Question:medium
Which of the following prostaglandins is the principal final mediator of fever (pyrogenesis) in the hypothalamus?
Which of the following prostaglandins is the principal final mediator of fever (pyrogenesis) in the hypothalamus?
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Cytokines act through the prostaglandin that NSAIDs block - PGE2 raises the hypothalamic set point.
Updated On: Jun 23, 2026
- PG E2
- PG D2
- PGF2 alpha
- PG I2
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Trace the fever cascade from the start. An infectious or inflammatory trigger makes immune cells secrete cytokines - $IL\text{-}1$, $IL\text{-}6$, $TNF\text{-}\alpha$ - which are the true endogenous pyrogens.
Step 2: These cytokines reach the hypothalamus and switch on cyclo-oxygenase, so the immediate downstream product that actually raises the set point is prostaglandin $E_2$.
Step 3: Confirm by pharmacology: COX inhibitors (NSAIDs, paracetamol) cut $PGE_2$ and abolish fever, proving $PGE_2$ is the effector molecule.
Step 4: Rule out the rest by their real jobs - $PGD_2$ promotes sleep, $PGF_{2\alpha}$ contracts smooth muscle, and $PGI_2$ is a vasodilator/antiplatelet agent; none reset temperature.
\[\boxed{\text{PG E2}}\]
Step 2: These cytokines reach the hypothalamus and switch on cyclo-oxygenase, so the immediate downstream product that actually raises the set point is prostaglandin $E_2$.
Step 3: Confirm by pharmacology: COX inhibitors (NSAIDs, paracetamol) cut $PGE_2$ and abolish fever, proving $PGE_2$ is the effector molecule.
Step 4: Rule out the rest by their real jobs - $PGD_2$ promotes sleep, $PGF_{2\alpha}$ contracts smooth muscle, and $PGI_2$ is a vasodilator/antiplatelet agent; none reset temperature.
\[\boxed{\text{PG E2}}\]
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