Pécot-Dechavassine M
J Physiol. 1986 Feb;371:167-77. doi: 10.1113/jphysiol.1986.sp015966.
The proportion of polyneuronal innervation was evaluated electrophysiologically in curare-blocked frog cutaneous pectoris muscles after local injury to the muscle fibres on one side. Focal polyneuronal innervation was revealed by recording end-plate potentials evoked by a gradual increase in the stimulus intensity applied to the motor nerve. An increase in the proportion of focally polyneuronally innervated muscle fibres appeared in the injured muscle 3-5 days after injury. The difference between the values obtained 3-5 days and 7-9 days (31 and 38%, respectively) and the control value (18%) was highly significant. A similar increase in the proportion of pluri-innervated muscle fibres was observed in the contralateral muscle, but after a longer period. The different components of complex end-plate potentials (e.p.p.s) usually had similar latencies and rise times in control and experimental muscles. This may indicate that the axons had similar conduction velocities and that synapses were located close to each other. A repeated muscle fibre section 24 h after the initial injury resulted in an enhanced polyneuronal innervation (52%) 7-9 days after the first section. The experiments were repeated on partially blocked muscles in order to detect small e.p.p.s with an amplitude similar to that of spontaneous miniature end-plate potentials (m.e.p.p.s). The proportion of polyneuronally innervated fibres estimated by this technique in control muscles approximated 40%. Polyneuronal innervation was also found to be significantly increased in cut muscles 7-9 days after muscle injury and a week later in contralateral muscles. Combined silver and cholinesterase staining was used to detect morphologically polyneuronal innervation. The comparison of morphological and electrophysiological data indicated that the increase in polyneuronal innervation after muscle injury is likely due to nerve sprouting and formation of new synapses. The results suggest that the signal for nerve sprouting originates from the damaged muscle cell and that it is transferred transneuronally to the contralateral side.
在一侧肌肉纤维局部损伤后，对箭毒阻断的青蛙胸皮肌进行电生理评估，以确定多神经元支配的比例。通过记录逐渐增加施加于运动神经的刺激强度所诱发的终板电位，揭示了局灶性多神经元支配。损伤后3 - 5天，损伤肌肉中局灶性多神经元支配的肌纤维比例增加。损伤后3 - 5天和7 - 9天（分别为31%和38%）所获得的值与对照值（18%）之间的差异非常显著。在对侧肌肉中观察到多支配肌纤维比例有类似增加，但时间较晚。在对照肌肉和实验肌肉中，复合终板电位（e.p.p.s）的不同成分通常具有相似的潜伏期和上升时间。这可能表明轴突具有相似的传导速度，且突触彼此靠近。初次损伤24小时后重复进行肌肉纤维切断，在第一次切断后7 - 9天导致多神经元支配增强（52%）。为了检测幅度与自发微小终板电位（m.e.p.p.s）相似的小e.p.p.s，在部分阻断的肌肉上重复进行实验。通过该技术估计，对照肌肉中多神经元支配的纤维比例约为40%。还发现肌肉损伤后7 - 9天，切断的肌肉以及一周后对侧肌肉中的多神经元支配显著增加。采用银染和胆碱酯酶联合染色法从形态学上检测多神经元支配。形态学和电生理数据的比较表明，肌肉损伤后多神经元支配的增加可能是由于神经发芽和新突触的形成。结果表明，神经发芽的信号源自受损的肌肉细胞，并通过神经元传递到对侧。
