Altered development in GABA co-release shapes glycinergic synaptic currents in cultured spinal slices of the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.
Increased environmental risk factors in conjunction with genetic susceptibility have been proposed with respect to the remarkable variations in mortality in amyotrophic lateral sclerosis (ALS). In vitro models allow the investigation of the genetically modified counter-regulator of motoneuron toxicity and may help in addressing ALS therapy. Spinal organotypic slice cultures from a mutant form of human superoxide dismutase 1 (SOD1G93A) mouse model of ALS allow the detection of altered glycinergic inhibition in spinal microcircuits. This altered inhibition improved spinal cord excitability, affecting motor outputs in early SOD1(G93A) pathogenesis.



Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset neurological disease characterized by a progressive degeneration of motoneurons (MNs). In a previous study, we developed organotypic spinal cultures from an ALS mouse model expressing a mutant form of human superoxide dismutase 1 (SOD1(G93A) ). We reported the presence of a significant synaptic rearrangement expressed by these embryonic cultured networks, which may lead to the altered development of spinal synaptic signalling, which is potentially linked to the adult disease phenotype. Recent studies on the same ALS mouse model reported a selective loss of glycinergic innervation in cultured MNs, suggestive of a contribution of synaptic inhibition to MN dysfunction and degeneration. In the present study, we further exploit organotypic cultures from wild-type and SOD1(G93A) mice to investigate the development of glycine-receptor-mediated synaptic currents recorded from the interneurons of the premotor ventral circuits. We performed single cell electrophysiology, immunocytochemistry and confocal microscopy and suggest that GABA co-release may speed the decay of glycine responses altering both temporal precision and signal integration in SOD1(G93A) developing networks at the postsynaptic site. Our hypothesis is supported by the finding of an increased MN bursting activity in immature SOD1(G93A) spinal cords and by immunofluorescence microscopy detection of a longer persistence of GABA in SOD1(G93A) glycinergic terminals in cultured and ex vivo spinal slices.
Department of Life Sciences, University of Trieste, Trieste, Italy.
Manuela
M
Medelin
Department of Life Sciences, University of Trieste, Trieste, Italy.
Vladimir
V
Rancic
Department of Life Sciences, University of Trieste, Trieste, Italy.
Giada
G
Cellot
Department of Life Sciences, University of Trieste, Trieste, Italy.
Jummi
J
Laishram
International School for Advanced Studies (SISSA/ISAS), Trieste, Italy.
Priyadharishini
P
Veeraraghavan
Neuroimmunology Unit, Division of Neuroscience, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, Milan, Italy.
Chiara
C
Rossi
Neuroimmunology Unit, Division of Neuroscience, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, Milan, Italy.
Luca
L
Muzio
Department of Neuroscience, Physiology and Pharmacology, University College London (UCL), London, UK.
Lucia
L
Sivilotti
Department of Life Sciences, University of Trieste, Trieste, Italy.|International School for Advanced Studies (SISSA/ISAS), Trieste, Italy.
Laura
L
Ballerini
D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D000818:Animals; D004195:Disease Models, Animal; D004622:Embryo, Mammalian; D005260:Female; D007395:Interneurons / Q000502:physiology*; D008822:Mice, Transgenic; D018009:Receptors, Glycine / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D000072105:Superoxide Dismutase-1 / Q000235:genetics*; D009435:Synaptic Transmission; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018009:Receptors, Glycine; C000606290:SOD1 protein, human; D005680:gamma-Aminobutyric Acid; D000072105:Superoxide Dismutase-1