FIGURE 1.

Synthetic and signal transduction pathways of prostaglandins. Arachidonic acid can be transformed into PGG₂ and PGH₂ via COX enzymes, which can be inhibited by NSAIDs. Then PGH₂ is converted into various prostaglandins via specific synthases. Prostaglandins then exert their actions by activating receptors on cell membranes, including DP1-2, EP1-4, FP, IP and TP. Nuclear receptors such as PPARγ and PPARδ can also be activated by prostaglandins or their metabolites. Abbreviations: PGG₂, prostaglandin G₂; PGH₂, prostaglandin H₂; PGDS, PGD synthase; PGES, PGE synthase; PGFS, PGF synthase; PGIS, PGI synthase; TBXAS1, TXA synthase; peroxisome proliferator-activated receptor (PPAR).