Neuromodulation exerted by ASICs channels after excitotoxic damage in a model of spinal injury

P. VEERARAGHAVAN; OSVALDO D UCHITEL; CARLOTA GONZÁLEZ INCHAUSPE; GRACIELA L MAZZONE; ANDREA NISTRI; P. VEERARAGHAVAN; OSVALDO D UCHITEL; CARLOTA GONZÁLEZ INCHAUSPE; GRACIELA L MAZZONE; ANDREA NISTRI

Copenhagen

Congreso; 10th FENS Forum of Neuroscience; 2016

Federation of European Neuroscience Societies (FENS)

In the spinal cord high extracellular glutamateconcentration-evoked excitotoxicdamage has large negative impact on loss of locomotor function and neuronaldeath. Cell dysfunction is associated with acidic pHfluctuations and acid-sensingion channels (ASICs) activation that may exert an important role in pathologiesrelated to neurodegeneration. We have shown that 1h application of the glutamate analogue kainatelargely destroys neurons via excitotoxicity with only modest whitematter damage (Mazzone et al, 2010). Our present goal was to enquire how kainatecould modulate the expression of ASICs, locomotorfunction and cell death. Mouse organotypic spinal slices (22 DIV) weretreated with kainate (0.01 or 0.1 mM) for 1h, and then washed for 24h prior toanalysis. The evaluation of cell viability by propidium iodide stainingdemonstrated stronger kainate-induced damage. RT-PCRresults showed that kainate (0.01 mM) increased the mRNA expression levels of ASIC1a, ASIC1b, ASIC2 and ASIC3. A more potent excitotoxicstimulation reduced theexpression of ASIC1a and ASIC2. Indeed, 4',6-diamidino-2-phenylindole(DAPI, 3.5 µM), a potent ASICs inhibitor, decreased mRNA expression levels. Immunohistochemistryindicated a much larger loss of neurons using kainate followed by delayed DAPIand amiloride (100 µM) treatment. Electrophysiological recording fromisolated spinal cords showed that fictive locomotion, slowed down by kainate,was fully abolished by continuous application of DAPI or amiloride. Thus,our data indicate that early rise of ASICs expression was associated with kainate-mediatedexcitotoxicity in spinal cordpreparations, with a potential effect on network plasticity and implications for neuroprotectivestrategies. Supported by FLENI, CONICET.