Objective To observe changes of discharges of the sciatic nerve branch and mast cell activities and collagen fibers in the acupoint area during manual acupuncture stimulation of "Zusanli"(ST 36)

so as to reveal the relationship between peripheral nerve and mast cell activities.Methods A total of 30 male SD rats were divided into normal

acupuncture control(an acupuncture needle was inserted into ST 36 without manipulation)

manual acupuncture(MA)

disodium cromoglycate(DSCG

suppressing mast cell activity) plus acupuncture(MA+DSCG) and collagenase(dissolving the collagen fibers) plus acupuncture(MA+collagenase) groups(6 rats/group).After dissection of a branch of the sciatic nerve innervating ST 36 region in the left hind-limb under anesthesia

the ipsilateral ST 36 was stimulated by manipulating the acupuncture needle for 20 min.Discharges of the sciatic nerve branch were recorded by using a pair of metal electrodes and data acquisition system(Power Lab).Skin and muscle tissues of ST 36 area were sampled

sliced and stained with Toluidine Blue for detecting the number of degranulated mast cells.Results Compared with the control group

the mean power spectrum of discharges of the sciatic nerve and the mean rates of the degranulated mast cells in "Zusanli"(ST 36) area in the MA group were significantly increased(P<0.01).Whereas the mean power spectrum of discharges of the sciatic nerve and the mean degranulation rates of mast cells were consi-derably lower in the MA +DSCG group and MA+collagenase group than in the MA group(P<0.01).No significant differences were found between the normal and control groups

and between the MA+DSCG and MA+collagenase groups in the mean power density and degranulation rates of mast cells(P>0.05).Conclusion Manual acupuncture stimulation of ST 36 can significantly potentiate the discharge activity of the sciatic nerve and induce degranulation of mast cells at the same time

suggesting an involvement of mast cells in initiating acupuncture signals by peripheral sensory nerve.