Prostaglandins
What is Prostaglandins
A large family of fast-acting lipid mediators primarily responsible for initiating INFLAMMATION, FEVER, and PAIN during the IMMUNE RESPONSE. Prostaglandins are also vital for numerous functions throughout the body. Thromboxane, one of the prostaglandins, facilitates PLATELET AGGREGATION to aid COAGULATION (BLOOD clotting). Other prostaglandins facilitate calcium transport to and from cells, the onset and progression of labor during CHILDBIRTH, and the functions of other hormones. Prostaglandins are also responsible for discomforts related to their release, such as after injury when inflammation results or when menstrual cramps (DYSMENORRHEA) occur.
Prostaglandin activity is autocrine (affects only cells that secrete it) or paracrine (affects cells within immediate proximity of the secreting cells). Prostaglandin activity is also intense but short lived, though the symptoms of the resulting inflammation continue for some time after prostaglandin release stops. Mast cells are the main source of prostaglandin synthesis and secretion. Epithelial cells (surface cells of the SKIN and mucous membranes) and platelets also produce as well as respond to prostaglandins.
PROSTAGLANDINS AND THE PROSTATE GLAND
The researchers who discovered prostaglandins in the 1930s isolated the first member of this biochemical family from SEMEN-the secretions of the PROSTATE GLAND. They named it for this connection. Over the following decades further research identified a number of prostaglandins and determined that nearly every cell in the body contains some form of prostaglandin. Aspirin was the first DRUG to block the synthesis of prostaglandins.
The enzymes cyclooxygenase 1 (COX-1) and COX-2 facilitate the synthesis of prostaglandins from arachidonic acid, an essential fatty acid (a fatty acid the body requires for health but cannot synthesize from other substances so must obtain from dietary sources) found in red meats and peanuts. Arachidonic acid is also the foundation for LEUKOTRIENES, other biochemicals also involved in the inflammatory response. The enzyme lipoxygenase facilitates the conversion of arachidonic acid to leukotrienes. COX-1 is primarily in the STOMACH, KIDNEYS, and walls of the blood vessels; it maintains the prostaglandins necessary for the body’s normal functioning. COX-2 is present in the tissues and becomes active during an inflammatory response.
NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS), including aspirin, block the action of COX, preventing prostaglandin production. This action provides pain relief, reduces fever, and mitigates the swelling associated with inflammation. Though much therapeutic focus is on blocking prostaglandin production, there are numerous therapeutic applications for synthetic prostaglandins. Therapeutic administration of synthetic prosta-glandin E1 (PGE1) maintains a patent ductus arteriosus in infants born with serious congenital heart defects. Prostaglandin E2 (PGE2) and prostaglandin F2 (PGF2) cause the UTERUS to contract, either initiating or strengthening labor.
See also CONGENITAL HEART DISEASE; CRAMP; HORMONE; IMMUNE RESPONSE; IMMUNOGLOBULIN; MAST CELL; PLATELET.
