Ecosanoids (Prostaglandins,Thrmboxane,Leukotrienes)

1. EICOSANOIDS
(Prostaglandins,Thromboxanes,
Leukotrienes)
Presented By
Ms.S.J.Kamble
Asst. Prof.
Ashokrao Mane College of Pharmacy,
Peth Vadgaon

2. Major Classes of Eicosanoids
•Prostaglandins
•Thromboxanes
•Prostacyclins
•Leukotrienes
•

3. Eicosanoids are synthesized by two pathways:
1.The Cyclooxygenase pathway produces:
A.Thromboxane
B. Prostaglandins (PG): PGE, PGF, PGD
C. prostacyclin (PGI2)
2.The lipoxygenase pathway produces:
A. leukotrienes

7. RECEPTORS:G-protein coupled receptors
PROSTAGLANDINS
• PGE - EP1, EP2, EP3, EP4.
• PGF – FP
• PGD - DP
THROMBOXANE –
• TP
PROSTACYCLINS
• PGI - IP
LEUKOTRIENES –
• LT1, LT2, LT3, LT4.

9.  Uterine smooth muscle.
• PGE2 and PGF2a cause
contraction of uterine
smooth muscle in pregnant
women.
 The non-pregnant uterus :
• has a more variable response
to prostaglandins
• PGF2a causes contraction
• PGE2 causes relaxation.
Vascular Smooth muscle :
• PGE2 & PGI2 are potent
vasodilator.
• Thrmboxane is potent
vasoconstrictor.

10.  Inflammation
○PGE2 and PGI2 cause an increase in
blood flow, but do not cause edema.
○leukotrienes cause chemotaxis of
neutrophils and eosinophils.

12.  Gastrointestinal tract
 PGE2 and PGF2a -
increase the rate of
longitudinal contraction
in the gut and decrease
transit time.
 The leukotrienes –
are potent stimulators of
gastrointestinal smooth
muscle.
 PGE2 and PGI2 -
inhibit acid and
pepsinogen secretion
in the stomach.

13. Bronchial smooth muscle
• PGFs cause smooth muscle contraction.
• PGEs cause smooth muscle relaxation.
• Leukotrienes and thromboxane are potent bronchoconstrictors
and are the most likely candidates for mediating allergic
bronchospasm

14. Blood :
•TXA2 - is a potent inducer of platelet aggregation.
•PGE2 - inhibit platelet aggregation.
• PGEs - induce erythropoiesis by stimulating the renal
release of erythropoietin.
•PGD - inhibit histamine release.