Collins W F, Mendell L M, Munson J B
J Physiol. 1986 Jun;375:587-609. doi: 10.1113/jphysiol.1986.sp016135.
Experiments were addressed to the following questions: when a muscle nerve is sectioned and regenerates to what extent are muscle receptors (spindles and tendon organs) reinnervated? is the reinnervation specific? that is, do group Ia and spindle group II fibres preferentially reinnervate spindles and do group Ib fibres preferentially reinnervate tendon organs? what are the consequences to the afferent of failure to re-establish appropriate receptor innervation? In normal cats, and in cats 3, 6 or 9 months after section and resuture of the medial gastrocnemius muscle nerve, medial gastrocnemius afferent fibres in continuity were impaled in dorsal rootlets for recording and stimulation. Receptor innervation was determined electrophysiologically by manipulation of the medial gastrocnemius muscle. Afferent fibre type was determined by the presence (group Ia or spindle group II) or absence (group Ib) of field potentials in the homonymous motoneurone pool in response to activation of the afferent fibre. In normal cats, two-thirds of recorded afferents innervated spindles; 89% of these generated field potentials detected in the motoneurone pool. One-third of recorded afferents innervated tendon organs; none of these generated such field potentials. In operated cats, about half of the recorded afferents innervated spindles, about one-third responded abnormally or not at all to muscle manipulation, and fewer than one-tenth innervated tendon organs. Numbers of afferents which innervated spindles increased with time. The proportion of afferents generating field potentials was smaller in operated than in normal animals (40% vs. 60%) and declined progressively with time. Field potentials were generated by fibres in all categories of receptor reinnervation. This ability was lost at long post-operative intervals by fibres failing to reach the muscle. Conduction velocity of fibres fell in operated animals. Fibres reinnervating their original type of receptor (e.g. group Ia fibre----spindle) exhibited greater conduction velocity than fibres innervating an inappropriate receptor or no receptor. From these findings and other considerations (see Discussion) we conclude that following section and resuture of the medial gastrocnemius muscle nerve: about 75% of afferents regenerate into the medial gastrocnemius muscle, many more spindles than tendon organs become reinnervated, random populations of groups Ia and Ib (and probably spindle group II) fibres reinnervate spindles, fibres which fail to re-establish appropriate receptor innervation also fail to recover normal conduction velocity.(ABSTRACT TRUNCATED AT 400 WORDS)
当肌肉神经被切断并再生时，肌肉感受器（肌梭和腱器官）的再支配程度如何？这种再支配是否具有特异性？也就是说，Ia类纤维和梭内肌II类纤维是否优先再支配肌梭，Ib类纤维是否优先再支配腱器官？未能重新建立适当感受器支配对传入神经会有什么后果？在正常猫以及内侧腓肠肌神经切断并重新缝合3、6或9个月后的猫中，将连续的内侧腓肠肌传入纤维刺入背根小支进行记录和刺激。通过对内侧腓肠肌的操作，以电生理方式确定感受器的支配情况。根据同名运动神经元池中对传入纤维激活的反应中是否存在场电位（Ia类或梭内肌II类）来确定传入纤维类型。在正常猫中，三分之二的记录传入神经支配肌梭；其中89%在运动神经元池中产生可检测到的场电位。三分之一的记录传入神经支配腱器官；这些传入神经均未产生此类场电位。在接受手术的猫中，约一半的记录传入神经支配肌梭，约三分之一对肌肉操作反应异常或无反应，支配腱器官的传入神经不到十分之一。支配肌梭的传入神经数量随时间增加。与正常动物相比，接受手术的动物中产生场电位的传入神经比例较小（40%对60%），且随时间逐渐下降。所有类型的感受器再支配纤维均能产生场电位。术后间隔时间较长时，未能到达肌肉的纤维会失去这种能力。接受手术的动物中纤维的传导速度下降。重新支配其原始类型感受器（如Ia类纤维——肌梭）的纤维比支配不适当感受器或无感受器的纤维具有更高的传导速度。根据这些发现和其他考虑因素（见讨论），我们得出结论：在内侧腓肠肌神经切断并重新缝合后，约75%的传入神经再生进入内侧腓肠肌，再支配的肌梭比腱器官多得多，Ia类和Ib类（可能还有梭内肌II类）纤维随机群体再支配肌梭，未能重新建立适当感受器支配的纤维也无法恢复正常传导速度。（摘要截选至400字）
