Figure 3. eNRG1 effects on GABA_A receptor agonist sensitivity of nigral dopamine neurons in vivo.

We examined the sensitivity of in vivo dopaminergic firing to muscimol under anaesthetic condition. (a) Typical effects of iontophoretic application of muscimol on the spontaneous firing activity are displayed in control and eNRG1-pretreated mice. The drug was applied for 1 min (horizontal bars) to the same cell with the driving current of +1 nA (left panel) and then +2 nA (right panel). (b) Firing rates were averaged for every 20 sec before and after local muscimol application. Mean firing rates for 1 min before drug application were set to 100% for each cell (n = 16 cells from 6 control mice and n = 20 cells from 6 eNRG1-pretreated mice). (c) The responses to muscimol (+1 nA and +2 nA) were averaged during the period of the 1 min current ejection and plotted. (d) We performed iontophoretic application of vehicle alone to a control mouse (1 mM NaCl, pH 4.0) with the driving current of +1 nA (left panel) or +2 nA (right panel). Histograms of typical spike rates are displayed. (e) Effects of control iontophoresis are averaged and shown (n = 5 cells from one mouse). *p < 0.05, **p < 0.01, ***p < 0.001, Mann-Whitney U test.