Effect of sensory stimulation (acupuncture) on sympathetic and parasympathetic activities in healthy subjects

It has been postulated that sensory stimulation (acupuncture) affects the c ardiovascular system via the autonomic nervous system. previously, skin tem perature, thermography, plethysmography and blood pressure changes have bee n used in evaluation of sympathetic nerve activity following acupuncture. B y using power spectral analysis, the low frequency and high frequency compo nents of heart rate variability can be calculated reflecting the sympatheti c and parasympathetic activity. The purpose of this study was to investigat e to what extent acupuncture applied into the thenar muscle and into the ca vum concha of the ear induced changes in the sympathetic and/or parasympath etic nervous system in healthy subjects. Materials and Methods. Twelve heal thy volunteers, six men and six women, mean age 34.4 (range 23-48) particip ated in three balanced, randomly distributed sessions. Pit an individual in itial visit the 12 volunteers were introduced to the needle sensation by ha ving a needle inserted into the point LI 11. The needle sensation was evoke d and the subject was trained to identify the characteristic needle sensati on The introduction was followed by three test sessions. Session A. A short acupuncture needle, (Seirin no 3, empty set 0.20x15 mm) was inserted perpe ndicular into the earpoint, Lu 1, in the left inferior hemi-conchae. Sessio n B. An acupuncture needle (Hwato, empty set 0.30x30 mm) was inserted perpe ndicular into the Hegu point (LI 4) in the middle of the right dorsal thena r muscle. Session C. An acupuncture needle (Hwato, empty set 0.30x30 mm) wa s inserted perpendicular superficially into the skin overlying the Hegu poi nt on the left hand. Results. Stimulation of the ear induced a significant increase in the parasympathetic activity during the stimulation period of 2 5 min (P<0.05) and during the post-stimulation period of 60 min (P<0.05). N o significant changes were observed in either the sympathetic activity, blo od pressure or heart rate. Stimulation of the thenar muscle resulted in a s ignificant increase in the sympathetic and the parasympathetic activity dur ing the stimulation period (P<0.01) and during the post-stimulation period (P<0.01 and P<0.001, respectively). A significant decrease in the heart rat e frequency (P<0.05) at the end of the post-stimulation period was also dem onstrated. The superficial needle insertion into the skin overlaying the ri ght thenar muscle caused a pronounced balanced increase in both the sympath etic and parasympathetic activity during the post stimulation period of 60 min (P<0.01) while no changes were observed during the stimulation period. Conclusion. It is indicated that sensory stimulation (acupunctura) in healt hy persons is associated with changed activity in the sympathetic and paras ympathetic nervous system depending on site of stimulation and period of ob servation. (C) 2000 Elsevier Science B.V. All rights reserved.