A novel pharmacological approach and identification of peripheral cellular biomarkers in Niemann-Pick Type C disease patients

In our electrophysiological results input-output curve, BST and PPF didn’t show significantdifferences in CA1 pyramidal layer of hippocampal formation both in WT and NPC1 -/- miceslices. On the contrary, synaptic plasticity was affected: in fact induction and maintenance ofNMDA-dependent LTP in the CA1 region of NPC1 -/- hippocampal slices were significantlyreduced, suggesting that NMDA receptor activity is impaired. In line with these observations,we found a significantly reduction in NMDA-induced calcium influx in NPC culturedhippocampal neurons as compared with WT neurons. To evaluate if glutamate receptors displayfunctional changes in NPC1 -/- mice slices, we studied synaptic transmission duringpharmacological stimulation by adding to the bath solution KA and AMPA (2M). While theperfusion of KA depressed synaptic transmission at CA3-CA1 synapses in both groups ofanimals, followed by a recovery during washout only in NPC1 -/- mice slices, AMPAapplication induced a disappearance of synaptic transmission only in NPC1 -/- mice slices; theseresults indicate that AMPA-Kainate receptors present quantitative and/or a qualitativedifferences probably linked to lipid rafts disruption. Moreover electrophysiological results aresupported by data outcoming from cell culture experiments on excitatory aminoacid-inducedintracellular calcium increase. Indeed, application of KA and AMPA in WT and NPC1 -/-cultured cells induced different calcium influxes, which were increased in homozygote cells.However, Western Blot analysis of synaptosomal membrane fractions from NPC and WT micedid not reveal any significant difference in AMPA (GluR1), KA (GluR6/7, KA2) or NMDA(R2) receptor expression in the two groups of animals. We further investigated whether thiscould result in compromised intracellular signal transduction pathways in NPC -/- slicesfollowing kainic acid perfusion.