While walking through Santiago, Chile, you are likely to come across at least one of the countless wandering dogs that live on the busy streets. Homeless dogs are a normal part of Santiago’s culture. They are quick to make friends with anyone who offers a welcoming hand or food. They are not quick, however, to forget their friends. If you make a canine companion in this city, as my classmates and I did, it will probably remember you the next time you come down the street.
The feeling of attachment between the dogs and people of Santiago reminded me of the way a mother and her infant gaze into each other’s eyes. This simple, mutual act of love causes an automatic reaction in both the mom and baby, which increases the levels of oxytocin in the body. Oxytocin is a hormone that plays a major role in social bonding between mothers and infants and between romantic partners. The release of oxytocin promotes a feeling of social well-being and may prevent stress. Interacting with the local dogs in Chile made me wonder if this same sense of happiness and bonding occurs between dogs and people.
A research study looking at the bond between humans and dogs found a similar release—and increase—of oxytocin during social interactions, such as gazing, in both the animals and people. The dogs’ hormone levels also increased when people talked to and petted them. Scientists think this looped interaction reaction (bonding in both directions between pooch and person) may be a reason that humans were able to domesticate wild dogs in the first place. Dogs are one of the only animals known to fully recognize human facial features and expressions. This ability likely helps dogs and people communicate, love and take comfort in one another’s presence.
This mutual interaction is likely the cause of a quick, yet memorable, friendship between humans and dogs both at home and in places like the streets of Santiago. So next time you see a dog in passing, don’t be afraid to gaze into its eyes and form a quick friendship.
Logan Goff is an exercise physiology major at the University of Dayton. Anne R. Crecelius, PhD, is an assistant professor in the Health and Sport Science Department at the University of Dayton. They spent four weeks in Chile as part of a study abroad program in partnership with the Universidad de los Andes studying nutrition, sports and research in the context of the Chilean culture. This is the final installment in a three-part series (read part one and part two) that spies physiology in this dynamic South American country.
Physiology, the study of function from microscopic cells to complete organ systems, encompasses a wide range of fascinating topics. The annual Experimental Biology (EB) meeting is a showcase for thousands of researchers studying humans and animals alike. Check out some of the research presented at last month’s meeting in Chicago:
Most people know that walking is good for heart health, weight management and flexibility. New research from New Mexico Highlands University reveals how your brain also benefits from walking. Each step you take sends pressure waves through your arteries and increases blood flow—and oxygen—to the brain. The researchers found that running also had a beneficial effect on blood flow, while sports like cycling that don’t involve foot impact were less likely to make a significant difference.
Do you like the calming scent of lavender when the pressure’s turned up? Turns out, you’re not alone. Research out of Albion College studied the effects of aromatherapy on horses. Much like people, competition horses get stressed out when they’re transported from their home to an unfamiliar venue. Stress reduction therapies are highly regulated in competition horses, and non-medicinal treatments could go a long way to calm the animals before they perform. The researcher found that stress hormone levels dropped significantly among trailered horses that were exposed to lavender aromatherapy when compared to distilled water mist.
Olympic-caliber athletes appear to be the picture of strength and power. But new research suggests that high-intensity workouts without a proper recovery period could interfere with optimum bone health. A study of female Olympic rowers from Canada’s Brock University showed that the levels of a protein that stops bone mineral loss dropped during extended periods of heavy training. Bone mineral loss weakens the bones and increases the risk of stress fractures and osteoporosis.
These studies just scratched the surface of all the top-notch physiology research presented at EB. Read more highlights from this year’s meeting:
Why vitamin A and a high-fat diet don’t mix
The role of immune cells in the cause—and treatment of—preeclampsia
How an ice bag on the face can help treat severe blood loss
An “exercise pill” may be in our future
How orange essential oil reduces PTSD symptoms
A jousting knight wears his heart on his sleeve. Credit: iStock
In medieval times, a jousting knight would wear the colors of the lady he was courting tied around his arm. Hence, the phrase “Wear your heart on your sleeve” was born. Today, we use this romantic phrase to describe someone who expresses their emotions openly. How applicable that ancient phrase really is to maintaining a healthy heart!
In a landmark paper, a group of scientists discussed how stress and social interactions with others affected the health of the heart. It is well-known that stress is a major factor in the development of heart disease. This is because stress is a double whammy: It activates the “fight-or-flight” nervous response, and it causes inflammation in the cells that line blood vessels. Both of these events can damage blood vessels in the heart.
Research shows that positive social interaction expressing emotion is important for heart health. Support from a spouse or partner, friends or other groups can reduce stress and help you stick to a healthy diet and exercise program to minimize your risks.
Heart disease is the leading cause of death worldwide, with annual deaths creeping up to 24 million. Reducing stress and anxiety is an important aspect of keeping your heart healthy. Exercise, yoga, meditation and even deep breathing can promote a sense of calm when tensions mount. Try running or yoga with a friend or join an exercise class to keep you on track for a healthy heart. Go ahead, wear your heart on your sleeve—it’s good for you!
February is American Heart Month. You can find more information about keeping your ticker ticking on the American Heart Association’s website.
During American Diabetes Month in November, you may notice more people are talking about diabetes, a disease that affects 29 million Americans. It’s a great time to learn more about diabetes and the ways that you can decrease or manage your risk of developing the disease.
Diabetes mellitus is a problem with how your body handles blood glucose (sugar). People who have type 2 diabetes aren’t able to use the hormone insulin properly to remove glucose from the bloodstream for use in the fat and muscle cells. Ultimately, this causes people with type 2 diabetes to have higher than normal levels of glucose in their blood.
You may have heard that someone who is overweight and has a large, apple-shaped body is more likely to develop metabolic syndrome—a group of health conditions such as elevated blood pressure, blood sugar and cholesterol levels—which may increase the risk of developing diabetes. However, there are a number of less well known risk factors for type 2 diabetes including:
Some research even links non-health-related factors such as job security to an increased diabetes risk. A recent study published in the Canadian Medical Association Journal analyzed data from 19 different studies including almost 141,000 participants which suggested that job insecurity was associated with a modest increased risk of diabetes. Job insecurity has also been associated with weight gain (a diabetes risk factor) and coronary artery disease (a complication of diabetes).
Recognizing risk factors for diabetes and dealing with them, if possible, is important for both children and adults. Consuming a healthy, nutrient-rich diet and staying physically active can help maintain weight, manage stress and avoid type 2 diabetes and its many related complications. To learn more about ways to prevent diabetes, visit the American Diabetes Association website.
Barb Goodman, PhD, is a professor of physiology at the University of South Dakota.
With Halloween next week, you may be planning to head to a haunted house or cozy up on the couch with popcorn and a horror flick. Either way, you’re probably hoping for a good scare.
Enjoying the thrill of a scary movie or riding a rollercoaster isn’t the same as a real life-threatening situation, but your body doesn’t always know the difference. This is because the same senses are triggered when you’re startled in a safe environment as when there’s a genuinely fearful situation. Whether the fear is real or fake, your body leaps into action to prepare for whatever is going to unfold:
- Your cardiovascular system pumps more blood and your heart beats faster.
- Your brain sends adrenaline to your skeletal muscles, getting ready to move.
- Your pupils dilate so you can see better.
- Your digestive system slows down until the threat has passed.
Referred to as the “fight or flight” response, the human body functions similarly to how it would have thousands of years ago when faced literally with these two options: fight (for food or for your life, for example) or flight (run away).
During the physiological reaction to fear, scientists believe the brain stimulates the production of dopamine, a chemical that activates the pleasure center of the brain. Many people enjoy the feeling of a good scare and pursue other thrill-seeking behaviors to get the same “high.” Research suggests that thrill-seekers may have different brain chemistry than those who don’t enjoy a heart-pounding experience. If you don’t like to be scared, skip the tricks, enjoy the treats and remember to breathe deeply during this spooky season.
No matter where you fall on the scare scale, be safe this Halloween!
– Erica Roth
When we have an extremely stressful experience, such as losing a loved one or being constantly bullied by a classmate, our body can react in different ways. Sometimes we overcome the psychological stress and come out stronger than before. Other times, we fall victim to the stress. These experiences build mental “toughness,” also called psychological resilience, which plays an important role in whether we develop mental health disorders, such as depression or anxiety, due to stress. Psychological resilience may sound like something that happens in our head, but it turns out that the immune system is involved in the process.
A group of scientists from the National Institutes of Health reported that the cells of the immune system can change during stress to protect the body from the harmful effects of psychological stress. They made this discovery by stressing out special mice called Rag2-/- mice that do not have immune cells. When stressed, the Rag2-/- mice became anxious and developed depression-like symptoms. When the researchers injected the Rag2-/- mice with the immune cells of stressed normal mice, the Rag2-/- mice became less anxious. This exciting finding tells us that stressed-out immune cells are important in increasing our mental toughness and helping us overcome stressful experiences.
Scientists do not yet understand exactly how stressed immune cells protect the body from psychological stress, but it is very promising that immune cells can one day be used to treat mental health disease and health problems, such as cardiovascular diseases, that are caused by psychological stress.
Dao H. Ho, PhD, is a biomedical research physiologist at Tripler Army Medical Center.
The views expressed in this blog post are those of the author and do not reflect the official policy or position of the U.S. Department of the Army, U.S. Department of Defense or the U.S. government.
Jessica C. Taylor, PhD
Stress is a part of all of our lives. From work, to family, to waiting in rush hour traffic, stress comes at us from all directions and in many shapes and sizes. Stress and other physical and mental health problems have been linked to increases in depression, which is a globally recognized public health problem.
To understand how stress leads to depression, it’s important to look at how the brain communicates with the rest of the body. Chemicals in the brain, known as neurotransmitters, send messages to help regulate brain activity, emotions, memory and health. The brain has receptors that help decode these messages so the body can act on them. One neurotransmitter, serotonin, has been linked to feelings of happiness and general well-being. Decreases in the level of serotonin and its receptors have been associated with feelings of sadness, fatigue and depression.
Luckily, there is a powerful tool that we can use to pump up serotonin levels and increase health and happiness: exercise. It is well known that exercise improves heart health and can leave a person feeling invigorated after a workout. But can it also decrease depression and improve mental health? Researchers say yes.
A recent mouse study in the International Neurology Journal supports exercise as an important part in the treatment of stress-related depression. The study demonstrated that stress decreased serotonin levels and quantities of the serotonin receptor. Serotonin and serotonin receptor levels could be elevated toward normal when the subjects participated in low-intensity exercise. The subjects also demonstrated anti-depressive behaviors after exercise, despite being exposed to stress.
So the next time you need to lift your spirits, get moving. Your body and your brain will be glad you did. For more information on depression and when to see a doctor, visit the Anxiety and Depression Association of America website.
Jessica C. Taylor, PhD, is an assistant professor of physiology in the College of Osteopathic Medicine at William Carey University in Hattiesburg, Miss.