Which of the following is a mediator released by damaged cells that enhances nociceptor signaling?

Which of the following is a mediator released by damaged cells that enhances nociceptor signaling?

• A. Substance P
• B. Insulin
• C. Glucose
• D. Hemoglobin

Answer: (A)

When tissue is damaged, cells release mediators that boost the sensitivity of nociceptors. Substance P is a neuropeptide released from sensory nerve endings during injury; it enhances nociceptor signaling by increasing neuronal excitability and promoting neurogenic inflammation (vasodilation, plasma extravasation) via NK1 receptors, which amplifies pain transmission. The other substances listed don’t act as mediators that amplify nociceptor signaling in damaged tissue—insulin regulates glucose uptake, glucose is an energy substrate, and hemoglobin carries oxygen. So Substance P best fits as the mediator that enhances nociceptor signaling.

When tissue is damaged, cells release mediators that boost the sensitivity of nociceptors. Substance P is a neuropeptide released from sensory nerve endings during injury; it enhances nociceptor signaling by increasing neuronal excitability and promoting neurogenic inflammation (vasodilation, plasma extravasation) via NK1 receptors, which amplifies pain transmission. The other substances listed don’t act as mediators that amplify nociceptor signaling in damaged tissue—insulin regulates glucose uptake, glucose is an energy substrate, and hemoglobin carries oxygen. So Substance P best fits as the mediator that enhances nociceptor signaling.