Key Physiological Parameters Dictate Triggering of Activity-Dependent Bulk Endocytosis in Hippocampal Synapses (original) (raw)
Figure 6
Inhibitory synapses preferentially form bulk endosomes and are slightly larger as compared to excitatory synapses.
(A) Experimental procedure. Functional synapses of rat hippocampal neurons were fluorescently labelled with αSyt1-cypHer5. In parallel, inhibitory synapses were identified with an anti-vGAT (vesicular GABA transporter) antibody, labelled with the green fluorescent dye Oyster488®. The cells were then electrically stimulated with 1200 AP, 40 Hz in the presence of 50 µM dextran-TMR. (B) Representative images of αSyt1-cypHer5 and anti-vGAT-oyster488® antibody-stained hippocampal neurons that were exposed to dextran-TMR during the electrical stimulation (“image”). Quantification was done by a Laplace operator based peak-detection (“mask”). (C) vGAT-positive synapses showed a larger percentage of dextran-TMR-staining than vGAT-negative ones or the total of synapses. The boxplot indicates median (red line), 25th and 75th percentiles (blue box) and extreme values (whiskers). Wilcoxon signed rank test, ***p<0.001. N = 4 experiments with 4 to 7 fields of view each; (D) vGAT-positive synapses were larger than vGAT-negative ones or the total of synapses.