The pituitary-adrenal system
The pituitary-adrenal system plays an important role in the overall adaptive response of the body, including in ensuring resistance to stress, maintaining ion homeostasis and regulating the immune system.
Significant age changes occur in the adrenal glands. The weight of these glands begins to decrease from 50 years. The most noticeable changes are noted in the adrenal cortex, the thickness of which decreases in 40-50 years, whereas in the brain substance, the age changes are less pronounced.
At the same time, different areas of the adrenal cortex are subject to age-related changes in an uneven degree. To a lesser extent, degenerative changes are manifested in the bundle zone producing HA.Cortisol plays an important role in adaptation processes and stress reactions. This hormone is extremely important during the aging period, which is sometimes regarded as a continuous adaptation. As the tissue ages, the tissue of the fascicle zone even grows in volume due to two other zones - the reticular, producing sex hormones, and the glomerular, the main hormone of which is aldosterone - regulates water and electrolyte metabolism. Some of its weakening occurs only after 60-70 years, and at 80 years the concentration of HA in the blood is about a third of that in middle age. In persons 90 years and older, the concentration of cortisol in the blood decreases by a factor of 1.5-2, but at the same time the sensitivity of cells and tissues to HA increases. The reason for this effect is unclear. Apparently, the long-liver system of regulation of the adrenal glands functions throughout life at a higher level than other people. Therefore, the functional state of the adrenal cortex is one of the factors contributing to longevity, and a good marker of the biological age of a person. There is a direct relationship between adrenal mass and longevity.
The function of the reticular zone producing steroids with androgenic activity - DHEA, DHEAS, androstenedione( and its 11p-analog), testosterone, decreases rather early - in 40-60 years. A particularly significant decrease is observed in men 50-59 years old, in women androgenic and glucocorticoid functions of the adrenal gland are maintained at a high
level before a very old age. In the deep old age, the production of androgen genes is significantly reduced - 3 times for men and 2 times for women compared to the mature age. The best markers for reducing the androgen function of the adrenal glands are DHEA and DHEAS, whose concentration in the blood decreases early( after 40 years in men), and in very old age they are practically not produced.
ACTH secretion varies little with age, and the basal level of the hormone in the blood remains approximately at the same level. At the same time, the effectiveness of hypothalamic-pituitary control over the activity of the adrenal cortex decreases with aging.