December 2002
Volume 43, Issue 13
Free
ARVO Annual Meeting Abstract  |   December 2002
Growth Rate Of Transected Axons Of Retinal Ganglion Cells In Adult Cat
Author Affiliations & Notes
  • M Watanabe
    Department of Physiology Inst for Devlpmntal Research Kasugai 480-0392 Japan
  • H Maki
    Neurosurgery Nagoya University School of Medicine Nagoya 466-8550 Japan
  • M Katoh
    Physiology Institute for Developmental research Kasugai 480-0392 Japan
  • Footnotes
    Commercial Relationships   M. Watanabe, None; H. Maki, None; M. Katoh, None. Grant Identification: Grants from The Ministry of Education, Culture, Science and Technology, Special Coordination Fund fo
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 761. doi:
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      M Watanabe, H Maki, M Katoh; Growth Rate Of Transected Axons Of Retinal Ganglion Cells In Adult Cat . Invest. Ophthalmol. Vis. Sci. 2002;43(13):761.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: Although transected axons of retinal ganglion cells (RGCs) regenerate into a transplanted peripheral nerve segment (PN), the numbers of RGCs with regenerated axons are fewer than 5000 in the cat retina (Watanabe et al., 1993). Enhancing axonal regrowth would be one of promising methods to obtain more regenerated RGCs. We estimated the rate of growth of RGC axons regenerating in a PN as the control value. Methods: The left transected ON of anesthetized cats was connected with a PN segment. After 4, 6, and 8 week survival, RGCs with regenerated axons were doubly labeled with two fluorescent dyes (dextran-fluorescein & -rhodamine) injected at 10 mm (2 day before enucleation) and 20 mm (4 day before enucleation) from the ON connection. Numbers of single- and double-labeled RGCs were counted. Proportions of alpha, beta and not alpha/beta (NAB) were estimated by Lucifer yellow (LY)injection. Results: Average numbers of RGCs with 10 mm-regenerated axons were 2250 on 4 wk, 4009 on 6 wk, and 2871 on 8 wk. Percentages of RGCs with 10 & 20 mm-regenerated axons were 17% (4 wk), 65% (6 wk), and 66% (8 wk) of RGCs with 10 mm-regenerated axons. These values indicate that most RGCs extended their axons to 10 mm by 6 wk. From a scatter diagram of ratios of double-labeling vs surviving weeks, we obtained a formula: Y= 73.6 ln(X)-78.3, where Y is double labeling ratio (%), X survival (week). The formula indicates that the fastest axon reached at 20 mm by 2.9 wk, the slowest one did by 11.1 wk. Supposing a lag of regrowth as 4.5 days (Cho & So, 1989), ratios of axonal growth were: 1.3 mm/day for the fastest, 0.27 mm/day for the slowest. LY injections did not show clear difference in rates among cell types so far. Conclusion: The value 1.3 mm/day is close to that in hamster RGCs, 2 mm/day. The present experiment provides a model system to search for methods to enhance regrowth of damaged CNS axons.

Keywords: 553 regeneration • 415 ganglion cells • 604 transcription 
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