In girls, estrogens are responsible for changes occurring in puberty, and for the development of secondary sexual characteristics. They contribute to the growth and development of the vagina, uterus and fallopian tubes. Estrogens are also involved in the development of mammary glands, stimulating the growth of ducts, stroma and the accumulation of adipose tissue. Axillary and pubic hair, as well as pigmentation in the genital area are also caused by the action of estrogens.
In women, estrogens participate in the control of ovulation, prepare the reproductive organs for fertilization and implantation. In the follicular phase of the cycle, the release of LH and FSH from the anterior lobe of the pituitary gland occurs under the influence of pulsatile GnRH secretion. FSH stimulates the growth of ovarian follicles and regulates the activity of aromatase in granulosa cells, thus stimulating the synthesis of estrogens. Estrogens, in turn, by the mechanism of negative feedback regulate the synthesis of FSH. In the early follicular phase, a low level of estrogen stimulates the synthesis of FSH, and as the concentration of estrogens increases, the synthesis of FSH decreases. In the late follicular phase, the elevation of the estrogen level by the positive feedback mechanism stimulates the release of LH and ovulation. In the follicular (proliferative) phase of the cycle, estrogens prepare the endometrium for ovulation. They stimulate the proliferation of glands, the growth of the stroma and vessels of the endometrium, and also increase the number of progesterone receptors on the surface of its cells, which allows progesterone to exercise its influence in the second, luteal, phase of the cycle. Progesterone stimulates the secretory transformation of the endometrium, providing the best conditions for implantation.
In men, estrogens act on bone tissue, affect spermatogenesis and control behavioral responses.
Estrogens also have an effect on mineral, carbohydrate, protein and fat metabolism. When acting on bone tissue, estrogens regulate the function of osteoblasts and increase the synthesis of type I collagen, osteocalcin, osteopontin, osteonectin, APF and other products of synthesis of differentiated osteoblasts. However, the main effect of estrogens is a decrease in the number and decrease in osteoclast activity, carried out by preventing the transition of progenitor cells to mature osteoclasts and increasing the rate of apoptosis in them. Thus, estrogens stimulate the synthesis and inhibit the resorption of bone tissue.
On the metabolism of fats, estrogens also exert a great influence. They increase the level of high density lipoproteins and reduce the level of low density lipoproteins. Detection of estrogen receptors in liver tissue suggests that this effect is due to the direct effect of estrogens on the metabolism of lipoproteins in the liver. Also, estrogens slightly increase the level of triglycerides in blood plasma, but lower the total level of cholesterol in the blood. At the same time, they increase the saturation of bile with cholesterol, which, apparently, is associated with an increase in the formation of stones in some women who have long-used estrogens.
Data on the effect of estrogens on carbohydrate metabolism are somewhat contradictory. It has been shown that the use of pure estrogens leads to a decrease in the level of glucose and insulin in the blood. Estrogens also have an effect on protein metabolism. In particular, they increase the synthesis of various plasma proteins in the liver, thereby increasing the level of cortisol binding globulin (transcortin), TSH and globulin binding sex hormones (SHGG) involved in the binding of estrogens and androgens in the blood plasma. Also, estrogens increase the synthesis of fibrinogen, VII, VIII, X and XI coagulation factors, which leads to an increase in blood clotting.
Estrogens have a certain short-term vasodilator effect, probably due to the activation of the production of nitric oxide and prostacyclin in the vascular endothelium. Also, estrogens stimulate the synthesis of the endothelium and inhibit the proliferation of smooth muscle cells of the vessels.>> Check this estrogen medication <<