Effects of excitatory amino acid antagonists on the phasic depolarizing events that occur in lumbar motoneurons during REM periods of active sleep.
The membrane potential of lumbar motoneurons is dominated during the tonic periods of active sleep by glycine-mediated inhibitory postsynaptic potentials (IPSPs). During the phasic rapid eye movement (REM) periods of active sleep there are also IPSPs but, in addition, the membrane potential exhibits depolarizing shifts and action potentials that occur in conjunction with the phasic activation of the somatic musculature. The present study was designed to provide evidence that an excitatory amino acid (EAA) neurotransmitter is responsible for these patterns of motoneuronal activation. It was found that juxtacellular microiontophoretic applications of kynurenic acid a non-NMDA antagonist of EAA neurotransmission, blocked the depolarizing potentials of motoneurons that arise during the REM periods of active sleep. In contrast, the selective NMDA receptor antagonist APV did not block these depolarizations. The conclusion is drawn that the myoclonic twitches and jerks that characterize that REM periods of active sleep are dependent upon the excitation of motoneurons that occurs as a result of EAAs acting at non-NMDA receptors.
Soja
P J
PJ
Department of Physiology, UCLA School of Medicine 90024, USA.
López-Rodríguez
F
F
Morales
F R
FR
Chase
M H
MH
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002415:Cats; D004585:Electrooculography / Q000187:drug effects; D005071:Evoked Potentials / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D007736:Kynurenic Acid / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000502:physiology*; D016202:N-Methylaspartate / Q000494:pharmacology; D012584:Sciatic Nerve / Q000502:physiology*; D012895:Sleep, REM; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
D018691:Excitatory Amino Acid Antagonists; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D007736:Kynurenic Acid