[재미있는 과학] Oxytocin stimulates bonding… It also regenerates damaged hearts.
Input: 2022.10.11 03:30
hormone
- ▲ /Graphic = Jinbonggi
Hormones produced in our body affect not only our physical health but also our emotions. Hormones are one of the key substances that keep the living environment constant. So, if there is a problem with the endocrine glands that secrete hormones, biological functions can be reduced. On the 30th of last month, a research team led by Professor Aitor Aguirre of Michigan State University in the United States also revealed that “oxytocin, the ‘love hormone’, has the potential to regenerate cardiomyocytes in heart attack patients.” What kind of hormone is oxytocin that heals the heart? Together with oxytocin, let’s take a look at the hormone that affects all parts of our body.
Oxytocin effect found in tropical fish
Oxytocin is a hormone secreted by the pituitary gland and released into the bloodstream. Oxytocin is known to play a role in stimulating bonding and strengthening the relationship between lovers and couples. That’s why it’s called the ‘love hormone’ and ‘happiness hormone’. It also helps the mother to contract the uterus to make labor easier when giving birth to the baby, and it also helps the milk flow out well when breastfeeding the baby. It also helps sperm reach the egg.
The human heart beats 80 times per minute and sends 8,000 liters of blood to every part of the body every day. However, once the heart is damaged, such as from a heart attack, there is no way to recover. This is because the myocardial cells that make up the heart die and lose their ability to regenerate.
However, unlike humans, the tropical fish ‘Zebrafish’ regenerates its heart within 30 to 60 days even if a quarter of its heart is lost. This is because myocardial cells divide and repair. Although the size of the zebrafish is only 5 cm, it has most of the organs that humans have, such as the heart, liver, pancreas, and kidneys, and about 70% of its genes are the same as humans, so it is widely used in human disease research.
A team of professors from Michigan State University used zebrafish to find a way to regenerate the human heart. First, the professor’s team paralyzed the fish’s heart. Then, three days later, the gene for making oxytocin was expressed up to 20 times higher than usual in the brain of the fish.
This activated oxytocin stimulated the migration of stem cells (cells capable of differentiating into cells of all tissues) in the epicardium, the outer layer of the heart, to the heart’s middle layer, the myocardium. Stem cells that moved to the myocardium grew into cardiomyocytes and blood vessels to repair the damaged heart.
Later, the research team confirmed the same effect in laboratory-cultured human heart tissue. As a result of an experiment similar to that of zebrafish, oxytocin produced twice as many epicardial stem cells as before, increasing their regenerative capacity. These findings mean that oxytocin could be used as a treatment to regenerate the heart of heart attack patients. Now, research on using oxytocin to improve heart recovery in people will be conducted everywhere.
Feeling hungry due to the action of hormones
Hormones make us feel hungry or full. Ghrelin, a hormone secreted by the stomach and the hypothalamus of the brain, stimulates the brain’s appetite center (the part where nerve cells are gathered) and makes you feel hungry. On the other hand, leptin, a hormone secreted by fat cells, sends a signal to the hypothalamus to feel full and suppress appetite. That’s why leptin is called the diet hormone.
However, in 2013, a joint research team at Asan Medical Center in Seoul and Harvard University discovered a new substance that stimulates leptin and plays a key role in appetite control. These are substances called ‘Clusterin’ and ‘LRP2’ in the hypothalamus of the brain. The two substances induce the activation of the leptin signaling system, thereby having a strong appetite suppressant action. It has been known that leptin acts as an appetite suppressant, but it is the first time that the signaling and activation pathways of leptin have been identified.
The researchers injected clustererin into the hypothalamus of obese mice. Then, the binding of LRP2 to the leptin receptor occurred, leptin was activated, and the obese mice started to eat less food. As a result, my abdominal circumference and weight decreased. This opens up a new way to treat obesity.
Cognitive ability improves by up to 30%
Down syndrome, for which there was no treatment, opened a way to improve symptoms with hormones. Human chromosomes are made up of 23 pairs. Down syndrome is a congenital genetic disorder in which the smallest 21st chromosome is made up of three instead of a pair. It is known that the expression of ‘gonadotropin-releasing hormone (GnRH)’ decreases and cognitive decline and olfactory disorders appear.
GnRH is secreted by the pituitary gland. When this hormone stimulates the gonads such as the testicles or ovaries, sex hormones are released and reproductive cells (eggs and sperm) mature. If GnRH does not come out normally, it can lead to infertility. So it is used to treat infertility.
On the 2nd of last month, a joint research team at the University of Lille in France and the University Hospital of Lausanne in Switzerland succeeded in increasing the cognitive ability of patients with Down syndrome by 30% using this hormone. First, the research team caused an abnormality in the chromosome of the experimental mouse, which is the 21st human being, like Down syndrome. Then, the gene that controls the production of GnRH did not work properly, and the cognitive ability and sense of smell of the mice were affected. To normalize this, the research team administered an alternative to GnRH (Lutrelev), which is used to treat infertility, to mice. As a result, my sense of smell and cognitive ability were restored within two weeks.
After confirming the effect, the research team administered GnRH to 7 men aged 20-50 with Down syndrome. The patient’s cognitive abilities improved by up to 30%. The results of this study are expected to help improve the daily life of patients with Down syndrome.