Learning a new task, mastering a musical instrument, or adapting to a constantly changing environment are all made possible by the brain’s plasticity, or its ability to modify itself by rearranging existing neural networks and forming new ones in order to acquire new functional properties. This also aids neural circuit health, robustness, and stability.
A team of Baylor College of Medicine and Texas Children’s Hospital researchers used mouse models to investigate how brain cells build connections with new neurons born in adult brains and better understand brain plasticity. The findings not only broaden our understanding of brain plasticity, but also open up new avenues for treating neurodevelopmental disorders and repairing damaged circuits in the future.
“In this study, we wanted to identify new molecules that help new neurons build connections in the brain,”
said Dr. Benjamin R. Arenkiel, corresponding author and professor of molecular and human genetics and neuroscience at Baylor.
Oxytocin Drives Neural Circuit Plasticity
The team focused on the olfactory bulb, the part of the brain responsible for smell. The olfactory bulb in mice is a highly plastic sensory area that can maintain plasticity into adulthood through continuous integration of adult-born neurons. They discovered that oxytocin, a neuropeptide or short protein produced in the brain, promotes neural circuit plasticity.
Oxytocin levels rise in the olfactory bulb, peaking around the time that new neurons integrate into neural networks, it turns out.
The team found that oxytocin activates a signalling pathway — a series of molecular events inside cells — that promotes the maturation of synapses, or the connections of newly integrated adult-born neurons. They made this discovery using viral labelling, confocal microscopy, and cell-type specific RNA sequencing.
Healthy Synapse Connections
When the oxytocin receptor was removed, the cells’ synapses were underdeveloped, and their functionality was compromised. Researchers discovered that synapse maturation is regulated by the morphological development of cells and the expression of a number of structural proteins.
“The most exciting aspect of this study is that our findings suggest that oxytocin drives development and synaptic integration of new neurons within the adult brain, directly contributing to adaptability and circuit plasticity,”
said first author Brandon T. Pekarek, a graduate student research assistant in the Arenkiel lab.
The findings, which are applicable to all mammals, including humans, present new opportunities for treating neurological disorders.
“Oxytocin is normally present in our brain, so if we understand how to turn it on or off or mobilize it, we can help keep our circuit connections healthy by promoting the growth of underdeveloped connections or strengthening new ones,”
The findings also suggest that oxytocin may stimulate the development of new neurons to aid in tissue repair. Additional research is required to investigate these possibilities.
Brandon T. Pekarek, Mikhail Kochukov, Brittney Lozzi, Timothy Wu, Patrick J. Hunt, Burak Tepe, Elizabeth Hanson Moss, Evelyne K. Tantry, Jessica L. Swanson, Sean W. Dooling, Mayuri Patel, Benjamin D.W. Belfort, Juan M. Romero, Suyang Bao, Matthew C. Hill, and Benjamin R. Arenkiel. Oxytocin signaling is necessary for synaptic maturation of adult-born neurons. Genes Dev., doi:10.1101/gad.349930.122