Fig. 2: ORCHID reports endogenous inhibitory receptor driving force in different neuronal populations.
From: All-optical reporting of inhibitory receptor driving force in the nervous system
a Schematics showing DFGABAA estimation by imaging Voltron2549-ST together with activation of endogenously expressed GABAARs via 100 ms soma-directed GABA application (puffer, red; 500 µM). CGP-55845 (5 µM) was used to block GABABRs. b Widefield fluorescence images of CaMKIIα+ pyramidal neurons (top) and GAD2+ interneurons (bottom) expressing Voltron2549-ST (left), and fluorescence recordings used to estimate DFGABAA from each cell type (right, yellow traces) in hippocampal organotypic slices, with recorded cells shown via inset if not in the main image; scale bar: 10 µm. The red bar indicates GABA application. Raw trace is shown in light yellow, and smoothed trace (window length = 7) is overlayed in darker yellow. c Population data showing estimated DFGABAA was different between cell types (CaMKIIα+: 5.85 ± 0.62 mV vs GAD2+: 8.52 ± 0.79 mV, Mann-Whitney test, two-tailed, P = 0.0068, n = 62 and 60 cells respectively). Green shading indicates the direction of anion flux. d Schematics depicting ORCHID’s use for estimating DFGABAA in neurons. e Left, confocal images of CaMKIIα+ pyramidal neurons (top) and GAD2+ interneurons (bottom) expressing ORCHID in mouse hippocampal organotypic brain slices. Right, fluorescence recordings were used to estimate DFGABAA from each cell type, with widefield images of the recorded cells inset; scale bar: 10 µm. f Estimated DFGABAA was significantly different between cell types (CaMKIIα+: −4.52 ± 0.57 mV vs GAD2+: −6.88 ± 0.72 mV, Mann-Whitney test, two-tailed, P = 0.0057, n = 51 and 49 cells respectively). -DFGABAA values plotted. ns = not significant (P > 0.05); *P ≤ 0.05; error bars indicate mean ± SEM.
