Functions of Prostaglandins

1. Inflammation

• PGE₂ and PGD₂ cause vasodilation and increase postcapillary venule permeability, potentiating edema and exudation.
• PGD₂ (mainly from mast cells) is also a chemoattractant for neutrophils.
• Prostaglandins are major mediators released during allergic and inflammatory reactions.
• COX-1 (constitutive) supports homeostatic functions; COX-2 (inducible) is upregulated at sites of inflammation to generate pro-inflammatory prostaglandins.

— Robbins & Kumar Basic Pathology, p. 1271–1286

2. Pain and Fever

• PGE₂ sensitizes peripheral nociceptors to painful stimuli (hyperalgesia).
• Prostaglandins act on the hypothalamus to raise the thermoregulatory set point, producing fever.
• NSAIDs (aspirin, ibuprofen) reduce pain and fever by blocking COX, thereby inhibiting prostaglandin synthesis.

— Lippincott Illustrated Reviews: Pharmacology, p. 1339

3. Vascular Tone and Platelet Function

— Basic Medical Biochemistry: A Clinical Approach, 6e, Table 31.1

4. Gastrointestinal Tract

• PGE₂ and PGI₂ inhibit gastric acid secretion and stimulate mucus production, providing cytoprotection to the GI mucosa.
• This is why NSAID use (which blocks COX-1–derived prostaglandins) can cause peptic ulcers.
• Misoprostol, a PGE₁ analog, is used clinically to protect the GI tract.

— Lippincott Illustrated Reviews: Pharmacology, p. 1339; Barash Clinical Anesthesia, p. 1758

5. Renal Function (COX-1 homeostatic role)

• Prostaglandins regulate renal blood flow, renin secretion, and fluid/electrolyte balance, particularly under conditions of reduced renal perfusion.
• NSAIDs can precipitate acute kidney injury by blocking renal prostaglandins in susceptible patients.

— Brenner and Rector's The Kidney; Robbins & Kumar Basic Pathology, p. 1271

6. Reproductive System

• PGE₂ and PGF₂α stimulate uterine contractions, playing a role in labor induction, dysmenorrhea, and cervical ripening.
• Prostaglandins are important in cervical dilation — exogenous administration (e.g., dinoprostone/PGE₂) mimics natural ripening.

— Creasy & Resnik's Maternal-Fetal Medicine; Lippincott Pharmacology, p. 1339

7. Immune Modulation

• PGI₂, PGE₂, and PGD₂ decrease leukocyte aggregation, IL-1, IL-2 levels, T-cell proliferation, and lymphocyte migration — acting as brakes on immune activation.

— Basic Medical Biochemistry, Table 31.1

8. Respiratory System

• PGF₂α causes bronchoconstriction.
• PGE₂ causes bronchodilation.
• This differential effect is relevant in aspirin-exacerbated respiratory disease (aspirin-sensitive asthma), where COX blockade shifts the balance toward bronchoconstriction.

Summary Table