Prostaglandins and related compound prostacyclin, thrombaxanes, leukotrienes and lipoxins are collectively known as eicosanoids.
Most are produced from arachidonic acid, a 20 carbon polyunsaturated fatty acid (5,8,11,14-eicosatetraenoic acid).
The eicosanoids are considered “local hormones”.
They have specific effect on target cells close to their site of formation.
They are not secreted from a gland, but rather are created at the time they are needed directly where the problem exists.
3. Introduction
Prostaglandins and related compound prostacyclin, thrombaxanes,
leukotrienes and lipoxins are collectively known as eicosanoids.
Most are produced from arachidonic acid, a 20 carbon
polyunsaturated fatty acid (5,8,11,14-eicosatetraenoic acid).
The eicosanoids are considered “local hormones”.
They have specific effect on target cells close to their site of
formation.
They are not secreted from a gland, but rather are created at the time
they are needed directly where the problem exists.
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5. Nomenclature of prostaglandins
Prostanoic acid (7-[(1s,2s)-2-octylclopentyl] heptanoic acid) is
a saturated fatty acid which contains a cyclopentane ring.
It is derivatives are prostaglandins- physiologically active lipid
substances.
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7. Receptors
PGs, TX act on their own specific receptors located on cell membrane.
Five families of prostanoid receptors (DP, EP, FP, IP, TP) have been
designated, each after the endogenous PG for which it has been designated
each after the endogenous PG for which it has the greatest affinity.
All prostanoid receptors are G- protein coupled receptor which can be
functionally categorized
Excitatory or contractile (EP, FP, TP) and generate IP3- DAG pathway
Inhibitory or relaxant (DP1, EP2, EP4 & IP) activate cAMP pathway
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9. Types of PGs
PG-D2
Acting on DP receptors
It causes vasodilatation
Inhibition of platelets aggregation
Relaxation of GI & uterine muscles
Side effects
Asthma
Low BP
Clotting time increases
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10. PG-E1 & E2
Acting on EP 1 receptors
Broncho constrictor
GI tract smooth muscle contraction
Acting on EP 2 receptors
Broncho dilatation
GI tract smooth muscle relaxation
Vasodilatation
Acting on EP 3 receptors
Decrease gastric acid secretion
Increase gastric mucus secretion
uterus contraction ( in pregnancy)
GI tract smooth muscles contraction 10
Side effects
watery diarrhoea
Diuresis
Rise the body temperature
Pain
Sedation
11. PG-F2
Acting on FP receptors
Myometrial contraction
Broncho constriction
Vasodilatation
Ocular inflammation
Side effects
Contraction of uterus
Dysmenorrhoea
Asthma
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12. PG-G2 & H2
Acting on DP receptors
It causes vasodilatation
Inhibition of platelets
aggregation
relaxation of GI & uterine
muscles
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13. PG-I
Acting on IP receptors
Vasodilatation
Inhibit platelet aggregation
Broncho dilation
Hyperalgesic effect.
Side effects
Diuretic effect
Fever
Algesia
Inflammation
Clotting time increases
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