Hormones, part 3

Stress and love

Atlas company blog, Geektimes

Today Atlas will talk about more famous hormones – cortisol, oxytocin, melatonin. We meet with their action every day, but as always – many of them do not work exactly as we expected.

Cortisol

It is a steroid hormone that is secreted in the adrenal cortex under the influence of adrenocorticotropic hormone (ACTH). Like all steroids, cortisol is able to influence the expression of other genes – and this quality largely determines its importance.

Cortisol is synthesized as a result of the body's reaction to stress, and the task of the hormone is to accumulate the body's forces and direct them to solve the problem. Cortisol has a "younger brother" – adrenaline, which is also released in the adrenal medulla. Adrenaline provides an instant response to stress – blood pressure increases, heart rate increases, pupils dilate. All this is necessary for a quick "hit or run" reaction. Cortisol acts slower and works for longer distances.

Under the influence of cortisol, blood sugar levels rise, the immune system is suppressed (so as not to waste energy), gastric juice is released. Increased cortisol for a long time slows down wound healing and can stimulate inflammatory processes in the body. Cortisol also reduces the activity of bone tissue construction and collagen synthesis.

Under the influence of sunlight on the pituitary gland, cortisol levels begin to rise shortly before waking up and helps a person wake up full of energy. During the day, cortisol helps us cope with normal stress (it is called eustress). This includes any tasks that require our reaction: to respond to a letter, to hold a meeting, to prepare statistics. Eustress does not harm our health – on the contrary, it is a necessary level of stress.

But when the stress level begins to go off the scale, eustress turns into distress – stress in its everyday understanding. Initially, these were life-threatening situations, but now any events that a person attaches great importance to have been added to them. It can be overloads at work, problems in relationships, failures, worries and losses, as well as a wedding, moving, awarding a Nobel Prize or just a million dollars – stress is not necessarily bad events, but any changes in circumstances that require changes from us. Evolutionarily, a person is prepared to respond to stress, but not to be in it all the time. If a stressful situation stretches over time, permanently elevated cortisol levels begin to negatively affect the body.

First of all, the hippocampus suffers, synaptic connections are destroyed, the volume of the brain decreases: these processes worsen thinking and creative abilities. Under the influence of cortisol, especially at an early age, methylation occurs – some genes may be "turned off". Children who have been subjected to severe stress in childhood or have not received enough maternal care, the ability to learn changes – and these changes persist for life. Memory in this case will be better to retain negative impressions, so the training of such children is better under the pressure of stress, whereas ordinary children need a safe environment.

Also, the prolonged effect of cortisol leads to a weakening of immunity and activation of inflammatory processes. That is why, after a nervous meeting or a sleepless night, a "cold" may appear on the lips – a manifestation of the herpes virus, which, according to statistics, is about 67% of the population, but which does not show itself in any way in "peacetime". Chronic stress leads to early signs of aging – due to the fact that cortisol blocks the synthesis of collagen, thinns and dehydrates the skin.

Warm hugs, sex, favorite music, meditation, jokes and laughter will help reduce cortisol levels. It helps to get a good night's sleep – and it's not so much the amount of sleep that matters, as its quality. If you have offended someone or quarreled with loved ones, reconciliation will reduce cortisol levels to background values.

Prolactin

It is a peptide hormone known for its defining value for lactation. The pituitary gland is mainly responsible for its synthesis, but in addition to the brain, prolactin is also synthesized by the placenta, mammary glands and even the immune system. Prolactin levels increase many times during pregnancy, childbirth and, most importantly, during breastfeeding. Applying the baby to the breast and biting the nipple stimulates the production of colostrum (such a natural protein cocktail with a high content of immunoglobulins, which is secreted by the mammary glands in the first few days after childbirth) and the transformation of colostrum into milk. Despite the high level of prolactin during pregnancy, lactation begins only after childbirth, when the level of progesterone drops, which previously prevented the launch of the "dairy plant". Also, a high level of prolactin blocks the synthesis of follicle-stimulating hormone necessary for ovulation. So regular feeding becomes a natural hormonal "contraceptive".

But the effect of prolactin does not end with lactation: it is also a stress hormone. Its level increases in response to anxiety, severe pain, physical exertion. Prolactin has an analgesic effect in inflammatory diseases and, unlike cortisol, activates the immune system – stimulates stem cells to hematopoiesis and participates in the development of blood vessels.

Prolactin levels increase during crying and orgasm. A high level of prolactin blocks dopamine D2 receptors, and dopamine, in turn, blocks the secretion of prolactin: from the point of view of evolution, nursing mothers do not need irrepressible curiosity and a craving for learning new things.

Oxytocin

It is an oligopeptide hormone – it consists of several amino acids. It is synthesized by the hypothalamus part of the brain, then it is released in the pituitary gland.

In women, oxytocin is released during childbirth – it contributes to the contraction of the uterus at the first and second stages of labor. A synthetic version of the hormone is even used to stimulate labor. Oxytocin reduces sensitivity to pain. In the postpartum period, under the influence of the hormone, bleeding stops and ruptures heal. The level of oxytocin increases many times during lactation – here the hormone acts together with prolactin. The activity of oxytocin receptors is also regulated by estrogen receptors.

In both women and men, oxytocin plays an important role in sexual arousal. The level of oxytocin increases hugs (any – not necessarily with sexual overtones), sex and orgasm. Oxytocin is considered an attachment hormone – it causes a sense of trust and calmness next to a partner. Although oxytocin can be called the hormone of carelessness to the same extent: it reduces the perception of alarm and fear signals (but does not affect the causes of such signals in any way).

Oxytocin is a well–known stress fighter: it blocks the release of adrenocorticotropic hormone (ACTH) and, as a result, cortisol (it is ACTH that gives the signal to produce cortisol). Therefore, under the influence of oxytocin, a person feels safe and opens up to the world. The work of oxytocin receptors depends on how much each of us is able to experience empathy. People with a less active variant of the OXTR gene will find it more difficult to understand the feelings of others and share experiences. According to research, this mechanism plays a role in the development of autism.

With the participation of oxytocin, a rather ancient mechanism for the formation of social ties in animals is carried out – this is due to the upbringing of offspring and the need to protect the mother during this period. The main role of oxytocin is in the formation of a mutual bond between mother and child and between partners. Based on his relationship with his mother or any other person who cares about him, the child forms ideas about himself and his personality. The acquired knowledge and experience help to predict the consequences of actions and form a picture of the world. Oxytocin is also involved in learning.

Vasopressin

Vasopressin is another peptide hormone of the hypothalamus. Vasopressin is also called an antidiuretic hormone – it regulates the water balance in the body: it reduces the reverse absorption of water by the kidneys and retains fluid in the body. Vasopressin reduces vascular smooth muscle and can increase blood pressure. A decrease in vasopressin secretion can cause diabetes insipidus, a disease in which a patient releases a huge amount of fluid (more than 6 liters per day) and constant thirst.

Vasopressin plays the role of a neuropeptide and acts on brain cells. It influences social behavior. Thus, the variant of the vasopressin AVPR1A receptor gene is associated with the probability of happy family relationships in men – this conclusion was made when comparing genotyping data and survey results. Experiments were conducted on mice that showed that stimulation of vasopressin receptors makes males more attached to their females – they preferred to spend more time with a familiar partner, even if they had previously distinguished polygamous behavior. It should be noted here that in animals, social monogamy has nothing to do with sexual – we are talking about attachment to a partner, and not about the complete absence of "extramarital" relationships. In humans, the effect of vasopressin as a neuropeptide is not so straightforward.

Oxytocin and vasopressin are paralogs: substances that were created as a result of DNA sequence doubling and are very similar to each other. Vasopressin begins to be synthesized in the fetus from the 11th week of pregnancy, oxytocin – from the 14th week, and both continue to participate in the development of the baby in the postnatal period. A high level of vasopressin receptor expression in the neonatal period may lead to increased aggression in adults.

If the level of oxytocin can vary greatly depending on the situation, then vasopressin is a hormone with a smaller range of changes, the level of which mainly depends on genetics. The formation of social behavior and stable (or not so stable) relationships between partners depends on the activity of vasopressin receptors and their genetic variant. These receptors are also involved in the development of long-term memory and affect the plasticity of neurons in the cerebral cortex.

Melatonin

Let's finish today's story on a happy note – let's go to bed. Melatonin, the sleep hormone, is produced by the epiphysis of the brain at nightfall (which is why shining a smartphone screen into your eyes before going to bed is a bad idea). It regulates the "internal clock" – circadian rhythms – and helps all body systems go into rest mode. During the day, the highest level of melatonin occurs during the period from midnight to 5 a.m. daylight hours; during the year, melatonin levels increase in winter.

In the body, melatonin is preceded by the amino acid tryptophan, which also plays the role of a serotonin precursor. Melatonin slows down aging and reproductive functions and increases serotonin levels. A special role is played by the interaction of melatonin with the immune system – the action of the hormone reduces inflammation. Melatonin has an antioxidant effect and protects DNA from damage.

Thanks to melatonin, the daily routine is restored after a time zone change or night work. A decrease in melatonin production – for example, due to bright lights or changes in the daily routine - can cause insomnia, which increases the risk of depression. To help your body get a good night's sleep and restore the regime, try to sleep in the dark – with the lights off and the curtains drawn if you are forced to sleep during the day.

Life in a big city sometimes consists entirely of stress, chronic lack of sleep, traffic jams, delays, meaningless work meetings and tasks of exaggerated importance and urgency. In such a rhythm, it is very difficult to find time to recover, so we simply begin to perceive the state of chronic fatigue as a given. But nature did not prepare us for this, and the same cortisol will not be released forever: if you are constantly under stress pressure, over time cortisol is depleted – and then the body is forced to respond to stress by other methods.

To make sure that your health corresponds to your stress load, consult with an endocrinologist: your body may need support. And you definitely need a rest.

Portal "Eternal youth" http://vechnayamolodost.ru 02.11.2016