Journal of Neuroscience, Vol 15, 4068-4076, Copyright © 1995 by Society for Neuroscience
Effects of excitatory amino acid antagonists on the phasic depolarizing events that occur in lumbar motoneurons during REM periods of active sleep
PJ Soja, F Lopez-Rodriguez, FR Morales and MH Chase
Department of Physiology, UCLA School of Medicine 90024, USA.
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.