CHANGES IN THE NUMERICAL DENSITY OF SYNAPTIC CONTACTS WITH LONG-TERM POTENTIATION IN THE HIPPOCAMPAL DENTATE GYRUS
CHANGES IN THE NUMERICAL DENSITY OF SYNAPTIC CONTACTS WITH LONG-TERM POTENTIATION IN THE HIPPOCAMPAL DENTATE GYRUS
复制标题
DOI：
10.1002/cne.902530404
复制
发表时间：
1986-11-22
影响因子：
2.5
通讯作者：
LEVY, WB
中科院分区：
文献类型：
--
作者：
DESMOND, NL;LEVY, WB
大鼠齿状回的长时程增强（LTP）是一种多层面的现象，包括突触增强；相邻的、非条件化突触同时出现的突触抑制；以及由特定量的突触电流所产生的细胞放电量的变化（见利维和德斯蒙德：在G.布扎基和C.范德沃尔夫（编）；《古皮质的电活动》，布达佩斯：阿卡代米亚基多出版社，第359 - 373页，1985b）。本研究展示了似乎与兴奋性突触改变相关的长期解剖学变化。这些解剖学改变出现得较早，并在条件刺激后至少持续60分钟。每只动物在接受许多LTP范式中典型的短暂单侧高频条件刺激前后，都接受交替施加于角束的测试脉冲刺激。解剖学准备遵循标准程序。双盲评分程序对齿状分子层中不对称突触的数量进行了量化。利用将几何推导理论和适度的连续切片相结合的体视学校正，将这些计数转换为单位体积的突触数量。方差的多变量分析评估了突触密度变化的统计学意义。在所有三组动物中，条件刺激并没有显著改变整个分子层的突触接触密度。在中间分子层（即受条件刺激激活的区域），突触接触密度有降低的趋势。在这里，在接受条件刺激的所有三组动物中，凹形棘突轮廓的密度显著增加。这种增加伴随着非凹形、简单和椭圆形棘突轮廓密度的显著降低。诱导LTP的条件刺激不会使轴突突触的密度发生显著变化。这些数据表明，凹形棘突轮廓与诱导LTP的刺激相关，可能是增强的突触。我们假设，随着突触增强，棘突突触会发生相互转化，使得一些非凹形棘突轮廓变为凹形棘突轮廓。这种相互转化显然在条件刺激后不久就开始，并至少持续60分钟。
Long-term potentiation (LTP) in the rat dentate gyrus is a multifaceted phenomenon, including synaptic potentiation; simultaneous synaptic depression at neighboring, unconditioned synapses; and a change in the amount of cell firing produced by a specified amount of synaptic current (see Levy and Desmond: In G. Buzsaki and C. Vanderwolf (eds); Electrical Activity of The Archicortex, Budapest: Akademiai Kiado, pp. 359-373, ''85b). This study presents long-term anatomical modifications that seem related to excitatory synaptic modification. These anatomical alterations appear early and persist for at least 60 minutes following conditioning stimulation. Each animal received test pulse stimulation delivered alternately to the angular bundles before and after brief, unilateral high-frequency conditioning stimulation that is typical of many LTP paradigms. Anatomical preparation followed standard procedures. Double-blind scoring procedures quantified the number of asymmetric synapses in the dentate molecular layer. These counts were converted to the number of synapses per unit volume using stereological corrections that combined geometrically derived theory and modest serial sectioning. Multivariate analysis of variance evaluated the statistical significance of changes in synapse density. Across all three groups of animals, conditioning stimulation does not significantly change the density of synaptic contacts across the entire molecular layer. There is a trend for a decreased density of synaptic contacts in the middle molecular layer, the region activated by the conditioning stimulation. Here the density of concave spine profiles increases significantly in all three groups of animals with conditioning stimulation. This increase accompanies significant decreases in the density of nonconcave, simple and ellipsoid, spine profiles. No significant changes in the density of shaft synapses occur with LTP-inducing conditioning stimulation. These data suggest that the concave spine profiles are a correlate of LTP-inducing stimulation and may be the potentiated synapses. We hypothesize that with synaptic potentiation there occurs an interconversion of spine synapses such that some nonconcave spine profiles become concave spine profiles. Such an interconversion apparently begins shortly after the conditioning stimulation and persists for at least 60 minutes.