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COX 2 regulates inhibits. (DNB Dec 2009)
Ans. B Cell Migration (Ref: BG Katzung, pp-626, 11th Edition, 2009)
- Prostanoids (20 carbon compounds) are the product of cyclooxygenase (COX) metabolism.
- Endothelial cells synthesize COX. At present, there are 3 isoforms of COXs: 1,2,3. COX-1 is a constitutive enzyme: that means, it is physiological while COX-2 is pathological.
- However, COX-2 too plays some physiological role. COX-3 is an anti-inflammatory enzyme.
- It has been proposed that if we could have drugs that can stimulate the activity of COX-3, we shall anti-inflammatory prostaglandins produced whose potency can be more than even that of corticosteroids. COX-2 has increasingly been known to physiologically relevant.
- It has been shown to affect cellular differentiation in tumors, bone marrow cells, bone cells (osteoblasts), embryonic cells, kidneys and gut mucosa cells.
- This has fueled fears for quite sometime that COX-2 inhibitors will be teratogenic if they are used in pregnancy. However, it remains to be clinically seen.
- Since, selective block of COX-2 has been known to potentiate cardio and vascular events; drugs like rofecoxib has been banned. Valdycoxib has also been banned because of the same plus due to high incidence of allergic reactions.