Effects of adenosine and cadmium on presynaptic fiber spikes in the CA1 region of rat hippocampus in vitro.
Effects of adenosine and cadmium on presynaptic fiber spikes in the CA1 region of rat hippocampus in vitro.
复制标题
腺苷和镉对体外大鼠海马 CA1 区突触前纤维尖峰的影响。
DOI：
10.1016/0028-3908(93)90071-a
复制
发表时间：
1993
影响因子：
4.7
通讯作者：
Miller,KK
中科院分区：
文献类型：
--
作者：
Dunwiddie,TV;Miller,KK
研究发现，在刺激谢弗侧支和连合传入神经后，腺苷可降低海马CA 1区放射层中记录的突触前纤维棘波的振幅。突触前纤维锋电位反映了在该投射的突触前纤维和神经末梢中激活的电流。然而，腺苷的作用主要是由于：（a）突触前纤维锋电位和场EPSP反应之间的时间重叠和（B）最有可能与CA 3神经元的超极化有关的间接作用，从而产生Schaffer侧支纤维。当用刀将CA 3区与CA 1区分开，用6，7-二硝基喹喔啉-2，3-二酮阻断EPSP时，腺苷的作用明显降低，但仍有显著性（突触前纤维锋电位振幅降低4.4 ± 1.4%）。然而，这一行动并没有模仿的钙离子通道拮抗剂镉，这表明它并没有反映腺苷的钙电流的抑制。在K+通道拮抗剂Ba 2+或二氨基吡啶存在下未观察到这种效应。这些结果表明，腺苷可能有一个小的超极化效应的突触前神经末梢，但这是不太可能的机制，腺苷调制传输在这个大脑区域。
Adenosine was found to decrease the amplitude of presynaptic fiber spikes recorded in stratum radiatum of the CA1 region of the hippocampus following stimulation of the Schaffer collateral and commissural afferents. The presynaptic fiber spike reflects currents activated in the presynaptic fibers and nerve terminals of this projection. However, the effect of adenosine was largely the result of: (a) temporal overlap between the presynaptic fiber spike and the field EPSP response and (b) an indirect effect most likely related to the hyperpolarization of CA3 neurons giving rise to the Schaffer collateral fibers. When the CA3 region was separated by a knife cut from the CA1 region and the field EPSP blocked with 6,7-dinitroquinoxaline-2,3-dione, the effect of adenosine was markedly reduced, but was still significant (4.4 ± 1.4% reduction in the amplitude of the presynaptic fiber spike). However, this action was not mimicked by the Ca2+channel antagonist cadmium, suggesting that it did not reflect an inhibition of Ca2+currents by adenosine. This effect was not observed in the presence of the K+channel antagonists Ba2+or diaminopyridine. These results suggest that adenosine may have a small hyperpolarizing effect on the presynaptic nerve terminals, but this is unlikely to be the mechanism by which adenosine modulates transmission in this brain region.