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

• Published in: PloS one Vol. 10; no. 8; p. e0135525
• Main Authors: Milan, Léa, Courtand, Gilles, Cardoit, Laura, Masmejean, Frédérique, Barrière, Grégory, Cazalets, Jean-René, Garret, Maurice, Bertrand, Sandrine S
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-08-2015; Public Library of Science (PLoS)
• Subjects: Age; Aging; Aging - metabolism; Alzheimer's disease; Amyotrophic lateral sclerosis; Animals; Animals, Newborn; Cholinergic Neurons; Cholinergic Neurons - drug effects; Cholinergic Neurons - metabolism; Cholinergic transmission; Clustering; Cognitive science; Correlation analysis; Dendrites; Immunoglobulins; Immunohistochemistry; Interneurons; Interneurons - drug effects; Interneurons - metabolism; Laboratories; Lumbar Vertebrae; Lumbar Vertebrae - pathology; Male; Mice; Mice, Transgenic; Morphology; Motor Neurons; Motor Neurons - drug effects; Motor Neurons - metabolism; Neurodegeneration; Neuromodulation; Neurons; Neuroscience; Neurosciences; Neurotransmitter Agents; Neurotransmitter Agents - pharmacology; Oxotremorine; Oxotremorine - pharmacology; Pathogenesis; Physiology; Presynapse; Presynaptic Terminals; Presynaptic Terminals - drug effects; Presynaptic Terminals - metabolism; Receptors; Receptors, Muscarinic; Receptors, Muscarinic - metabolism; Reconfiguration; Rodents; Spinal Cord; Spinal Cord - metabolism; Superoxide Dismutase; Superoxide Dismutase - genetics; Terminals; Zinc; France; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0135525

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.