Maggio Nicola, Segal Menahem
Department of Neurobiology, The Weizmann Institute, 76100 Rehovot, Israel.
J Neurosci. 2007 May 23;27(21):5757-65. doi: 10.1523/JNEUROSCI.0155-07.2007.
The ability to express long-term potentiation (LTP) of reactivity to afferent stimulation along the septotemporal axis was explored in transverse rat hippocampal slices. The ventral pole of the hippocampus (VH) was found to be much impaired in ability to express LTP compared with the rest of the hippocampus. An exposure to acute stress before the rat was killed reversed this trend, and slices from VH now expressed a large LTP, whereas in the rest of the hippocampus, it was much suppressed. The enhanced LTP in VH was mediated by activation of a mineralocorticoid receptor (MR), whereas the suppressed LTP was mediated by activation of a glucocorticoid receptor, and indeed selective agonists of the respective steroid receptors mimicked the effects of stress, whereas selective antagonists blocked them. The MR-enhanced LTP in VH was not mediated by activation of the NMDA receptor but by enhancement of voltage-gated calcium channels. Because the VH has an unique efferent system to the hypothalamus, these results indicate that stress may activate this system while suppressing the ability of the rest of the hippocampus to express plastic properties under stressful conditions.
在横断的大鼠海马切片中，研究了沿海马隔颞轴对传入刺激反应的长时程增强（LTP）表达能力。与海马其他部分相比，发现海马腹侧极（VH）表达LTP的能力严重受损。在处死大鼠前暴露于急性应激可逆转这一趋势，VH的切片现在表达大量LTP，而在海马其他部分，LTP受到很大抑制。VH中增强的LTP由盐皮质激素受体（MR）的激活介导，而受抑制的LTP由糖皮质激素受体的激活介导，事实上，相应类固醇受体的选择性激动剂模拟了应激的作用，而选择性拮抗剂则阻断了这些作用。VH中MR增强的LTP不是由NMDA受体的激活介导，而是由电压门控钙通道的增强介导。由于VH对下丘脑有独特的传出系统，这些结果表明，应激可能激活该系统，同时抑制海马其他部分在应激条件下表达可塑性特性的能力。
