Stress and hormones

Stress weakens the cellular defense of the body

Polina Gershberg, Naked Science

Stress is an organism's reaction aimed at adapting to any unfavorable conditions. In case of danger, hormones are sharply released into the bloodstream, which help to react more actively in the event of an attack, defense or flight in an emergency situation. 

Earlier studies have shown that stress, especially prolonged stress, negatively affects various aspects of physical and mental health. Neuroscientists from the National University of the South, Argentina, together with colleagues from the University of Massachusetts have found out what stress does to the body's cells. The study, conducted by a team of neuroscientists, is published in the journal Nature (De Rosa et al., The flight response impairs cytoprotective mechanisms by activating the insulin pathway).

A round worm, the nematode C.elegans, was chosen as a "test subject". This is a standard model organism on which many biological studies are carried out. Stress is not a human prerogative, rather, it is an inheritance we have received from animals. Various forms of this condition also affect such simple animals as worms. Of course, they will not experience it because of difficulties in social interaction, but it is not difficult to create stressful conditions for them. As in humans, nematode stress can be abrupt and severe (for example, due to the appearance of a predator), or prolonged (chronic food shortage, high temperatures or oxidation).

"As in humans, the repeated activation of the escape reaction in C.elegans dramatically shortened life expectancy," said Jeremy Florman, one of the authors of the work. "The escape reaction is extremely important for a worm fleeing from predators. But we found that this is fraught with costs; reactivating the escape reaction reduces the worm's ability to cope with other problems it faces in the environment."

A study has shown that in C.elegans, the hormone tyramine controls stress reactions. In invertebrates, this is an analogue of adrenaline. Under severe stress, the escape reaction is activated by a pair of neurons that secrete tyramine, and prolonged stress, on the contrary, reduced the release of tyramine. 

Further analysis showed that tyramine stimulates the insulin pathway by activating an adrenergic receptor in the intestine. Activating the insulin pathway can quickly provide enough energy for the worm to escape (for obvious reasons, the "beat" option is not available to it). Suppression of the insulin pathway is necessary in order to save energy for cell protection during prolonged stress.

"This shows how the dynamic regulation of the stress neurohormone regulates the trade–off between acute and long-term stress response," explains lead study author Dr. Mark Alkema. 

This study reveals important molecular and neural mechanisms that, in a simplified form, show the basis of disorders underlying stress disorders in humans. The work lays the foundation for studying the mechanism of damage to human cells under different types of stress, such as activation and deactivation of the insulin pathway. In the future, these data may help in the search for treatment of various types of stress disorders, side effects of stress and aging.

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