[Effects of L-glutamic acid, gamma-aminobutyric acid and their respective antagonists on spontaneous discharge of nucleus paragigantocellularis lateralis neurons in rats].
Using multibarrel microelectrode techniques, we studied the effects of iontophoretic application of L-glutamic acid (L-Glu), gamma-aminobutyric acid (GABA) and their respective antagonists DL-2-amino-5-phosphonovaleric acid (AP5), bicuculline (BIC) on the spontaneous discharge of the caudal half of nucleus paragigantocellularis lateralis (cPGCL) neurons (including respiratory related neurons) and the influences of AP5 and BIC on the effects of L-Glu and GABA respectively in 22 anesthetized spontaneously breathing Sprague-Dawley rats. The spontaneous discharges of all the cPGCL neurons tested were inhibited by GABA(n = 53). Most of the tested neurons were excitated by L-Glu (30/36). AP5 and BIC both showed three kinds of effects on the cPGCL neuronal spontaneous discharge; excitatory, inhibitory and no-effect. The excitatory effects of L-Glu and BIC and the inhibitory effects of GABA showed a dose-response relationship. AP5 could block partially the excitatory effect of L-Glu on a large part of neurons tested (14/19). BIC blocked, partially or completely, the inhibitory effect of GABA also on a large part of the neurons tested(18/24). The results implicate that there might exist endogenous L-Glu and GABA acting as neurotransmitters in the cPGCL area and excitatory amino acids (EAA, including NMDA and non-NMDA) and GABA-receptors on cPGCL neurons. These neurotransmitters and receptors may mediate the regulatory action of cPGCL on respiration and other functional systems.
Li
L
L
Department of Physiology, School of Basic Medical Sciences, Chengdu.
Zheng
Y
Y
Xu
M
M
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology*; D004594:Electrophysiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology*; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D015763:2-Amino-5-phosphonovalerate; D001640:Bicuculline