- There is evidence that following pyrogenic stimuli, cytokines produced by the CNS cause fever, possibly by local release of prostaglandins. Accordingly, the following statements have been proposed:
A. Cytokines act independently and directly on thermoregulatory centres
B. Intrahypothalamic injection of prostaglandin receptor agonists will prevent fever
C. Antipyretic effect of aspirin is exerted on the hypothalamus to prevent prostaglandin synthesis
D. Aspirin blocks infections and eventually prevents fever.
Which one of the following combination of above statements is correct?
(1) A and D (2) B and C
(3) B and D (4) A and C
The Mechanism of Fever: Cytokines, Prostaglandins, and Aspirin Action
Fever is a common physiological response triggered by pyrogenic stimuli such as infections and inflammation. Recent research has demonstrated that cytokines produced by the central nervous system (CNS) play a pivotal role in fever induction, primarily by stimulating local production of prostaglandins in the hypothalamus, the body’s thermoregulatory center.
Analyzing the Proposed Statements
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A. Cytokines act independently and directly on thermoregulatory centres
This statement is generally considered incorrect. Cytokines do not usually act directly on thermoregulatory centers. Instead, they stimulate the production of prostaglandins, especially prostaglandin E2 (PGE2), which then acts on the hypothalamus to raise the body temperature. -
B. Intrahypothalamic injection of prostaglandin receptor agonists will prevent fever
This is false. Injection of prostaglandin receptor agonists into the hypothalamus actually induces fever rather than preventing it, as prostaglandins mediate the febrile response. -
C. Antipyretic effect of aspirin is exerted on the hypothalamus to prevent prostaglandin synthesis
This is true. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) reduce fever by inhibiting cyclooxygenase (COX) enzymes, thereby decreasing prostaglandin synthesis in the hypothalamus. -
D. Aspirin blocks infections and eventually prevents fever.
This is false. Aspirin does not block infections; instead, it acts symptomatically by reducing fever through inhibiting prostaglandin production.
Correct Combination of Statements
From the above analysis, the correct combination of statements is:
(4) A and CSummary Table: Fever Mechanism and Aspirin Action
Statement Description Correctness A Cytokines act independently and directly on thermoregulatory centres Incorrect B Prostaglandin receptor agonists injected into hypothalamus prevent fever Incorrect C Aspirin inhibits prostaglandin synthesis in hypothalamus to reduce fever Correct D Aspirin blocks infections and prevents fever Incorrect Conclusion
Fever generation involves cytokines prompting prostaglandin release to act on the hypothalamus. Aspirin exerts its antipyretic effect by inhibiting prostaglandin synthesis centrally but does not affect the underlying infection. Hence, only statement C is fully correct, whereas statement A, as provided, is not entirely accurate.
The correct answer to the question is:
(4) A and C -
