Function of prostanoid receptors: studies on knockout mice.

Prostanoids consisting of the prostaglandins (PGs) and the thromboxanes (TXs) are the cyclooxygenase metabolites of arachidonic acid. They exert a range of actions mediated by their respective receptors expressed in the target cells. The receptors include the DP, EP, FP, IP and TP receptors for PGD, PGE, PGF, PGI and TXA, respectively. Furthermore, EP is subdivided into four subtypes, EP1, EP2, EP3 and EP4, which are encoded by different genes and differ in their responses to various agonists and antagonists. Recent developments in the molecular biology of the prostanoid receptors have enabled the investigation of physiological roles of each receptor by disruption of the respective gene. At this point, all the eight types and subtypes of the prostanoid receptors have been individually knocked out in mice, and various phenotypes have been reported for each strain. Here, we review the findings obtained in these studies. The results from these knockout mice studies may be useful in the development of novel therapeutics that can selectively manipulate actions mediated by each receptor.