Figure 5.

mGlu4 receptors regulates excitatory transmission through coupling to Cav2.2 channels. Evoked EPSCs were recorded in lamina II neurons from spinal cord slices of 2- to 3-week-old mice using the whole-cell patch-clamp technique. A, Bottom, Time course of eEPSC amplitude before and after bath application of ω-Cgtx, a selective blocker of Cav2.2 channels, and 50 μm LSP4–2022, an mGlu4 agonist. The amplitude of eEPSCs is normalized to amplitude before drug application. Top, Sample current traces recorded before drug application, after ω-Cgtx, and in the presence of ω-Cgtx and LSP4–2022. B, Histogram of mean ± SEM of eEPSC amplitude in the absence and in the presence of LSP4–2022 and different channel blockers: ω-Cgtx, a selective blocker of Cav2.2 channels; ω-Agtx, a selective blocker of Cav2.1 channels; and tertiapin Q, a selective blocker of GIRK channels. Current amplitudes are expressed as the percentage of amplitude before drug application. C, Histogram of mean ± SEM of inhibition of eEPSC amplitude in the presence of the different channel blockers. Current amplitudes are expressed as the percentage of inhibition of the amplitude before LSP4–2022 application. **p < 0.01. ***p < 0.001. ns, Not significant.