On gonads and gadflies: the estrus angle

The first sex steroid to be crystallized was the vertebrate ovarian hormone, estrone - a less potent metabolite of 17βestradiol, which in mammals stimulates the female urge to mate (estrus). The gadfly (Greek oistros) lent its name to the process of estrus, as an insect that bites and torments in classical Greek mythology. With the crystallization of a moult-inducing steroid (ecdysone) from insects, an interesting parallel emerged between mating and moulting in mammals and arthropods. Ecdysterone (potent ecdysone metabolite) has anabolic effects in mammalian muscle cells that can be blocked by selective estrogen receptor-antagonists. And insects utilise ecdysteroids in similar ways that vertebrates use estrogens, including stimulation of oocyte maturation. Finally, ecdysteroids enhance the receptiveness of female insects to males before copulation (i.e. the equivalent of vertebrate estrus), which further endorses the gonad-gadfly/mate-moult analogy.

http://ift.tt/2o8zHem