Activation of group I metabotropic glutamate receptors depresses recurrent inhibition of motoneurons in the neonatal rat spinal cord in vitro.
This study examined whether activation of group I metabotropic glutamate receptors (mGluRs) could modulate synaptic inhibition of spinal motoneurons in the neonatal rat isolated spinal cord. Recurrent inhibitory postsynaptic potentials (IPSPs) generated by Renshaw cells were evoked via antidromic stimulation of motor axon collaterals and recorded intracellularly from lumbar motoneurons. The selective agonist of group I mGluRs DHPG (5 micromol L-1) depressed the recurrent IPSP, an effect prevented by the selective antagonist AIDA (500 micromol L-1). The depression by DHPG was use-independent and could be partly counteracted by increasing stimulus strength. Paired pulse depression observed at <or=50-ms intervals was blocked by DHPG in an AIDA-sensitive manner. These results suggest that, in the presence of DHPG, smaller recurrent IPSPs can contribute to the excitatory action of mGluR activation on spinal networks, including the generation of synchronous oscillations recorded from motoneurons.
Neurobiology Sector and Istituto Nazionale di Fisica della Materia Unit, International School for Advanced Studies (SISSA), Via Beirut 4, 34014, Trieste, Italy.
Cristina
C
Marchetti
Giuliano
G
Taccola
Andrea
A
Nistri
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D003998:Dicarboxylic Acids / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000494:pharmacology; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D003998:Dicarboxylic Acids; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D011725:Pyridines; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; C017302:alpha-ethylglutamic acid; D008734:Methoxyhydroxyphenylglycol; C121465:6-methyl-2-(phenylethynyl)pyridine; C010117:3,4-dihydroxyphenylglycol