Wild birds help shed light on stress resilience in humans

Stress is a common everyday experience, particularly in the world today. A new study might open the doors for the prevention and treatment of stress disorders, thanks to wild songbirds.

A team of researchers at Louisiana State University wanted to determine individual physiological variation among humans in stress response. They pioneered a study that could pave the way for better understanding the role of dopamine in stress resilience in humans by studying wild songbirds.

House sparrow, Passer domesticus. Image Credit: Erni / Shutterstock
House sparrow, Passer domesticus. Image Credit: Erni / Shutterstock

Dopamine and stress

Dopamine is one of the brain’s neurotransmitters, a chemical that transmits information between neurons. It helps regulate attention, emotional responses, learning, memory, and movement. It also helps recognize reward and act to move toward them.

Even though dopamine is best known in reward-motivated behavior, two major pathways of the dopaminergic system also respond to stress. While many catecholaminergic systems are stimulated by stressful stimuli, the mesoprefrontal dopamine system is also vulnerable to stress, including the nigrostriatal dopamine pathway.

Dopamine is also imperative in responding to long-lasting stressors, the researchers found while analyzing data from wild songbirds.

“Although a rise in dopamine may be important for learning about and responding appropriately to threats, laboratory animal and human studies suggest that neurobiological mechanisms limiting the extent and duration of dopamine effects on the brain may contribute to stress resilience,” the researchers explained in the study.

The results of the study, which was published in the Scientific Reports, can help in wildlife conservation efforts as a result of environmental stressors, including extreme weather events, increase in predation, natural disasters, climate change, and habitat destruction.

Positron Emission Tomography (PET) scan for songbirds

The researchers used Positron Emission Tomography (PET) scan, which is commonly used in humans only, to determine and measure dopamine receptors in house sparrows. PET scan is commonly used in humans, but rarely on wild animals.

"This study is exciting because it is the first time PET scans have been used in wildlife to quantify dopamine receptors in the brain,” Professor Christine Lattin, Biological Sciences Assistant, said.

“Developing this technique has opened the door to being able to scan animals and release them back into the wild. We need to know how these wild birds are coping with stressors and responding to changes to the environment so we can understand how to best protect them,” she added.

Birds become resilient to stress over time

Aside from biomedical imaging, the researchers followed the birds and tracked their body mass and hormone levels. Also, they used a remotely operated video camera to analyze the birds’ response to captivity for over one month. They scanned the birds after they were brought into the laboratory and then scanned them again a month after. The researchers studied how the stress of captivity influenced the birds in the long run, using PET scans.

“We found that individuals that coped better with captivity (fewer anxiety-related behaviors, more time spent feeding, higher body mass) had a lower baseline and higher stress-induced corticosteroid titers at capture,” the researchers wrote in the study.

On the other hand, birds with higher striatal D2 receptor binding spent more time feeding in captivity but has a lower weight, than the birds with lower D2 receptor binding.

The findings of the study have shown that one type of dopamine receptor lowers overtime during captivity, suggesting that birds became less resilient to stress in the long run. The bigger the reduction in dopamine receptors, the more they manifested anxiety-related behaviors like feather-ruffling and body mass decrease.

"These physiological, neurobiological and behavioral changes suggest that songbirds are not able to habituate to captivity, at least over short periods of time. It is very important that scientists studying stress in wildlife find more ways to study them in their natural habitat," Lattin explained.

The results of the study, though conducted in wild songbirds, can give an insight on stress resilience in humans, too. Stress is a part of life, especially because everything is fast-paced today. Studying how humans and animals respond to stress over time is important in formulating preventive measures as well as treatment approaches for stress-related disorders, including anxiety and depression.

Journal reference:

Lattin, C., Merullo, D., Riters, L., and Carson, R. (2019). 'In vivo imaging of D2 receptors and corticosteroids predict behavioural responses to captivity stress in a wild bird'. Scientific Reports. DOI: 10.1038/s41598-019-46845-x
ID, https://www.nature.com/articles/s41598-019-46845-x

Angela Betsaida B. Laguipo

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Angela Betsaida B. Laguipo

Angela is a nurse by profession and a writer by heart. She graduated with honors (Cum Laude) for her Bachelor of Nursing degree at the University of Baguio, Philippines. She recently completed a Master's Degree where she specialized in Maternal and Child Nursing and is now working as a clinical instructor and educator in the School of Nursing at the University of Baguio.

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Comments

  1. Dr. T Dr. T United States says:

    There are a few key facts omitted from this report, including the fate of the birds involved, who were all eventually killed after extended captivity. Dr. Lattin and a team of researchers from Yale University captured 21 wild birds in 2016 and subjected them to the trauma of long-term captivity. These highly social birds were housed alone in cages, restrained in cloth bags for thirty minutes at a time to induce acute stress, and held in captivity for eight weeks or more before being killed. Some of these birds were apparently used in multiple experiments. The main conclusion from this experiment was that wild birds do not habituate well to captivity, and wildlife should be studied in their habitat—a realization that is far from groundbreaking.

    Birds are intelligent and highly attuned to their environment, and many species form close familiar and communal bonds.  Although birds experience many of the same emotions that we do, their physiology differs from ours and experimental results in birds do not mirror humans or other animal species. Additionally, birds themselves vary widely in their physiological responses, and findings in one bird species do not necessarily correlate with another species.

    These experiments lack real-world applicability, and if Dr. Lattin and her team want to help wild birds, she should stop harming and killing them, and instead adopt noninvasive and observational studies that will truly benefit wild animals.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
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