In the first of a new series of London Group lectures – held on 13 September 2017 at Marks and Clerk in Long Acre – Professor Rod Flower FRS spoke about ‘The Prostaglandins: What are they, where are they found and why are they important?’. He began his lecture by introducing the history of prostaglandins.
Image: Ulf Svante von Euler (1905-1983), Swedish physiologist, pharmacologist and Nobel laureate; Credit: Wellcome Trust
In the 1930s, Ulf Von Euler discovered the compounds, having isolated them from seminal plasma. He demonstrated that prostaglandins could cause contraction in strips of uterus and small intestines, as well as provoke hypotension in animals. Sune Bergström studied the vesicular tissues that had been used by Von Euler and purified the prostaglandin extracts, enabling him to identify and characterise prostaglandin E and prostaglandin F.
Bengt Samuelsson found that prostaglandins are biologically synthesised from essential fatty acids via the intermediate: arachidonic acid, which takes either the cyclooxygenase (COX) pathway or the lipoxygenase pathway. It is the former pathway that produces prostaglandins, prostacyclins, and thromboxane.
Different functional groups also define different types of prostaglandins and prostacyclins (e.g. PGE2, PGH2, PGI2). PGE2 can cause uterus and gastrointestinal smooth muscle contraction, as well as increase platelet response. PGI2 is a vasodilator and inhibits platelet aggregation.
Prostaglandins have a wide range of functions in the body. In the stomach, PGs suppress acid production and provide gastric cyto-protection. In joints, they regulate pain transmission and increase the production of autonomic neurotransmitters.
A further advance in the study of prostaglandins was made with John Vane’s discovery in 1971. Vane found that prostaglandin production is inhibited by salicylic acid – widely known as aspirin – and indomethacin in minced guinea pig lung tissues. The therapeutic effects of aspirin are directly related to their suppression of prostaglandins.
Aspirin counters the effects of prostaglandins by blocking their production by cyclooxygenase, the enzyme required for prostaglandin synthesis. Therefore, aspirin is able to act as an analgesic, antipyretic, and platelet aggregation inhibitor.
The study of prostaglandins and the pharmacology of aspirin-like drugs emphasises the medical importance of prostaglandins. Its legacy is apparent in the creation of drugs such as Misoprostol, Iloprost, and Gemeprost – medications that are analogues of prostacylins and prostaglandins.
The importance of prostaglandins was realised globally when Sune Bergström, Bengt Samuelsson and John Vane were jointly awarded the 1982 Nobel Prize in Physiology or Medicine ‘for their discoveries concerning prostaglandins and related biologically active substances’.
Anna Chen and Muxin Han are both pre-medical track students at New York University