Properties of glutamate receptors are modified during long-term depression in rat cerebellar Purkinje cells.
Long-term depression (LTD) of synaptic transmission at parallel fiber (PF)-Purkinje cell (PC) synapses occurs when these synapses are activated in conjunction with direct activation of voltage-gated calcium (Ca2+) channels of PCs. In the present study, we have used Aniracetam to test whether the expression of LTD at PF-PC synapses is due to a genuine modification of properties of alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptors of these neurons. Whole-cell recordings of PF-mediated EPSCs were performed in thin slices taken from 16-22-day-old rats. In all tested cells, bath application of Aniracetam potentiated PF-mediated EPSCs and prolonged their decay without notably changing their rising phase. On the other hand, Aniracetam prevented the induction of LTD by a pairing protocol with Ca2+ spikes and, conversely, the nootropic compound had a larger potentiating effect on PF-mediated EPSCs during expression of LTD than normally, when this change in synaptic efficacy had been induced prior to Aniracetam application. These data strongly suggest that LTD involves a desensitization of postsynaptic AMPA receptors at PF-PC synapses, or, at least, a change in their functional characteristics.
Hémart
N
N
URA CNRS 1121, Université Paris-Sud, Orsay, France.
Daniel
H
H
Jaillard
D
D
Crépel
F
F
D000818:Animals; D002118:Calcium / Q000502:physiology; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000187:drug effects; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects
D011760:Pyrrolidinones; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; C036466:aniracetam; D002118:Calcium