Pharmacogenetic inhibition of ventral tegmental area (VTA)/substantia nigra compacta (SNc) dopaminergic (DAergic) neurons in tyrosine hydroxylase (TH)-Cre mice.

<p>Schematic representation of Cre-dependent adeno-associated virus (AAV) vectors expressing hM3Dq/hM4Di-mCherry under the control of human synapsin (hSyn) promoter. CNO, clozapine-N-oxide; IP, intraperitoneal; WPRE, woodchuck hepatitis virus post-transcriptional regulatory element. (B) Microinjection of AAV-DIO-hM4Di-mCherry into the VTA induced hM4Di expression (red). Ml, medial lemniscus; SNc, substantia nigra, compacta; SNr, substantia nigra, reticular part. (C) Representative photomicrographs of the VTA depicting mCherry expression (red), TH (green), and DAPI (blue) immunoreactivity and merge images (yellow) from a TH-Cre mouse microinjected with Cre-dependent AAV vectors containing hM4Di. (D) Statistics of the coexpression of TH and mCherry immunofluorescence of VTA neurons (<i>n</i> = 3, per group). (E) Drawings of superimposed AAV-injected area in the VTA (left, <i>n</i> = 8) and SNc (right, <i>n</i> = 8) of TH-Cre mice with different colors. (F, H) Representative photomicrographs of mCherry expression after microinjection of AAVs containing hM4Di into the VTA (F) and SNc (H). (G, I) CNO (G, I; top) and saline (G, I; bottom) did not induce c-Fos expression in hM4Di-expressing DAergic neurons in VTA (G) or SNc (I). (J) In TH-Cre mice, the firing property of a recorded VTA hM4Di/mCherry-positive DAergic neuron with hyperpolarization-activated cation current (<i>I</i><sub>h</sub>) (top) and CNO perfusion inhibited its firing rate (bottom). Underlying data can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2002909#pbio.2002909.s001" target="_blank">S1 Data</a>.</p>