Figure 6.

cAMP-Dependent Regulation of GABA_AR and GlyR Diffusion

(A) Quantum dot (QD) trajectories of Dendra2-GABA_ARγ2-containing receptor complexes (red traces) in control neurons and in the presence of either forskolin or 007-AM. Synapses were identified with FM4-64 labeling (white areas). Scale bar, 5 μm.

(B) Cumulative probabilities of QD-tagged Dendra2-GABA_ARγ2 diffusion coefficients at synapses in the three experimental conditions (median D values: D_Ctr = 0.0022 μm²/s, D_For = 0.0031, D₀₀₇ = 0.0028, n_Ctr = 730 trajectories from 41 cells, n_For = 318 trajectories from 42 cells, n₀₀₇ = 384 trajectories from 40 cells, 7 coverslips per condition, 3 experiments).

(C) The median diffusion coefficients of Dendra2-GlyRα1 at spinal cord synapses were similar in the control and forskolin condition (in the absence of the drug, after a 30-min forskolin incubation; D_Ctr = 0.0083 μm²/s, D_For = 0.0076, n > 1,000 trajectories from 5 experiments).

(D) Synaptic diffusion coefficients of Dendra2-GlyRα3L and α3K splice variants. Forskolin application specifically increased the speed of diffusion of Dendra2-GlyRα3L at synapses (α3L: D_Ctr = 0.0041, D_For = 0.0058, n > 1,000; α3K: D_Ctr = 0.0060 μm²/s, D_For = 0.0066, n > 900 QD trajectories; 5 experiments).

(E) Model of cAMP-dependent pathways regulating inhibitory receptor dynamics at mixed spinal cord synapses, including the pharmacological agents used in this study (see text for details).