Fluorogenic Detection of Monoamine Neurotransmitters in Live Cells
Abstract
Monoamine neurotransmission is key to neuromodulation, but imaging monoamines in live neurons has remained a challenge. Here we show that externally added ortho-phthalaldehyde (OPA) can permeate live cells and form bright fluorogenic adducts with intracellular monoamines (e.g., serotonin, dopamine, and norepinephrine) and with L-DOPA, which can be imaged sensitively using conventional single-photon excitation in a fluorescence microscope. The peak excitation and emission wavelengths (λ_(ex) = 401 nm and λ_(em) = 490 nm for serotonin; λ_(ex) = 446 nm and λ_(em) = 557 nm for dopamine; and λ_(ex) = 446 nm and λ_(em) = 544 nm for norepinephrine, respectively) are accessible to most modern confocal imaging instruments. The identity of monoamine containing structures (possibly neurotransmitter vesicles) in serotonergic RN46A cells is established by quasi-simultaneous imaging of serotonin using three-photon excitation microscopy. Mass spectrometry of cell extracts and of in vitro solutions helps us identify the chemical nature of the adducts and establishes the reaction mechanisms. Our method has low toxicity, high selectivity, and the ability to directly report the location and concentration of monoamines in live cells.
Additional Information
© 2017 American Chemical Society. Received: October 12, 2017; Accepted: December 11, 2017; Published: December 11, 2017. We thank Dr. Bappaditya Chandra (TIFR) and Prof. Soumen Basak (SINP) for their help and support. The authors declare no competing financial interest.Attached Files
Supplemental Material - cn7b00391_si_001.pdf
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- CaltechAUTHORS:20171211-154134854
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2017-12-12Created from EPrint's datestamp field
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2021-11-15Created from EPrint's last_modified field