In vivo intracellular demonstration of an ischemia-induced postsynaptic potential from CA1 pyramidal neurons in rat hippocampus.

Pyramidal neurons in the CA1 field of the hippocampus die a few days after transient cerebral ischemia. Excessive excitatory synaptic activation following reperfusion is thought to be responsible for such delayed cell death. However, it remains controversial whether excitatory synaptic transmission in the CA1 field is increased following reperfusion. Here we report a novel postsynaptic potential evoked from CA1 pyramidal neurons preceding cell death after transient forebrain ischemia with intracellular recording and staining techniques in vivo. This result indicates the dramatic alteration of synaptic transmission in CA1 neurons after transient ischemia. The ischemia-induced postsynaptic potential may be associated with the postischemic neuronal injury.