Pavlides C, Kimura A, Magariños A M, McEwen B S
Rockefeller University, New York, NY 10021, USA.
Neuroscience. 1995 Sep;68(2):379-85. doi: 10.1016/0306-4522(95)94332-s.
The effects of adrenal steroids on synaptic plasticity were investigated in the dentate gyrus of the hippocampus. Experiments were performed in either adrenalectomized or intact (non-adrenalectomized), anesthetized rats. 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 steroid receptor agonist RU 28362. High-frequency stimulation prior to RU 28362 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 RU 28362, high-frequency stimulation produced a long-term depression (in comparison to baseline). In the experiments in which high-frequency stimulation was applied both pre- and post-RU 28362 administration, the size of the population spike was initially potentiated and then depotentiated after the RU 28362 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 depression/depotentiation, while 100 Hz was the most effective. Long-term depression/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 RU 28362. However, in a number of experiments long-term potentiation could still be induced after RU 28362 administration, even after long-term depression/depotentiation had been established. In these cases, stimulation at the higher frequencies was necessary.(ABSTRACT TRUNCATED AT 250 WORDS)
在海马齿状回中研究了肾上腺类固醇对突触可塑性的影响。实验在肾上腺切除或完整（未肾上腺切除）的麻醉大鼠身上进行。以三种不同频率（100、200或400Hz）对内侧穿通通路施加高频刺激，分别在给予特异性II型肾上腺类固醇受体激动剂RU 28362之后，或之前及之后。在给予RU 28362之前进行高频刺激会产生群体峰电位的频率依赖性长时程增强，100Hz未显示长时程增强，400Hz的增强程度最高。相反，给予RU 28362之后，高频刺激产生长时程抑制（与基线相比）。在RU 28362给药之前和之后都施加高频刺激的实验中，群体峰电位的大小最初增强，在注射RU 28362后又减弱。这种效应也是频率依赖性的，尽管与长时程增强效应相反。也就是说，400Hz是诱导长时程抑制/减弱最无效的频率，而100Hz是最有效的。高频刺激后长时程抑制/减弱立即出现，并持续整个记录过程，在某些情况下超过1小时。与随附论文中报道的结果相似，RU 28362可显著抑制长时程增强的诱导。然而，在一些实验中，即使在建立了长时程抑制/减弱之后，给予RU 28362后仍可诱导长时程增强。在这些情况下，需要以更高频率进行刺激。（摘要截选至250字）
