title: Endogenous activation of metabotropic glutamate receptors contributes to burst frequency regulation in the lamprey locomotor network.
abstract: The effect of metabotropic glutamate receptor (mGluR) agonists and antagonists on the spinal cord network underlying locomotion in the lamprey has been analysed. The specific group I mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) and the broad-spectrum mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) both increased the burst frequency of N-methyl-D-aspartic acid (NMDA)-induced fictive locomotion and depolarized grey matter neurons. The burst frequency increase induced by the mGluR agonists was counteracted by the mGluR antagonists (+)-alpha-methyl-4-carboxyphenylglycine ((+)-MCPG), cyclopropan[b]chromen-1a-carboxylic acid ethylester (CPCCOEt) and (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA). Application of CPCCOEt alone reduced the locomotor burst frequency, indicating that mGluRs are endogenously activated during fictive locomotion. The mGluR antagonist CPCCOEt had no effect on NMDA-, or (S)-alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA)-induced depolarizations. The mGluR agonists 1S,3R-ACPD and DHPG increased the amplitude of NMDA-induced depolarizations, a mechanism which could account for the increase in burst frequency. The group III mGluR agonist L-2-amino-4-phosphonobutyric acid reduced intraspinal synaptic transmission and burst frequency.
authors.affiliation: The Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Krieger
authors.forename: S
authors.initials: S
authors.lastname: Grillner
authors.forename: A
authors.initials: A
authors.lastname: El Manira
mesh_terms: D000818:Animals; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D007798:Lampreys; D008124:Locomotion / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D010507:Periodicity; D011422:Propionates / Q000494:pharmacology; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D012118:Resorcinols / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: C114785:2-amino-4-phosphono-propinate; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D011422:Propionates; D018094:Receptors, Metabotropic Glutamate; D012118:Resorcinols; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; C079215:3,5-dihydroxyphenylglycine; D016202:N-Methylaspartate; D005998:Glycine