Match each of the following classes of eicosanoids with its function:
Leukotrienes: Mediate allergic and inflammatory reactions
Prostacyclin: Inhibit(s) blood clotting and vasoconstriction
Prostaglandins: Relax and/or contract smooth muscle
Thromboxanes: Stimulate(s) vasoconstriction and clotting
The correct answer and explanation is :
Correct Matching of Eicosanoids and Their Functions:
- Leukotrienes → Mediate allergic and inflammatory reactions
- Prostacyclin → Inhibit(s) blood clotting and vasoconstriction
- Prostaglandins → Relax and/or contract smooth muscle
- Thromboxanes → Stimulate(s) vasoconstriction and clotting
Explanation:
Eicosanoids are lipid-derived signaling molecules synthesized from arachidonic acid and play crucial roles in physiological and pathological processes. They include leukotrienes, prostacyclins, prostaglandins, and thromboxanes, each with distinct biological effects.
- Leukotrienes: These molecules are primarily produced by leukocytes and are involved in immune responses, particularly in inflammation and allergic reactions. They contribute to bronchoconstriction in asthma, increased vascular permeability, and chemotaxis (the attraction of immune cells to sites of infection or injury).
- Prostacyclin (PGI₂): This eicosanoid is produced by endothelial cells and plays a vital role in cardiovascular homeostasis. It inhibits platelet aggregation (preventing clot formation) and promotes vasodilation, thereby reducing blood pressure and maintaining smooth blood flow.
- Prostaglandins (PGs): These compounds have diverse effects depending on the specific type (PGE₂, PGF₂α, etc.). Some prostaglandins cause smooth muscle relaxation (e.g., PGE₂ in the vasculature and bronchi), while others induce contraction (e.g., PGF₂α in the uterus during labor). They also regulate inflammation, fever, and pain.
- Thromboxanes (TXA₂): Produced mainly by platelets, thromboxanes have the opposite effect of prostacyclins. They promote platelet aggregation, vasoconstriction, and blood clot formation, which is essential for stopping bleeding but can also contribute to conditions like thrombosis if excessively activated.
Understanding eicosanoids is critical in pharmacology and medicine, as drugs like aspirin and NSAIDs inhibit their synthesis to reduce inflammation, pain, and clotting risks.