Estradiol is the predominant estrogen throughout a female’s reproductive years, having a significant impact on reproductive function and various parts of the body. The changes that occur around puberty are driven by estradiol. These changes are promoted by enhanced estradiol during the reproductive age and then become less pronounced after the menopause, as estradiol levels decline.
The main functions of estradiol and other estrogens include:
Female reproductive development
Estradiol acts primarily as a growth hormone for the reproductive organs including the lining of the vagina, the fallopian tubes, the endometrium, the cervical glands and the womb’s muscle layer, the myometrium. In addition, the hormone maintains oocytes (eggs in the ovary) and triggers a series of events that lead to ovulation. Estradiol is also required for normal breast development, alteration of body shape, skin changes, and the fat distribution profile that is typical of females.
Function in males
In males, estradiol is produced by the Sertoli cells of the testes and aids in sperm maturation as well as maintaining a healthy libido.
In women, estradiol is responsible for reducing bone resorption and increasing bone formation. Bone loss can be accelerated in women of post-menopausal age, who may have a relative deficiency in estradiol.
Estradiol influences the synthesis of several proteins and increases the production of binding proteins, lipoproteins and the proteins involved in blood clotting.
Mechanism of action
Estradiol is a nuclear hormone, meaning it acts on receptors present inside the cell, that can activate or deactivate transcription in the nucleus. Estradiol interacts with a target cell receptor (Erα or Erβ) within the cytoplasm of the cell. Once estradiol is bound to its receptor ligand, the receptor can enter the nucleus of the target cell and induce the formation of messenger RNA. This mRNA then interacts with ribosomes to produce specific proteins that exert the effects of estradiol on the cell.