title: Developmental shift from long-term depression to long-term potentiation in the rat medial vestibular nuclei: role of group I metabotropic glutamate receptors.
abstract: The effects of high frequency stimulation (HFS) of the primary vestibular afferents on synaptic transmission in the ventral part of the medial vestibular nuclei (vMVN) were studied during postnatal development and compared with the changes in the expression of the group I metabotropic glutamate receptor (mGluR) subtypes, mGluR1 and mGluR5. During the first stages of development, HFS always induced a mGluR5- and GABAA-dependent long-term depression (LTD) which did not require NMDA receptor and mGluR1 activation. The probability of inducing LTD decreased progressively throughout the development and it was zero at about the end of the second postnatal week. Conversely, long-term potentiation (LTP) appeared at the beginning of the second week and its occurrence increased to reach the adult value at the end of the third week. Of interest, the sudden change in the LTP frequency occurred at the time of eye opening, about the end of the second postnatal week. LTP depended on NMDA receptor and mGluR1 activation. In parallel with the modifications in synaptic plasticity, we observed that the expression patterns and localizations of mGluR5 and mGluR1 in the medial vestibular nuclei (MVN) changed during postnatal development. At the earlier stages the mGluR1 expression was minimal, then increased progressively. In contrast, mGluR5 expression was initially high, then decreased. While mGluR1 was exclusively localized in neuronal compartments and concentrated at the postsynaptic sites at all stages observed, mGluR5 was found mainly in neuronal compartments at immature stages, then preferentially in glial compartments at mature stages. These results provide the first evidence for a progressive change from LTD to LTP accompanied by a distinct maturation expression of mGluR1 and mGluR5 during the development of the MVN.
authors.affiliation: INSERM U432, University of Montpellier II, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Puyal
authors.forename: Silvarosa
authors.initials: S
authors.lastname: Grassi
authors.forename: Cristina
authors.initials: C
authors.lastname: Dieni
authors.forename: Adele
authors.initials: A
authors.lastname: Frondaroli
authors.forename: Danielle
authors.initials: D
authors.lastname: Demêmes
authors.forename: Jaqueline
authors.initials: J
authors.lastname: Raymond
authors.forename: Vito Enrico
authors.initials: VE
authors.lastname: Pettorossi
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D015153:Blotting, Western; D002867:Chromones / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D058787:GABA-A Receptor Antagonists; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology*; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5; D011963:Receptors, GABA-A / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology; D014726:Vestibular Nuclei / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure
chemical_list: C117789:7-(hydroxyimino)cyclopropan(b)chromen-1a-carbxoylic acid ethyl ester; D002867:Chromones; D058787:GABA-A Receptor Antagonists; C578937:Grm5 protein, rat; D011725:Pyridines; D064529:Receptor, Metabotropic Glutamate 5; D011963:Receptors, GABA-A; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C104077:metabotropic glutamate receptor type 1; D015763:2-Amino-5-phosphonovalerate; C121465:6-methyl-2-(phenylethynyl)pyridine; D001640:Bicuculline