Stimulating environments may help to foster stress resilience

Artistic representation of the impact of the environment on brain development. Painting and photo by Rupshi Mitra.

Affecting almost one in ten people worldwide, anxiety disorders are the most common mental health condition. While the feeling of fear in response to dangerous situations is important for survival, excessive anxiety can lead to debilitating panic attacks and phobias, which can affect an individual’s ability to function normally in everyday life.

As the brain develops substantially during early life, severe experiences of stress during this time, such as maternal separation, can cause the development of anxiety in later life. To investigate the effects of maternal separation during early life on stress response and the development of anxiety-like behaviour, a team of researchers led by Asst Prof Rupshi Mitra from NTU’s School of Biological Sciences compared rats that were separated from their mothers as pups to those which grew up with their mothers.

Adult rats that experienced maternal separation early in life displayed more anxiety-like behaviour when placed in the centre of an open field than non-separated rats. They had higher levels of glucocorticoids, a type of stress hormone, as well as compromised activation of the stress hormone receptors within the amygdala, a brain region known to be involved in anxiety. Moreover, neurons in the amygdala were also different in highly anxious rats compared to their normal counterparts.

However, the researchers found that separated rat pups that grew up in sensory-rich and stimulating environments exhibited less anxiety-related behaviour as adults than those growing up in standard low-sensory environments. They also exhibited fewer changes to their brains as well as stress hormone- and receptor-levels compared to their non-enriched counterparts.

“Stressful experiences early in life may shape the biological and behavioural responses to stress later in life,” said Asst Prof Mitra.

“Our findings in a rat model suggest that a stimulating and engaging environment might help to alleviate the harmful effects of severe stress in early life, reducing the likelihood of developing anxiety as adults.”

The study “Earlylife shortterm environmental enrichment counteracts the effects of stress on anxietylike behaviour, brainderived neurotrophic factor and nuclear translocation of glucocorticoid receptors in the basolateral amygdala” was published in Scientific Reports (2020), DOI: 10.1038/s41598-020-70875-5.  

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