Prostaglandin

Prostaglandins are fatty substances that act in a manner similar to hormones. The prostaglandins are all characterized by having 20 carbon atoms. Each prostaglandin is characterized by a letter, which indicates different types of ring structures of the carbon atoms, and a number, which represents the number of double bonds with hydrogen atoms. They are synthesized from fatty acids by enzymes. They are found in almost every tissue throughout the body. 
The differing structure of each prostaglandin determines it's function. Prostaglandins bind to receptors, but unlike other hormones and neurotransmitters, their effect depends on the nature of each tissue and what receptors are available. As such, depending on where it is, a prostaglandin can encourage production of another substance in one part of the body, while discouraging it in another part of the body. 
Unlike true hormones, which are produced in a distinct gland, many prostaglandins can be created in many locations throughout the body, and almost every cell with a nucleus in the body can create one or more of the prostaglandins. At first, since they were found in semen, it was thought that they originated only in the prostate gland.
Among the many functions of prostaglandins are causing contraction of muscle cells, regulating clotting, making neurons sensitive to pain, inducing labor, decreasing pressure within the eyes, regulating inflammation, and regulating hormones. 
Several pharmaceuticals work by restricting the prostaglandins, including aspirin, ibuprofen and steroids.In addition, there are pharmaceutical preparations of prostaglandins used to induce labor and to treat glaucoma, erectile dysfunction and peptic ulcers.
Prostaglandin at Wikipedia
Category:Endocrinology