Prostanoid receptors

• The prostanoids, as well as other eicosanoids, interact with their target cells primarily via G-protein-coupled receptors.
• There are one or more receptors for each prostanoid.
• Each prostanoid receptor activates a particular signaling cascade; Gs, Gi, or Gq
  • Different prostanoids may have different effects on a particular cell type. For example, thromboxane (TXA) and prostacyclin (PGI) have opposite effects on vascular smooth muscle cells: TXA promotes constriction while PGI promotes dilation.
  • The same prostanoid may have different effects on different cell types.

  Some properties of prostanoid receptors (examples only, not to be memorized)
  Receptor*	Signaling Pathway	Signal	Effect on smooth muscle/other effects
  PGD receptors
  DP1	Gs	Increase cAMP	Relaxation; inflammation; allergy
  DP2	Gi	Decrease cAMP	Immune activation
  PGE receptors
  EP1	Gq	Increase Ca++	Constriction; mediates pain
  EP2	Gs	Increase cAMP	Relaxation
  EP3	Gi	Decrease cAMP	Constriction; fever
  EP4	Gs	Increase cAMP	Relaxation
  PGF receptor
  FP	Gq	Increase Ca2+	Uterine contraction
  PGI receptor
  IP	Gs	Increase cAMP	Relaxation; Anti-thrombotic
  TXA receptor
  TP	Gq	Increase Ca2+	Constriction; Platelet aggregation
  * Prostanoid receptors are named by the prostanoid letter (A-K), followed by the letter P with subscript to denote subtype.

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