Tissue-specific modification of cellular bioelectrical activities using the chemogenetic tool, DREADD, in zebrafish

Cellular electronic activity plays an essential role in neuronal communication. Manipulation and visualization of cellular membrane potential remain essential tasks in order to study electrical signaling in living organisms. Light-controlled optogenetic and designed chemical-controlled chemogenetic tools were developed to manipulate cellular electric activities for neuroscience research. One of the most common chemogenetic tools is DREADD (designer receptors exclusively activated by designer drugs). It has been extensively utilized due to its convenience and long-lasting effects in murine and primate models, but not in zebrafish, a leading model organism in various research fields. Here, we first establish multiple tissue-specific transgenic zebrafish lines that express two different DREADDs with a genetically encoded voltage indicator, ASAP2s. We observed voltage changes in zebrafish melanophores, epidermis, and neurons by hM4DGi or rM3DGs receptors measured by ASAP2s fluorescence intensity. Alteration to melanophore bioelectricity by DREADD generated dynamic electric signals and resulted in morphological alterations to pigment cells. We also tested a few agonists and found that the latest generation performs better than clozapine N-oxide (CNO). Collectively, our experiments demonstrate that DREADD can be utilized to manipulate cell-specific membrane potential in the zebrafish model. The availability of this tool in zebrafish will offer a new resource for a variety of bioelectricity research fields such as neuroscience, cardiology, and developmental biology.