Dorsal root potential produced by a TTX-insensitive micro-circuitry in the turtle spinal cord.
1, The mechanisms underlying the dorsal root potential (DRP) were studied in transverse slices of turtle spinal cord. DRPs were evoked by stimulating one filament in a dorsal root and were recorded from another such filament. 2. The DRP evoked at supramaximal stimulus intensity was reduced but not eliminated after blockade of GABAA receptors. The remaining component was eliminated by blocking NMDA and AMPA receptors. 3. The DRP was reduced but not eliminated after blockade of AMPA receptors. The early component of the remaining DRP was dependent on GABAA receptors and the residual component on NMDA receptors. 4. The DRP was reduced but not eliminated by TTX. GABAA, NMDA and AMPA receptors contributed to the generation of the TTX-insensitive DRP. The early component of the DRP in the presence of TTX depended on GABAA receptor activation, and the late component mainly on the activation of NMDA receptors. 5. Our results show that part of the DRP is generated by a TTX-resistant, probably non-spiking micro-circuit with separate components mediated by GABA and glutamate.
Russo
R E
RE
Unidad Asociada Neurofisiología, Facultad de Ciencias, Avenida Italia 3318, Montevideo, Uruguay.
Delgado-Lezama
R
R
Hounsgaard
J
J
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D066298:In Vitro Techniques; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011930:Reaction Time / Q000187:drug effects; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013126:Spinal Nerve Roots / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology*; D014426:Turtles
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D013779:Tetrodotoxin; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001640:Bicuculline