Iteration of high-frequency stimulation enhances long-lasting excitatory responses in the spinal dorsal horn of rats: characterization by optical imaging of signal propagation.
To investigate plastic changes in nociceptive sensitivity of the dorsal horn, slow excitatory responses elicited by iteration of high-frequency stimulation were spatiotemporally observed in spinal cord slices of young-adult rats using membrane excitation imaging techniques. Single-pulse stimulation to the dorsal root elicited membrane excitation in lamina II, and high-frequency pulse-train stimulation evoked long-lasting excitation that expanded widely in the dorsal horn. Iteration of high-frequency stimulation enhanced the strength and extent of the excitatory responses, but such augmentation of the excitatory responses disappeared in the presence of an NMDA receptor antagonist (CPP) and was hindered by an NK1 receptor antagonist (L-703.606). The results suggest that activation of both NMDA and NK1 receptors is involved in the enhancement of slow excitatory responses evoked by iteration of high-frequency stimulation.
Ogawa
Mayumi
M
Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Niigata, Japan.
Takamatsu
Misako
M
Okamoto
Manabu
M
Baba
Hiroshi
H
Seo
Kenji
K
Fujiwara
Naoshi
N
D000200:Action Potentials / Q000502:physiology*; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D064729:Neurokinin-1 Receptor Antagonists; D009619:Nociceptors / Q000502:physiology*; D055095:Optics and Photonics / Q000295:instrumentation; D009924:Organ Culture Techniques; D020671:Posterior Horn Cells / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000378:metabolism; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D013126:Spinal Nerve Roots / Q000502:physiology; D013373:Substance P / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D064729:Neurokinin-1 Receptor Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D018040:Receptors, Neurokinin-1; D013373:Substance P; D018698:Glutamic Acid