Functional morphology on the synaptic plasticity : Rapid remodeling of the synapse during long-term potentiation.

条件性刺激后的长时程增强(LTP)被认为表达突触的可塑性，并在中枢神经系统(CNS)的突触水平上提供学习过程和记忆形成的基本机制(Bliss和Lomo，1973)。类似的LTP现象不仅见于中枢神经系统，也见于周围神经系统的交感神经节。本文对猫颈上神经节在完整血供条件下的突触可塑性进行了电生理和超微结构的原位研究。以10赫兹强直刺激节前神经纤维50s进行条件化处理，然后以1赫兹强直刺激1h进行监测。记录刺激节前神经后的节后复合动作电位(PGP)以检测突触效能的增加。在许多情况下，长时程增强(LTP)被发现是…的持续增强PGP较多，约为对照组的120%，持续时间长达1小时。在破伤风前或破伤风后，通过舌动脉快速固定神经节进行电子显微镜检查。节前神经末梢与主细胞之间的突触被Gray‘s I型轴树突触所独占，该突触与缺少树突棘的树干相接触。轴树突触的特征是破伤风后人群中穿孔突触和突触棘突的增加。伴随突触棘突的穿孔突触在这里被称为“棘突-突触”。破伤风后穿孔突触的数量从对照组的5%增加到约30%。在LTP期间，棘突突触的数量在对照中很少，增加到约9%。穿孔突触的穿孔部位在LTP早期宽度较小，以后逐渐变大。综上所述，条件性破伤风引起长时程增强，导致轴-树突触重塑，导致突触接触增多。较少

Long-term potentiation (LTP) following a conditioning stimulation is considered to express synaptic plasticity and to provide elementary mechanisms of learning processes and memory formation at the synaptic level in the central nervous system (CNS) (Bliss and Lomo, 1973). Similar phenomenon of LTP is observed not only in CNS but also in the sympathetic ganglion of the peripheral nervous system. In the present investigation synaptic plasticity following a conditioning stimulation was electrophysiologically and ultrastructurally studied in the cat superior cervical ganglion in situ under intact blood supply. The preganglionic nerve fiber was tetanically stimulated at 10 Hz for 50 seconds for conditioning and then at 1 Hz for 1 hour for monitoring. The postganglionic compound action potential (PGP) in response to preganglionic nerve stimulation was recorded for detecting increase in synaptic efficacy. Long-term potentiation (LTP) was in many cases found to be a persistent potentiation of … More PGP, around 120% of the control, which lasted for 1 hour as long as monitored. The ganglia were rapidly fixed for electron microscopy via the lingual artery before or after the tetanus. The synapse between the preganglionic nerve terminal and the principal cell was exclusively occupied by the axodendritic synapse of Gray's type I, which contacted the dendritic shaft lacking the dendritic spine. The axodendritic synapse was characterized by increase of the perforated synapse and synaptic spinule in population following the tetanus. The perforated synapse accompanying a synaptic spinule was termed here as a 'spinule-synapse'. The population of perforated synapse augmented from 5% in control to ca. 30% after the tetanus. The spinule-synapse, few in number in control, increased to ca. 9% during LTP period. The perforation site of the perforated synapse was small in width at earlier stages of LTP and became larger later. In summary, the conditioning tetanus, inducing LTP, brought about remodeling of axodendritic synapses, which resulted in an increase in number of synaptic contacts. Less