Excitatory amino acid receptors in the parallel fibre pathway in rat cerebellar slices.
The grease-gap technique was used on young rat cerebellar slices to study the synaptic pharmacology of the parallel fibre pathway. Electrical stimulation of the parallel fibres produced a characteristic response in Purkinje cells: a sharp negative (N) potential, representing the population action potential and underlying parallel fibre EPSP, followed by a slow positive (P) wave, the population inhibitory postsynaptic potential (IPSP). In the presence of 1.2 mM Mg2+, D-2-amino-5-phosphonovalerate (APV, 30 microM) had no effect but both potentials could be inhibited by 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX, 10 microM). Removal of Mg2+ had no effect on the N-potential but enhanced the P-wave in an APV-sensitive fashion, particularly when CNQX was present. The results provide further evidence that glutamate is the parallel fibre transmitter and suggest that its acts only on non-NMDA (non-N-methyl-D-aspartate) receptors at synapses with Purkinje cells but on both NMDA and non-NMDA receptors at synapses with inhibitory interneurones. At the latter synapses, the NMDA system is likely to be brought into operation in an activity-dependent manner.
Garthwaite
J
J
Department of Physiology, University of Liverpool, U.K.
Beaumont
P S
PS
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002531:Cerebellum / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*
D011810:Quinoxalines; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione