Pre- and Postsynaptic Mechanisms of the Deprivation Potentiation of Neuron Population Responses in Rat Hippocampal Field CA1

Studies using in vitro rat hippocampal slices addressed the mechanism of deprivation potentiation (DeP) of neuron population responses in field CA1 developing as a result of prolonged (60 or 120 min) cessation of rare (0.05 Hz) test stimuli of Schaffer collaterals (SC). The development of DeP was found to involve two independent mechanisms: pre- and postsynaptic, responsible for induction of the short-term and long-term components of DeP, respectively. These studies showed that the interaction of DeP and long-term post-tetanic potentiation (LTP) is competitive in nature, providing evidence of similarity in the mechanisms of the long-term phase of DeP and the phase of LTP associated with protein phosphorylation. Our investigation showed that the Ca²⁺-dependent mechanism of induction of the postsynaptic component of DeP does not involve NMDA receptors, but does involve purine P2 receptors. A common curve for the relationship between the efficiency of synaptic transmission and the use/non-use of synapses including DeP, long-term depression (LTD), and LTP zones is presented.

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