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The eicosanoids: prostaglandins, thromboxanes, leukotriens. By S.Bohlooli, PhD. Pathways of arachidonic acid (AA) release and metabolism. Cylcooxygenase pathway. Lipoxygenase pathway. Prostanoids Metabolism. Basic pharmacology of eicosanoids. Receptor mechanisms Organ effects.
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The eicosanoids: prostaglandins, thromboxanes, leukotriens By S.Bohlooli, PhD Ardabil University of Medical Sciences
Pathways of arachidonic acid (AA) release and metabolism Ardabil University of Medical Sciences
Cylcooxygenase pathway Ardabil University of Medical Sciences
Lipoxygenase pathway Ardabil University of Medical Sciences
Prostanoids Metabolism Ardabil University of Medical Sciences
Basic pharmacology of eicosanoids Receptor mechanisms Organ effects Ardabil University of Medical Sciences
Prostanoid receptors and their signaling pathways Ardabil University of Medical Sciences
Effect of prostaglandins and thromboxanes Ardabil University of Medical Sciences
Smooth muscle • Vascular: • vasocontrictors • TXA2 mitogen • PGF2 • Vasodilators • PGI2 • PGE2 • Gastrointestinal tract • Longitudinal muscle: PGE2, PGF2 • Circular muscle: PGF2, PGI2, relaxed by PGE2 • Airways: • Relaxed: PGD2, PGE1, PGE2, PGI2 • Contracted:PGF2, TXA2 Ardabil University of Medical Sciences
Platelets and Blood Cells • Aggregation: • Inhibtion:PGE1, PGI2 • Aggregator: TXA2 Ardabil University of Medical Sciences
Kidney • Major one: PGE2, PGI2 • GFR (vasodilator effect) • Some effects of loop diuretics • TXA2: renal vasoconstrictor may play a role in renal function? ( inflammatory renal disease) Ardabil University of Medical Sciences
Reproductive Organs • Female reproductive organ • Male reproductive organ • Fertility? PGE, PGF • Penile erection: PGE: alprostadil Ardabil University of Medical Sciences
Central and Peripheral nervous system • Fever • Sleep • Neurotransmission • Inhibition of Norepinephrine release postganglionic sympathetic nerves Ardabil University of Medical Sciences
Neuroendocrine organs • PGE: • GH, prolactin, TSH,ACTH, FSH, LH • LTC4, LTD4: • LHRH, LH Ardabil University of Medical Sciences
Bone metabolism • Increasing bone turnover • PGE2 ? Ardabil University of Medical Sciences
EYE • PGE, PGF • Increasing outflow of aqueous humor Ardabil University of Medical Sciences
Effect of Lipoxygenase & Cytochrome P450 derived Metabolites • Blood Cell and Inflammation • Chemoattractant: • Neutrophils: LTB4, lipoxin A • Eosinophils: LTC4, LTD4 • Heart and Smooth Muscle • Cardiovascular • Smooth Muscle Chemoattractant: 12(S)-HETE • Gastrointestinal: LTB4 • Airways:LTC4, LTD4 • Increased vascular permeability, mucus secretion • Renal system • Speculative? • Product of free radical attack: 8-epi-PGF2 Ardabil University of Medical Sciences
Inhibition of Eicosanoid synthesis • Corticosteroids • By producing annexins, lipocortins • Inhibiting phospholipase A2 • NSAIDs • Inhibition of COX activity • May increase the lipoxygenase activity? Ardabil University of Medical Sciences
Clinical pharmacology of Eicosanoids Stable oral or long acting parenteral analogs Enzyme inhibitors and receptor antagonists Dual Cox and Lipoxygenase inhibitors Decreasing preexisting side effects Dietary manipulation Change the polyunsaturated fatty acid Ardabil University of Medical Sciences
Chemistry-1 Ardabil University of Medical Sciences
Chemistry-2 Ardabil University of Medical Sciences
Female reproductive system • Abortion • PGF2, PGE2: oxytocic and ripening and priming of the cervix • Dinoprostone ( PGE2) • Plasma t1/2: 2-2.5 min • Carboprost tromethamine (PGF2) • Drawback: pulmonary hypertension • Facilitation of labor • Potency:PGE2 >> PGF2 • Side effect: PGF2 >> PGE2 • Dysmenorrhea Ardabil University of Medical Sciences
Male Reproductive system • Erectile dysfunction: • Alprostadil (PGE1) • Intracavernosal injection • Urethral suppository Ardabil University of Medical Sciences
Cardiovascular system • Pulmonary hypertension • Prostacylin (epoprostenol) • As intravenous infusion • Peripheral vascular diseases • PGE , PGI • Patent Ductus Arteriosis • PGE, PGI Ardabil University of Medical Sciences
Blood TXA2, PGI2 involved in thrombosis Respiratory System Peptidoleukotriens; LTC4, LTD4 synthesis and receptor inhibitors Gastrointestinal System Cytoprotection: misoprostol (PGE1 analog) Glaucoma Latanoprost (PGF2), bimatoprost, unoprostone Ardabil University of Medical Sciences
Immune system • Cell mediated organ transplant rejection • Inflammation • Rheumatoid arthritis • infection Ardabil University of Medical Sciences