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Age-Related Changes in Pre- and Postsynaptic Partners of the Cholinergic C-Boutons in Wild-Type and SOD1G93A Lumbar Motoneurons.

Milan L, Courtand G, Cardoit L, Masmejean F, Barrière G, Cazalets JR, Garret M, Bertrand SS - PLoS ONE (2015)

Bottom Line: In WT motoneurons, both C-bouton terminals and associated M2 postsynaptic receptors presented a complex age-related dynamic that appeared completely disrupted in SOD1 motoneurons.Finally, we showed that early C-bouton system alterations have no physiological impact on the cholinergic neuromodulation of newborn motoneurons.Altogether, these data suggest a complete reconfiguration of the spinal cholinergic system in SOD1 spinal networks that could be part of the compensatory mechanisms established during spinal development.

View Article: PubMed Central - PubMed

Affiliation: INCIA, Université de Bordeaux, CNRS UMR5287, Bordeaux, France.

ABSTRACT
Large cholinergic synaptic terminals known as C-boutons densely innervate the soma and proximal dendrites of motoneurons that are prone to neurodegeneration in amyotrophic lateral sclerosis (ALS). Studies using the Cu/Zn-superoxide dismutase (SOD1) mouse model of ALS have generated conflicting data regarding C-bouton alterations exhibited during ALS pathogenesis. In the present work, a longitudinal study combining immunohistochemistry, biochemical approaches and extra- and intra-cellular electrophysiological recordings revealed that the whole spinal cholinergic system is modified in the SOD1 mouse model of ALS compared to wild type (WT) mice as early as the second postnatal week. In WT motoneurons, both C-bouton terminals and associated M2 postsynaptic receptors presented a complex age-related dynamic that appeared completely disrupted in SOD1 motoneurons. Indeed, parallel to C-bouton morphological alterations, analysis of confocal images revealed a clustering process of M2 receptors during WT motoneuron development and maturation that was absent in SOD1 motoneurons. Our data demonstrated for the first time that the lamina X cholinergic interneurons, the neuronal source of C-boutons, are over-abundant in high lumbar segments in SOD1 mice and are subject to neurodegeneration in the SOD1 animal model. Finally, we showed that early C-bouton system alterations have no physiological impact on the cholinergic neuromodulation of newborn motoneurons. Altogether, these data suggest a complete reconfiguration of the spinal cholinergic system in SOD1 spinal networks that could be part of the compensatory mechanisms established during spinal development.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical observation of cleaved caspase 3 in lamina X cholinergic interneurons in P100 mice.Representative epifluorescence photomicrographs of double labeling of CholineAcetylTransferase (ChAT, red channel) and cleaved caspase 3 (Caspase 3, green channel) in two motoneurons and two lamina X cholinergic interneurons in L2 lumbar segments from 100 postnatal days (P100) SOD1 mice. Note that cleaved caspase 3-positive motoneurons exhibit a weak ChAT staining. Scale bar: 15 μm.
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pone.0135525.g006: Immunohistochemical observation of cleaved caspase 3 in lamina X cholinergic interneurons in P100 mice.Representative epifluorescence photomicrographs of double labeling of CholineAcetylTransferase (ChAT, red channel) and cleaved caspase 3 (Caspase 3, green channel) in two motoneurons and two lamina X cholinergic interneurons in L2 lumbar segments from 100 postnatal days (P100) SOD1 mice. Note that cleaved caspase 3-positive motoneurons exhibit a weak ChAT staining. Scale bar: 15 μm.

Mentions: This enrichment was no more present in SOD1 P100 mice, suggesting a loss of lamina X ChIns at this stage. Because the death-mediating protease, caspase-3, is activated in SOD1G93A motoneurons [27,28], we investigated the possible activation of this apoptosis marker in lamina X ChIns in SOD1 P100 spinal cord. While cleaved caspase 3 staining was not detected in L2 spinal cord sections of age-matched WT littermates (data not shown), cleaved caspase 3 immunopositivity was observed both in motoneurons demonstrating weak ChAT expression (Fig 6, left panel) and in lamina X ChIns (Fig 6, right panel) in P100 SOD1 mice. These data further validate that Mns are not the only neurons to degenerate in the SOD1 spinal motor network and indicate for the first time that lamina X ChIns are subject to neurodegeneration in the SOD1 ALS model.


Age-Related Changes in Pre- and Postsynaptic Partners of the Cholinergic C-Boutons in Wild-Type and SOD1G93A Lumbar Motoneurons.

Milan L, Courtand G, Cardoit L, Masmejean F, Barrière G, Cazalets JR, Garret M, Bertrand SS - PLoS ONE (2015)

Immunohistochemical observation of cleaved caspase 3 in lamina X cholinergic interneurons in P100 mice.Representative epifluorescence photomicrographs of double labeling of CholineAcetylTransferase (ChAT, red channel) and cleaved caspase 3 (Caspase 3, green channel) in two motoneurons and two lamina X cholinergic interneurons in L2 lumbar segments from 100 postnatal days (P100) SOD1 mice. Note that cleaved caspase 3-positive motoneurons exhibit a weak ChAT staining. Scale bar: 15 μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4549056&req=5

pone.0135525.g006: Immunohistochemical observation of cleaved caspase 3 in lamina X cholinergic interneurons in P100 mice.Representative epifluorescence photomicrographs of double labeling of CholineAcetylTransferase (ChAT, red channel) and cleaved caspase 3 (Caspase 3, green channel) in two motoneurons and two lamina X cholinergic interneurons in L2 lumbar segments from 100 postnatal days (P100) SOD1 mice. Note that cleaved caspase 3-positive motoneurons exhibit a weak ChAT staining. Scale bar: 15 μm.
Mentions: This enrichment was no more present in SOD1 P100 mice, suggesting a loss of lamina X ChIns at this stage. Because the death-mediating protease, caspase-3, is activated in SOD1G93A motoneurons [27,28], we investigated the possible activation of this apoptosis marker in lamina X ChIns in SOD1 P100 spinal cord. While cleaved caspase 3 staining was not detected in L2 spinal cord sections of age-matched WT littermates (data not shown), cleaved caspase 3 immunopositivity was observed both in motoneurons demonstrating weak ChAT expression (Fig 6, left panel) and in lamina X ChIns (Fig 6, right panel) in P100 SOD1 mice. These data further validate that Mns are not the only neurons to degenerate in the SOD1 spinal motor network and indicate for the first time that lamina X ChIns are subject to neurodegeneration in the SOD1 ALS model.

Bottom Line: In WT motoneurons, both C-bouton terminals and associated M2 postsynaptic receptors presented a complex age-related dynamic that appeared completely disrupted in SOD1 motoneurons.Finally, we showed that early C-bouton system alterations have no physiological impact on the cholinergic neuromodulation of newborn motoneurons.Altogether, these data suggest a complete reconfiguration of the spinal cholinergic system in SOD1 spinal networks that could be part of the compensatory mechanisms established during spinal development.

View Article: PubMed Central - PubMed

Affiliation: INCIA, Université de Bordeaux, CNRS UMR5287, Bordeaux, France.

ABSTRACT
Large cholinergic synaptic terminals known as C-boutons densely innervate the soma and proximal dendrites of motoneurons that are prone to neurodegeneration in amyotrophic lateral sclerosis (ALS). Studies using the Cu/Zn-superoxide dismutase (SOD1) mouse model of ALS have generated conflicting data regarding C-bouton alterations exhibited during ALS pathogenesis. In the present work, a longitudinal study combining immunohistochemistry, biochemical approaches and extra- and intra-cellular electrophysiological recordings revealed that the whole spinal cholinergic system is modified in the SOD1 mouse model of ALS compared to wild type (WT) mice as early as the second postnatal week. In WT motoneurons, both C-bouton terminals and associated M2 postsynaptic receptors presented a complex age-related dynamic that appeared completely disrupted in SOD1 motoneurons. Indeed, parallel to C-bouton morphological alterations, analysis of confocal images revealed a clustering process of M2 receptors during WT motoneuron development and maturation that was absent in SOD1 motoneurons. Our data demonstrated for the first time that the lamina X cholinergic interneurons, the neuronal source of C-boutons, are over-abundant in high lumbar segments in SOD1 mice and are subject to neurodegeneration in the SOD1 animal model. Finally, we showed that early C-bouton system alterations have no physiological impact on the cholinergic neuromodulation of newborn motoneurons. Altogether, these data suggest a complete reconfiguration of the spinal cholinergic system in SOD1 spinal networks that could be part of the compensatory mechanisms established during spinal development.

No MeSH data available.


Related in: MedlinePlus