Calcium signaling at single mossy fiber presynaptic terminals in the rat hippocampus.
Calcium signaling at single mossy fiber presynaptic terminals in the rat hippocampus.
复制标题
大鼠海马单个苔藓纤维突触前末端的钙信号传导。
DOI：
10.1152/jn.00661.2001
复制
发表时间：
2002
影响因子：
2.5
通讯作者：
Gray,Richard
中科院分区：
文献类型：
--
作者：
Liang,Yong;Yuan,Li-Lian;Johnston,Daniel;Gray,Richard
我们研究了海马CA3锥体神经元（苔藓纤维终端，MFTs）上苔藓纤维突触的内部Ca2+释放。突触前Ca2+内流是通过给予苔藓纤维通路100赫兹的20个简短的刺激来诱导的。使用Ca2+成像技术，我们记录Ca2+反应为ΔF/F，随着刺激迅速增加，但通常伴随着在训练后出现的延迟峰值。400 μM Cd2+可完全阻断突触前[Ca2+]的升高。此外，II组mGluR激动剂可减少引起的Ca2+信号。在相同的实验条件下，我们研究了几种药物对MFTs的影响，这些药物会破坏细胞内Ca2+储存的调节，导致内部Ca2+的消耗。我们发现，ryanodine、cyclopiazonic acid、thapsigargin和ruthenred均能降低Ca2+信号的早期和延迟增加。我们使用l-2-氨基-5-磷酸戊酸（d,l-APV, 50 μM）和6,7-二硝基喹啉-2,3-二酮（DNQX, 20 μM）来排除n-甲基-d-天冬氨酸（NMDA）和非NMDA受体的作用。实验采用替代的Ca2+亲和力较低的指示剂（fura-2FF和calcium green-2）和瞬时K+通道阻滞剂4-氨基吡啶来控制fura-2可能的饱和。综上所述，这些结果有力地支持了一种假设，即记录的终末来自齿状回的苔藓纤维，并表明部分突触前Ca2+信号响应于短暂的刺激序列是由于Ca2+从内部储存的释放。
We investigated internal Ca2+release at mossy fiber synapses on CA3 pyramidal neurons (mossy fiber terminals, MFTs) in the hippocampus. Presynaptic Ca2+influx was induced by giving a brief train of 20 stimuli at 100 Hz to the mossy fiber pathway. Using Ca2+imaging techniques, we recorded the Ca2+response as ΔF/F,which increased rapidly with stimulation, but was often accompanied by a delayed peak that occurred after the train. The rise in presynaptic [Ca2+] could be completely blocked by application of 400 μM Cd2+. Furthermore, the evoked Ca2+signals were reduced by group II mGluR agonists. Under the same experimental conditions, we investigated the effects of several agents on MFTs that disrupt regulation of intracellular Ca2+stores resulting in depletion of internal Ca2+. We found that ryanodine, cyclopiazonic acid, thapsigargin, and ruthenium red all decreased both the early and the delayed increase in the Ca2+signals. We appliedd,l-2-amino-5-phosphonovaleric acid (d,l-APV; 50 μM) and 6,7-Dinitroquinoxaline-2,3-dione (DNQX; 20 μM) to exclude the action ofN-methyl-d-aspartate (NMDA) and non-NMDA receptors. Experiments with alternative lower affinity indicators for Ca2+(fura-2FF and calcium green-2) and the transient K+channel blocker, 4-aminopyridine were performed to control for the possible saturation of fura-2. Taken together, these results strongly support the hypothesis that the recorded terminals were from the mossy fibers of the dentate gyrus and suggest that a portion of the presynaptic Ca2+signal in response to brief trains of stimuli is due to release of Ca2+from internal stores.