The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids
Prostaglandins have diverse hormone-like effects.
Found in almost every tissue in humans.
Prostaglandins are found in most tissues and organs, and produced by almost all nucleated cells.
They are autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells.
Prostaglandins are synthesized in the cell from the fatty acid arachidonic acid.
((Arachidonic acid)) is brought to either the cyclooxygenase pathway or the lipoxygenase pathway.
Prostaglandins are produced following the sequential oxygenation of
arachidonic acid, docosahexaenoic or eicosapentaenoic by cyclooxygenases (COX-1 and COX-2) and terminal prostaglandin synthases.
Prostaglandins are produced following the sequential oxygenation of
arachidonic acid, docosahexaenoic or eicosapentaenoic by cyclooxygenases (COX-1 and COX-2) and terminal prostaglandin synthases.
COX-1 is responsible for the baseline levels of prostaglandins.
COX-2 produces prostaglandins through stimulation.
COX-1 and COX-2 are both located in the blood vessels, stomach and the kidneys, prostaglandin levels are increased by COX-2 in scenarios of inflammation and growth.
Prostaglandin E2 (PGE2) is the most abundant prostaglandin.
The cyclooxygenase pathway produces thromboxane, prostacyclin and prostaglandin D, E and F.
The lipoxygenase enzyme pathway is active in leukocytes and in macrophages and synthesizes leukotrienes.
Prostaglandin transporter (PGT) mediates the cellular uptake of prostaglandin.
The release of prostaglandin is mediated by a specific transporter, the multidrug resistance protein 4.
Prostaglandins are derived enzymatically from the fatty acid arachidonic acid.
Produced by tissue specific response to conditions that require cellular activation, such as infection, trauma and others stressors.
Metabolized from lipid cell membrane components by enzymes specific to particular tissues.
Terminal prostaglandin synthases have are responsible for the formation of other prostaglandins.
Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring.
Structural differences between prostaglandins account for their different biological activities.
A prostaglandin may have different and even opposite effects in different tissues, dependent upon the type of receptor to which the prostaglandin binds.
Prostaglandins are named with a letter indicating the type of ring structure present. followed by a number indicating the number of double bonds in the hydrocarbon structure.
In the mucosa of the large intestine inflammatory or mitogenic activity produces prostaglandin E2(PGE2)via a reaction catalyzed by the cyclooxygenase-2 (COX-2)enzyme.
PGE2 promotes wound healing, epithelial cell invasion, epidermal growth factor signaling, and angiogenesis.
There are ten known prostaglandin receptors on various cell types.
Prostaglandins act on an array of cells and have a wide variety of effects.
With menstruation prostaglandins are released by destroyed endometrial cells.
Prostaglandins release by endometrial cells along with other inflammatory mediators in the uterus cause the uterus to contract: major factor in primary dysmenorrhea.
Prostaglandin antagonists are:
Aspirin
NSAIDs
COX-2 selective inhibitors or coxibs
Corticosteroids
Synthetic prostaglandins are used:
To induce childbirth or abortion with or without mifepristone, a progesterone antagonist.
To prevent closure of ductus arteriosus in newborns with cyanotic heart defects.
As a vasodilator in severe Raynaud’s phenomenon or ischemia of a limb.
In pulmonary hypertension
In treatment of glaucoma
To treat erectile dysfunction or in penile rehabilitation following surgery
To measure erect penis size in a clinical environment