Navarrete R, Shahani U, Vrbová G
Department of Anatomy and Developmental Biology, University College, London, U.K.
J Neurol Sci. 1990 May;96(2-3):257-67. doi: 10.1016/0022-510x(90)90137-c.
The reflex activity of motoneurones to the extensor digitorum longus (EDL) muscle following sciatic nerve crush during the first 5 days after birth (neonatal crush) or in the adult (adult crush) was studied 3-6 months later, when the axons had reinnervated their target muscles. Electromyograms (EMG) and muscle tension were recorded from the EDL muscle (a physiological flexor) on the injured and uninjured sides. Reflex responses were evoked by stimulation of the common peroneal (CP), the tibial (T) and the sural (S) nerves, ipsilateral and contralateral to the side of injury. In animals which had sustained a neonatal crush, stimulation of branches of the injured sciatic nerve elicited ipsilateral reflex responses that were about 3 times larger than those recorded from the uninjured side or in normal animals. Stimulation of the CP nerve on the uninjured side invariably elicited a contralateral reflex response from the reinnervated muscles, while stimulation of the CP nerve on the injured side either failed to produce a response or produced a very weak reflex response from the control muscles. Reflexes recorded from the reinnervated muscles by stimulation of the tibial and sural branches of the uninjured sciatic nerve were 3-7 times greater than those recorded from the uninjured side or in normal animals. The reflex responses obtained from reinnervated muscles of animals with nerve injury in adulthood were similar to those obtained from control, unoperated adult rats. These results indicate that sciatic nerve injury during a critical development period leads to a permanent enhancement of reflex responses from reinnervated fast flexor muscles not seen after similar injury in adults.
在出生后的前5天（新生期挤压）或成年期（成年期挤压）对坐骨神经进行挤压后3至6个月，当轴突重新支配其目标肌肉时，研究了运动神经元对趾长伸肌（EDL）的反射活动。在受伤侧和未受伤侧的EDL肌肉（一种生理性屈肌）上记录肌电图（EMG）和肌肉张力。通过刺激腓总神经（CP）、胫神经（T）和腓肠神经（S）来诱发反射反应，这些神经分别位于损伤侧的同侧和对侧。在遭受新生期挤压的动物中，刺激受伤坐骨神经的分支会引发同侧反射反应，其幅度比未受伤侧或正常动物记录到的反应大约大3倍。刺激未受伤侧的CP神经总是会从重新支配的肌肉中诱发对侧反射反应，而刺激受伤侧的CP神经要么无法产生反应，要么从对照肌肉中产生非常微弱的反射反应。通过刺激未受伤坐骨神经的胫神经和腓肠神经分支从重新支配的肌肉中记录到的反射比未受伤侧或正常动物记录到的反射大3至7倍。成年期神经损伤动物重新支配的肌肉所获得的反射反应与未手术的成年对照大鼠所获得的反射反应相似。这些结果表明，在关键发育时期的坐骨神经损伤会导致重新支配的快速屈肌的反射反应永久性增强，而在成年期类似损伤后则不会出现这种情况。
