A new study has found that activating natural resilience in the brain could reduce susceptibility for stress in mice, and potentially humans.

Depressive behaviors in mice are often linked to “out-of-balance” neuron activity in the brain’s reward circuit. Suppressing or stopping this hyperactive neuron activity was typically thought to treat this susceptibility to depression or anxiety — but the new study has found quite the opposite.

“To our surprise, neurons in this circuit harbor their own self-tuning, homeostatic mechanism of natural resilience,” Ming-Hu Han of the Icahn School of Medicine at Mount Sinai in New York City, explained in a press release. What this means is that instead of suppressing this excessive neuron activity, boosting it provided a self-stabilizing response, re-establishing balance and producing an antidepressant-like effect.

The mice that were once vulnerable to being anxious, listless, depressed or withdrawn after socially stressful experiences stopped exhibiting these behaviors after their neuron activity received a boost. “As we get to the bottom of a mystery that has perplexed the field for more than a decade, the story takes an unexpected twist that may hold clues to future antidepressants that would at through this counterintuitive resilience mechanism,” Dr. Thomas Insel, NIMH Director, said in the press release.

In susceptible mice, neurons that secrete dopamine — a feel-good hormone — from a reward circuit area called the ventral tegmental area (VTA) become unusually hyperactive. This hyperaction was much higher in mice that were resilient to stress, “even though they were spared the runaway dopamine activity and depression-related behaviors,” the press release reads. Using this logic, the susceptible mice just needed a boost in activation in these neurons to produce resilience.

What is interesting about this study is that it points to the power of the body and brain’s self-correcting prowess. “Homeostatic mechanisms finely regulate other critical components of physiology required for survival — blood glucose and oxygen, body temperature, blood pressure,” Lois Winsky, chief of the NIMH Molecular, Cellular, and Genomic Neuroscience Research Branch, said in the press release. “Similar mechanisms appear to also maintain excitatory balance in brain cells. This study shows how they may regulate circuits underlying behavior.”



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