Electrical stimulation at hand and leg acupuncture points reduced cervical distension pain in rats by suppressing spinal immune-cell activation.
Researchers induced acute cervical distension in rats and measured abdominal muscle electrical activity as an indicator of pain over time. They examined spinal cord tissue for activated microglia, compared untreated and sham-treated animals, administered a microglial inhibitor through a spinal catheter, and tested electrical stimulation at Hegu and Sanyinjiao acupuncture points. Spinal tissue from lower thoracic and upper lumbar segments was analysed using immunohistochemical staining for a microglial marker.
Cervical distension increased pain-related muscle activity and activated microglia in spinal regions associated with pelvic sensory input. Blocking microglial activation reduced the pain response, supporting a causal role for these immune cells in acute visceral pain. Electrical acupuncture similarly reduced pain-related activity and microglial activation, suggesting that its analgesic effect may operate through suppression of spinal microglial activation.
