Reduction of axonal transport in the rat optic system after direct application of methylmercury

Michael Aschner, Patricia M. Rodier, Jacob N. Finkelstein

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Fast axonal transport of proteins in the optic nerve and tract was quantified by scintillation counts of protein-bound radioactivity along the visual pathway after an intraocular injection of [3H]proline. In control rats the label traveled at a rate of about 60 mm/day, reaching the optic chiasm at 4 h and the lateral geniculate body at 8 h postinjection. When methylmercury was injected simultaneously with [3H]proline, the label traveled at a rate of about 30 mm/day. At 8 h postinjection, the labeled protein had reached the optic chiasm, but the more distal pathway was unlabeled. The same pattern was observed histologically by emulsion autoradiography of the pathway. Some label was detected in the lateral geniculate of methylmercury-treated animals at 8 h, but this may have resulted from local incorporation, as judged by a similar level of labeling in the contralateral visual pathway. Alternatively, it may be the case that a small fraction of the axons in the treated pathway continued to transport proteins in a normal fashion. The very heavy label observed throughout the pathway in controls was present only in the proximal half of the pathway in methylmercury-treated rats. Methylmercury signficantly reduced incorporation of [3H]proline in the rat retina, but this reduction was not as great as the effect in the optic nerve. In contrast, cycloheximide, a potent protein synthesis inhibitor, reduced labeled protein in the optic nerve only to the same extent as it reduced incorporation. These results suggest that methylmercury's effect on transport is not dependent solely on its effects on protein synthesis, but represents a separate mechanism of neurotoxicity.

Original languageEnglish (US)
Pages (from-to)244-250
Number of pages7
JournalBrain Research
Volume381
Issue number2
DOIs
StatePublished - Sep 3 1986
Externally publishedYes

Fingerprint

Axonal Transport
Optic Nerve
Proline
Optic Chiasm
Visual Pathways
Carrier Proteins
Proteins
Intraocular Injections
Geniculate Bodies
Protein Synthesis Inhibitors
Cycloheximide
Emulsions
Autoradiography
Radioactivity
Axons
Retina

Keywords

  • autoradiography
  • axonal transport
  • methylmercury
  • rat
  • scintillation spectrometry

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this

Reduction of axonal transport in the rat optic system after direct application of methylmercury. / Aschner, Michael; Rodier, Patricia M.; Finkelstein, Jacob N.

In: Brain Research, Vol. 381, No. 2, 03.09.1986, p. 244-250.

Research output: Contribution to journalArticle

Aschner, Michael ; Rodier, Patricia M. ; Finkelstein, Jacob N. / Reduction of axonal transport in the rat optic system after direct application of methylmercury. In: Brain Research. 1986 ; Vol. 381, No. 2. pp. 244-250.
@article{05ddf8b24a0243d38a29bfa419bf1f1f,
title = "Reduction of axonal transport in the rat optic system after direct application of methylmercury",
abstract = "Fast axonal transport of proteins in the optic nerve and tract was quantified by scintillation counts of protein-bound radioactivity along the visual pathway after an intraocular injection of [3H]proline. In control rats the label traveled at a rate of about 60 mm/day, reaching the optic chiasm at 4 h and the lateral geniculate body at 8 h postinjection. When methylmercury was injected simultaneously with [3H]proline, the label traveled at a rate of about 30 mm/day. At 8 h postinjection, the labeled protein had reached the optic chiasm, but the more distal pathway was unlabeled. The same pattern was observed histologically by emulsion autoradiography of the pathway. Some label was detected in the lateral geniculate of methylmercury-treated animals at 8 h, but this may have resulted from local incorporation, as judged by a similar level of labeling in the contralateral visual pathway. Alternatively, it may be the case that a small fraction of the axons in the treated pathway continued to transport proteins in a normal fashion. The very heavy label observed throughout the pathway in controls was present only in the proximal half of the pathway in methylmercury-treated rats. Methylmercury signficantly reduced incorporation of [3H]proline in the rat retina, but this reduction was not as great as the effect in the optic nerve. In contrast, cycloheximide, a potent protein synthesis inhibitor, reduced labeled protein in the optic nerve only to the same extent as it reduced incorporation. These results suggest that methylmercury's effect on transport is not dependent solely on its effects on protein synthesis, but represents a separate mechanism of neurotoxicity.",
keywords = "autoradiography, axonal transport, methylmercury, rat, scintillation spectrometry",
author = "Michael Aschner and Rodier, {Patricia M.} and Finkelstein, {Jacob N.}",
year = "1986",
month = "9",
day = "3",
doi = "10.1016/0006-8993(86)90073-9",
language = "English (US)",
volume = "381",
pages = "244--250",
journal = "Brain Research",
issn = "0006-8993",
publisher = "Elsevier",
number = "2",

}

TY - JOUR

T1 - Reduction of axonal transport in the rat optic system after direct application of methylmercury

AU - Aschner, Michael

AU - Rodier, Patricia M.

AU - Finkelstein, Jacob N.

PY - 1986/9/3

Y1 - 1986/9/3

N2 - Fast axonal transport of proteins in the optic nerve and tract was quantified by scintillation counts of protein-bound radioactivity along the visual pathway after an intraocular injection of [3H]proline. In control rats the label traveled at a rate of about 60 mm/day, reaching the optic chiasm at 4 h and the lateral geniculate body at 8 h postinjection. When methylmercury was injected simultaneously with [3H]proline, the label traveled at a rate of about 30 mm/day. At 8 h postinjection, the labeled protein had reached the optic chiasm, but the more distal pathway was unlabeled. The same pattern was observed histologically by emulsion autoradiography of the pathway. Some label was detected in the lateral geniculate of methylmercury-treated animals at 8 h, but this may have resulted from local incorporation, as judged by a similar level of labeling in the contralateral visual pathway. Alternatively, it may be the case that a small fraction of the axons in the treated pathway continued to transport proteins in a normal fashion. The very heavy label observed throughout the pathway in controls was present only in the proximal half of the pathway in methylmercury-treated rats. Methylmercury signficantly reduced incorporation of [3H]proline in the rat retina, but this reduction was not as great as the effect in the optic nerve. In contrast, cycloheximide, a potent protein synthesis inhibitor, reduced labeled protein in the optic nerve only to the same extent as it reduced incorporation. These results suggest that methylmercury's effect on transport is not dependent solely on its effects on protein synthesis, but represents a separate mechanism of neurotoxicity.

AB - Fast axonal transport of proteins in the optic nerve and tract was quantified by scintillation counts of protein-bound radioactivity along the visual pathway after an intraocular injection of [3H]proline. In control rats the label traveled at a rate of about 60 mm/day, reaching the optic chiasm at 4 h and the lateral geniculate body at 8 h postinjection. When methylmercury was injected simultaneously with [3H]proline, the label traveled at a rate of about 30 mm/day. At 8 h postinjection, the labeled protein had reached the optic chiasm, but the more distal pathway was unlabeled. The same pattern was observed histologically by emulsion autoradiography of the pathway. Some label was detected in the lateral geniculate of methylmercury-treated animals at 8 h, but this may have resulted from local incorporation, as judged by a similar level of labeling in the contralateral visual pathway. Alternatively, it may be the case that a small fraction of the axons in the treated pathway continued to transport proteins in a normal fashion. The very heavy label observed throughout the pathway in controls was present only in the proximal half of the pathway in methylmercury-treated rats. Methylmercury signficantly reduced incorporation of [3H]proline in the rat retina, but this reduction was not as great as the effect in the optic nerve. In contrast, cycloheximide, a potent protein synthesis inhibitor, reduced labeled protein in the optic nerve only to the same extent as it reduced incorporation. These results suggest that methylmercury's effect on transport is not dependent solely on its effects on protein synthesis, but represents a separate mechanism of neurotoxicity.

KW - autoradiography

KW - axonal transport

KW - methylmercury

KW - rat

KW - scintillation spectrometry

UR - http://www.scopus.com/inward/record.url?scp=0022446132&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0022446132&partnerID=8YFLogxK

U2 - 10.1016/0006-8993(86)90073-9

DO - 10.1016/0006-8993(86)90073-9

M3 - Article

C2 - 2428435

AN - SCOPUS:0022446132

VL - 381

SP - 244

EP - 250

JO - Brain Research

JF - Brain Research

SN - 0006-8993

IS - 2

ER -