Ca(2+)-dependent plasticity of miniature inhibitory postsynaptic currents after amputation of dendrites in central neurons

1. The effects of cutting off the bulk (> 2/3) of the dendritic tree (dendrotomy) on GABAergic miniature inhibitory postsynaptic currents (mIPCSs) were studied in granule cells of the adult rat dentate gyrus in 400-microns-thick slices in vitro. 2. After dendrotomy carried out in warm (32 degrees C) control artificial cerebrospinal fluid (ACSF), only small antidromic population spikes could be evoked in the granule cell layer, and no viable whole cell recordings could be obtained. However, when dendrotomy was performed in cold (8-10 degrees C) control ACSF, the amplitude of the antidromic population spikes increased, and stable whole cell recordings became possible. 3. Whole cell recordings, with CsCl-filled pipettes, from granule cells dendrotomized in cold control ACSF, revealed significant alterations, lasting > 10 h, in the decay kinetics of mIPSACs. The change consisted of a calcium-dependent transformation of the normal, single exponential decay into a prolonged double exponential that effectively i...