Role of GABA(B) receptor in the regulation of excitatory synaptic transmission in trigeminal motoneurons.
The aim of the present study was to determine if excitatory synaptic transmission onto trigeminal motoneurons is subject to a presynaptic modulation by gamma-aminobutyric acid (GABA) via GABA(B) receptor in this system. Whole cell recordings were made from trigeminal motoneurons in longitudinal brain stem slices taken from 8-day-old rats. Monosynaptic excitatory postsynaptic potential (EPSP) activity was evoked by placing bipolar stainless steel electrodes dorsal-caudal to the trigeminal motor nucleus. Bath application of the GABA(B) receptor agonist, baclofen, produced a marked reduction in the mean amplitude and variance of evoked EPSPs and also increased the portion of transmission failures. It also produced a decrease in the frequency, but not in the mean amplitude, of spontaneous miniature EPSPs. Bath application of GABA(B) receptor antagonists 6-hydroxy-saclofen and CGP35348 increased both the amplitude and frequency of miniature EPSP activity. Taken together the above results suggest that the excitatory synaptic inputs onto trigeminal motoneurons are controlled by tonic presynaptic modulation by GABA(B) receptor.
Min
Ming-Yuan
MY
Department of Physiology, Chinese Medical College, Taichung, Taiwan, ROC. mmy@mail.cmc.edu.tw
Appenteng
Kwabena
K
Yang
Hsui-Wen
HW
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001418:Baclofen / Q000031:analogs & derivatives* / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D018080:Receptors, GABA-B / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D014276:Trigeminal Nerve / Q000166:cytology / Q000378:metabolism*; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; D018080:Receptors, GABA-B; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C056639:2-amino-5-phosphopentanoic acid; D001418:Baclofen; D014633:Valine; C080629:saclofen