Role of the calcium-binding protein parvalbumin in short-term synaptic plasticity

GABAergic (GABA = gamma -aminobutyric acid) neurons from different brain re gions contain high levels of parvalbumin, both in their soma and in their n eurites, Parvalbumin is a slow Ca2+ buffer that may affect the amplitude an d time course of intracellular Ca2+ transients in terminals after an action potential, and hence may regulate short-term synaptic plasticity. To test this possibility, we have applied paired-pulse stimulations (with 30- to 30 0-ms intervals) at GABAergic synapses between interneurons and Purkinje cel ls, both in wild-type (PV+/+) mice and in parvalbumin knockout (PV-/-) mice . We observed paired-pulse depression in PV+/+ mice, but paired-pulse facil itation in PV-/- mice. In paired recordings of connected interneuron-Purkin je cells, dialysis of the presynaptic interneuron with the slow Ca2+ buffer EGTA (1 mM) rescues paired-pulse depression in PV-/- mice. These data show that parvalbumin potently modulates short-term synaptic plasticity.