年間 4 号発行
ISSN 印刷: 2155-014X
ISSN オンライン: 2155-0158
Frequency-Dependent Modulation of Short-Term Plasticity of GABAergic Synaptic Transmission
要約
Changes in amplitudes of evoked inhibitory postsynaptic currents (eIPSCs) from rat cultured hippocampal neurons were examined using whole-cell patch-clamp technique and local extracellular electrical paired pulse stimulation of a single presynaptic axon. Both paired pulse facilitation (PPF) and paired pulse depression (PPD) of postsynaptic currents were observed in response to paired pulse stimulation of a single presynaptic axon with interstimulus interval (ISI) ranging from 20 to 1200 ms. The longer interstimulus interval, the less depression was observed. Maximum depression of the second eIPSC was observed during the shortest interstimulus interval (20 ms) with paired pulse ratio (PPR) of 42 ± 6%. Minimum depression of the second eIPSC was during the longest interstimulus interval (1200 ms) with PPR of 98 ± 6%. The rate of recovery from PPD is well described by a single exponential function with time constant of 83 ms. PPF was maximal at ISI of 150 ms (PPR of 118 ± 4%), and it recovered within 500 ms (n = 6). The recovery rate from PPF was bell-shaped. In 7 neurons, we observed depression of eIPSC amplitude after consecutive stimulations of a single presynaptic axon by four stimuli at ISI ranging from 50 to 200 ms. The relation between normalized amplitude and frequency of stimulation well fitted by exponential function with time constant ranged from 41 ms (ISI = 50 ms) to 119 ms (ISI = 200 ms).