Scientists Can Now Turn the “Love Hormone” On With Light

Researchers have developed a molecular ‘light switch’ for the so-called love hormone oxytocin, offering new insights into how social behaviour, partnership bonding, emotions, and mental health are wired in the brain.

Professor Markus Muttenthaler from UQ’s Institute for Molecular Bioscience said a light used at a specific wavelength releases neuropeptides, enabling researchers to observe their effects on individual synapses, neurons, and neuronal circuits.

“Until now, scientists have lacked effective tools to study oxytocin’s effects without interference from neighbouring brain areas,’’ Professor Muttenthaler said.

“This new approach allows us to study oxytocin signalling, and its closely related neuropeptide vasopressin, in specific brain regions of interest.

“We can begin to understand how social emotions and behaviours emerge in the brain, and separate cause from effect.’’

Oxytocin plays a key role in social connections, including trust, bonding, parenting, emotional regulation, empathy, learning and memory. 

Changes in oxytocin signalling are also linked to conditions including autism, anxiety, depression, addiction, post-traumatic stress disorder, schizophrenia and psychotic disorders.

Professor Muttenthaler said the research will provide a better understanding of brain circuits involved in social behaviour and could lead to improved therapies.

“The same strategy can be adapted to study many other neuropeptides, making this work part of a much wider effort to understand how the brain communicates,’’ he said.

The probes do not produce toxic by-products and can be activated with very high precision – including at the individual cell level.

“Researchers have tried before to control brain chemicals with light, but doing this reliably to oxytocin has been challenging,’’ Professor Muttenthaler said.

“By shining laser light at the desired location and time, we can release oxytocin and vasopressin in the brain with unprecedented precision and observe how the brain cells and neurons respond in real time.

“The tools we developed here can be used broadly, including in tissues and systems where genetic approaches are difficult or impossible.

“It also gives researchers more precise ways to study oxytocin/vasopressin signalling pathways that can inform new therapeutic strategies.’’

Reference: Raabe K, Kalaba P, Yong XLH, et al. Photocaged oxytocin and vasopressin probes to decipher neuropeptide signalling with high spatiotemporal resolution. Angew Chem Int Ed. 2026:e13373. doi: 10.1002/anie.202513373

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