A genetically encoded fluorescent sensor for rapid and specific in vivo detection of norepinephrine

Norepinephrine (NE) and epinephrine (Epi), two key biogenic monoamine neurotransmitters, are involved in a wide range of physiological processes. However, their precise dynamics and regulation remain poorly characterized, in part due to limitations of available techniques for measuring these molecules in vivo . Here, we developed a family of GPCR Activation-Based NE/Epi (GRABNE) sensors with a 230% peak ΔF/F response to NE, good photostability, nanomolar-to-micromolar sensitivities, sub-second rapid kinetics, high specificity to NE vs. dopamine. Viral- or transgenic- mediated expression of GRABNE sensors were able to detect electrical-stimulation evoked NE release in the locus coeruleus (LC) of mouse brain slices, looming-evoked NE release in the midbrain of live zebrafish, as well as optogenetically and behaviorally triggered NE release in the LC and hypothalamus of freely moving mice. Thus, GRABNE sensors are a robust tool for rapid and specific monitoring of in vivo NE/Epi transmission in both physiological and pathological processes. ### Author Contributions Y. L conceived and supervised the project. J.F., M.J., H.Wang, A.D., and Z.W. performed experiments related to sensor development, optimization, and characterization in culture HEK cells, culture neurons and brain slices. Y.Z., P.Z. and J.J.Z designed and performed experiments using Sindbis virus in slices. C.Z., W.C., and J.D. designed and performed experiments on transgenic fish. J.L., J.Zhou, H.Wu, J.,Zou, S.A.H., G.C., and D.L. designed and performed experiments in behaving mice. All authors contributed to data interpretation and data analysis. Y. L and J.F. wrote the manuscript with input from M.J., J.L., and D.L. and help from other authors. This work was supported by the National Basic Research Program of China (973 Program; grant 2015CB856402), the General Program of National Natural Science Foundation of China (project 31671118), the NIH BRAIN Initiative grant U01NS103558, the Junior Thousand Talents Program of China, the grants from the Peking-Tsinghua Center for Life Sciences, and the State Key Laboratory of Membrane Biology at Peking University School of Life Sciences to Y. L; the Key Research Program of Frontier Sciences (QYZDY-SSW-SMC028) of Chinese Academy of Sciences, and Shanghai Science and Technology Committee (18JC1410100) to J.D.; the NIH grants R01MH101377 and R21HD090563 and an Irma T. Hirschl Career Scientist Award to D.L.; and the Intramural Research Program of the NIH/NIEHS of the United States (1ZIAES103310) to G.C. We thank Yi Rao for sharing the two-photon microscope and Xiaoguang Lei for the platform support of the Opera Phenix high-content screening system at PKU-CLS. We thank the Core Facilities at the School of Life Sciences, Peking University for technical assistance. We thank Bryan L. Roth and Nevin A. Lambert for sharing stable cell lines and plasmids. We thank Yue Sun, Sunlei Pan, Lun Yang, Haohong Li for inputs on sensors’ characterization and application. We thank Yanhua Huang, Liqun Luo and Mickey London for valuable feedback of the manuscript.