ARKHANGELSK, September 27. /TASS/. Scientists of the Arctic federal research center for complex studies of the Arctic (the Russian Academy of Sciences’ Urals Branch) proved a stimulating effect of dopamine (the so-called ‘feel-good’ hormone) on thyroid glands of people living in the Arctic regions. Such studies were conducted for the first time. The studies’ results were used to identify groups of the North’s indigenous peoples, who risk developing pathological conditions, head of the Professor Tkachev Endocrinology Lab, Elena Tipisova, told TASS.

"Increasing dopamine increased the thyroid gland activity," she said. "Dopamine’s excess values did not cause suppression, and the thyroid gland activity continued to increase… We have identified a group, which in particular needs special attention to health. This is the North’s settled population, the indigenous population - that is those who have changed nomadic life styles to sedentary. Former reindeer herders, who have changed the lifestyle, now have problems with thyroid and with dopamine levels."

Dopamine is a mediator of the sympathetic adrenal (SA) system. It is released in response to stress, including cold, to adapt and mobilize the body's energy reserves. However, it works literally for minutes. Thyroid hormones also stimulate the formation of energy in the body, including in response to cold. They, on the opposite, act for long. "Dopamine breaks down in the blood within five minutes. When it's cold - here’s the energy, and that’s it, its reserve gets exhausted. Whenever a person is in a "cold" situation, the increased level of thyroid hormones stays for several days," she continued.

Studies of the correlation between dopamine and the level of thyroid hormones were active in the 1960s, but at that time scientists made experiments on animals, cells and tissue cultures. In surveying people, scientists focused on pathology conditions, such as schizophrenia and Parkinson's disease. Results were contradictory: the researchers received proofs of dopamine’s both stimulating effect on the thyroid gland and the suppressive effect. In the experiment and in diseases, dopamine in high doses inhibited the thyroid hormones production.

The studies on practically healthy people, who live in the Arctic, were conducted for the first time. Scientists have been working from 2009 in the Arctic districts of the Arkhangelsk, Nenets and Yamalo-Nenets regions. Over more than ten expeditions they have surveyed about 600 people.

Response to stress and frost

They collected samples only in spring - to observe similar day length, since the level of hormones and mediators depends on photo-periods. In the studies, scientists scheduled tests to coincide with regular nomad voyages. Experts surveyed not only the indigenous peoples - the Nenets and Komi, but also the Caucasian people, who live in the North since birth. For the project, they picked only people who did not suffer from major disorders of the endocrine or cardiovascular systems.

The studies have shown that whenever dopamine’s level is low, the level of thyroid hormones is also low. When it grows, the level of hormones is also growing. In case of dopamine’s ultra-high values, the level of thyroid hormones does not decrease, as it may be expected, but continues to grow. The Yamalo-Nenets Region’s residents had higher levels of dopamine and thyroid activity than those who live in the European North. "However, this is not a pathology, this is a trend: in the European North, the thyroid gland activity is lower, and in the Asian North, the living conditions are more extreme," the expert told TASS. "The share men with high dopamine levels among those surveyed in the region is 40%." The researcher explained that the North is generally characterized by expanded norms of physiological indicators.

Former deer herders, who had stopped to nomad, had lower thyroid hormones. This group requires ongoing monitoring, the expert said. "The indigenous people, who continue to nomad, have high dopamine levels; and we will look into this in relation to the social and economic factors," she added.

Dopamine can influence the thyroid gland indirectly and can suppress antibodies to thyroid components. Noteworthy, many people living in the North, especially women, have an increased thyroid gland autoimmunization. "Dopamine in that case suppresses those antibodies and prevents suppression of the thyroid gland," the scientist said.

Further studies

The scientists plan to analyze how dopamine influences levels of sex hormones, and indirectly through them again those of the thyroid gland. Dopamine affects the conversion of testosterone into estradiol, or the male hormone into the female hormone. "In the North, men have higher levels of estradiol, or a tendency for higher levels against the norm," she explained. "Most likely, it is an adaptive syndrome, and it supports both the cardiovascular system and the musculoskeletal tissue, and at the same time it supports the level of thyroid hormones."

The laboratory’s experts will continue to study fluctuations in dopamine levels in the people living in the North depending on seasons and, thus, on the daylight duration. In addition to this direction, the researchers plans to study how dopamine levels influence the psycho-emotional conditions of people, living in the North.