Stress Affects Synaptic Plasticity and Basal Synaptic Transmission in the Rat Hippocampus In Vivo

Acute as well as prolonged stress produces cognitive deficits. Long term potentiation (LTP) and depression (LTD) in the hippocampus are cellular basic mechanisms implicated in learning and memory. Male Wister rats were used to evaluate the effect of stress on hippocampal synaptic plasticity in vivo. The hippocampus CA1 area was implanted with stimulating and recording electrodes. The field excitatory post synaptic responses were recorded before and after induction of stress (unexpected 15 electrical shocks to the feet of the animals during 10 min/twice daily for 2 days). Results showed that the base line synaptic transmission was increased in the stressed rats compared to the control. The induction of LTP (by 100 Hz trains of stimulation) was inhibited in the stressed animals. We concluded that this protocol affected significantly the hippocampal synaptic plasticity. This may explain the effect of stress on some aspects of hippocampus function like learning and memory.