Key Mechanism for Oxytocin Release Identified, Influencing Social Behavior
A new study led by the Institute for Neurosciences (IN), a joint center of the Spanish National Research Council (CSIC) and the Miguel Hernández University of Elche (UMH), has pinpointed a crucial molecular mechanism regulating oxytocin release within the brain. This discovery, published in Communications Biology, sheds light on how this hormone contributes to the quality of social interactions and maintains a “social tone.”
The Role of Oxytocin in Social Behavior
Oxytocin is a hormone well-known for its role in emotional bonding, sociability, and emotional regulation. Unlike traditional neurotransmitters that act quickly and locally, oxytocin, a neuropeptide, can be released from the cell body (soma) and dendrites, affecting broader brain regions in a slower, more diffuse manner. Until now, the molecular mechanisms underlying this process remained largely unknown.
SNAP-47: A Key Protein in Oxytocin Release
Researchers identified the protein SNAP-47 as essential for the transport and release of oxytocin from the soma and dendrites of hypothalamic neurons – the brain region responsible for producing the hormone. SNAP-47 belongs to the SNARE family of proteins, which are involved in vesicle fusion and chemical signal release. But, SNAP-47 operates more slowly than other proteins in this family, aligning with the sustained release pattern observed for oxytocin within the brain.
“We knew that oxytocin is released within the brain from compartments other than the axon, but we had limited understanding of how this process is regulated,” explains researcher Sandra Jurado, who leads the Synaptic Neuromodulation Laboratory at the IN CSIC-UMH and headed the study. “Our work focuses precisely on understanding the mechanisms that enable this slow and sustained release, which likely prepares the brain for social interaction.”
How the Study Uncovered the Mechanism
The research team combined experiments in neuronal cultures with studies in mice. Reducing SNAP-47 expression disrupted oxytocin release from the soma and dendrites without affecting the conventional axonal release pathway. This alteration impacted the animals’ social behavior; while mice still exhibited sociability, their interactions were shorter and less robust.
“The effects are subtle, but highly revealing,” explains Jurado. “This is not a complete loss of sociability, but rather a fine-tuning of the quality of interactions. This suggests that this release pathway maintains a basal level of oxytocin that primes the brain to respond appropriately to social stimuli.”
Implications for Understanding Brain Function and Neuropsychiatric Disorders
The findings suggest that this mechanism functions as a background system regulating the brain’s social state, maintaining a steady flow of oxytocin that modulates processes like social anxiety, motivation, and the propensity to interact. Researchers believe this represents a basal tone that doesn’t trigger strong responses on its own but shapes reactions to social stimuli.
This discovery expands our understanding of hormonal signaling regulation in the brain and opens new research avenues into how subtle alterations in these mechanisms might contribute to neuropsychiatric disorders where oxytocin plays a role. The team plans to identify the remaining components of this molecular machinery and understand how different oxytocin release modes are coordinated.
This study received funding from the Spanish State Research Agency–Ministry of Science, Innovation and Universities, the Prometeo Programme of the Valencian Regional Government (Generalitat Valenciana), and the Severo Ochoa Programme for Centres of Excellence.
Source: Mirage News