Acupuncture stimulation reduces mental sweating via mechanisms that differ with the stimulation frequency

Abstract

We studied the effects of acupuncture stimulation at various frequencies and at various sites on mental sweating, and speculated on the mechanisms involved. Acupuncture stimulation was delivered for 20 min to Zusanli (lower leg) or Hegu (hand) acupoint at frequencies of 5 Hz, 100 Hz or 300 Hz, respectively. Sweating was induced by mental arithmetic or pain stimulation, and the rate of sweating in response to such mental stress was measured continuously on the palms and/or soles. Sudomotor mechanisms were analyzed using measurements of the sweat expulsion rate. Acupuncture stimulation reduced sweating on the palms and soles induced by mental stress. Sweat reduction occurred only during stimulation when a unilateral acupoint was stimulated, while reduction persisted for 15 min during the recovery as well as during stimulation when bilateral acupoints were stimulated. Sweat reduction was usually bilateral. As a general rule, sweating was reduced on both palms and soles when stimulated at 5 Hz at an acupoint on the hand or leg, while it was not reduced or was reduced on either the palms or soles when stimulated at 100Hz or 300Hz. It was assumed that stimulation at 5Hz affects mainly the supraspinal mechanisms, while that at 100Hz or 300Hz affects the spinal mechanisms. Thus, acupuncture stimulation affects supraspinal and/or spinal mechanisms to reduce mental sweating. [Jpn J Physiol 55 Suppl:S190 (2005)]