Figure 2.

In Vivo Specificity Evaluation of DIO-AAV Vectors to Transplanted TH-Cre-Positive Neuroblasts and Off-Target In Vivo Activation of the DREADD Ligands

(A and B) Expression of DIO-hM3Dq and DIO-rM3Ds DREADDs, following viral infusion into the striatum of WT animals (A) and animals grafted with dopaminergic fetal tissue from TH-Cre transgenic rats (B). ^∗Denotes position of viral infusion (see also Figure S3).

(C–E) Assessment of virally transduced, grafted mCherry-positive neurons that appeared TH negative under normal laser power conditions. (C) Overview of dopaminergic fetal graft within the striatum with an mCherry-positive neuron that appeared TH negative (white box). When comparing high-magnification z stacks of these mCherry-positive grafted neurons under normal laser power conditions (D) with high laser power conditions (E), it is clear that these mCherry-positive (red) neurons are indeed TH positive (green), although at low levels. We hypothesize based on cell morphology and heterogeneous TH expression that these are grafted neurons originating from the VTA (see also Figure S1).

(F) Control measurements in the intact striatum using electrochemical chronoamperometric recordings of DA release. Local KCl administration (red arrow) evoked strong DA release while neither CNO (blue arrow) nor SalB (black arrow) administration resulted in any measurable increase in extracellular DA.

Scale bar, 200 μm (B), 100 μm (C), and 10 μm (E).