Effects of Chronic Stress and Phenytoin on the Long-term Potentiation (LTP)in Rat Hippocampal CA1 Region

Hui ZHENG*, Quan
YANG, and Chong-Tao XU
( Mental Health Center, Shantou University Medical College, Shantou 515063,
China )

Abstract To investigate the
changes of LTP in hippocampal CA1 region induced by chronic stress and the effect
of phenytoin on them, thirty-two adult male Sprague-Dawley rats were randomly
divided equally into four groups: control group, control-phenytoin group, stress-saline
group and stress-phenytoin group. Isolated hippocampal slices of rats were used
to observe the changes of long-term potentiation (LTP) in hippocampal CA1 field
using electrophysiological technique. Amplitude of population spike (PS) and
field excitatory postsynaptic potentials (fEPSPs) slope were used to indicate
the changes of LTP. High-frequency stimulation (HFS) was applied to Schaffer
collaterals of hippocampal CA3 field, and the changes of PS amplitude and fEPSPs
slope in CA1 field were observed. The results showed that the LTP induction
rate, the increases of PS amplitude and fEPSPs slope after HFS in control and
stress-phenytoin groups were significantly greater than those in stress-saline
group (P<0.05). There were no significant differences between control group and stressphenytoin group or between control and control-phenytoin groups in these indexes (P>0.05). It is suggested that chronic stress can
damage the development of LTP in hippocampal CA1 field, while phenytoin can
protect the LTP of stressed hippocampal slices in normal state.

Key words phenytoin;
long-term potentiation; hippocampus; stress

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Received: October 8, 2003 Accepted:
March 29, 2004
*Corresponding author: Tel, 86-754-8900440; E-mail, [email protected]