| Summary: | 碩士 === 中國醫藥學院 === 醫學研究所 === 89 === In this study,we want to know the effect of chronic depletion of NE fibers on the bi-directional synaptic plasticity in rat hippocampus.Postnatal rat pups were given with 6-hydroxydopamine (100mg/Kg) or the vehicle (0.1% ascorbic acid in saline)for 4 days,starting at the day of birth.These procedures caused loss of NE fibers in the cortex and hippocampus,while spared those in subcortical areas,when estimated by dopamine-β- hydroxylase immunohisto- chemistry at postnatal day 35-40.Hippocampal slices taken from NE depleted or control animals aged from 25-40 days were subjected to standard electro- physiology techniques for induction of long term potentiation or depression (LTP or LTD) in CA1 synapses,using 100HZ theta burst or 900 pulse of 1 HZ stimulation.In control slices,both LTP （41.32±11.33%,N=8）and LTD（73.18±5.28%,N=8） were successfully induced;But in NE depleted slices,while the induction and expression of LTD （73.47±4.73%,N=8）seemed to be normal,LTP（2.84±5.27%,N=8） could not be induced successfully.Bath application of NE during the theta burst stimulation restored LTP（50.22± 8.50%,N=8） in NE depleted slices,it has no further effect of NE in control slices（58.04±14.81%,N=8）. But bath application of NE not only in control（98.69±8.58%,N=8） but also NE depleted slices（102.92± 5.52% ,N=8）could inhibit the expression of LTD.While exchange the NE into dopamine into the bath,another depleted neuromodulator,it has no effect on bi-directional plasticity both in control and NE depleted slices.These results suggested that endogenous Ne but not dopamine is crucial for induction of LTP and inhibition of LTD.
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