A C-fiber reflex inhibition induced by electroacupuncture with different intensities applied at homotopic and heterotopic acupoints in rats selectively destructive effects on myelinated and unmyelinated afferent fibers.
The aims of this study were to explore the C-fiber reflex inhibition induced by electroacupuncture with different intensities applied at homotopic or heterotopic acupoints, and to determine the influence selectively destroyed myelinated and unmyelinated afferent fibers on the C-fiber reflex inhibition. In the ipsilateral local acupoint, the general behavior of the C-fiber reflex can be depressed by electroacupuncture below the threshold of Adelta-fiber activation. Electroacupuncture stimulation within the intensity of Adelta-fiber activation applied to the ipsilateral limb pretreated with cobra venom did not elicit inhibition of C-fiber reflex in rats with demyelinated sciatic nerve. However, heterotopic electroacupuncture below the threshold of Adelta-fiber activation was totally ineffective. In contralateral heterotopic acupoints, the C-fiber reflex can be depressed only by electroacupuncture with stimulating intensities exceeding thresholds of Adelta and C-fiber activation. Electroacupuncture stimuli applied to capsaicin-pretreated limb in the intensities of threshold of Adelta-fiber and treble thresholds of C-fiber activation produced only a little inhibition of C-fiber reflex. Inhibitory intensity was roughly similar to that induced by the stimulation with intensity for the activation of Adelta-fiber in normal animal. In the spinalized animals transections at T6-T7 segments, regardless of intensities, the homotopic electroacupuncture stimulation only induced moderate depression of C-fiber reflex similar to that of Adelta-fiber activation; whereas, no matter what intensities of application, the inhibitory effects of C-fiber reflex disappeared totally by using heterotopic noxious electroacupuncture in these animals.
Zhu
Bing
B
Institute of Acupuncture, China Academy of Traditional Chinese Medicine, 16 Nanxiaojie of Dongzhimen, Beijing 100700, China. zhubing@mail.cintcm.ac.cn
Xu
Wei-Dong
WD
Rong
Pei-Jing
PJ
Ben
Hui
H
Gao
Xin-Yan
XY
D015669:Acupuncture Points; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D015671:Electroacupuncture / Q000379:methods; D004576:Electromyography; D007839:Functional Laterality / Q000502:physiology; D006614:Hindlimb / Q000294:innervation / Q000502:physiology; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology*; D012584:Sciatic Nerve / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000503:physiopathology; D013497:Sural Nerve / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors
D002211:Capsaicin