Figure 6.

Functional expression of 5-HT_3ARs and nAChRs in 5-HT_3AR-expressing interneurons. Intrinsic firing patterns to step current injections recorded from three different types of cortical interneurons from 5HT3aR-BAC^EGFP (A1), B13 (B1), and GIN (C1) transgenic mice. Application of a 5-HT_3AR selective agonist (mCPBG; 100 μm; 30 ms puffing) causes strong depolarization and evokes a burst of spikes in 5-HT_3AR cells (A2) but not in FS (B2) or SST-expressing cells (C2) (30 ms puff indicated by red line below). D, Functional expression of nACh receptors in EGFP-positive neurons of 5HT3aR-BAC^EGFP mouse. D1, Carbachol application (1 mm) strongly depolarizes and evokes burst of spikes in a 5-HT_3AR neuron recorded in whole-cell configuration in current clamp. The inset shows intrinsic firing pattern of recorded cell to step current injections. D2, Functional expression of nicotinic ACh receptors in EGFP-positive neurons of 5HT3aR-BAC^EGFP mouse. Nicotine puffing (100 μm for 30 ms) depolarizes the 5-HT_3AR neuron (D2), but muscarine application (D3) to the same neuron did not change membrane potential, indicating 5-HT_3AR interneurons express nicotinic AChRs (30 ms puff indicated by red line below). The insets in A1 and D1–D3 show schematics of the recording configuration.