Acute stress impairs (or induces) synaptic long-term potentiation (LTP) but does not affect paired-pulse facilitation in the stratum radiatum of rat hippocampus.

Rats were exposed to restraint coupled with 60, 1-sec, 1-mA, 60-Hz tail shocks. One hippocampus was immediately dissected for in vitro measurement of paired-pulse facilitation and LTP of the excitatory postsynaptic potential (EPSP) recording from the stratum radiatum of field CA1. There was no change in paired-pulse facilitation, suggesting that acute exposure to the stressor does not result in a decrease in presynaptic neurotransmitter release. There was, however, a significant decrease in the percent LTP produced by theta burst stimulation relative to naive controls. These results are consistent with the hypothesis that the stress-induced impairment of LTP is a result of changes in the postsynaptic glutamate receptors, specifically the AMPA type.