Figure 7.

Enhancing neuronal activity increases phosphorylation of β3S383, the number of cell surface GABA_A receptors and tonic current. (A) Hippocampal neurons were incubated with 4-AP for times indicated. Immunoblots show p-S383, surface and total β3. (B) Graph shows the quantification of cell surface β3/total β3 band intensity ratio normalized to values at time 0 (data are plotted as mean±s.e. *P<0.05, n=3, t-test). (C) Graph shows the quantification of the ratio of p-S383 to total β3 band intensities, normalized to values at time 0 (*P<0.05, n=3, t-test). (D) Acute hippocampal slices incubated with 4-AP. Immunoblots show p-S383 and total β3. Graph shows the quantification of the ratio of p-S383 to total β3 band intensities, normalized to values at time 0 (*P<0.05, n=3, t-test). (E) Control whole-cell voltage-clamp recordings before (top) and after (bottom) application of 4-AP. Right panels: corresponding all-point histograms of 10-s traces before () and after () etomidate application. Histograms were fitted with single Gaussian functions, and means were determined. After subtracting baseline from current evoked by etomidate, tonic current was normalized to cell size. (F) Data plotted are values from individual neurons and their mean values±s.e. (control, n=14, 4-AP, n=19, four independent cultures; *P<0.05; t-test).