Fig. 4
Astrocyte VMAT2 deletion leads to synapse impairments. a Top: Example traces shows superimposed fEPSP as stimulation intensity increases. Calibration bars: 5 ms, 0.5 mV. Bottom: Graph shows the maximum EPSP slope plotted against stimulus. The PFC slices prepared from aVMAT2cKO mice (green) show enhanced basal synaptic transmission with respect of control LoxTAM mice (grey) (P45-60). The enhanced basal synaptic transmission in aVMAT2cKO mice is rescued with astrocyte-targeted lentiviral vectors encoding VMAT2 (lentiVMAT2) (orange) or with chronic treatment with L-DOPA/benserazide (20 mg/kg + 12.5 mg/kg) (pink). b Top: Example traces showing facilitation at 50 ms ISI. Calibration bars: 10 ms, 0.5mV. Bottom: Graph shows pooled paired-pulse ratios (slope2/slope1 x100 −100) plotted against the inter-stimuli interval (ISI). The deletion of astrocyte VMAT2 leads to a clear deficit in short-term facilitation, which indicates an increased probability of release. Note that the deficit is rescued by lentiVMAT2 (orange) and L-DOPA (pink). c Top: Representative traces of the intracellular recording of L5 pyramidal neurons. Bottom: Histograms showing that mEPSC frequency is increased in mice lacking astrocyte VMAT2 (lower left panel, green), whereas mEPSC amplitude remains unchanged. Note that the increased mEPSC frequency is rescued by lentiVMAT2 (orange) and L-DOPA/benserazide (pink) (lower right panel). d The administration of tetanic stimulation (6 x 50 Hz, 2 s) is indicated by an arrow and the baseline by a dashed line. Representative traces showing responses before (dashed line) and 60 min after tetanus delivery (bold line). Calibration bars: 5 ms, 0.2 mV. LTP is significantly reduced in aVMAT2cKO mice 60 min after induction. Note that LTP is rescued by lentiVMAT2 (orange) and L-DOPA/benserazide (pink). e Representative confocal images showing L5 PFC dendritic spines in recombined aVMAT2cKO-ThyEGFP (green), recombined aVMAT2cKO-ThyEGFP + lentiVMAT2 (orange), recombined aVMAT2cKO-ThyEGFP + L-DOPA/benserazide (pink), and control LoxTAM-ThyEGFP mice (grey) (P40). Scale bar: 1 μm f Histograms of spine density calculated in L5 of the PFC of recombined aVMAT2cKO-ThyEGFP (green), recombined aVMAT2cKO-ThyEGFP + lentiVMAT2 (orange), recombined aVMAT2cKO-ThyEGFP + L-DOPA/benserazide (pink), and control LoxTAM-ThyEGFP mice (grey) at three developmental stages (P20, P28, P40) (n = 3 mice per group). The error bars indicate the SEM. g–i Histograms showing the proportion of thin and mushroom spines in L5 of the PFC of recombined aVMAT2cKO-ThyEGFP (green), recombined aVMAT2cKO-ThyEGFP + lentiVMAT2 (orange), recombined aVMAT2cKO-ThyEGFP + L-DOPA/benserazide (pink), and control LoxTAM-ThyEGFP mice (grey) at three developmental stages (P20, P28, P40). The error bars indicate the SEM
