Studies of the mechanism of development of "deprivation" potentiation of population responses of neurons in field CA1 of living hippocampal slices.

Experiments on rat hippocampal slices were performed with testing of the synaptic connections of Schaffer collaterals and neurons in field CA1 to study the effects of interrupting low-frequency test stimulation (0.05 Hz) on the amplitude of population spikes. These studies demonstrated a correlation between the duration of pauses in stimulation (form 10 to 120 min) and increases in the amplitude of spikes (on average by 30-100% of baseline response magnitude). This "deprivation" potentiation was additive and could persist for long periods of time (testing was up to 1 h). Preliminary induction of long-term post-tetanic potentiation, which prevented the subsequent development of the late, but not the shortterm phase, for 1-3 h, led to suppression of the development of "deprivation" potentiation after a 60-min pause in stimulation. Similar results were obtained in experiments using 20 microM polymyxin B, which blocks protein kinase C and the PKC-dependent phase of long-term post-tetanic potentiation; this is evidence supporting the previously advanced hypothesis that the development of deprivation potentiation and the late. PKC-dependent phase of long-term post-tetanic potentiation share common mechanisms, associated with people phosphorylation.