Prostaglandin Pain Sensitisation — MFDS Part 1 MCQ

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ModeratePhysiologyProstaglandin Pain SensitisationMFDS Part 1

During acute inflammation, which eicosanoid sensitises peripheral nociceptors by acting at EP receptors, activating protein-kinase signalling and increasing the activity of TRPV1 and voltage-gated sodium channels?

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Correct answer: E — Prostaglandin E2 (PGE2)

Prostaglandin E2 is the mediator described. PGE2 binds EP receptors on peripheral nociceptors and activates intracellular protein-kinase pathways. These pathways enhance the activity of channels including TRPV1 and voltage-gated sodium channels, lowering the nociceptor activation threshold and producing peripheral sensitisation and hyperalgesia. Prostacyclin is the strongest distractor because it can also contribute to inflammatory pain, but it acts through IP rather than EP receptors. Thromboxane A2 is principally associated with platelet activation and vasoconstriction, while leukotriene B4 is predominantly a neutrophil chemoattractant. Prostaglandin F2α is better known for effects on smooth muscle and is not the EP-receptor-mediated sensitising mediator described.

Reference: Chen O, Luo X, Ji RR. Macrophages and microglia in inflammation and neuroinflammation underlying different pain states. Figure 3 text on PGE2-mediated peripheral sensitisation. 2023. https://pubmed.ncbi.nlm.nih.gov/9612089/