title: Strychnine- and bicuculline-induced changes in the firing pattern of motoneurones during in vitro fictive locomotion reveal a possible N-methyl-D-aspartic acid (NMDA)-mediated suppression of motor discharge in wallaby (Macropus eugenii) pouch young.
abstract: Inhibitory pathways in the spinal cord play an important role in establishing the pattern of motor discharge. In the wallaby spinal cord preparation, disruption of glycinergic and gamma-amino butyric acid (GABA)ergic neurotransmission abolished the alternation between antagonistic motor pools during fictive locomotion. A new pattern of motor discharge also appeared when both glycine and GABA(A) receptors were blocked simultaneously. This discharge pattern was biphasic, characterized by a distinct pause between two bursts of motoneurone firing during each cycle of motor activity. Whole cell patch recordings showed that the second burst of motor discharge was not caused by a separate inward current at a delayed time course. Furthermore, local injection of an N-methyl-D-aspartic acid (NMDA) specific antagonist converted the biphasic discharge to a continuous burst pattern. The result suggests an NMDA-mediated mechanism, which causes a suppression of motoneurone firing when glutamate release from interneurones is enhanced in the absence of glycinergic and GABAergic inhibition.
authors.affiliation: Developmental Neurobiology, Research School of Biological Sciences, Australian National University, Canberra.
authors.forename: S M
authors.initials: SM
authors.lastname: Ho
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D003864:Depression, Chemical; D018756:GABA Antagonists / Q000494:pharmacology*; D018684:Glycine Agents / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects*; D007614:Macropodidae / Q000502:physiology*; D009046:Motor Neurons / Q000187:drug effects*; D016202:N-Methylaspartate / Q000502:physiology*; D018408:Patch-Clamp Techniques; D013331:Strychnine / Q000494:pharmacology
chemical_list: D018756:GABA Antagonists; D018684:Glycine Agents; D016202:N-Methylaspartate; D013331:Strychnine; D001640:Bicuculline