Pharmacological inhibition of NO-production increases the number of postsynaptic gephyrin molecules and synaptic GABAARs. A, Representative images of dendrites (30 × 7 μm) immunostained for gephyrin (red) and the presynaptic marker VGAT (green) at 14 DIV. B, Size of gephyrin clusters and VGAT puncta upon incubation with L-VNIO. Gephyrin cluster size: 0.33 ± 0.02 and 0.49 ± 0.03 μm2; n = 24 for DMSO and n = 18 for L-VNIO, p < 0.001, Student's t test. C, Density of dendritic gephyrin clusters and VGAT puncta (normalized to 20 μm segments). D, Quantification of colocalization between gephyrin clusters and VGAT in control and L-VNIO-treated neurons. E, Representative Western blots of cell-surface biotinylation experiments. F, Quantification of band intensities of cell surface expressed GABAAR subunits in L-VNIO-incubated neuronal cultures compared with control neurons. Intensity of bands in L-VNIO-incubated samples compared with DMSO-controls: α1, 121.1 ± 3.5%; β2/3, 124.1 ± 6.0%, and γ2, 133.3 ± 8.9%; n = 3, *p < 0.05, **p < 0.01, Student's t test. All data are expressed as mean ± SEM.