Spying on the dynamics of octopamine by genetically-encoded GRABOA sensor in Drosophila
Authors: Mingyue Lv 1,2; Ruyi Cai 1,2; Huan Wang 1,2; Yulong Li 1,2,3,4
Affiliations: 1) State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China; 2) PKU-IDG/McGovern Institute for Brain Research, Beijing, China; 3) Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; 4) Chinese Institute for Brain Research, Beijing, China
Keywords: f. learning/memory; b. live imaging
Small molecular neurotransmitters are essential for neuronal communication in the nervous system. Octopamine (OA), the analog of norepinephrine in invertebrates, is an important monoamine neurotransmitter involved in many physiological events of insects, such as the aggression, flight, ovulation, learning and memory. Although much is known regarding the properties of OA, its spatial and temporal dynamics are poorly understood at the in vivo level due to the limited detecting methods. Here, to directly visualize the release of OA, we developed a genetically encoded G-protein-coupled receptor (GPCR) – activation – based OA (GRABOA) sensor. In response to extracellular OA, GRABOA shows large fluorescent increase (~500% DF/F0), high selectivity and fast kinetics to micromolar OA. In living flies, we observed GRABOA expressed in the Kenyon cells (KCs) responses to electrical stimulation in a dose dependent pattern. For optogenetic activation of octopaminergic neurons, we detected homogenous fluorescent increase across mushroom body, which is the center for Drosophila olfactory associative learning. Moreover, GRABOA was able to reports physiological stimulation including odorant and abdomen shock induced OA release. Thus, GRABOA2m enables spatiotemporally precise measurements of OA dynamics in vivo in Drosophila, which provides the possibility to explore the role of OA in different interesting physiological process in invertebrates.