Which substances modulate the inhibition of pain signals?

Which substances modulate the inhibition of pain signals?

• A. Serotonin, Norepinephrine, and Endogenous Opioids
• B. Dopamine
• C. Acetylcholine
• D. GABA

Answer: (A)

Pain signals are shaped by descending inhibitory pathways in the brain and spinal cord that dampen nociceptive transmission before it reaches higher centers. Serotonin and norepinephrine released from brainstem centers act in the spinal cord to reduce the excitability of dorsal horn neurons and to curb the release of excitatory transmitters like glutamate and Substance P. Endogenous opioids (endorphins, enkephalins) bind to opioid receptors to further suppress nociceptive transmission and enhance this inhibitory control. Together, these substances modulate the inhibition of pain signals, making serotonin, norepinephrine, and endogenous opioids the best answer. Dopamine, acetylcholine, and GABA play roles in various CNS circuits, but the classic modulators of descending pain inhibition are the monoamines and endogenous opioids.

Pain signals are shaped by descending inhibitory pathways in the brain and spinal cord that dampen nociceptive transmission before it reaches higher centers. Serotonin and norepinephrine released from brainstem centers act in the spinal cord to reduce the excitability of dorsal horn neurons and to curb the release of excitatory transmitters like glutamate and Substance P. Endogenous opioids (endorphins, enkephalins) bind to opioid receptors to further suppress nociceptive transmission and enhance this inhibitory control. Together, these substances modulate the inhibition of pain signals, making serotonin, norepinephrine, and endogenous opioids the best answer. Dopamine, acetylcholine, and GABA play roles in various CNS circuits, but the classic modulators of descending pain inhibition are the monoamines and endogenous opioids.