Reversible silencing of endogenous receptors in intact brain tissue using 2-photon pharmacology

Two-photon fluorescent probes to image intracellular calcium and other biochemical processes have revolutionized cell biology. In neurobiology, 2-photon calcium indicators produce signals that indirectly reflect action potential firing in neurons deep in the brain, and have become essential to record and correlate large-scale neural activity at high spatiotemporal resolution. Here we show that 2-photon excitable, diffusible photoswitches allow the activation and deactivation of neurotransmitter receptors with higher subtype-specificity and spatial resolution compared with previous molecular tools, and combined with calcium indicators enables to both control and readout activity using 2-photon excitation. Specifically, we used a potent and selective antagonist to switch on/off at the micrometer scale the activity of mGlu₅ receptors expressed endogenously in neurons and astrocytes of intact brain tissue.