Figure 1.

DREADD/ligand delivery methods in vivo. A, Systemic ligand administration. DREADDs are expressed Cre-dependently via virus (as shown) or via transgenic methods. Intraperitoneal injection of CNO will manipulate activity of only cells expressing the DREADD. B, Localized ligand administration. Alternatively, once DREADDs are expressed, an infusion cannula can be implanted over a downstream region of choice; CNO can be infused at this point to affect only downstream targets of a selected projection. C, Using retrogradely transporting viruses to express Cre, subsequent Cre-dependent AAV-DREADD injection at cell bodies will only affect cells projecting to the Cre virus injection site. Subsequent intraperitoneal CNO injection will only affect this projection.