I occasionally receive queries regarding the use of retrovirally delivered DREADDs to newly born neurons in dentate gyrus. Here is a nice use of this technology along with optogenetics in hippocampus in Neuron.
UNC is no longer offering single-unit AAV for DREADDs although we expect that these will be available via ADDGENE shortly.
To get onto the ADDGENE notification list contact: Leila Haery firstname.lastname@example.org with serotype and genotype needs for DREADD constructs. She will be helping Addgene coordinate production and distribution of DREADD viruses.
In the meantime, you can order plasmids from ADDGENE and simply ask UNC to make a custom prep for you or send the plasmids to the Penn Vector core.
Alternatively it looks like the Duke vector core is also offering DREADD-based AAVs.