Figure 3.

Anatomically associated pairs of hilar NG2⁺ cell and interneurons exhibit synchronized synaptic activity A, single-plane merged confocal image showing the dentate gyrus of a P15 CNP-EGFP (green) transgenic mouse immunostained for the proteoglycan NG2 (blue) and the neuronal marker NeuN (red). The dotted box indicates an NG2⁺EGFP⁺ cell associated to hilar neurons. Right panels show the individual staining for the area delimited by the dotted box. B, confocal images showing a hilar interneuron (red) and its sNG2⁺ cell (green) filled with biocytin (red in B and grey in right lower panel) and tetramethylrhodamine dextran (green in B and grey in right upper panel), respectively. C, example of synchronized bursts observed in a hilar interneuron (V_h=–60 mV, upper trace) and its sNG2⁺ cell (V_h=–80 mV, lower trace) recorded in a whole hippocampal slice preparation in the presence of 100 μm picrotoxin. The grey boxes indicate the interval of the trace in A magnified in the right panels. In the right panels, dotted lines indicate recurrent EPSCs, which are usually observed after the initial discharge of EPSCs indicated by a continuous line. D, example of spontaneous activity recorded in a hilar interneuron (V_h=–60 mV, upper trace) and its sNG2⁺ cell (V_h=–80 mV, lower trace) by using a specific caesium methanesulphonate internal solution to isolate EPSCs from GABAergic activity (E_Cl=–80 mV and E_cation= 0 mV). The application of 20 μm carbachol was used to increase the spontaneous EPSC activity in both cells. Asterisks indicate synaptic current that are synchronized between both cells.