Exogenous glutamate induces short and long-term potentiation in the rat medial vestibular nuclei.
In rat brain stem slices, high concentrations of exogenous glutamate induce long-term potentiation (LTP) of the field potentials evoked in the medial vestibular nuclei (MVN) by vestibular afferent stimulation. At low concentrations, glutamate can also induce short-term potentiation (STP), indicating that LTP and STP are separate events depending on the level of glutamatergic synapse activation. LTP and STP are prevented by blocking NMDA receptors and nitric oxide (NO) synthesis. Conversely, blocking platelet-activating factor (PAF) and group I metabotropic glutamate receptors only prevents the full development of LTP. Moreover, in the presence of blocking agents, glutamate causes transient inhibition, suggesting that when potentiation is impeded, exogenous glutamate can activate presynaptic mechanisms that reduce glutamate release.
Grassi
S
S
Department of Internal Medicine, Section of Human Physiology, University of Perugia, Via del Giochetto, I-06100 Perugia, Italy.
Frondaroli
A
A
Pessia
M
M
Pettorossi
V E
VE
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D004224:Diterpenes; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D046934:Ginkgolides; D018698:Glutamic Acid / Q000494:pharmacology*; D007189:Indans / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D014726:Vestibular Nuclei / Q000502:physiology*
C095756:1-aminoindan-1,5-dicarboxylic acid; D004224:Diterpenes; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D016166:Free Radical Scavengers; D046934:Ginkgolides; D007189:Indans; D007783:Lactones; D018698:Glutamic Acid; D015763:2-Amino-5-phosphonovalerate; C045856:ginkgolide B; D019331:NG-Nitroarginine Methyl Ester