Peripheral nerve opioid receptors are located on which cells?

Peripheral nerve opioid receptors are located on which cells?

• A. Motor neurons and Schwann cells
• B. Sensory neurons and immune cells
• C. Oligodendrocytes and astrocytes
• D. Endothelial cells and smooth muscle

Answer: (B)

Opioid receptors in the peripheral nervous system are found on the nerves that carry sensory information as well as on immune cells near the nerve. When these receptors on sensory neurons are activated, they reduce the release of neurotransmitters (like substance P and CGRP) and dampen excitability, which lowers nociceptive signaling and provides peripheral analgesia. Receptors on immune cells can modulate inflammatory responses, linking immune activity to pain control. This combination—sensory neurons and immune cells—best fits the peripheral location of opioid receptors. Motor neurons and Schwann cells, CNS glial cells like oligodendrocytes and astrocytes, or endothelial/smooth muscle cells aren’t the primary peripheral sites where these receptors mediate the common analgesic effects.

Opioid receptors in the peripheral nervous system are found on the nerves that carry sensory information as well as on immune cells near the nerve. When these receptors on sensory neurons are activated, they reduce the release of neurotransmitters (like substance P and CGRP) and dampen excitability, which lowers nociceptive signaling and provides peripheral analgesia. Receptors on immune cells can modulate inflammatory responses, linking immune activity to pain control. This combination—sensory neurons and immune cells—best fits the peripheral location of opioid receptors.

Motor neurons and Schwann cells, CNS glial cells like oligodendrocytes and astrocytes, or endothelial/smooth muscle cells aren’t the primary peripheral sites where these receptors mediate the common analgesic effects.