Neural Circuit Controls Aggression Intensity in Stressed Mice

For many animals, aggression is essential for territorial defense. However, excessive aggression increases the risk of serious injury. To prevent escalation, animals such as male mice frequently employ threat displays to show their strength before biting. Previous research has shown that this balance can be disrupted in mice exposed to early-life stress, leading to disproportionate biting attacks. In this new study, the researchers investigated the brain mechanisms that help maintain the balance between intimidation and physical aggression.

The researchers found that projections from the LH to the DRN are critical for preserving this behavioral balance. Experimentally increasing the activity of this pathway increased the occurrence of attacks-particularly, stronger "hard bites"-, without affecting threat displays. Conversely, inhibiting the pathway decreased attack bites leaving threat behaviors unaffected. Further, mice avoided behaviors that activated this pathway, suggesting that its engagement may induce an aversive internal state.

Despite obvious differences between humans and mice, people can become irritable or unexpectedly aggressive under intense stress. These findings provide insights into how stress and negative emotions may fuel intense or maladaptive aggression, helping inform future research on the neural basis of stress-related aggression.

This study was supported by Japan Society for the Promotion of Science (JSPS) DC-2 Grant Number 24KJ0492 (K.M.), Japan Science and Technology Agency (JST) FOREST Program Grant Number JPMJFR214A, JSPS KAKENHI Grant Numbers 22K19744, 22H02660, and a research grant from the Astellas Foundation for Research on Metabolic Disorders (A.T.).