Nitric oxide/cGMP pathway mediates orofacial antinociception induced by electroacupuncture at the St36 acupoint.
The aim of the present study was to test the hypothesis that electroacupuncture (EA) at acupoint St36 induces antinociception by activation of the L-arg/NO/cGMP pathway. Nociception was produced by thermal stimuli applied to the face of Wistar rats and latency was measured by face withdrawal. Electric stimulation of acupoint St36 for 20 min induced antinociception in this model, which was maintained for 150 min. For comparison, a so-called dry needle group (DN) was used, which received needling at the same point without stimulation. The antinociception obtained by stimulation of acupoint St36 was only achieved when high frequency (100 Hz) was used, whereas low frequencies (5 and 30 Hz) were not capable of achieving this effect. Subcutaneous administration of both inhibitors of NO synthase (N-nitro-L-arginine) and guanylyl cyclase (ODQ) and intraperitoneal administration of specific antagonists of neuronal NO synthase (L-NNA) and inductible NO synthase (aminoguanidine) antagonized the antinociception induced by St36 stimulation. The results of this paper suggest that stimulation of acupoint St36 at high frequency induces antinociception, which seems to be related to L-arg/NO/cGMP pathway activation.
Department of Pharmacology, Institute of Biological Sciences, UFMG, Av. Antônio Carlos, 6627, Belo Horizonte, Brazil.
Renato Teixeira
RT
Almeida
Igor Dimitri Gama
ID
Duarte
D015669:Acupuncture Points; D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D015671:Electroacupuncture / Q000379:methods*; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005157:Facial Pain / Q000378:metabolism* / Q000503:physiopathology / Q000628:therapy*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006358:Hot Temperature / Q000009:adverse effects; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D009619:Nociceptors / Q000378:metabolism* / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D006162:Guanylate Cyclase; D006152:Cyclic GMP