Karten Y J, Slagter E, Joëls M
Institute of Neurobiology, University of Amsterdam, The Netherlands.
Neurosci Lett. 1999 Apr 9;265(1):41-4. doi: 10.1016/s0304-3940(99)00211-6.
Daily injections with high doses of corticosterone for 3 weeks were previously found to result in atrophy of the dendritic tree of hippocampal CA3 neurons, which form a major input source to CA1 pyramidal cells. In this study we examined if exposure of rats to a similar chronic corticosterone treatment is associated with changes in field responses of CA1 neurons to stimulation of Schaffer collateral/commissural fibers. In line with earlier studies, we observed that corticosterone injections for 1 day or 1 week reduce the maximal amplitude of the population spike and synaptic potentiation observed after theta burst stimulation, respectively. Yet, animals which were exposed to high corticosterone levels during 3 weeks did not exhibit significant suppression of either the field potential amplitude or the synaptic potentiation compared with the control group. The data suggest that exposure of rats for 3 weeks to very high corticosterone levels induces adaptational changes in the CA1 hippocampal network function which partly normalize the effects seen with less prolonged corticosterone treatment.
先前发现，连续3周每天注射高剂量皮质酮会导致海马CA3神经元树突萎缩，而CA3神经元是CA1锥体细胞的主要输入源。在本研究中，我们检测了大鼠暴露于类似的慢性皮质酮处理是否与CA1神经元对Schaffer侧支/联合纤维刺激的场反应变化有关。与早期研究一致，我们观察到，注射1天或1周的皮质酮分别降低了群体峰电位的最大幅度和theta爆发刺激后观察到的突触增强。然而，与对照组相比，暴露于高皮质酮水平3周的动物在场电位幅度或突触增强方面均未表现出明显抑制。数据表明，大鼠暴露于非常高的皮质酮水平3周会诱导海马CA1网络功能的适应性变化，这部分地使皮质酮处理时间较短时所观察到的效应正常化。
