A report on Osteoporosis and Estrogen receptor

$Elderly woman with osteoporosis showing a curved back from compression fractures of her back bones.$

A dimer of the ligand-binding region of ERβ (PDB rendering based on ).

Illustration depicting normal standing posture and osteoporosis

The domain structures of ERα and ERβ, including some of the known phosphorylation sites involved in ligand-independent regulation.

Progression of the shape of vertebral column with age in osteoporosis

A dimer of the ligand-binding region of ERα (PDB rendering based on ).

Bone density peaks at about 30 years of age. Women lose bone mass more rapidly than men.

The body regulates calcium homeostasis with two pathways; one is signaled to turn on when blood calcium levels drop below normal and one is the pathway that is signaled to turn on when blood calcium levels are elevated.

$Multiple osteoporotic wedge fractures demonstrated on a lateral thoraco-lumbar spine X-ray$

$Age-standardised hip fracture rates in 2012.$

Light micrograph of an osteoclast displaying typical distinguishing characteristics: a large cell with multiple nuclei and a "foamy" cytosol.

Light micrograph of osteoblasts, several displaying a prominent Golgi apparatus, actively synthesizing osteoid containing two osteocytes.

Collapse of vertebra on the right, normal on the left

Tamoxifen, for example, is an antagonist in breast and is, therefore, used as a breast cancer treatment but an ER agonist in bone (thereby preventing osteoporosis) and a partial agonist in the endometrium (increasing the risk of uterine cancer).

- Estrogen receptor

The α-form of the estrogen receptor appears to be the most important in regulating bone turnover.

- Osteoporosis

$Elderly woman with osteoporosis showing a curved back from compression fractures of her back bones.$

3 related topics with Alpha

Estrogen

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Category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics.

Reference ranges for the blood content of estradiol, the primary type of estrogen, during the menstrual cycle.

Steroidogenesis, showing estrogens at bottom right as in pink triangle.

Once inside the cell, they bind to and activate estrogen receptors (ERs) which in turn modulate the expression of many genes.

Due to hypoestrogenism, the risk of osteoporosis increases during menopause.

Raloxifene

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Raloxifene, sold under the brand name Evista among others, is a medication used to prevent and treat osteoporosis in postmenopausal women and those on glucocorticoids.

Raloxifene is a selective estrogen receptor modulator (SERM) and therefore a mixed agonist–antagonist of the estrogen receptor (ER).

Aromatase inhibitor

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Aromatase inhibitors (AIs) are a class of drugs used in the treatment of breast cancer in postmenopausal women and in men, and gynecomastia in men.

Often used as a cancer treatment in postmenopausal women, AIs work by blocking the conversion of androstenedione and testosterone into estrone and estradiol, respectively, which are both crucial to the growth of developing breast cancers (AIs are also effective at treating ovarian cancer, but less commonly so). In the diagram, the adrenal gland (1) releases androstenedione (3) while the ovaries (2) secrete testosterone (4). Both hormones travel to peripheral tissues or a breast cell (5), where they would be converted into estrone (8) or estradiol (9) if not for AIs (7), which prevent the enzyme CYP19A1 (also known as aromatase or estrogen synthase) (6) from catalyzing the reaction that turns androstenedione and testosterone into estrone and estradiol. In the diagram, Part A represents the successful conversion of androstenedione and testosterone into estrone and estradiol in the liver. Part B represents the blockage of this conversion by aromatase inhibitors both in peripheral tissues and in the breast tumor itself.

Tamoxifen (a SERM) traditionally was the drug treatment of choice, but the ATAC trial (Arimidex, Tamoxifen, Alone or in Combination) showed that in women with localized estrogen receptor-positive breast cancer, women receiving the AI anastrozole had better results than the tamoxifen group.

In women, side effects include an increased risk for developing osteoporosis and joint disorders such as arthritis, arthrosis, and joint pain.