Eicosanoids Flashcards
Who discovered prostaglandins and in what year?
Ulf von Euler in 1938
The structure was described by Bergstrom in 1950, who won the Nobel Prize in 1982.
What are the three main classes of eicosanoids?
Prostaglandins, leukotrienes, thromboxanes
From what substance are eicosanoids produced?
Membrane arachidonic acid
What is the molecular structure characteristic of eicosanoids?
A five-membered ring and two side chains
What type of hormones are eicosanoids considered?
Local hormones or paracrine substances
What is the full name of the fatty acid from which prostanoids are synthesized?
5,8,11,14-eicosatetraenoic acid
What enzymes liberate arachidonic acid from plasma membranes?
Phospholipases (PLA)
Which two forms of cyclooxygenase are involved in prostaglandin production?
COX-1 and COX-2
Name the four principal in-vivo prostaglandins.
PGE2, PGI2, PGD2, PGF2α
What is the role of COX-1 in the body?
Responsible for gastric epithelial cytoprotection and homeostasis
What does COX-2 respond to?
Induced by inflammation, hormones, and growth factors
What is the common substrate produced by both COX isoforms?
PGH2
What are the effects of TXA2?
Potent vasoconstrictor and smooth muscle mitogen
What are the two key isoenzymes for prostaglandin synthesis?
PGH-1 synthase (COX-1) and PGH-2 synthase (COX-2)
What type of receptors do eicosanoids activate?
G-protein coupled receptors
How do eicosanoids primarily act on their target cells?
By activating adenylyl cyclase to increase intracellular cAMP
Fill in the blank: The cysteinyl leukotrienes are known as _______.
Bronchoconstrictors
What is the role of corticosteroids in eicosanoid synthesis?
Block all known pathways of eicosanoid synthesis
What is the therapeutic use of Alprostadil?
Used in erectile dysfunction
What is the effect of PGE2 on uterine contractions at low concentrations?
Promotes uterine contractions
True or False: PGI2 is a potent inhibitor of platelet aggregation.
True
What is the primary action of PGE2 in the CNS?
Increases body temperature
What is the effect of PGE2 and PGI2 in inflammation?
Chemoattractants and enhance edema formation
What are the effects of LTC4 and LTD4?
Potent bronchoconstrictors
What is the role of lipoxygenases in metabolism?
Play important roles in inflammation
What is the significance of LTB4?
Potent chemoattractant for T lymphocytes, neutrophils, eosinophils, monocytes, and mast cells
Fill in the blank: The leukotriene products are proposed to have a role in _______.
Renal regulation
What are the effects of PGF2α in the reproductive system?
Contracts uterine muscle
What are the effects of PGE2 in the kidneys?
Increases medullary blood flow and inhibits tubular sodium reabsorption
What is the therapeutic use of Dinoprostone?
Induction of labour
What does TXA2 do in the cardiovascular system?
Potent platelet aggregator
What is the relationship between eicosanoids and asthma?
Cysteinyl leukotrienes are implicated in asthma
Fill in the blank: NSAIDs inhibit _______ activity.
PGH-1 synthase
What is the effect of PGE2 on smooth muscle?
Ca++ dependent relaxation
What is the role of COX-2 derived prostanoids in the kidneys?
Increase medullary blood flow
What does PGD2 promote in the CNS?
Induces sleep
What is the effect of PGE2 on platelet aggregation?
Inhibits platelet aggregation
What is the significance of the isoeicosanoid pathway?
One of the routes of arachidonic acid metabolism
What are the effects of PGE2 and PGI2 in the respiratory system?
Relax respiratory muscles
What do the cysteinyl leukotrienes promote at the site of inflammation?
Endothelial permeability and migration of inflammatory cells
Fill in the blank: PGE2 and PGI2 are the major _______ associated with inflammation.
Prostanoids
What is the therapeutic use of Latanoprost?
Reduction of intraocular pressure
What is the effect of PGE2 on bone turnover?
Increases bone turnover
What is the effect of PGE2 on the respiratory system?
PGE2 is a potent bronchodilator
PGE2 plays a significant role in widening the air passages in the lungs.
Which substances are powerful bronchoconstrictors?
PGF2α and TXA2
These substances can induce narrowing of the airways, making breathing more difficult.
What role do LTC4 and LTD4 play in asthma?
They are important cytokines in asthma
These leukotrienes contribute to inflammation and bronchoconstriction in asthmatic patients.
Name two LT-receptor inhibitors effective in asthma.
Zafirlukast and Montelukast
These medications help to block the action of leukotrienes in asthma management.
How do corticosteroids work in asthma?
By inhibiting eicosanoid synthesis
Corticosteroids reduce inflammation in the airways by blocking the production of eicosanoids.
What is the mechanism of action of Cromolyn in asthma treatment?
Inhibits the liberation of eicosanoids, histamine, and platelet activating factor from mast cells
Cromolyn stabilizes mast cells to prevent the release of inflammatory mediators.
What is Misoprostol used for in gastrointestinal treatment?
It provides cytoprotection in peptic ulcer
Misoprostol is a PGE1 analogue that protects the stomach lining.
What are the effects of PGE2 on T-lymphocyte proliferation?
Limits T-lymphocyte proliferation
PGE2 plays a role in modulating immune responses.
What does TXA2 stimulate in T-cells?
T-cell clonal expansion
TXA2 promotes the proliferation of T-cells, which can enhance immune responses.
True or False: Aspirin inhibits COX activity during inflammation.
True
Aspirin is known for its anti-inflammatory properties by inhibiting cyclooxygenase enzymes.
What is Latanoprost used for?
It is used in glaucoma
Latanoprost is a PGF2α derivative that helps lower intraocular pressure.
How do corticosteroids inhibit eicosanoid synthesis?
By stimulating the synthesis of inhibitory proteins called annexins or lipocortins
These proteins help to block the activity of phospholipase A2.
What are 5-LOX inhibitors used for?
Indicated in mild to moderate asthma
These inhibitors target leukotriene synthesis to reduce asthma symptoms.
What is Ergotism?
Dementia, hallucinations, vasospasm, stimulation of uterine muscle
Ergotism is a condition resulting from excessive consumption of ergot alkaloids.
What are semi-synthetic ergot alkaloids?
Bromocriptine and Cabergoline
These are modified forms of natural ergot alkaloids with specific therapeutic uses.
What receptors do ergot alkaloids affect?
Adrenoceptors and serotonin receptors: 5-HT1A and 5-HT1D
They can act as agonists or partial agonists at these receptors.
What is the clinical use of ergotamine?
Used clinically in migraine
Ergotamine’s action on 5-HT receptors helps relieve migraine headaches.
What is the primary function of Oxytocin during labor?
Mediates myometrial contractility
Oxytocin is essential for stimulating uterine contractions.
What is the half-life of Oxytocin?
5 minutes
This short half-life necessitates careful dosing during labor.
What does Atosiban do?
It is an oxytocin receptor antagonist used to treat pre-term labor
Atosiban helps to inhibit contractions and prevent premature delivery.
What does Oxytocin stimulate in mammary glands?
Contraction of myoepithelial cells around the mammary alveoli
This action promotes milk ejection during breastfeeding.
