The research provides insights into the neurobiology of aggression and intimidation

Duke-NUS researchers have discovered that a growth factor protein, called brain-derived neurotrophic factor (BDNF), and its receptor, the tropomyosin (kinase B) receptor (TrkB), influence social dominance of the mouse. The research has implications for understanding the neurobiology of aggression and intimidation.

"Humans and rodents are social animals, and each of our interactions follows rules according to a social hierarchy, and not navigating this hierarchy can be detrimental." explained the principal author A / Prof. Hyunsoo Shawn I, the iconic research program on neuroscience and behavioral disorders of the Duke-NUS Medical School. "Our article could be the first to demonstrate that specific molecular signaling pathways in specialized nerve cells, at a particular location in the brain, are important for balanced navigation in social hierarchies."

Difficulties navigating these hierarchies can lead to problems such as aggression and intimidation. "Given the high social cost of intimidation and aggression for society, understanding biological causes is a step towards effective prevention and treatment," Prof. said. I added.

The activity in the brain is mediated by circuits consisting of excitatory neurons, which increase activity, and GABA-ergic interneurons, which inhibit and slow the excitatory activity. Previous studies have shown that BDNF-TrkB signaling is important for the maturation of GABA-ergic interneurons and the development of nerve circuits in the brain. The researchers, however, were unable to determine the behavioral consequences of the disruption of BDNF-TrkB signaling.

A / Prof. The I team generated transgenic mice in which the TrkB receptor was specifically eliminated in GABAergic interneurons located in the brain area regulating emotional and social behavior, called the cortico-limbic system. Transgenic mice exhibited unusual aggressive behavior when housed with normal mice. To understand the origin of this behavior, the team performed behavioral tests. They found that the mice were not aggressive to protect their territory. They were not aggressive either because they were stronger. transgenic mice were more injured than other mice during acts of aggression. Instead, their aggressive behavior was the result of the increased struggle for status and dominance over other mice in the group.

The researchers found that because of the loss of BDNF-TrkB, GABA-ergic interneurons in these transgenic mice had a lower inhibition of surrounding excitatory cells, which became too active. They then closed excitatory neurons in a specific area of ​​the brain of the transgenic mice, which restored the "excitatory / inhibitory" equilibrium and "instantly reversed the abnormal social dominance," says Dr. Dr Duc, a post-graduate researcher. Ph.D. Shawn Pang Hao Tan, who was the first author of the journal.

A significant amount of research has focused on the roles of family networks and peers in aggressive behavior. This study, along with other recently published findings, demonstrates that genetic and biological factors may play an unexpected role in social behaviors, I said.