title: Postsynaptic origin of N-methyl-D-aspartate-induced slow currents in substantia gelatinosa neurons: an in vitro voltage-clamp study in adult rat.
abstract: We investigated whether N-methyl-D-aspartate (NMDA)-induced slow current in substantia gelatinosa (SG) neurons might be of presynaptic or postsynaptic origin. Whole-cell voltage-clamp recordings were made from adult rat spinal cord slices to examine the effect of NMDA receptor upon miniature excitatory postsynaptic currents (mEPSCs) in SG neurons. At a holding potential of -70 mV, bath application of NMDA (10 microM, 30s), an NMDA receptor agonist, affected neither the frequency nor the mean amplitude of mEPSCs, while NMDA induced a slow excitatory membrane current which persisted in the presence of tetrodotoxin. On the other hand, AP-5 (an NMDA receptor antagonist) had no noticeable effects on mEPSCs in the SG neurons tested, while it markedly depressed the NMDA-induced slow currents. The NMDA-induced slow currents varied with the changing of holding potentials (from -70 to 0 mV). The results suggested that the NMDA-induced slow currents in SG neurons were of postsynaptic origin.
authors.affiliation: Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, 710032, People's Republic of, Xi'an, China.
authors.forename: K
authors.initials: K
authors.lastname: Yang
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Li
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D008297:Male; D016202:N-Methylaspartate / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D013376:Substantia Gelatinosa / Q000166:cytology / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate