The effect of hypophysectomy on acupuncture analgesia in the mouse

Acupuncture analgesia was quantitated in the phenylquinone induced writhing test in mice. Both manual acupuncture and electroacupuncture significantly reduced the number of writhes, i.e. 47% and 51% reduction respectively. Naloxone (2 mg/kg) pretreatment abolished this antinocicpetive effect suggesting that an endogenous opiate-like substance was involved. Hypophysectomy did not alter the electroacupuncture induced inhibition of writhing. These results confirm previous reports that acupuncture causes the release of an endogenous substance(s) with opioid activity, but disagree with previous reports in that our data show that the hypophysis is not involved in the release of this endogenous opiate or in any other mechanism of acupuncture analgesia in the mouse.