Alterations of synapses on axotomized motoneurones.
Alterations of synapses on axotomized motoneurones.
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轴突运动神经元上突触的改变。
DOI：
10.1113/jphysiol.1976.sp011270
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
J. G. Scott
中科院分区：
文献类型：
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作者：
L. Mendell;J. Munson;J. G. Scott
1.部分切断猫腓肠肌内侧神经后1~77天，用细胞内电极检测腓肠肌内侧运动神经元的特性。2.确定了三个连续的反应阶段：(1)轴突切断运动神经元的传导速度下降，但E.p.P.结果显示：(1)运动诱发电位的特性和Ia运动神经元的连通性是正常的；(2)其次，EPPS的特征是上升时间和半宽度延长，波幅降低；(3)最后，也可以看到连接的失败，即Ia纺锤形传入纤维连接的轴断比正常的同名运动神经元更少。3.更改E.P.P.的原因。这些因素可能包括：(1)运动神经元细胞膜的特性和形态的改变；(2)突触在完全分离之前的部分分离；(3)终止于运动神经元胞体上的Ia传入分支先于树突上的传入分支的分离。4.先前的结论是E.P.P.的改变。运动神经元切断后的轮廓是由于在胞体和近端树突上形成突触的Ia纤维完全分离(“体细胞剥离”)，必须对其进行修改，以解释E.P.P.在连通性更改之前即可看到更改。
1. Properties of medial gastrocnemius motoneurones in cats were examined with intracellular electrodes 1‐77 days after partial transection of the medial gastrocnemius muscle nerve. 2. Three sequential stages of reaction were defined: (i) firstly, conduction velocity of axotomized motoneurones fell, but e.p.s.p. properties and Ia‐motoneurone connectivity were normal; (ii) secondly, e.p.s.p.s became characterized by prolonged rise times and half‐widths and by diminished amplitudes; (iii) finally, failures of connectivity were also seen, that is, Ia spindle afferent fibres connected with fewer axotomized than normal homonymous motoneurones. 3. The reason for the change of e.p.s.p. properties cannot be stated with certainty: among the factors may be (i) a change of motoneurone membrane properties and morphology; (ii) partial detachment of synaptic boutons before their total disconnexion, and (iii) detachment of Ia afferent branches terminating on the motoneurone soma before those on the dendrites. 4. The previous conclusion that alteration of e.p.s.p. profiles following motoneurone axotomy was due to total disconnexion of those Ia fibres making synapses on the soma and proximal dendrites ("somatic stripping") must be modified to account for the findings that e.p.s.p. changes are seen before connectivity changes.