Review of Nat Rev Neurosci︱ Yulong Li's team was invited to write a review of new technologies for neurotransmitter detection

Authors︱Wu Zhaofa, Zheng Yu, Li Yulong and editors︱Wang SizhenThe nervous system is one of the most important and complex systems
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In the nervous system, neurotransmitters and neuromodulators are the mediators of information exchange between cells and have extensive and important regulatory roles
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Monitoring the dynamics of specific neurotransmitters and neuromodulators can help decode the communication characteristics between cells in neural networks in healthy or diseased states, and can provide insights into complex neural activity and disease treatment
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However, due to the lack of in vivo detection methods with high spatiotemporal resolution, the dynamic changes of neurotransmitters and neuromodulators under physiological or pathological conditions have been difficult to accurately assess, so they are also known as "dark matter" in the brain
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To achieve precise monitoring of neurotransmitter release with high spatial and temporal resolution, scientists have developed a variety of tools based on different principles
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 On March 31, 2022, Yulong Li's team from Peking University published a research review on the frontiers of neurotransmitter and neuromodulator detection technology online in the journal Nature Reviews Neuroscience, entitled "Pushing the Frontiers: Tools for Monitoring Neurotransmitters and Neuromodulators" "
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This review systematically summarizes methods that can be used to monitor neurotransmitters and neuromodulators, with a view to leveraging the development of new technologies to drive new discoveries and new ideas
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 Research progress 1.
Non-genetically encoded detection tools This review first reviews the advantages and limitations of traditional non-genetically encoded detection tools
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For example, microdialysis technology can accurately detect the concentration of specific neurotransmitters around the target area in living animals, but it takes a long time to collect samples, and it is difficult to quickly track the dynamic changes of neurotransmitters; traditional electrophysiological, electrochemical and other methods can quickly report Neurotransmitters change dynamically, but there are also limitations, such as technical difficulties, high-throughput detection, and low discrimination of molecules with similar chemical properties
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 2.
Gene-encoded detection tools In the main part of the review, the author summarizes the design principles, main characteristics, applications, limitations and future prospects of gene-encoded neurotransmitter fluorescent probes
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Compared with traditional signal detection methods, fluorescence imaging methods usually have higher temporal and spatial resolution and less invasiveness, and are more suitable for monitoring the dynamic changes of neurotransmitters in vivo; combined with genetic coding methods, fluorescent probes can be used in specific Long-term expression in cell types, enabling long-term, multiple imaging
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The currently developed fluorescent probes for gene-encoded neurotransmitters are mainly divided into two categories according to their backbones, which are bacterial periplasmic binding protein (PBP) and G protein-coupled receptor (GPCR) as backbones
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Probes developed with PBP as backbone include glutamate probe iGluSnFR, etc.
Probes developed with GPCR as backbone include dopamine probes GRABDA and dLight
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The two types of probes have their own strengths and complementary advantages in affinity, selectivity, kinetics and pharmacological properties, and provide a powerful tool for finely monitoring the dynamic regulation of neurotransmitters and neuromodulators
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Figure 1 Principles and characteristics of fluorescent probes for gene-encoded neurotransmitters (Source: Wu Z, Lin D, Li Y, Nat Rev Neurosci, 2022) 3.
Application of gene-encoded detection tools Probes with these characteristics are suitable for different research needs, and illustrate the application scenarios of gene-encoded neurotransmitter fluorescent probes
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Combined with the optical fiber recording system, the genetically encoded adenosine probe can finely characterize the dynamic changes of adenosine during sleep-wake in freely moving mice; combined with wide-field microscopy, the genetically encoded glutamate probe can monitor the entire Dynamic changes in glutamate upon visual stimulation at the cortical level; combined with two-photon microscopy, genetically encoded acetylcholine probes enable precise tracking of acetylcholine dynamics in the retina
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In addition, probes based on serotonin receptor engineering have great application prospects in new drug screening
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Figure 2 Combination and application of genetically encoded neurotransmitter fluorescent probes with various imaging methods (Source: Wu Z, Lin D, Li Y, Nat Rev Neurosci, 2022) Summary and Outlook Finally, this review also provides insights into neurotransmitters.
The future development and application of the probe are prospected
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For probe tool development, a new generation of probes will be developed towards more sensitive, more specific, faster and more colors
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For probe tool applications, new fluorescent probes for genetically encoded neurotransmitters can help researchers characterize the dynamic properties of neurotransmitters in unprecedented detail at multiple levels, including cells, tissues, and model animals.
The neural activity opens up a new window; at the same time, the new scientific discoveries brought by these new probes will also provide important clues and enlightenments for the prevention, diagnosis and treatment of many neurological diseases
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 It is worth mentioning that on March 22, 2022, Li Yulong's team and Lin Tian's team from UC Davis were invited to co-author a paper entitled "Fluorescence Imaging of Neural Activity, Research Review of Neurochemical Dynamics, and Drug-Specific Receptor Conformation with Genetically Encoded Sensors"
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This review systematically introduces the working principle and development history of genetically encoded fluorescent probes, focuses on neurotransmitter probes, and discusses their applications in neuroscience research and drug discovery
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Different from the previous review, this article focuses on the development process of gene-encoded neurotransmitter probes and establishes a theoretical model to guide probe optimization
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In addition, it is also worth noting that on March 22, 2022, Li Yulong's team and Lin Tian's team from UC Davis were invited to co-author a paper entitled "Fluorescence Imaging of Neural" in the journal Annual Review of Neuroscience.
Activity, Neurochemical Dynamics, and Drug-Specific Receptor Conformation with Genetically Encoded Sensors"
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This review systematically introduces the working principle and development history of genetically encoded fluorescent probes, focuses on neurotransmitter probes, and discusses their applications in neuroscience research and drug discovery
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Different from the previous review, this article focuses on the development process of gene-encoded neurotransmitter probes and establishes a theoretical model to guide probe optimization
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It is worth mentioning that on March 22, 2022, Li Yulong's team and Lin Tian's team from UC Davis were invited to co-author a paper entitled "Fluorescence Imaging of Neural Activity, Neurochemical Dynamics, and Drug-Specific Receptor Conformation with Genetically Encoded Sensors" research review
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This review systematically introduces the working principle and development history of genetically encoded fluorescent probes, focuses on neurotransmitter probes, and discusses their applications in neuroscience research and drug discovery
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Different from the previous review, this article focuses on the development process of gene-encoded neurotransmitter probes and establishes a theoretical model to guide probe optimization
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"Nature Reviews Neuroscience" research review: Dr.
Wu Zhaofa from the School of Life Sciences of Peking University is the first author, Professor Li Yulong is the corresponding author, and Professor Dayu Lin of New York University (NYU) made important contributions to the writing of this review; this research review Relevant research work has been funded by the Beijing Municipal Science and Technology Commission, the National Key R&D Program, the Biomedical Summit Fund, the Boehringer Ingelheim Postdoctoral Fund, the Peking University-Tsinghua Life Science Joint Center, and the State Key Laboratory of Membrane Biology
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 "Annual Review of Neuroscience" research review: Dong Chunyang, a doctoral student at UC Davis, and Zheng Yu, a doctoral student at the Joint Center for Life Sciences of Peking University are the co-first authors, and Professor Li Yulong and Professor Lin Tian are the corresponding authors; the research work related to this research review was obtained Funded by the American Brain Project, the Beijing Municipal Science and Technology Commission, the National Science Foundation for Distinguished Young Scholars, and the Tencent Foundation
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Link to the original text: https:// https://doi.
org/10.
1146/annurev-neuro-110520-031137 Corresponding author Professor Li Yulong (photo courtesy of Li Yulong’s experiment at Peking University Room) Laboratory Introduction (swipe up and down to read) Li Yulong, Professor, School of Life Sciences, Peking University, Peking University McGovern Institute for Brain Science PI Peking University-Tsinghua Joint Center for Life Sciences PI Research Field: The human brain is composed of billions of neurons, The latter in turn form complex neural networks through trillions of synapses
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Different types of neurons project far or near, communicate with other neurons through synapses, and realize advanced neural functions such as perception, decision-making, and movement
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The biggest challenge in studying the brain is its high complexity
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Our laboratory focuses on synapses, the fundamental structures of neuronal communication, and conducts research at two levels: one is the development of cutting-edge tools, namely the development of novel imaging probes for dissecting the complexities of the nervous system on both temporal and spatial scales The second is to explore the regulation mechanism of synaptic transmission with the help of advanced tools, especially the regulation of neurotransmitter release under physiological and pathological conditions
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Specifically, for tool development, we focused on: 1.
Combining optogenetics and fluorescence imaging to non-invasively study electrical synaptic connections between neurons
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Abnormal electrical synapses can lead to diseases such as deafness, epilepsy, brain tumors and abnormal heart function
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2.
Develop genetically encoded fluorescent probes for the detection of neurotransmitters/modulators
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Neurotransmitters/modulators are key mediators of chemical synaptic transmission in neurons and are closely related to perception, learning and memory, and emotion
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 Using the above fluorescent probes, our functional and physiological research focuses on: 1.
Systematic exploration and identification of potential novel small molecule neurotransmitters by combining bioinformatics, analytical chemistry, biochemistry, physiology and imaging methods
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2.
To study the proteomics of "high-density core vesicles", important secretory vesicles in neurons, and to analyze the composition of neuropeptides in the vesicles
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These neuropeptides are important regulators of food intake, aggressive behavior, and biological rhythms
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3.
Find the corresponding receptors of the above-mentioned novel chemical transmitters/modulatory small molecules, that is, find the ligands of the "orphan" receptors
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4.
Combining two-photon imaging and genetically encoded fluorescent probes, using Drosophila and mice as model organisms, to study the working mechanism of the brain during olfactory conduction or sleep
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 For more information about the work of Li Yulong's laboratory, please refer to: http://yulonglilab.
org/; in addition, Li Yulong's laboratory is looking for associate researchers, postdoctoral fellows and research assistants with different disciplinary backgrounds.

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Selected previous articles【1】Nat Commun︱New progress in monitoring technology of cerebral cortex activity in free state of small animals: intelligent fiber-optic two-photon microscope【2】J Neuroinflammation︱Quan/Luan Guoming team collaboration reveals new pathogenesis of Rasmussen encephalitis【3】 JCI︱Liang Zhang/Zhanxiang Wang's team discovered that autocrine pathway regulates oligodendrocyte differentiation and promotes remyelination【4】Front Cell Neurosci Review︱The role of microglial membrane proteins or receptors in neuroinflammation and degeneration and its effects Research progress【5】Nat Biomed Eng︱Using infrared light through the brain to regulate deep brain neural activity【6】Review of Neurosci Bull︱Research progress, problems and prospects of humoral biomarkers in Alzheimer's disease【7】Current Biology︱ Chen Zhong's team has made new achievements in the mechanism of histamine regulation of feeding: H2 receptor-dependent medial septal histaminergic return【8】Nat Commun︱Guo Ming's team discovered a new mechanism of mitochondrial fission and a new target for the prevention and treatment of Parkinson's disease【9 】Front Cell Neurosci︱Shi Peng/Liu Zhen’s research group collaborated to reveal the common molecular mechanism of sensorineural hearing loss caused by multiple factors 【10】Cell Death Dis︱Li Xian’s research group revealed that ferroptosis of oligodendrocyte precursor cells plays a role in cerebral hemorrhage The role of posterior white matter injury High-quality scientific research training courses recommended [1] Symposium on Patch Clamp and Optogenetics and Calcium Imaging Technology Tencent Conference on May 14-15 [2] Scientific Research Skills ︱ The 4th NIR Brain Function Data Analysis Class (Online: 2022.
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18~4.
30) [3] Scientific Research Skills︱Introduction to Magnetic Resonance Brain Network Analysis (Online: 2022.
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6~4.
16) Plate making︱Wang Sizhen End of this article