Prostaglandins

Figure 1. The chemical structure of Prostaglandin I₂.

Prostaglandins are a group of physiologically active lipid compounds called eicosanoids. They are derived enzymatically from the fatty acid arachidonic acid. Prostaglandins have diverse hormone-like effects in animals, and they can be found in almost every tissue in humans and other animals. However, unlike hormones, Prostaglandins aren’t released from a specific gland. Instead, the body has a number of tissues that can synthesise Prostaglandins.

Prostaglandins may have different and even opposite effects in different tissues in some cases. The stimulating or inhibitory behaviour of the same Prostaglandin is determined by the type of receptor the prostaglandin binds to. For example, depending on the containing tissue, the same Prostaglandin may exert the following effects:

• constriction or dilation of blood vessels
• forming platelets into a cluster or breaking them up
• opening or closing up airways
• contracting or relaxing smooth muscle in the gastrointestinal (GI) tract
• causing uterine contractions in pregnancy and when not pregnant

Too many or too few Prostaglandins in the body can cause health complications. Known problems with too many Prostaglandins include arthritis and menstrual cramping. Conditions that can result from too few Prostaglandins include glaucoma and stomach ulcers. Pharmaceutical companies manufacture a number of medications that affect Prostaglandins in the body. These are as varied as the actions of Prostaglandins themselves and include:

• Bimatoprost (Lumigan, Latisse). This is a medication used to treat glaucoma as well as to promote eyelash growth.
• Carboprost (Hemabate). This medication produces uterine contractions that may help reduce postpartum bleeding.
• Dinoprostone (Cervidil). This medication is used to promote labor by dilating a woman’s cervix.
• Misoprostol (Cytotec). This has a variety of uses, including to prevent gastric ulcers, to induce labor, and also to induce abortion. Doctors may also prescribe it to reduce postpartum bleeding.
• Latanoprost (Xalatan). This is an eye drop prescribed to treat glaucoma.