Fig. 4: VGLUT2 deletion in astrocytes alters nigrostriatal circuit function in situ and DA levels in vivo.

a, The breeding scheme for generating astrocyte-specific conditional VGLUT2 mice and related controls (details as in Fig. 3a, but for VGLUT2). b, The experimental paradigm and timeline of mouse treatments for electrophysiology recordings (left). Right, schematic of midbrain slices showing the STN, SNpc and substantia nigra pars reticulata (SNpr) with the position of the stimulating and recording electrodes. c, sEPSCs recorded in SNpc DA neurons of VGLUT2^GFAP-KO (15 cells, 6 mice), VGLUT2^GFAP-WT (20 cells, 7 mice) and VGLUT2^WT-TAM (13 cells, 5 mice) mice. Representative current traces (left), and histograms showing, in VGLUT2^GFAP-KO mice, increased sEPSC frequency (middle; one-way ANOVA with Tukey’s test; **P = 0.00187 (bottom), **P = 0.00233 (top)) and unchanged amplitude compared with the controls (right). d, Group III mGluR agents differently affect sEPSCs in VGLUT2^GFAP-KO mice compared with the control mice (two-tailed paired t-test). The histograms show the percentage change induced by group III mGluR agonist l-SOP (10 μM) and antagonist MSOP (10 μM) on the baseline sEPSC frequency (left) and amplitude (right) in VGLUT2^GFAP-KO mice (l-SOP: 12 cells, 5 mice, ***P = 0.0005; MSOP: 8 cells, 3 mice) and VGLUT2^GFAP-WT mice (l-SOP: 10 cells, 5 mice; MSOP: 7 cells, 4 mice; **P = 0.0041, *P = 0.024). e, EPSCs evoked in SNpc DA neurons by STN stimulation in VGLUT2^GFAP-KO (24 cells, 7 mice), VGLUT2^GFAP-WT (19 cells, 7 mice) and VGLUT2^WT-TAM (12 cells, 5 mice) mice. Left, representative traces of paired pulse-evoked EPSCs. Right, histograms showing a reduced PPR in VGLUT2^GFAP-KO mice compared with in the control mice (one-way ANOVA with Fisher’s test; *P = 0.020 (top), *P = 0.023 (bottom)). f, Differential effects (expressed as the percentage change versus the control) induced by group III mGluRs agents on PPR in VGLUT2^GFAP-KO (l-SOP: 10 cells, 4 mice; ***P = 0.00065; MSOP: 6 cells, 4 mice) compared with in VGLUT2^GFAP-WT (l-SOP: 10 cells, 5 mice; **P = 0.0079; MSOP: 6 cells, 4 mice; *P = 0.038) mice. Statistical analysis was performed using two-tailed paired t-tests. g, The experimental paradigm and timeline of mouse treatments for in vivo microdialysis measures of DA levels in the dST. h, The baseline DA levels in VGLUT2^GFAP-KO mice (n = 12) compared with in VGLUT2^GFAP-WT mice (n = 13; Kolmogorov–Smirnov test; *P = 0.039). For the box plots, the box limits show the 25th to 75th percentiles, the centre lines are medians, and the whiskers show the minimum to maximum values. i, Time course of DA levels after amphetamine challenge (AMPH, 2 mg per kg; arrow). The DA levels were significantly (Friedman ANOVA with Wilcoxon signed rank test) increased only at 40 min in VGLUT2^GFAP-WT mice (*P = 0.0175), whereas DA levels were significantly increased at 20, 40, 60, 80, 100 and 120 min in VGLUT2^GFAP-KO mice (^##P = 0.00253, ^##P = 0.00253, ^##P = 0.0025, ^##P = 0.0042, ^#P = 0.010, ^#P = 0.03, respectively). The amphetamine-induced increase was higher in VGLUT2^GFAP-KO mice compared with in VGLUT2^GFAP-WT mice at any tested time (Kolmogorov–Smirnov test; ***P = 0.00049, **P = 0.009, ***P = 0.00049, **P = 0.00231, **P = 0.00913, **P = 0.00231). All data are mean ± s.e.m.

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