title: Role of GABA(B) receptor in the regulation of excitatory synaptic transmission in trigeminal motoneurons.
abstract: 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.
authors.affiliation: Department of Physiology, Chinese Medical College, Taichung, Taiwan, ROC. mmy@mail.cmc.edu.tw
authors.forename: Ming-Yuan
authors.initials: MY
authors.lastname: Min
authors.forename: Kwabena
authors.initials: K
authors.lastname: Appenteng
authors.forename: Hsui-Wen
authors.initials: HW
authors.lastname: Yang
mesh_terms: 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
chemical_list: 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