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. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Nat Neurosci. 2015 Feb 9;18(3):386–392. doi: 10.1038/nn.3945

Figure 6. Photo-stimulation of mesoaccumbens VGluT2 fibers expressing ChR2 under the control of the VGluT2 promoter elicits EPSCs and dopamine release in nAcc (VGluT2::Cre mice).

Figure 6

(a-c) Photo-stimulation of nAcc fibers from VGluT2 VTA neurons (n = 6 VGluT2-ChR2-mCherry mice). (b) Optically-evoked EPSCs recorded in nAcc shell. (c) Paired pulse ratios (P2/P1) in nAcc neurons (n = 9 per time point).

(d) Electrically- or optically-evoked dopamine were measured by voltammetry. (e) Optically-evoked dopamine release was increased in response to the increment of the number of pulses; 5 ms pulses (blue box) at 25 Hz. (f) dopamine voltammogram in response to 10 pulses of photo-stimulation. (g) Electrically-evoked dopamine release (10 × 1 ms pulses at 25 Hz; arrow) at the same location of photo-stimulation. (h) Summary of dopamine release in response to the number of optical pulses (n = 6 slices from 3 mice). (i) Bath application of the VMAT2 inhibitor tetrabenazine (TBZ, 10 μM) significantly reduced optically-evoked dopamine release (p = 0.02 vs control, paired t-test, n = 4 slices from 2 mice). (j) optically-evoked dopamine responses from VGluT2-TH neurons are not dependent on glutamate receptors. Traces show optically-evoked (25 Hz, 5 pulses, 5 ms) nAcc voltammetric currents measured prior to and following application of the glutamate receptor antagonists NBQX (5μM) and AP-5 (40 μM). Graph shows the time course summary (mean ± s.e.m., n = 4 recordings from 2 mice); NBQX and AP-5 were applied during the time indicated by the bar. No significant effect on the dopamine signals was observed (two-tailed paired t-test, t(3) = 0.1239, p = 0.9093).