Caged compounds for multichromic optical interrogation of neural systems.

Area of Science:

• Neuroscience
• Cellular Signaling
• Optical Probing

Background:

• Caged compounds are vital tools for neurophysiologists, enabling precise study of cellular signaling in neurons and glia.
• Traditional nitroaromatic caging chromophores (e.g., CNB, DMNB, MNI, CDNI) have been widely used for uncaging experiments.
• Existing methods were limited to 'monochrome' (single-color) uncaging, restricting simultaneous investigations.

Purpose of the Study:

• To introduce novel caging chromophores that enable multicolor optical probing of neuronal function.
• To demonstrate the combination of new blue-light sensitive chromophores with traditional nitroaromatic compounds.
• To showcase the ability to perform simultaneous, spatially precise uncaging for advanced cellular studies.

Main Methods:

• Utilized recently developed caging chromophores, rutheniumbipyridial (RuBi) and 7-diethylaminocoumarin (DEAC)450, photolyzed with blue light (430-480 nm).
• Combined these with traditional nitroaromatic caged compounds (e.g., CDNI) for two-color uncaging experiments.
• Employed one-photon and two-photon uncaging techniques with specific laser wavelengths (e.g., 473 nm, 720 nm, 900 nm) to manipulate neuronal activity.

Main Results:

• Demonstrated facile one-photon uncaging of RuBi-GABA or DEAC450-GABA to block nonlinear currents.
• Showcased two-photon uncaging of CDNI-Glu at 720 nm to evoke nonlinear currents, which could be blocked by blue-light uncaging.
• Successfully used two-photon uncaging of DEAC450-Glu and CDNI-GABA to simultaneously fire and block action potentials.

Conclusions:

• New caging chromophores (RuBi, DEAC450) have advanced uncaging techniques beyond the 'monochrome era'.
• Multichromic interrogation of neuronal function is now possible with single-synapse precision.
• These developments offer powerful new tools for detailed investigation of complex neural circuits and signaling pathways.