Student Memory Support
Topic 9 — Prostaglandins: Biological Actions and Clinical Applications
3rd Year MBBS • Infection and Inflammation • High-yield revision and memory reinforcement
1. High-Yield Flashcards
Tap each question to reveal the answer.
What is the main precursor from which prostaglandins are synthesized?
Arachidonic acid released from membrane phospholipids.
Which pathway converts arachidonic acid into prostaglandin intermediates?
The cyclooxygenase pathway.
Which receptor family mediates most prostaglandin effects?
G-protein-coupled receptors.
Which prostanoid is mainly produced by vascular endothelium?
PGI₂, also called prostacyclin.
What are the two major vascular and platelet effects of PGI₂?
Vasodilation and inhibition of platelet aggregation.
Which prostanoid is produced mainly by activated platelets?
Thromboxane A₂.
What are the principal effects of thromboxane A₂?
Vasoconstriction and promotion of platelet aggregation.
How does PGE₂ contribute to inflammatory pain?
It sensitizes peripheral nociceptive nerve endings, producing hyperalgesia.
How does PGE₂ contribute to fever?
It raises the hypothalamic thermoregulatory set point.
Which prostaglandin is especially associated with strong uterine smooth-muscle contraction?
PGF₂α.
Which prostanoid is particularly associated with mast cells and allergic airway responses?
PGD₂.
How do renal PGE₂ and PGI₂ help preserve renal perfusion?
They produce local renal vasodilation.
Which drug is a PGE₂ preparation used for cervical ripening?
Dinoprostone.
Which PGE₁ analogue combines gastric mucosal protection with uterine effects?
Misoprostol.
Which PGF₂α analogue has a strong uterotonic action?
Carboprost.
Which two prostaglandin-related drugs are linked with glaucoma and ductal patency respectively?
Latanoprost for glaucoma and alprostadil for maintaining ductus arteriosus patency.
2. Mnemonics
Mnemonic Title: Major Prostanoids
E-F-D-I-T
Meaning: PGE₂ → PGF₂α → PGD₂ → PGI₂ → TXA₂.
Mnemonic Title: Prostanoid Receptors
E-F-D-I-T
Meaning: PGE → EP, PGF → FP, PGD → DP, PGI₂ → IP, TXA₂ → TP.
Mnemonic Title: Prostaglandin Clinical Uses
U-G-D-P
Meaning: Uterus/cervix → Gastric protection → Ductus arteriosus → Pressure in the eye/pulmonary vessels.
3. Memory Tables
PGI₂ vs TXA₂
| Feature | PGI₂ | TXA₂ |
|---|---|---|
| Main source | Vascular endothelium | Activated platelets |
| Vascular effect | Vasodilation | Vasoconstriction |
| Platelet effect | Inhibits aggregation | Promotes aggregation |
| Receptor | IP | TP |
Important Prostaglandin Drugs
| Drug | Related mediator | High-yield use |
|---|---|---|
| Dinoprostone | PGE₂ | Cervical ripening / labor induction |
| Misoprostol | PGE₁ analogue | Gastric protection and uterine effects |
| Carboprost | PGF₂α analogue | Strong uterotonic effect |
| Latanoprost | PGF₂α analogue | Glaucoma |
| Alprostadil | PGE₁ | Maintains ductus arteriosus patency |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- Prostaglandins are arachidonic-acid-derived local lipid mediators.
- Cyclooxygenase converts arachidonic acid into prostaglandin intermediates.
- Prostanoid receptors are mainly G-protein-coupled receptors.
- PGE₂ is a major mediator of hyperalgesia and fever.
- PGI₂ dilates vessels and inhibits platelet aggregation.
- TXA₂ constricts vessels and promotes platelet aggregation.
- PGF₂α has a strong uterine contractile effect.
- PGE₂ and PGI₂ help maintain renal blood flow through vasodilation.
- Latanoprost lowers intraocular pressure by increasing uveoscleral outflow.
- Alprostadil can maintain ductus arteriosus patency.
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Common KMU Trap: Do not reverse PGI₂ and TXA₂. PGI₂ is anti-aggregatory and vasodilator; TXA₂ is pro-aggregatory and vasoconstrictor.
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5. Clinical Memory Hooks
Inflamed painful tissue → increased PGE₂ → peripheral nociceptor sensitization → hyperalgesia.
Fever during inflammation → hypothalamic PGE₂ → raised thermoregulatory set point.
Glaucoma treated with latanoprost → increased uveoscleral outflow → lower intraocular pressure.
Duct-dependent congenital cardiac lesion → alprostadil → maintained ductus arteriosus patency.
Uterine atony requiring strong contraction → PGF₂α analogue carboprost → uterotonic effect.
6. Starred High-Yield Exam Points
- ⭐ PGI₂ from vascular endothelium causes vasodilation and inhibits platelet aggregation.
- ⭐ TXA₂ from activated platelets causes vasoconstriction and promotes platelet aggregation.
- ⭐ PGE₂ sensitizes nociceptors and raises the hypothalamic temperature set point.
- ⭐ Prostaglandins act mainly through GPCRs, with tissue-specific second-messenger responses.
- ⭐ Dinoprostone is linked with cervical ripening, while carboprost produces strong uterine contraction.
- ⭐ Latanoprost lowers intraocular pressure by increasing uveoscleral outflow.
- ⭐ Alprostadil maintains ductus arteriosus patency in selected duct-dependent congenital cardiac lesions.