Schröder H, Schlichthaar R, Krug M
Institute of Pharmacology and Toxicology, O. V. Guericke University, Magdeburg, Germany.
Neuroscience. 1994 May;60(2):337-42. doi: 10.1016/0306-4522(94)90247-x.
In the present study, the time-course of changes in glutamate binding and aspartate release in the rat hippocampus following tetanization of perforant pathway and of pentylenetetrazol-induced kindling was investigated. The K+ (48 mM)-stimulated [3H]D-aspartate release from hippocampal slices and the specific [3H]L-glutamate binding to crude synaptic membranes of the hippocampus were measured 1, 4 and 24 h after the last tetanization train or one, five and nine weeks after the last pentylenetetrazol injections, respectively. The tetanization of the fascia dentata was followed by a significant increase in K(+)-stimulated [3H]D-aspartate release from hippocampal slices only 1 h after the last tetanization train, but the specific [3H]L-glutamate binding was enhanced 4 h afterwards. No further deviations from controls have been seen 24 h after tetanization. After pentylenetetrazol kindling, the K(+)-stimulated amino acid release from hippocampal slices was not changed. However, at one week as well as at five and nine weeks after the pentylenetetrazol kindling the specific [3H]L-glutamate binding in the hippocampus was significantly increased by about 50% compared to controls. From these findings it can be assumed that after long-term potentiation induction presynaptic transmitter release and post- (and/or pre-)synaptic glutamate binding are elevated with a different time course only in the early phase of potentiation. In contrast, kindling results in a long lasting increase in activity state of glutamatergic transmission. Therefore, it can be concluded that differences of the synaptic excitability following long-term potentiation and kindling are reflected by a different activation of glutamatergic system in the central nervous system.
在本研究中，对大鼠海马体在穿通通路强直刺激和戊四氮诱导点燃后谷氨酸结合及天冬氨酸释放的时程变化进行了研究。在末次强直刺激序列后1小时、4小时和24小时，以及在末次戊四氮注射后1周、5周和9周，分别测量了海马体切片中由K⁺（48 mM）刺激的[³H]D - 天冬氨酸释放以及海马体粗制突触膜上特异性[³H]L - 谷氨酸结合。仅在末次强直刺激序列后1小时，齿状回的强直刺激导致海马体切片中K⁺刺激的[³H]D - 天冬氨酸释放显著增加，但特异性[³H]L - 谷氨酸结合在随后4小时增强。强直刺激后24小时未观察到与对照组的进一步偏差。戊四氮点燃后，海马体切片中K⁺刺激的氨基酸释放未改变。然而，在戊四氮点燃后1周以及5周和9周，海马体中特异性[³H]L - 谷氨酸结合与对照组相比显著增加约50%。从这些发现可以推测，在长时程增强诱导后，仅在增强的早期阶段，突触前递质释放和突触后（和/或突触前）谷氨酸结合以不同的时程升高。相比之下，点燃导致谷氨酸能传递的活动状态长期增加。因此，可以得出结论，长时程增强和点燃后突触兴奋性的差异通过中枢神经系统中谷氨酸能系统的不同激活得以体现。
