M. Takahashi et al., PRESYNAPTIC AND POSTSYNAPTIC DETERMINANTS OF EPSC WAVE-FORM AT CEREBELLAR CLIMBING FIBER AND PARALLEL FIBER TO PURKINJE-CELL SYNAPSES, The Journal of neuroscience, 15(8), 1995, pp. 5693-5702
Excitatory postsynaptic currents (EPSCs) at the parallel fiber and cli
mbing fiber to Purkinje cell synapses were studied by whole-cell clamp
ing Purkinje cells in cerebellar slices. Reducing glutamate release wi
th adenosine or GABA decreased the amplitude of the EPSCs, with a larg
er suppression being produced at the parallel fiber synapse. Reducing
glutamate release also speeded the decay of the EPSCs, and this effect
was not a series resistance artefact since postsynaptic reduction of
the current with CNQX did not speed the EPSC decay. Blocking glutamate
uptake slowed the decay of the EPSCs. At the climbing fiber synapse,
adenosine had little suppressive effect on the smaller EPSC evoked by
the second of a pair of stimuli. Blocking desensitization of postsynap
tic AMPA receptors prolonged the EPSC decay, preferentially increased
the size of the second EPSC, and resulted in adenosine having a simila
r suppressive effect on the first and second EPSC. These data suggest
that, at these synapses, the fall of glutamate concentration in the sy
naptic cleft overlaps with the decay of the EPSC, and that the EPSC si
ze and duration are controlled by the amount of glutamate released, th
e rate of glutamate uptake, and desensitization.