Effects of Thalamic Sensory Relay Nucleus Stimulation on Trigeminal Subnucleus Caudalis Neurons in the Cat —Nociceptive Activity in Response to Tooth Pulp Stimulation—

Abstract

We investigated the effects of electrical stimulation of the thalamic sensory relay nucleus (TSRN) on the nociceptive neural activity within the trigeminal subnucleus caudalis in the cat. We found that the nociceptive activity of the trigeminal subnucleus caudalis neurons in response to tooth pulp or facial skin stimulation was inhibited by both single-pulse and repetitive TSRN stimulation. However, the period of inhibition induced by single-pulse TSRN stimulation was clearly shorter than that induced by periaqueductal gray (PAG) or nucleus raphe magnus (NRM) stimulation. Furthermore, the nociceptive neurons inhibited by PAG stimulation were not always inhibited by TSRN stimulation. The opioid antagonist naloxone (2.0 mg/kg, i.v.) significantly antagonized the inhibition induced by PAG or NRM stimulation but failed to antagonize that produced by TSRN stimulation. These results are discussed in relation to the differences in clinical effects produced by TSRN and PAG stimulation. © 1987, The Japan Neurosurgical Society. All rights reserved.