Two distinct glutamatergic synaptic inputs to striatal medium spiny neurones of neonatal rats and paired-pulse depression.
Excitatory postsynaptic currents (EPSCs) were recorded from the medium spiny neurones of neonatal rat striatal slices using the whole-cell patch clamp method. EPSCs were selectively elicited in the presence of picrotoxin with a glass stimulating pipette placed in the striatum. We found two distinct unitary EPSCs that were evoked by stimulation of single presynaptic fibres. The major type of EPSC, termed 'S-type', failed frequently and had a small mean amplitude (2.05 pA). They probably represented cortical afferents. The other type of unitary EPSC, the 'H-type', seldom failed and was 13 times larger than the S-type. Spontaneous EPSCs with amplitudes similar to those of H-type EPSCs could be induced. H-type EPSCs were mediated by both non-NMDA and NMDA receptors. The two types of EPSCs could be evoked in the same neurons. The intensity of stimulation for H-type EPSCs was higher than that for S-type EPSCs. H-type EPSCs could be polysynaptically activated, suggesting the presence of glutamatergic interneurones in the striatum that generated H-type EPSCs. H-type EPSCs displayed particularly long-lasting paired-pulse depression, while that displayed by the S-type EPSCs was short. The paired-pulse depression of both EPSCs was Ca2+ dependent and involved presynaptic mechanisms. We have demonstrated that the medium spiny neurones of neonatal rats receive two different glutamatergic input systems having different amplitudes, origins and paired-pulse depression, reminiscent of cerebellar Purkinje cells. This suggests that the two types of EPSCs also play distinctive roles in striatal neuronal circuitry.
Mori
A
A
Department of Physiology, Faculty of Medicine, University of Tokyo, Japan.
Takahashi
T
T
Miyashita
Y
Y
Kasai
H
H
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002118:Calcium / Q000502:physiology; D003864:Depression, Chemical; D004594:Electrophysiology; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010852:Picrotoxin / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000187:drug effects; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D002118:Calcium; D010852:Picrotoxin; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate