Fig. 5: Functional characterization of the striatal astrocyte-converted neurons in the R6/2 mouse brain slices.

a Phase and fluorescent images of a native neuron (mCherry⁻, top row) and a converted neuron (mCherry⁺, bottom row). Scale bar: 10 µm. b Representative traces of Na⁺-K⁺ currents recorded in native (gray) and converted neurons (red). c Repetitive action potentials (AP) evoked by step-wise current injections. Note a significant delay to the initial action potential firing upon depolarization stimulation in both native and converted neurons. Such delayed firing is a typical MSN electrophysiological property. d, e Typical traces of sEPSCs and sIPSCs recorded from native (gray traces, top row) and converted neurons (red traces, bottom row). f, g I–V plot of Na⁺-K⁺ currents recorded from striatal neurons in the viral-injected R6/2 mice and non-treated WT mice. The Na⁺ currents in both converted (red) and non-converted striatal neurons (gray) in the R6/2 mice were smaller than that recorded from the striatal neurons in the WT mice (black). The K⁺ current in converted neurons was significantly larger than that in non-converted neurons in the R6/2 mouse striatum (unpaired Student’s t-test). *p < 0.05, **p < 0.01. Data are shown as mean ± SEM. h–m Summary graphs in scatter-plot showing electrical properties among the converted (red dots) and non-converted neurons (gray dots) in the R6/2 mice, together with the wild-type neurons (black dots): input resistance (h), capacitance (i), resting membrane potential (j), AP threshold (k), AP amplitude (l), and AP frequency (m). There were no significantly differences between the converted and non-converted neurons in the R6/2 mice, but neurons from R6/2 mice showed some differences from the wild-type neurons. One-way ANOVA with Bonferroni’s post hoc test. n–q Summary graphs in scatter-plot showing similar synaptic responses among the wild-type neurons (black dots), and the converted (red dots) and non-converted neurons (gray dots) in the R6/2 mice: sEPSC frequency (n), sEPSC amplitude (o), sIPSC frequency (p), and sIPSC (q). p > 0.4 for all groups, one-way ANOVA with Bonferroni’s post hoc test. r Pie chart showing the percentage of neurons with different firing pattern among the converted neurons.