Electroacupuncture at stomach thirty-six uniquely improved arthritis-related pain and restored systemic metabolic balance, unlike stimulation at spleen six.
Rats with inflammatory knee arthritis induced by complete Freund's adjuvant received no electroacupuncture or electroacupuncture at either spleen six or stomach thirty-six. Researchers assessed hindlimb weight-bearing as a measure of pain-related behaviour, examined synovial inflammation, and analysed serum metabolites using targeted gas chromatography–mass spectrometry. They also injected two-hydroxybutyric acid into the joint to test whether this metabolite directly influenced pain.
Both stimulation sites reduced inflammation in the joint lining, but only stomach thirty-six clearly improved weight-bearing. Arthritis altered multiple circulating metabolites, with two-hydroxybutyric acid showing the most prominent change; stimulation at stomach thirty-six selectively restored it toward normal levels. Because joint injection of this metabolite did not change pain behaviour, it appears to reflect systemic inflammatory and metabolic stress rather than directly causing pain.
