17α-Estradiol (also known as 17α-E2, 17-epiestradiol, alfatradiol, or estra-1,3,5(10)-triene-3,17α-diol) is a minor and weak

endogenous Endogenous substances and processes are those that originate from within a living system such as an organism, tissue, or cell. In contrast, exogenous substances and processes are those that originate from outside of an organism. For example, es ...

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...

that is related to 17β-estradiol (better known simply as estradiol). It is the C17

epimer In stereochemistry, an epimer is one of a pair of diastereomers. The two epimers have opposite configuration at only one stereogenic center out of at least two. All other stereogenic centers in the molecules are the same in each. Epimerization is ...

of estradiol. It has approximately 100-fold lower

potency Potency may refer to: * Potency (pharmacology), a measure of the activity of a drug in a biological system * Virility * Cell potency, a measure of the differentiation potential of stem cells * In homeopathic dilutions, potency is a measure of how ...

than 17β-estradiol. The compound shows preferential

affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Par ...

for the

ERα Estrogen receptor alpha (ERα), also known as NR3A1 (nuclear receptor subfamily 3, group A, member 1), is one of two main types of estrogen receptor, a nuclear receptor (mainly found as a chromatin-binding protein) that is activated by the sex ...

over the

ERβ Estrogen receptor beta (ERβ) also known as NR3A2 (nuclear receptor subfamily 3, group A, member 2) is one of two main types of estrogen receptor—a nuclear receptor which is activated by the sex hormone estrogen. In humans ERβ is encoded by ...

. Although 17α-estradiol is far weaker than 17β-estradiol as an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

of the

nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...

estrogen receptor Estrogen receptors (ERs) are a group of proteins found inside cells. They are receptors that are activated by the hormone estrogen ( 17β-estradiol). Two classes of ER exist: nuclear estrogen receptors (ERα and ERβ), which are members of the ...

s, it has been found to bind to and activate the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

-expressed

ER-X ER-X is a membrane-associated receptor that is bound and activated by 17α-estradiol and 17β-estradiol and is a putative membrane estrogen receptor (mER). It shows sequence homology with ERα and ERβ and activates the MAPK/ERK pathway. The re ...

with a greater potency than that of 17β-estradiol, suggesting that it may be the predominant endogenous

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

for the receptor.

Aging

Supplementation with 17α-Estradiol increases the median lifespan of male mice by 19%, while not affecting female lifespan. This treatment does not lead to feminization of male mice. 17α-Estradiol furthermore alleviates age-related metabolic and inflammatory dysfunction and improves glucose tolerance in male mice. The exact reason for this sex-specific increase in lifespan is unknown, however, the effect on male lifespan is gone in castrated mice, suggesting that the metabolic response to 17α-Estradiol requires the presence of male gonadal hormones. Whether these results are translatable to humans is currently unknown.

References

{{DEFAULTSORT:Estradiol, 17α- Secondary alcohols Estranes Estrogens Hormones of the hypothalamus-pituitary-gonad axis Sex hormones

Aging

See also

References