Stress can lead to structural changes in brain

The findings showed that when mice experienced prolonged stress, the amygdala-a part of the brain that regulates basic emotions, such as fear and anxiety-retracts. 

In the medial amygdala, the neuronal branches, which form crucial connections to other parts of the brain, appeared to shrink. 

Such shrinking can harm the brain, distorting its ability to adapt to new experiences, leaving it trapped in a state of anxiety or depression, the researchers said.

"When we took a closer look at three regions within amygdala, we found that neurons within one, the medial amygdala, retract as a result of chronic stress,” said lead author Carla Nasca, post doctoral researcher at Rockefeller University in the US.

"While this rewiring can contribute to disorders such as anxiety and depression, our experiments with mice showed that the neurological and behavioural effects of stress can be prevented with treatment by a promising potential antidepressant that acts rapidly," Nasca added.

In the research, published in the journal Molecular Psychiatry, the team found that the protective approach increased resilience among mice most at risk for developing anxiety or depression-like behaviours.

The team first subjected mice to 21 days of periodic confinement within a small space-an unpleasant experience for mice. 

Afterward, they tested the mice to see if their behaviours had changed, for instance, if they had begun to avoid social interaction and showed other signs of depression. They also analysed the neurons of these mice within the the regions of the amygdala.

The scientists repeated the stress experiment and this time they treated the mice with acetyl carnitine-a molecule known for its potential to act as a rapid-acting antidepressant.