see also:

• eicosanoids including prostaglandins
• corticosteroids
• non-steroidal anti-inflammatory drugs (NSAIDs)

• prostaglandins are substances derived from membrane phospholipids via the actions of the enzymes phosholipase A2, phospholipase C and then cyclooxygenase
• these metabolic products of phospholipids and arachidonic acid are autacoids forming the prostanoid class of fatty acid derivatives (and these also include thromboxane and the leukotrienes) which are a subclass of eicosanoids including prostaglandins
• every prostaglandin contains 20 carbon atoms, including a 5-carbon ring.
• they have a variety of critically important roles in physiology
• they have key roles in the physiology of inflammation
• it is thought that COX-1 synthesises baseline levels of PG's while COX-2 activity is increased during inflammation
• PG production is inhibited by:
  • cyclooxyenase inhibitors such as non-steroidal anti-inflammatory drugs (NSAIDs)
  • phosholipase A2 inhibitors such as corticosteroids
• most PGs are rapidly metabolised by PG 15-OH dehydrogenase (PGDH), mainly in the lungs

• produced from PG H2 via PGE synthase
• acts on a variety of PG E receptors as below plus
  • causes hyperalgesia and fevers
  • appears to help maintain urine output when renal blood flow is decreased

• bronchoconstriction
• contraction of pulmonary venous smooth muscle
• GIT smooth muscle contraction
• induces contractions of the smooth muscle fibers in the myometrium and relaxation of the uterine cervix
• may play roles in:
  • inhibition of sleep
  • regulation of peripheral circadian clock
  • renal vasoconstriction ¹⁾
• misoprostol
  • E1 receptor agonist used to assist in expelling RPOC in miscarriage

• bronchodilation
• GIT smooth muscle relaxation
• vasodilatation
• increased renin secretion via direct effect on JG cells
• decreased ADH mediated reabsorption of water
• downregulation of protease-activated receptors (PARs)
• promotion of cell growth such as chondrocytes
• inhibition of TNFα release from alveolar macrophages
• reduction of intraocular pressure
• augmentation of G-CSF secretion and suppression of GM-CSF release from airway smooth muscle cells
• ?role in carcinogenesis in prostate cancer²⁾

• decreases gastric acid secretion
• increases gastric mucus secretion
• GIT smooth muscle contraction
• uterine contraction in pregnancy
• inhibits lipolysis
• increases autonomic neurotransmitters
• increases platelet response
• increases atherothrombosis
• may be involved in:
  • mediation of adrenocorticotropic hormone response
  • fever generation

• activates T-cell factor signaling
• suppresses the release of cytokines and chemokines from macrophages and T-cells
• induces expression of early growth response 1 (EGR1),
• regulates the level and stability of cyclooxygenase-2 mRNA
• phosphorylation of glycogen synthase kinase-3
• vasodilation
• bronchodilation
• inhibition of platelet aggregation
• negatively regulates aberrant synovial overgrowth and the development of osteoclast activity in rheumatoid arthritis
• inhibition of LPS-induced mucus secretion from airway epithelial cells
• may be involved in:
  • neonatal adaptation of circulatory system incl. closure of ductus arteriosus
  • osteoporosis
  • initiation of skin immune responses
  • promotion of sleep
  • development of abdominal aortic aneurysm (AAA)

• acts on the PG IP receptor
• vasodilation
• inhibits platelet aggregation
  • PG I2 released from endothelium presumably is the physiologic antagonist of thromboxane A2 for platelet aggregation
• bronchodilation
• augmentation of glucocorticoid-induced gene expression
• inhibition of chemokine release

• acts on PG FP receptor
• causes uterine contraction and bronchoconstriction
• tafluprost
  • selective FP receptor agonist used topically to increase uveoscleral outflow in Rx glaucoma