title: 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.
abstract: 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.
authors.affiliation: Institute of Acupuncture, China Academy of Traditional Chinese Medicine, 16 Nanxiaojie of Dongzhimen, Beijing 100700, China. zhubing@mail.cintcm.ac.cn
authors.forename: Bing
authors.initials: B
authors.lastname: Zhu
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Xu
authors.forename: Pei-Jing
authors.initials: PJ
authors.lastname: Rong
authors.forename: Hui
authors.initials: H
authors.lastname: Ben
authors.forename: Xin-Yan
authors.initials: XY
authors.lastname: Gao
mesh_terms: 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
chemical_list: D002211:Capsaicin