Repetitive afferent stimulation propagates excitation in the trigeminal caudalis.
A high-speed optical imaging technique was employed for visualizing neuronal excitation propagation elicited by afferent stimulation in the mouse trigeminal caudalis (Vc) to clarify the central nociceptive modulation mechanism. Membrane depolarization evoked by a single-pulse stimulation to the spinal trigeminal tract (Tr) was propagated rostrally to the Vc, which was suppressed by CNQX. This is consistent with our morphological observation that axons expand from the Tr into the Vc. A trained-pulse (tetanus) stimulation to the Tr evoked a broad, persistent excitation in the Vc, while MK-801 suppressed it. Neonatally capsaicin-treated mice maintained a single-pulse response but a lacked tetanus-evoked one. These indicated that prolonged depolarization elicited by repetitive stimulation is a prerequisite to C-fiber excitation for activating the NMDA receptors.
Seo
Kenji
K
Division of Dental Anesthesiology, Department of Tissue Regeneration and Reconstruction, Niigata University School of Health Sciences, 2-746, Asahimachi, Niigata, 951-9518, Japan. seo@dent.niigata-u.ac.jp
Fujiwara
Naoshi
N
Takeuchi
Kiichi
K
Maeda
Takeyasu
T
Someya
Genji
G
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000344:Afferent Pathways / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014275:Trigeminal Caudal Nucleus / Q000187:drug effects / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D016291:Dizocilpine Maleate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D002211:Capsaicin