Ca2+-permeable AMPA receptors mediate induction of test pulse depression of naive synapses in rat visual cortical slices at early postnatal stage
Abstract
Synaptic depression in the hippocampus at early postnatal stage can be induced by test pulse stimulation (<1 Hz). However, the receptor mechanism for induction of this synaptic depression is unclear. In the present study, we used whole-cell patch clamp recording in vitro to investigate how excitatory and inhibitory synapses onto layer II/III pyramidal neurons of the primary visual cortex adapt to test pulse activation from a previously non-activated (naive) state. We found that excitatory postsynaptic currents (EPSCs) of pyramidal neurons were rapidly depressed by 0.1 Hz stimulation in acutely prepared slices from rats at 11-12 postnatal days, while this phenomena disappeared in slices from young adolescent rats (23-24 postnatal days). By contrast, inhibitory postsynaptic currents (IPSCs) were relatively stable following 0.1 Hz stimulation of rat slices at the same early postnatal stage. Moreover, the test pulse depression of EPSCs was associated with a decrease in 1/coefficient of variation (CV)(2) and no change in the paired-pulse ratio. These data imply silencing of synapses and no significant change either in postsynaptic receptor density or presynaptic terminal release probability. This synaptic depression was unaffected b...Continue Reading
References
Long-term depression in hippocampal interneurons: joint requirement for pre- and postsynaptic events
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