Hippocampal homosynaptic long-term @entity308 /depotentiation induced by adrenal XXXX .

@entity308 @entity35 @entity134 @entity7834 @entity230
The effects of adrenal @entity230 on synaptic plasticity were investigated in the dentate gyrus of the hippocampus. Experiments were performed in either adrenalectomized or intact (non-adrenalectomized), anesthetized @entity35 . High-frequency stimulation was applied to the medial perforant pathway at three different frequencies; 100, 200 or 400 Hz, either post- or pre- and post-administration of the specific Type-II adrenal @entity134 receptor agonist @entity7834 . High-frequency stimulation prior to @entity7834 administration produced a frequency-dependent long-term potentiation of the population spike, with 100 Hz showing no long-term potentiation and 400 Hz the highest degree of potentiation. In contrast, following administration of @entity7834 , high-frequency stimulation produced a long-term @entity308 (in comparison to baseline). In the experiments in which high-frequency stimulation was applied both pre- and post- @entity7834 administration, the size of the population spike was initially potentiated and then depotentiated after the @entity7834 injection. This effect was also frequency dependent, although opposite to the long-term potentiation effect. That is, 400 Hz was the least effective frequency for inducing long-term @entity308 /depotentiation, while 100 Hz was the most effective. Long-term @entity308 /depotentiation was immediate following high-frequency stimulation and lasted for the extent of the recording session, in some cases longer than 1 h. Similar to the finding reported in the accompanying paper, induction of long-term potentiation was substantially suppressed by @entity7834 . However, in a number of experiments long-term potentiation could still be induced after @entity7834 administration, even after long-term @entity308 /depotentiation had been established. In these cases, stimulation at the higher frequencies was necessary.(ABSTRACT TRUNCATED AT 250 WORDS)
