The amplitude of quantal currents is reduced during short-term depression at neuromuscular synapses in Drosophila.

Focal extracellular excitatory postsynaptic currents were recorded to investigate short-term depression at glutamatergic Drosophila neuromuscular synapses. The amplitudes of quantal excitatory postsynaptic currents (qEPSCs) elicited before and after depolarizations eliciting large release were compared. Depression reduced the amplitude of the qEPSCs to 0.65 +/- 0.14 of control. Recovery from depression and of the receptor channels from desensitization follow a similar time course. Thus receptor desensitization seems to be involved in short-term depression at Drosophila neuromuscular junctions.