People experienced less stress and anxiety while listening to nature soundscapes, but the addition of road traffic noise increased their stress and anxiety
Photo by Lucas Davies on Unsplash
Manmade sounds such vehicle traffic can mask the positive impact of nature soundscapes on people’s stress and anxiety, according to a new study published November 27, 2024, in the open-access journal PLOS ONE by Paul Lintott of the University of the West of England, U.K., and Lia Gilmour of the Bat Conservation Trust, U.K.
Existing research shows that natural sounds, like birdsong, can lower blood pressure, heart, and respiratory rates, as well as self-reported stress and anxiety. Conversely, anthropogenic soundscapes, like traffic or aircraft noise, are hypothesized to have negative effects on human health and wellbeing in a variety of ways.
In the new study, 68 student volunteers listened to three 3-minute soundscapes: a nature soundscape recorded at sunrise in West Sussex, U.K., the same soundscape combined with 20 mile per hour road traffic sounds, and the same soundscape with 40 mile per hour traffic sounds. General mood and anxiety were assessed before and after the soundscapes using self-reported scales.
The study found that listening to a natural soundscape reduced self-reported stress and anxiety levels, and also enhanced mood recovery after a stressor. However, the benefits of improved mood associated with the natural soundscape was limited when traffic sounds were included. The natural soundscape alone was associated with the lowest levels of stress and anxiety, with the highest levels reported after the soundscape that included 40 mile per hour traffic.
The authors conclude that reducing traffic speed in urban areas might influence human health and wellbeing not only through its safety impacts, but also through its effect on natural soundscapes.
The authors add: “Our study shows that listening to natural soundscapes can reduce stress and anxiety, and that anthropogenic sounds such as traffic noise can mask potential positive impacts. Reducing traffic speeds in cities is therefore an important step towards more people experiencing the positive effects of nature on their health and wellbeing.”
In a large multi-ethnic group of adults in the United States without cardiovascular disease, those with work-related stress were more likely to have unfavourable measures of cardiovascular health. The findings are published in the Journal of the American Heart Association.
For the analysis, investigators assessed data collected between 2000 and 2002 for 3579 community-based men and women aged 45–84 years enrolled in the Multi-Ethnic Study of Atherosclerosis. Cardiovascular health was determined based on seven metrics – smoking, physical activity, body mass index, diet, total cholesterol, blood pressure, and blood glucose – with each metric contributing zero points, one point, or two points if in the poor, intermediate, or ideal range, respectively, for a range of 0–14 points.
Work-related stress, which was assessed through a questionnaire, was reported by 20% of participants. After adjusting for potentially influencing factors, individuals with work-related stress, had 25% and 27% lower odds of having average (9–10 points) and optimal (11–14 points) cardiovascular health scores, respectively, compared with individuals without work-related stress.
“To address the public health issue of work-related stress and its detrimental effects on cardiovascular health, future research should prioritise the use of longitudinal studies to identify the mechanisms underlying this association,” said first author Oluseye Ogunmoroti, MD, MPH, of Emory University and senior author Erin Michos, MD, MHS, of Johns Hopkins University. “Additionally, conducting thorough workplace intervention studies is essential for the development and implementation of effective stress management strategies that can enhance employee well-being and improve cardiovascular health.”
As the world continues to face unprecedented challenges, including geopolitical tensions, extreme weather events, disease outbreaks, and economic uncertainty, the mental health of employees has become a pressing concern. This year’s World Mental Health Day theme, “Mental Health at Work”, is a crucial reminder for organisations to take action to safeguard their workforce’s mental health and wellbeing. In alignment with this theme, International SOS, the world’s leading health and security risk services company, encourages organisations worldwide to recognise the critical importance of mental wellbeing and resilience within their workforce.
Heightened anxiety
The increasing frequency and intensity of global crises, coupled with elevated job demands, are contributing to heightened levels of stress and anxiety, further exacerbating mental health concerns among the global workforce. According to the World Health Organization (WHO), an estimated 15% of working-age adults are experiencing a mental disorder at any single point in time.
Additionally, International SOS assistance data(2022 – 2024) reveals that over the past two years, the top five mental health-related assistance requests the organisation received are:
Anxiety
Depression
Panic disorder
Attention Deficit Hyperactivity Disorder (ADHD)
Acute stress
Burnout has also become a prominent issue among employees, with one in four employees worldwide reporting symptoms of burnout. The International SOS Risk Outlook 2024 report highlights employee burnout as a major threat impacting organisations.
Economic impact
Moreover, the economic impact of mental health issues cannot be ignored. The WHO estimates that globally, approximately 12 billion working days are lost annually to depression and anxiety, resulting in US$ 1 trillion in lost productivity per year. These figures highlight the importance for employers to create a workplace that promotes mental wellbeing and underscores the immense cost of neglecting employee mental health and wellbeing at work. Organisations play a pivotal role in shaping the mental health landscape by implementing policies and practices that promote wellbeing.
Dr Chris van Straten, Global Health Advisor Clinical Governance at International SOS said, “World Mental Health Day is a timely reminder for organisations to acknowledge and address the profound importance of mental wellbeing within their workforce. The workplace environment can have a significant impact on employee mental health, both positive and negative, by either fostering wellbeing or contributing to stress and anxiety. Just as we invest in employee physical safety, it is important to also understand that mental health is integral to overall health. It is therefore imperative to prioritise mental resilience.”
“Organisations can empower their employees to navigate challenges, thrive and contribute to a more positive and productive workplace by creating a supportive work environment that fosters open communication, empathy and understanding. Providing access to mental health professionals, counselling services, and employee assistance programmes is essential to ensure employees are equipped to navigate the complexities of today’s global landscape.”
To support the mental health and wellbeing of their workforce, International SOS provides advice for organisations:
Cultivate a supportive work culture with strong leadership commitment: Create a workplace culture and environment that prioritises and promotes open communication on mental health. Ensure mental wellbeing initiatives are seamlessly integrated into relevant policies and practices to provide robust support.
Provide accessible resources: Ensure employees have a toolkit of mental health resources at their fingertips, from counselling to self-guidance materials.
Promote work-life balance: Offer flexible work arrangements and remote work options to help employees manage their personal and professional lives effectively. Encourage regular breaks and empower employees to prioritise their wellbeing.
Training and education: Implement comprehensive mental health awareness campaigns to reduce stigma. Roll out mental health training, enabling everyone to spot, understand and assist with mental health challenges.
Monitor and assess: Seek feedback and continuously monitor the mental health of employees through surveys and assessments, and adapt programmes as needed.
Invest in emotional wellbeing: provide access to mindfulness sessions and stress management training—partner with certified mental health professionals to offer confidential counselling and support services.
Employee Assistance Programmes (EAPs): Provide EAPs that offer confidential counselling and support services to employees. Promoting the availability and benefits of EAPs can encourage employees to seek help without fear of stigma, fostering a culture of openness and support.
A lesser-known cannabinoid that is gaining in popularity, Cannabigerol (CBG), was shown to effectively reduce anxiety in a clinical trial – without the intoxication typically associated with whole plant cannabis. It may even have some memory enhancing effects, according to a new study in Scientific Reports.
For the study, Carrie Cuttler, an associate professor of psychology at Washington State University, and colleagues conducted the first human clinical trial investigating the acute effects of CBG on anxiety, stress and mood.
The research revealed that 20mg of hemp-derived CBG significantly reduced feelings of anxiety at 20, 45 and 60 minutes after ingestion compared to a placebo. Stress ratings also decreased at the first time point compared to the placebo. The findings align with survey data from a previous study led by Cuttler that indicated 51% of CBG users consume it to decrease anxiety, with 78% asserting its superiority over conventional anxiety medications.
“CBG is becoming increasingly popular, with more producers making bold, unsubstantiated claims about its effects,” Cuttler said. “Our study is one of the first to provide evidence supporting some of these claims, helping to inform both consumers and the scientific community.”
For the study, Cuttler’s team at WSU and colleagues at the University of California, Los Angeles, conducted a double-blind, placebo-controlled, experimental trial with 34 healthy cannabis users. The participants completed two sessions over Zoom during which they provided baseline ratings of their anxiety, stress and mood.
They then ingested either 20mg of hemp-derived CBG or a placebo tincture mailed to them ahead of time. The participants then rerated their mood, stress, anxiety and other variables such as feelings of intoxication and whether they liked how the drug made them feel at three different time points post-ingestion. Additionally, they reported on potential side effects like dry eyes and mouth, increased appetite, heart palpitations and sleepiness.
The sessions were repeated a week later with the participants taking the alternate product prior to completing the same assessments. The design ensured that neither the participants nor the research assistants knew which product was administered.
Surprising outcomes
One of the most surprising outcomes was CBG’s effect on memory. Contrary to expectations based on THC’s known effects on memory, CBG significantly enhanced the ability to recall lists of words. Participants were able to recall more words after taking 20mg of CBG than after taking a placebo.
“We triple-checked to ensure accuracy, and the enhancement was statistically significant,” Cuttler said.
Furthermore, the study found that CBG did not produce cognitive or motor impairments, or other adverse effects commonly associated with THC, the psychoactive ingredient in cannabis. Participants in the experimental group reported low intoxication ratings and minimal changes in symptoms like dry mouth, sleepiness and appetite. Contrary to previous self-report surveys where users touted CBG’s antidepressant effects, the participants in the current study did not report significant mood enhancement after taking CBG.
While the research is promising, Cuttler cautions the results should be interpreted carefully due to the study’s limitations. The use of experienced cannabis users, the modest dose of CBG and the timing of assessments might have influenced the findings. Additionally, the study’s remote nature, conducted via Zoom, and lack of physiological measurements further constrain the conclusions.
“We need to avoid claims that CBG is a miracle drug. It’s new and exciting, but replication and further research are crucial,” Cuttler said. “Ongoing and future studies will help build a comprehensive understanding of CBG’s benefits and safety, potentially offering a new avenue for reducing feelings of anxiety and stress without the intoxicating effects of THC.”
Moving forward, Cuttler and her team are designing a new clinical trial to replicate their findings and include physiological measures such as heart rate, blood pressure and cortisol levels. They also plan to extend the research to non-cannabis users. Additionally, Cuttler is planning a study on CBG’s effects on menopause symptoms in women.
The 2020 Tokyo Olympics were unique not just for taking place during the COVID pandemic but for being the first athletic event to measure and broadcast competitors’ heart rates as world-class archers took a shot at Olympic gold. Analysis of these biometric data by Yunfeng Lu (Nanjing University) and Songfa Zhong (National University of Singapore, New York University Abu Dhabi) in Psychological Scienceprovides empirical support for something sports fans have long suspected: When athletes feel the pressure, their performance suffers.
“We found that high contactless real-time heart rate is associated with poor performance,” said Lu and Zhong in an interview. “This suggests that even the best professional athletes are negatively influenced by psychological stress, even though they are generally well trained to cope with pressure.”
Olympic archery includes several types of individual and team-based competitions, but for this study, Lu and Zhong focused on cisgender individual competitions for which heart-rate data were available. During these competitions, the heart rates of 122 male and female archers were broadcast as they took 2247 shots. The World Archery Federation, in collaboration with Panasonic, measured athletes’ heart rates using high-frame-rate cameras that are designed to detect skin reflectance and can determine a person’s heart rate 96% as accurately as a pulse oximeter or electrocardiogram.
During each match, individual archers shot a set number of arrows at a target, with a 20s time limit for each shot. Archers could earn a maximum of 10 points for a perfect bulls-eye shot, with points decreasing the farther an arrow landed from the centre of the target.
Lu and Zhong found that athletes whose heart rates were higher before taking a shot consistently scored lower on those shots. While archers’ age and gender were not found to significantly influence the relationship between stress and performance, a number of factors related to the nature of the competition did.
Increased heart rate was more likely to reduce the performance of lower-ranking archers and of all archers who shot second in a match or who had a lower score than their opponent at that point in the match. There was also a stronger relationship between stress and performance closer to the end of each match, possibly due to the increase in pressure as athletes progressed in the competition, the authors wrote.
“Elite athletes usually receive training to manage psychological stress, but our results suggest that they continue to be subject to the influence of psychological stress,” wrote Lu and Zhong.
In addition to offering evidence for the link between stress and performance in a real-life setting, this research demonstrates that heart rate captured by high-frame-rate cameras can serve as a reliable source of biometric data, according to Lu and Zhong, particularly in situations like the COVID pandemic in which researchers and participants may be unable to meet in person.
“This method could become increasingly important in diverse settings, ranging from sports and business to mental health and medicine,” the researchers wrote. “In this regard, our study can be viewed as a proof of concept by showing that contactless real-time heart rates captured psychological stress.”
In future work, this technology could be used to observe how psychological stress influences athletic performance across different sports, Lu and Zhong said. The researchers would also like to further investigate how contactless real-time heart rate can be incorporated into behavioural studies in laboratory and field settings.
While mentally stimulating activities and life experiences can improve cognition in memory clinic patients, stress undermines this beneficial relationship. This is according to a new study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
Researchers in the late 1980s found that some individuals who showed no apparent symptoms of dementia during their lifetime had brain changes consistent with an advanced stage of Alzheimer’s disease.
It has since been postulated that so-called cognitive reserve might account for this differential protective effect in individuals.
Cognitively stimulating and enriching life experiences and behaviours such as higher educational attainment, complex jobs, continued physical and leisure activities, and healthy social interactions help build cognitive reserve.
Increased risk of dementia
However, high or persistent stress levels are associated with reduced social interactions, impaired ability to engage in leisure and physical activities, and an increased risk of dementia.
Researchers from Karolinska Institutet have now examined the association between cognitive reserve, cognition, and biomarkers for Alzheimer’s disease in 113 participants from the memory clinic at the Karolinska University Hospital, Huddinge, Sweden.
They also examined how this association is modified by physiological stress (cortisol levels in saliva) and psychological (perceived) stress.
Greater cognitive reserve was found to improve cognition, but interestingly, physiological stress appeared to weaken the association.
“These results might have clinical implications as an expanding body of research suggests that mindfulness exercises and meditation may reduce cortisol levels and improve cognition,” says the study’s lead author Manasa Shanta Yerramalla, researcher at the Department of Neurobiology, Care Sciences and Society. “Different stress management strategies could be a good complement to existing lifestyle interventions in Alzheimer’s prevention.”
The relatively small sample of participants reduces the possibility of drawing robust conclusions, but the results are generalisable to similar patient groups.
Link between sleep and cognition
Moreover, since stress disrupts sleep, which in turn disrupts cognition, the researchers controlled for sleeping medications; they did not, however, consider other aspects of sleep that might impair cognition.
“We will continue to study the association between stress and sleeping disorders and how it affects the cognitive reserve in memory clinic patients,” says Dr Yerramalla.
Atrial fibrillation may lead to blood clots, stroke, heart failure or other cardiovascular complications. It primarily affects older adults.
“In my general cardiology practice, I see many postmenopausal women with picture perfect physical health who struggle with poor sleep and negative psychological emotional feelings or experience, which we now know may put them at risk for developing atrial fibrillation,” said lead study author Susan X. Zhao, M.D., a cardiologist at Santa Clara Valley Medical Center in California. “I strongly believe that in addition to age, genetic and other heart-health related risk factors, psychosocial factors are the missing piece to the puzzle of the genesis of atrial fibrillation.“
Researchers reviewed data from more than 83 000 questionnaires by women ages 50-79 from the Women’s Health Initiative, a major US study. Participants were asked a series of questions in key categories: stressful life events, their sense of optimism, social support and insomnia. Questions about stressful life events addressed topics such as loss of a loved one; illness; divorce; financial pressure; and domestic, verbal, physical or sexual abuse. Questions about sleeping habits focused on if participants had trouble falling asleep, wake up several times during the night and overall sleep quality, for example. Questions about participants’ outlook on life and social supports addressed having friends to talk with during and about difficult or stressful situations; a sense of optimism such as believing good things are on the horizon; and having help with daily chores.
During approximately a decade of follow-up, the study found:
About 25% or 23 954 women developed atrial fibrillation.
A two-cluster system (the stress cluster and the strain cluster).
For each additional point on the insomnia scale, there is a 4% higher likelihood of developing atrial fibrillation. Similarly, for each additional point on the stressful life event scale, there is a 2% higher likelihood of having atrial fibrillation.
“The heart and brain connection has been long established in many conditions,” Zhao said. “Atrial fibrillation is a disease of the electrical conduction system and is prone to hormonal changes stemming from stress and poor sleep. These common pathways likely underpin the association between stress and insomnia with atrial fibrillation.”
Researchers noted that stressful life events, poor sleep and feelings, such as depression, anxiety or feeling overwhelmed by one’s circumstances, are often interrelated. It’s difficult to know whether these factors accumulate gradually over the years to increase the risk of atrial fibrillation as women age.
Chronic stress has not been consistently associated with atrial fibrillation, and the researchers note that a limitation of their study is that it relied on patient questionnaires from the start of the study. Stressful life events, however, though significant and traumatic, may not be long lasting, Zhao notes. Further research is needed to confirm these associations and evaluate whether customised stress-relieving interventions may modify atrial fibrillation risk.
New research from Duke University found that shifting to a curious mindset helps memory – such as video game players who imagined being a thief scouting a virtual art museum in preparation for a heist. This mindset resulted in better recalling the paintings there. Adopting a high-pressure mindset, such as players trying to execute the heist, resulted in fewer paintings being recalled.
These subtle differences in motivation – urgent, immediate goal-seeking versus curious exploration for a future goal – have big potential for framing real-world challenges such encouraging vaccination. The findings appeared in PNAS.
Alyssa Sinclair, PhD ’23, a postdoctoral researcher working in the lab of Duke Institute for Brain Sciences director Alison Adcock, PhD, MD, recruited 420 adults to pretend to be art thieves for a day. The participants were then randomly assigned to one of two groups and received different backstories.
“For the urgent group, we told them, ‘You’re a master thief, you’re doing the heist right now. Steal as much as you can!’,” Sinclair said. “Whereas for the curious group, we told them they were a thief who’s scouting the museum to plan a future heist.”
After getting these different backstories, however, participants in the two groups played the exact same computer game, scored the exact same way. They explored an art museum with four coloured doors, representing different rooms, and clicked on a door to reveal a painting from the room and its value. Some rooms held more valuable collections of art. No matter which scenario they were pretending to be in, everyone earned real bonus money by finding more valuable paintings.
The impact of this difference in mindset was most apparent the following day. When participants logged back in, they were met with a pop quiz about whether they could recognise 175 different paintings (100 from the day before, and 75 new ones). If participants flagged a painting as familiar, they also had to recall how much it was worth.
Sinclair and her co-author, fellow Duke psychology & neuroscience graduate student Candice Yuxi Wang, were gratified after they graded the tests to see their predictions had played out.
“The curious group participants who imagined planning a heist had better memory the next day,” Sinclair said. “They correctly recognized more paintings. They remembered how much each painting was worth. And reward boosted memory, so valuable paintings were more likely to be remembered. But we didn’t see that in the urgent group participants who imagined executing the heist.”
Urgent group participants, however, had a different advantage. They were better at figuring out which doors hid more expensive pieces, and as a result snagged more high value paintings. Their stash was appraised at about $230 more than the curious participants’ collection.
The difference in strategies (curious versus urgent) and their outcomes (better memory versus higher-valued paintings) doesn’t mean one is better than the other, though.
“It’s valuable to learn which mode is adaptive in a given moment and use it strategically,” Dr Adcock said.
For example, being in an urgent, high-pressure mode might be the best option for a short-term problem.
“If you’re on a hike and there’s a bear, you don’t want to be thinking about long-term planning,” Sinclair said. “You need to focus on getting out of there right now.”
Opting for an urgent mindset might also be useful in less grisly scenarios that require short-term focus, Sinclair explained, like prompting people to get a COVID vaccine.
For encouraging long-term memory or action, stressing people out is less effective.
“Sometimes you want to motivate people to seek information and remember it in the future, which might have longer term consequences for lifestyle changes,” Sinclair said. “Maybe for that, you need to put them in a curious mode so that they can actually retain that information.”
Sinclair and Wang are now following up on these findings to see how urgency and curiosity activate different parts of the brain. Early evidence suggests that, by engaging the amygdala, an almond-shaped brain region best known for its role in fear memory, “urgent mode” helps form focused, efficient memories. Curious exploration, however, seems to shuttle the learning-enhancing neurochemical dopamine to the hippocampus, a brain region crucial for forming detailed long-term memories.
With these brain results in mind, Dr Adcock is exploring how her lab’s research might also benefit the patients she sees as a psychiatrist.
“Most of adult psychotherapy is about how we encourage flexibility, like with curious mode” Dr Adcock said. “But it’s much harder for people to do since we spend a lot of our adult lives in an urgency mode.”
These thought exercises may give people the ability to manipulate their own neurochemical spigots and develop “psychological manoeuvres,” or cues that act similar to pharmaceuticals, Dr Adcock explained.
“For me, the ultimate goal would be to teach people to do this for themselves,” Dr Adcock said. “That’s empowering.”
Reaching for a high-calorie snack is a common reaction when stressed – but this could be driving a vicious circle. Australian scientists report that stress combined with calorie-dense ‘comfort’ food creates brain changes that drive more eating, boost cravings for sweet, highly palatable food and lead to excess weight gain.
A team from the Garvan Institute of Medical Research reported in the journal Neuron that stress overrode the brain’s natural response to satiety, leading to non-stop reward signals that promote eating more highly palatable food. This occurred in a part of the brain called the lateral habenula, which when activated usually dampens these reward signals.
“Our findings reveal stress can override a natural brain response that diminishes the pleasure gained from eating — meaning the brain is continuously rewarded to eat,” says Professor Herzog, senior author of the study and Visiting Scientist at the Garvan Institute of Medical Research.
“We showed that chronic stress, combined with a high-calorie diet, can drive more and more food intake as well as a preference for sweet, highly palatable food, thereby promoting weight gain and obesity. This research highlights how crucial a healthy diet is during times of stress.”
From stressed brain to weight gain
Most people will eat more than usual during times of stress and choose calorie-rich options high in sugar and fat. To understand what drives these eating habits, the team investigated in mouse models how different areas in the brain responded to chronic stress under various diets.
“We discovered that an area known as the lateral habenula, which is normally involved in switching off the brain’s reward response, was active in mice on a short-term, high-fat diet to protect the animal from overeating. However, when mice were chronically stressed, this part of the brain remained silent – allowing the reward signals to stay active and encourage feeding for pleasure, no longer responding to satiety regulatory signals,” explains first author Dr Kenny Chi Kin Ip.
“We found that stressed mice on a high-fat diet gained twice as much weight as mice on the same diet that were not stressed.”
The researchers discovered that at the centre of the weight gain was the molecule NPY, which the brain produces naturally in response to stress. When the researchers blocked NPY from activating brain cells in the lateral habenula in stressed mice on a high-fat diet, the mice consumed less comfort food, resulting in less weight gain.
Driving comfort eating
The researchers next performed a ‘sucralose preference test’ – allowing mice to choose to drink either water or water that had been artificially sweetened.
“Stressed mice on a high-fat diet consumed three times more sucralose than mice that were on a high-fat diet alone, suggesting that stress not only activates more reward when eating but specifically drives a craving for sweet, palatable food,” says Professor Herzog.
“Crucially, we did not see this preference for sweetened water in stressed mice that were on a regular diet.”
Stress overrides healthy energy balance
“In stressful situations it’s easy to use a lot of energy and the feeling of reward can calm you down — this is when a boost of energy through food is useful. But when experienced over long periods of time, stress appears to change the equation, driving eating that is bad for the body long term,” says Professor Herzog.
The researchers say their findings identify stress as a critical regulator of eating habits that can override the brain’s natural ability to balance energy needs.
“This research emphasises just how much stress can compromise a healthy energy metabolism,” says Professor Herzog. “It’s a reminder to avoid a stressful lifestyle, and crucially – if you are dealing with long-term stress – try to eat a healthy diet and lock away the junk food.”
A new study published in Science Advances shows that female and male hearts respond differently to the stress hormone noradrenaline. The study in mice may have implications for human heart disorders like arrhythmias and heart failure and how different sexes respond to various drugs.
Using fluorescence imaging, the researchers were able to see in real time and in vivo how a mouse heart responds to hormones and neurotransmitters, including noradrenaline.
The results reveal that male and female mouse hearts respond uniformly at first after exposure to noradrenaline. However, some areas of the female heart return to normal more quickly than the male heart, producing differences in the heart’s electrical activity.
“The differences in electrical activity that we observed are called repolarisation in the female hearts. Repolarisation refers to how the heart resets between each heartbeat and is closely linked to some types of arrhythmias,” said Jessica L. Caldwell, first author of the study.
“We know that there are sex differences in the risk for certain types of arrhythmias. The study reveals a new factor that may contribute to different arrhythmia susceptibility between men and women,” Caldwell said.
Methods
The novel imaging system uses a genetically modified ‘CAMPER’ mouse to emit light during a very specific chemical reaction in the heart: cAMP binding.
The cAMP molecule (an abbreviation of cyclic adenosine 3′,5;-monophosphate) is an intermediate messenger that turns signals from hormones and neurotransmitters, including noradrenaline, into action from heart cells.
The light signals from the CAMPER mouse are transmitted by a biosensor that uses a fluorescence signal that can be picked up at high speed and high resolution by a new imaging system specially designed for hearts. This allows the researchers to record the heart’s reaction to noradrenaline in real time, along with changes in electrical activity.
This new imaging approach revealed the differences in the breakdown of cAMP in female and male mice and the associated differences in electrical activity.
Including female mice leads to discoveries
The researchers had not planned to study sex-based responses, according to Crystal M. Ripplinger, senior author of the study. But the researchers started seeing a pattern of different reactions, which led them to realise the differences were sex-based.
When Ripplinger started her lab at the UC Davis School of Medicine over a decade ago, she exclusively used male animals. That was the norm for most research at the time. But several years ago, she began including male and female animals in her studies.
“Sometimes the data between the two sexes is the same. But if the data start to show variation, the first thing we do is look at sex differences. Using both male and female mice has revealed clues into differences we would never have suspected. Researchers are realising you can’t extrapolate to both sexes from only studying one,” Ripplinger said.
She notes that with the current study, it’s not clear what the differences in cAMP and electrical activity may mean.
“The response in the female mice may be protective – or it may not. But simply documenting that there is a measurable difference in the response to a stress hormone is significant. We are hoping to learn more in future studies,” Ripplinger said.
