20-hydroxyecdysone

20-Hydroxyecdysone (ecdysterone or 20E) is a naturally occurring ecdysteroid hormone which controls the ecdysis (moulting) and metamorphosis of arthropods. It is therefore one of the most common moulting hormones in insects, crabs, etc. A phytoecdysteroid produced by and extracted from various plants, including Cyanotis vaga, Ajuga turkestanica and Rhaponticum carthamoides, it is thought to be a plant defense against herbivory that disrupts the reproduction of insect pests. In arthropods, 20-hydroxyecdysone acts through the ecdysone receptor. Although mammals (including humans) lack this receptor, 20-hydroxyecdysone affects mammalian biological systems. 20-Hydroxyecdysone is an ingredient of some supplements that aim to enhance physical performance. In mammals, it is hypothesized to bind to the estrogen receptor beta (ERβ) protein.

==Sources in arthropods== The primary sources of 20-hydroxyecdysone in larvae are the prothoracic gland, ring gland, gut, and fat bodies. These tissues convert dietary cholesterol into the mature forms of the hormone 20-hydroxyecdysone. For the most part, these glandular tissues are lost in the adult, with exception of the fat body, which is retained as a sheath of lipid tissue surrounding the brain and organs of the abdomen. In the adult female, the ovary is a substantial source of 20-hydroxyecdysone production. Adult males are left with, so far as is currently known, one source of 20-hydroxyecdysone, which is the fat body tissue. These hormone-producing tissues express the ecdysone receptor throughout development, possibly indicating a functional feedback mechanism.