Analgesia induced by manual acupuncture: its potency and implication.

In urethan-anesthetized rats, unitary discharges of wide dynamic range (WDR) neurons were extracellularly recorded from the lumber cord. Repetitive electrical shocks were delivered through needle electrodes in the receptive field with sufficient strength to activate C fibers. The number of evoked discharges was compared before and after application of manual acupuncture to the LI 4 Hegu [symbol: see text] or ST 36 Zusanli [symbol: see text] for 30 seconds. The effects of acupuncture were followed up to 5 minutes after removal of the acupuncture needle. Two different analgesic effects were observed: acupuncture to the LI 4 Hegu resulted in long-lasting inhibition following insertion of the needles and stimulation of the ST36 Zusanli produced short-term and long-lasting inhibition similar to that seen in acupuncture to the LI 4 Hegu.