Author/Editor		Gerber, G; Černe, R; Randić, M
Title		Participation of excitatory amino acid receptors in the slow excitatory synaptic transmission in rat spinal dorsal horn
Type		članek
Source		Brain Res
Vol. and No.		Letnik 561, št. 2
Publication year		1991
Volume		str. 236-51
Language		eng
Abstract		In a rat spinal slice preparation the participation of excitatory amino acid (EAA) receptors in the responses of deep dorsal horn neurons to repetitive stimulation of lumbar dorsal roots was investigated using 3 EAA receptor antagonists, kynurenic acid, D-(-)-2-amino-4-phosphonovaleric acid (D-APV) and 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX) and current-clamp and voltage-clamp techniques. We found that the slow excitatory synaptic response evoked by 10-20 Hz electrical stimulation of primary afferent fibers consisted of two depolarizing components: an initial component lasting 1-5 s and a late one of 1-3 min duration. The initial and late components of the slow excitatory synaptic response can also be distinguished on the basis of their voltage-dependence and sensitivity to Mg2+ ions, kynurenate, D-APV and CNQX. In the presence of Mg2+, the initial component of the slow excitatory synaptic response increased with membrane hyperpolarization, whereas the late component decreased in most of the cells examined. In a zero-Mg2+ medium, the initial component was potentiated, but the late component was reduced. In both transverse and longitudinal spinal cord slices perfused with 1.2 mM Mg(2+)-containing medium, bath application of kynurenic acid (0.1-0.5 mM), D-APV (0.05-0.1 mM) and CNQX (5-7 microM) caused a reversible reduction of the peak amplitude of the initial slow depolarizing component that was greater in transverse (kynurenic acid: by 92.6 +/- 5.0 percent ; D-APV: by 69.1 +/- 7.8 percent ; CNQX: by 76.6 +/- 9.8 percent) than in longitudinal slices (kynurenic acid: by 53.3 +/- 1.3 percent ; D-APV: by 31.5 +/- 9.1 percent ; CNQX: by 35.3 +/- 11.1 percent). In contrast, all 3 antagonists of EAA receptors produced no consistent change in the peak amplitude or half-duration of the late depolarizing component of the slow excitatory synaptic response.(trunc.)
Descriptors		AMINO ACIDS NEUROTRANSMITTERS RECEPTORS, NEUROTRANSMITTER SPINAL CORD SYNAPSES SYNAPTIC TRANSMISSION SYNAPTIC TRANSMISSION AMINO-5-PHOSPHONOVALERATE ELECTRIC STIMULATION EVOKED POTENTIALS KYNURENIC ACID MAGNESIUM N-METHYLASPARTATE QUINOXALINES RATS RATS, INBRED STRAINS RECEPTORS, NEUROTRANSMITTER SPINAL CORD SYNAPSES