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. 2018 Sep 4;7:e37487. doi: 10.7554/eLife.37487

Figure 4. Blocking the effects of nicotine selectively in the VTA.

(A) Experimental design for photoswitch injection and subsequent juxtacellular recording coupled to photocontrol. (B) Representative electrophysiological recording of one VTA DA neuron, during an i.v. injection of nicotine (30 μg/kg), under 520 (top, green) and 390 nm light (bottom, purple), showing greater electrical activity in green light. (C) Representative change in firing frequency (top) and in bursting activity (bottom) of a VTA DA neuron, elicited by an i.v. injection of nicotine (30 μg/kg), under 390 and 520 nm light, showing reversible photo-inhibition. (D) Top, average change in firing rate for VTA DA neurons (n = 7) upon nicotine injection under 390 (41.0 ± 15.7 %, purple) and 520 nm light (102.0 ± 14.0 %, green), normalized to the initial response in darkness. Change in firing frequency in 520 nm light is significantly different for 390 nm (p=0.015, Wilcoxon-Mann-Whitney test with Holm-Bonferroni correction) but not from darkness (p=0.81). Bottom, average change in SWB for bursting VTA DA neurons (n = 3) upon nicotine injection under 390 (37.7 ± 15.3 %, purple) and 520 nm light (77.5 ± 20.3 %, green), normalized to the initial response in darkness. All values represent mean ± SEM.

Figure 4—source data 1. Source data for Figure 4D.
elife-37487-fig4-data1.xlsx (9.2KB, xlsx)
DOI: 10.7554/eLife.37487.014

Figure 4.

Figure 4—figure supplement 1. The response of VTA DA neurons to nicotine is similar in WT and in β2E61C-transduced animals.

Figure 4—figure supplement 1.

(A) Example of a recorded transduced DA neuron labeled with neurobiotin (blue) and identified with TH (red) and GFP (green) labeling. 3 out of 7 recorded neurons have been filled with neurobiotin, of which all were confirmed as DAergic by TH labeling. (B) Left, average change in firing rate for VTA DA neurons (n = 7) upon nicotine injection in darkness, and under 390 (purple) and 520 nm light (green). Right, average change in burst firing frequency upon nicotine injection in darkness, and under 390 (purple) and 520 nm light (green); only the busting VTA DA neurons were considered here (n = 3). (C) Average changes in firing rate (top) and in the percent of spikes within bursts (SWB, bottom) for VTA DA neurons from control (left, light grey, n = 37) and β2E61C-transduced animals (right, dark grey, n = 7), upon nicotine i.v. injection (30 μg/kg) in darkness. (D) Changes in firing frequency are not different between control (Δfiring rate = 39.4 %, n = 37) and β2E61C-transduced animals (Δfiring rate = 31.7 %, n = 7, p=0.53). Similarly, changes in the percent of SWB are not different between control and β2E61C-transduced animals (Δ%SWB = 6.44 % and 10.72%, respectively, p=0.68). All values represent mean ± SEM.