Figure 6.
α6* nAChRs function in sSC neurons. A, α6-dependent nicotinic currents in sSC neurons. Coronal slices were prepared from α6 L9′S transgenic mice, and sSC neurons were studied with patch-clamp electrophysiology. sSC cells recorded in whole-cell mode were stimulated with nicotine (1 μm) to activate nAChRs. Responses to 1 μm nicotine were sensitive to blockade by αCtxMII (lower current trace). A representative response is shown. Scale bar, 25 pA; 1 s. B, Quantification of peak nicotine-evoked currents in sSC neurons. Peak nicotine-elicited (1 μm nicotine) currents from each sSC neuron in nontransgenic control or α6 L9′S slices are plotted. C, Higher nicotine concentrations are required to activate nAChRs in nontransgenic control sSC neurons. sSC neurons in nontransgenic control slices did not respond to 1 μm nicotine but responded with typical nAChR inward currents when stimulated with 100 μm nicotine. Scale bar, 20 pA; 1 s. D, Firing responses of sSC α6(+) neurons. sSC neurons from α6 L9′S slices that respond to 1 μm nicotine were recorded in current-clamp mode. Membrane potential was recorded in response to depolarizing, zero, or hyperpolarizing current injections. Representative traces are shown, and the average resting membrane potential for all studied α6(+) sSC neurons is indicated. Scale bar, 30 mV; 400 ms. E, Ih current in α6(+) sSC neurons. The same group of cells analyzed in D were held in voltage-clamp mode at −60 mV, and membrane currents were recorded during hyperpolarizing voltage steps (−60 mV, −70 mV, −80 mV, −90 mV, −100 mV, −110 mV, and −120 mV). Representative traces are shown. Scale bar, 40 pA; 300 ms. F, Current-voltage relations for Ih currents shown in E. Peak current changes were measured immediately before the end of each hyperpolarizing pulse. Data are mean ± SEM. ***p < 0.0001.