Studies on the enhanced effect of acupuncture analgesia and acupuncture anesthesia by D-phenylalanine (first report)--effect on pain threshold and inhibition by naloxone.
Kitade T, Odahara Y, Shinohara S, Ikeuchi T, Sakai T, Morikawa K, Minamikawa M, Toyota S, Kawachi A, Hyodo M. Acupunct Electrother Res. 1988; 13(2-3):87-97.