The hyper-reinnervation of rat skeletal muscle

This study examines muscle recovery and related changes in the motor unit population of 'hyper-reinnervated' rat skeletal muscle. Medial gastrocnemius (MG) muscles were hyper-reinnervated by either cutting the MG nerve and implanting it on the MG muscle together with additional hind limb nerves, or by crushing the MG nerve and excising the medial portion (50-70%) of the MG muscle. Our findings were that muscles hyper-reinnervated with multiple nerves recovered muscle mass and strength more fully than did the self-reinnervated muscles, more motor units were formed (up to three times the normal number were found), and the mean motor unit size was significantly smaller. A relatively small percentage of muscle fibers became polyneuronally innervated. In contrast, the number of motor units that were formed in the muscle reduction experiments were not significantly larger than was expected considering the mass of the muscles. We conclude that hyper-reinnervation improves muscle recovery, it may be a useful technique for improving function in denervated muscle, and may serve to provide added sources of EMG control signals in some amputees.

[1]  J. M. Peyronnard,et al.  Motor, sympathetic and sensory innervation of rat skeletal muscles , 1986, Brain Research.

[2]  T. Taxt.  Motor unit numbers, motor unit sizes and innervation of single muscle fibres in hyperinnervated adult mouse soleus muscle. , 1983, Acta physiologica Scandinavica.

[3]  D. Kuffler,et al.  Isolated satellite cells of a peripheral nerve direct the growth of regenerating frog axons , 1986, The Journal of comparative neurology.

[4]  P. Murphy,et al.  Motor units and histochemistry in rat lateral gastrocnemius and soleus muscles: evidence for dissociation of physiological and histochemical properties after reinnervation. , 1987, Journal of neurophysiology.

[5]  P. Murphy,et al.  Reinnervation of the lateral gastrocnemius and soleus muscles in the rat by their common nerve. , 1986, The Journal of physiology.

[6]  G. Vrbóva,et al.  Reinnervation of fast and slow mammalian muscles by a superfluous number of motor axons , 1986, Neuroscience.

[7]  R. Blanks,et al.  Motoneurons of the rat sciatic nerve , 1986, Experimental Neurology.

[8]  R. Burke,et al.  Medial gastrocnemius motor nucleus in the rat: Age‐related changes in the number and size of motoneurons , 1988, The Journal of comparative neurology.

[9]  C. Sorbie,et al.  Reinnervation of paralysed muscles by direct motor nerve implantation. An experimental study in the dog. , 1969, The Journal of bone and joint surgery. British volume.

[10]  J. Holle,et al.  An Experimental Comparison of the Different Kinds of Muscle Reinnervation: Nerve Suture, Nerve Implantation, and Muscular Neurotization , 1982, Plastic and reconstructive surgery.

[11]  D. Grob,et al.  Staining for nerve fiber and cholinesterase activity in fresh frozen sections. , 1967, American journal of clinical pathology.

[12]  M. Abercrombie.  Estimation of nuclear population from microtome sections , 1946, The Anatomical record.

[13]  J. Iles,et al.  Motor neuron columns in the lumbar spinal cord of the rat , 1983, The Journal of comparative neurology.

[14]  E. Frank,et al.  Maintained Function of Foreign Synapses on Hyperinnervated Skeletal Muscle Fibres of the Rat , 1974, Nature.

[15]  The Current Status of Peripheral Nerve Regeneration , 1990 .

[16]  T. Taxt.  Cross-innervation of fast and slow-twitch muscles by motor axons of the sural nerve in the mouse. , 1983, Acta physiologica Scandinavica.

[17]  R. Stein,et al.  Time course and extent of recovery in reinnervated motor units of cat triceps surae muscles , 1982, The Journal of physiology.

[18]  R. O'brien,et al.  Observations on the elimination of polyneuronal innervation in developing mammalian skeletal muscle. , 1978, The Journal of physiology.