Figure 6.

CSPGs decrease synapse formation and spontaneous activity of drNPC-O2-derived neurons through activation of LAR and PTPσ receptors. A, B, Synaptic density was assessed by co-immunostaining for β-tubulin, presynaptic (synaptophysin) and postsynaptic (PSD-95) markers. F, Quantification of synaptophysin/PSD-95 co-localization indicated that CSPGs decreased synapse formation and ILP/ISP co-treatment was able to significantly reverse these effects. Values represent mean ± SEM, *p < 0.05; one-way ANOVA, N = 4, 20–25 neurons per condition (each N). C, Electrophysiological recording of EPSC of drNPC-O2-derived neurons in presence of picrotoxin (50 μm) for blocking GABAergic synapses, strychnine (2 μm) for blocking glycinergic synapses and TTX (1 μm) to block action potentials. Specificity of EPSC recording was further verified by using AMPA receptor antagonist (CNQX), which completely abolished EPSC events. D, CSPGs significantly decreased frequency of spontaneous neuronal activity and ILP/ISP co-treatment moderately (but not significantly) improved it. E, CSPGs and/or ILP/ISP treatment did not affect amplitude of spontaneous activity in neurons. Values represent mean ± SEM, *p < 0.05; one-way ANOVA. N = 3, 5 neurons per condition. ns: non-significant.