Optopharmacological tools for precise spatiotemporal control of oxytocin signaling in the central nervous system and periphery

Abstract

Oxytocin is a neuropeptide critical for maternal physiology and social behavior, and is thought to be dysregulated in several neuropsychiatric disorders. Despite the biological and neurocognitive importance of oxytocin signaling, methods are lacking to activate oxytocin receptors with high spatiotemporal precision in the brain and peripheral mammalian tissues. Here we developed and validated caged analogs of oxytocin which are functionally inert until cage release is triggered by ultraviolet light. We examined how focal versus global oxytocin application affected oxytocin-driven Ca2+ wave propagation in mouse mammary tissue. We also validated the application of caged oxytocin in the hippocampus and auditory cortex with electrophysiological recordings in vitro, and demonstrated that oxytocin uncaging can accelerate the onset of mouse maternal behavior in vivo. Together, these results demonstrate that optopharmacological control of caged peptides is a robust tool with spatiotemporal precision for modulating neuropeptide signaling throughout the brain and body.

A Biomimetic C-Terminal Extension Strategy for Photocaging Amidated Neuropeptides

“…OT plays important roles in childbirth and lactation, social bonding, and sexual function. It also has analgesic effects in the brain and spinal cord. , Although several side chain-caged analogues of OT were reported recently, C-terminus caging has not been explored. SP contributes to the transmission of pain signals from the periphery to the central nervous system and to inflammation by promoting cytokine release.…”

“…To circumvent these limitations, we and others have developed several photoactivatable or “caged” neuropeptides. These include caged variants of the opioid peptides enkephalin and dynorphin, , as well as somatostatin, orexin, and oxytocin . Caged molecules are advantageous because they can be pre-equilibrated in brain tissue in an inactive form prior to activation with millisecond flashes of light.…”

“…These include caged variants of the opioid peptides enkephalin and dynorphin, 3 , 4 as well as somatostatin, 5 orexin, 6 and oxytocin. 7 Caged molecules are advantageous because they can be pre-equilibrated in brain tissue in an inactive form prior to activation with millisecond flashes of light. Because pre-equilibration distributes the caged neuropeptide uniformly in the tissue, receptor activation by photoactivated peptide is not limited by diffusion.…”

An integrated microfluidic and fluorescence platform for probing in vivo neuropharmacology

“…Depending on the capability of a user’s fiber photometry system, the photo-fluidic device can also readily be used for photopharmacology (e.g. optopharmacology) experiments (McClain et al 2023, Ahmed et al 2023, Gómez-Santacana et al 2022, Hüll et al 2018), providing an additional level of control for more biological insights.…”

Understanding Neuropeptide Transmission in the Brain by Optical Uncaging and Release

“…Later, the same group synthesized a new caged analogue of LE ( N -MNVOC-LE) to reduce the residual activity and demonstrated the feasibility in brain slices of rat locus coeruleus . Caged compounds can be extended to other caged peptides, including dynorphin, gastrin-releasing peptide, oxytocin, cholecystokinin, and substance P. However, caged peptides have some limitations. First, each caged compound requires a separate optimization process to ensure biological inertness, solubility at physiological pH, resistance to aqueous hydrolysis, fast uncaging speed, and high uncaging efficiency .…”