermediate zone, while NA cells of the A5 and
A7 groups project to motoneurons of the ventral horn and the
intermediolateral cell column.