Roles of prostanoids revealed from studies using mice lacking specific prostanoid receptors

The actions of prostanoids in various physiological and pathophysiological conditions have been being examined using mice lacking different prostanoid receptors. Prostaglandin (PG) I-2 worked not only as a mediator of inflamm ation but also as an antithrombotic agent. PGF(2 alpha) was found to be an essential inducer of labor. Several important actions of PGE(2) are exerted via each of the four PGE(2) receptor subtypes: EP1, EP2, EP3 and EP4. PGE( 2) participated in colon carcinogenesis via the EP1. PGE(2) also participat es in ovulation and fertilization and contributes to the control of blood p ressure under high-salt intake via the EP2. PGE(2) worked as a mediator of febrile responses to both endogenous and exogenous pyrogens and as a regula tor of bicarbonate secretion induced by acid-stimulation in the duodenum vi a the EP3. It regulated the closure of ductus arteriosus and showed bone re sorbing action via the EP4. PGD(2) was found to be a mediator of allergic a sthma. These studies have revealed important roles of prostanoids, some of which had not previously been known.