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Ultrastructural synaptic features differ between alpha- and gamma-motoneurons innervating the tibialis anterior muscle in the rat

Ichiyama, Ronaldo M. ; Broman, Jonas LU ; Edgerton, V. Reggie and Havton, Leif A. (2006) In Journal of Comparative Neurology 499(2). p.306-315
Abstract
We investigated the synaptology of retrogradely labeled spinal motoneurons after injection of horseradish peroxidase into the tibialis anterior (TA) muscle of adult rat. In total, 32 TA motoneurons were investigated in the electron microscope and demonstrated a bimodal size distribution with cell diameter peaks at 40 mu m and 20 mu m, likely representing alpha- and gamma-motoneurons, respectively. Both alpha- and gamma-motoneurons were apposed by S- and F-type synaptic boutons, whereas only alpha-motoneurons demonstrated inputs by the large M- and C-type boutons. The proportion of cell body membrane covered by synaptic inputs was surprisingly indistinguishable between alpha-motoneurons (72.2%) and gamma-motoneurons (63.5%). The ratio... (More)
We investigated the synaptology of retrogradely labeled spinal motoneurons after injection of horseradish peroxidase into the tibialis anterior (TA) muscle of adult rat. In total, 32 TA motoneurons were investigated in the electron microscope and demonstrated a bimodal size distribution with cell diameter peaks at 40 mu m and 20 mu m, likely representing alpha- and gamma-motoneurons, respectively. Both alpha- and gamma-motoneurons were apposed by S- and F-type synaptic boutons, whereas only alpha-motoneurons demonstrated inputs by the large M- and C-type boutons. The proportion of cell body membrane covered by synaptic inputs was surprisingly indistinguishable between alpha-motoneurons (72.2%) and gamma-motoneurons (63.5%). The ratio between the number of F- and S-type boutons in apposition with the motoneuron cell body (F/S ratio) and the ratio between the soma membrane coverage provided by F- and S-type boutons were both significantly higher in alpha- than in gamma-motoneurons. When comparing our data with previous findings in other species, we conclude that rat TA alpha-motoneurons are similar to cat and primate alpha-motoneurons with regard to synaptic terminal morphology, frequency, and distribution. However, rat gamma-motoneurons show a markedly higher total synaptic coverage and frequency than cat gamma-motoneurons, although both species exhibit appositions made by the same synaptic types and similar ratios between inhibitory and excitatory inputs. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
spinal cord, horseradish peroxidase, electron microscopy, labeling, retrograde
in
Journal of Comparative Neurology
volume
499
issue
2
pages
306 - 315
publisher
John Wiley and Sons
external identifiers
  • pmid:16977622
  • wos:000240809400009
  • scopus:33749030203
ISSN
1096-9861
DOI
10.1002/cne.21110
language
English
LU publication?
yes
id
3240c8c9-3432-41ab-bae2-cfe1817cecd7 (old id 392690)
date added to LUP
2016-04-01 12:07:23
date last changed
2021-02-17 06:31:49
@article{3240c8c9-3432-41ab-bae2-cfe1817cecd7,
  abstract     = {We investigated the synaptology of retrogradely labeled spinal motoneurons after injection of horseradish peroxidase into the tibialis anterior (TA) muscle of adult rat. In total, 32 TA motoneurons were investigated in the electron microscope and demonstrated a bimodal size distribution with cell diameter peaks at 40 mu m and 20 mu m, likely representing alpha- and gamma-motoneurons, respectively. Both alpha- and gamma-motoneurons were apposed by S- and F-type synaptic boutons, whereas only alpha-motoneurons demonstrated inputs by the large M- and C-type boutons. The proportion of cell body membrane covered by synaptic inputs was surprisingly indistinguishable between alpha-motoneurons (72.2%) and gamma-motoneurons (63.5%). The ratio between the number of F- and S-type boutons in apposition with the motoneuron cell body (F/S ratio) and the ratio between the soma membrane coverage provided by F- and S-type boutons were both significantly higher in alpha- than in gamma-motoneurons. When comparing our data with previous findings in other species, we conclude that rat TA alpha-motoneurons are similar to cat and primate alpha-motoneurons with regard to synaptic terminal morphology, frequency, and distribution. However, rat gamma-motoneurons show a markedly higher total synaptic coverage and frequency than cat gamma-motoneurons, although both species exhibit appositions made by the same synaptic types and similar ratios between inhibitory and excitatory inputs.},
  author       = {Ichiyama, Ronaldo M. and Broman, Jonas and Edgerton, V. Reggie and Havton, Leif A.},
  issn         = {1096-9861},
  language     = {eng},
  number       = {2},
  pages        = {306--315},
  publisher    = {John Wiley and Sons},
  series       = {Journal of Comparative Neurology},
  title        = {Ultrastructural synaptic features differ between alpha- and gamma-motoneurons innervating the tibialis anterior muscle in the rat},
  url          = {http://dx.doi.org/10.1002/cne.21110},
  doi          = {10.1002/cne.21110},
  volume       = {499},
  year         = {2006},
}