Enkephalin blocks primary afferent depolarization of A delta tooth pulp afferents evoked by stimulation in nucleus raphe magnus in the decerebrate cat.
Electrical stimulation in nucleus raphe magnus (NRM) in decerebrate cats produced an increase in the excitability of tooth pulp afferent terminals in trigeminal nucleus oralis and caudalis. Iontophoretic application of Met5-enkephalin near the terminal region did not affect resting terminal excitability but reduced the effectiveness of NRM stimulation to increase terminal excitability. This effect of enkephalin was blocked by naloxone. It is concluded that enkephalin may have reduced the primary afferent depolarization (PAD) evoked from NRM by inhibiting GABA-containing neurones which mediate PAD in the spinal trigeminal nucleus.
D000344:Afferent Pathways / Q000187:drug effects; D000818:Animals; D001933:Brain Stem / Q000187:drug effects*; D002415:Cats; D003655:Decerebrate State; D003782:Dental Pulp / Q000294:innervation*; D004558:Electric Stimulation; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects; D011903:Raphe Nuclei / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D014279:Trigeminal Nucleus, Spinal / Q000187:drug effects
D009270:Naloxone; D004744:Enkephalin, Methionine