August 26, 2022
Keio University School of Medicine
A research group led by Associate Professor Mutsuo Nuriya of the Department of Pharmacology, Keio University School of Medicine; Kaho Nakamura, a second-year student in the Master's Program at the Graduate School of Environment and Information Sciences, Yokohama National University; Keiko Karasawa (at the time of the research) of the Department of Pharmacology, Keio University School of Medicine; and Professor Masato Yasui of the same department has succeeded in developing and applying a tool to "visualize" the peptide hormone oxytocin in the brain, which has been shrouded in mystery as it could not be directly observed until now.
Oxytocin has long been known as a crucial hormone for mothers in childbirth and child-rearing, as it is involved in promoting labor, lactation, and maternal behavior. In recent years, in addition to these effects, it has been revealed to play an important role in the social behaviors that build human relationships in daily life, and its role as a neurotransmitter in the brain that powerfully regulates the psyche of humans and other animals is gaining attention. It is also popularly known as the "happy hormone" or "love hormone" due to its effects of reducing aggression and fear, increasing trust in others, and improving social skills, a core symptom of autism spectrum disorder, making it a topic of great interest.
However, despite its importance, the sites of action and dynamics of oxytocin in the brain have remained a mystery. This is because oxytocin is colorless and transparent with a very small molecular weight, so attaching a fluorescent label (tag), which is typically used for "visualization," would affect its original movement and properties, making it impossible to capture its true state. In this study, we successfully developed "alkyne-oxytocin," which has an alkyne (an acetylenic hydrocarbon), an extremely small tag that minimizes these effects, attached to oxytocin. Furthermore, by applying this new "visualization" tool to living mouse brain tissue under various conditions, we have succeeded for the first time in capturing the sites of action and spatiotemporal dynamics of oxytocin in the brain, which had been shrouded in mystery.
It was also confirmed that the new tool developed in this study is not limited to oxytocin but can be widely applied to peptide neurotransmitters in general, which also play important roles in the brain. Therefore, the results of this study are expected to enable the visualization of various neurotransmitters, including oxytocin, deepen our understanding of the molecular basis of mental functions, which are still largely mysterious, and significantly advance brain research.
The results of this research were published in the online edition of Analytical Chemistry , published by the American Chemical Society (ACS), on August 26, 2022 (US Eastern Time).
For the full press release, please see below.