Collateral sprouting in the electrosensory lateral line lobe of weakly electric teleosts (gymnotiformes) following ricin ablation

Michael Lannoo, L. Maler, R. Hawkes

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Sprouted collateral axons were observed in the electrosensory lateral line lobe (ELL) of gymnotiform teleosts (Apteronotus leptorhynchus) following the ablation of the supraorbital branch of the anterior lateral line nerve. Ablation was accomplished by using microinjections of the toxic lectin ricin. Sprouted axons were followed for up to 26 weeks postablation. Ricin exposure severely reduced axonal numbers and the peripheral electroreceptors in the region innervated by these fibers. To visualize sprouted fibers, intact lateral line afferent nerve branches were anterogradely labelled with the neuronal tract tracers horseradish peroxidase or cobalt chloride, or the monoclonal antibody Q26A3. Within the four somatotopically organized ELL segments, sprouted collaterals were first observed two weeks after ricin injection in the medial and centromedial segments, and four weeks postinjection in the centrolateral and lateral segments. Sprouting involved intrasegmental, horizontally directed axons from adjacent nerve branch terminal fields, and mixed intra- and extrasegmental, dorsally directed axons from the ELL deep fiber layer. The sprouting response was robust but variable in its timing, peaking between 6 and 12 weeks. Subsequently, the intrasegmental, horizontally directed fibers were retained but the mixed dorsally directed fibers, including all extrasegmental axons, were retracted. Therefore, this sprouting response appears to consist of a collateral overproduction followed by a selective axonal retraction. In our view, the most likely explanation for this axonal retraction is that the descending inputs from the isthmus and the cerebellum, as well as commissural fibers from the contralateral ELL, maintain established somatotopic relationships by eliminating somatotopically mismatched sprouted collaterals.

Original languageEnglish
Pages (from-to)246-256
Number of pages11
JournalJournal of Comparative Neurology
Volume333
Issue number2
StatePublished - 1993

Fingerprint

Gymnotiformes
Ricin
Axons
Neuronal Tract-Tracers
Poisons
Microinjections
Horseradish Peroxidase
Lectins
Cerebellum
Monoclonal Antibodies
Injections

Keywords

  • Apteronotus leptorhynchus
  • double labelling
  • immunocytochemistry
  • pattern formation
  • sensory maps

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Collateral sprouting in the electrosensory lateral line lobe of weakly electric teleosts (gymnotiformes) following ricin ablation. / Lannoo, Michael; Maler, L.; Hawkes, R.

In: Journal of Comparative Neurology, Vol. 333, No. 2, 1993, p. 246-256.

Research output: Contribution to journalArticle

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