DREADD Agonist 21 Is an Effective Agonist for Muscarinic-Based DREADDs in Vitro and in Vivo
Chemogenetic tools, such as designer receptors exclusively activated by designer drugs (DREADDs), are widely used to modulate neuronal and non-neuronal signaling in a minimally invasive manner. First-generation muscarinic-based DREADDs were engineered from the human muscarinic acetylcholine receptor family, rendering them relatively insensitive to endogenous acetylcholine while being selectively activated by clozapine-N-oxide (CNO).
Although CNO has been highly effective in activating muscarinic DREADDs, it undergoes low-rate metabolic conversion to clozapine, prompting the search for alternative actuators. Here, we demonstrate that DREADD agonist 21 (C21) (11-(1-piperazinyl)-5H-dibenzo[b,e][1,4]diazepine) is a potent and selective agonist of both excitatory (hM3Dq) and inhibitory (hM4Di) DREADDs. C21 exhibits high bioavailability, favorable pharmacokinetics, and strong brain penetrability.
In vivo, C21-induced activation of hM3Dq and hM4Di modulates bidirectional feeding responses in defined neural circuits in mice. These findings establish C21 as a viable alternative to CNO,CNO agonist particularly in studies where metabolic conversion to clozapine is a concern.