Role Of SP,CGRP,NO In Tooth Nociception And TENS Analgesia

Pain not only is a common symptom of illnesses which occur in the hard tissue of the tooth and the pulp, but is a fearful symptom for the patients when they accept the operating procedures on the tooth and pulp with vital tooth. Therefore, it is impor-tante to investigate the mechanism of toothache and to find out the effective analgesic method. Substance P(SP),calcitonin gene - related peptide(CGRP) and nitric oxide (NO) may be involved in the transmission of pulpalgia and facial inflammatory pain. However, during the mechanical noxious stimulation to the face and the teeth, and transcutaneous electrical nerve stimulation (TENS) to the face, the role of the three substances is still unclear.To observe the effect of pulpal inflammatory and mechanical noxious stimulation and facial TENS on release of SP and CGRP from the trigeminal primary sensory neurons, and exame the distribution of the excited neurons in the spinal trigeminal subnucleus caudalis( Vc) following these stimulation, we analyzed the pathway which the information transmission induced by differently noxious stimulation and facial TENS (a non — noxious stimulation), and discussed the role of SP,CGRPand NO in the transmission and modulation of pain.The present results showed that SP immunoreactivity (SP— IR) and CGRP immunoreactivity (CGRP— IR) decreased in Vc — Ⅰ, Ⅱ layers after 1 hour following the noxious stimulation and the facial TENS (5min). It is found in dot hybridization that the expression of preprotachykinin A (PPTA) mRNA and CGRP mRNA showed an increase following the noxious stimulation. It suggested the noxious stimulation promote the synthesis of SP and CGRP. The three kinds of stimulation evoked in-...