Partial denervation of the rat soleus muscle at two different developmental stages

fisher, T.J.; Vrbová, Gerta; Wijetunge, A.

doi:10.1016/0306-4522(89)90020-1

Cited by 45 publications

(23 citation statements)

References 16 publications

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“…It is possible that the calpains in the motor neurons may supply spatially restricted signals that are needed for the cytoskeletal adaptations necessary for synaptogenesis. In this respect, it is of interest to note that the application of leupeptin (a potent inhibitor of calcium activated neutral protease) to partially denervated muscle results in an increase in the motor unit size and an increase in axonal sprouting when compared to untreated denervated muscle (Fisher et al, 1989). The presence of plentiful calpain I1 mRNA in the motor neurons suggests that this leupeptin induced sprouting may derive from inhibition of calpain 11.…”

Section: Discussionmentioning

confidence: 98%

Regional differences in gene expression for calcium activated neutral proteases (calpains) and their endogenous inhibitor calpastatin in mouse brain and spinal cord

Grynspan

Berman

et al. 1996

J. Neurobiol.

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Section: Discussionmentioning

confidence: 98%

Regional differences in gene expression for calcium activated neutral proteases (calpains) and their endogenous inhibitor calpastatin in mouse brain and spinal cord

Grynspan

Berman

et al. 1996

J. Neurobiol.

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“…It has also been found that following partial denervation of a muscle earlier in development before the reduction of polyneuronal innervation takes place. the size of the large neonatal motor units is maintained (Lowrie et al, 1985;Betz et al, 1980;Fisher et al, 1989). Maintained expansion of motor units over and above their neonatal size has not been achieved in these experiments.…”

Section: Introductionmentioning

confidence: 86%

The Effect of Inhibiting the Calcium Activated Neutral Protease, on Motor Unit Size after Partial Denervation of the Rat Soleus Muscle

Vrbová

fisher

1989

Eur J of Neuroscience

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Rat soleus muscles were partially denervated by removal of the L5 ventral ramus at either 4 - 6 days or 17 - 19 days. Local application of leupeptin, a potent inhibitor of the calcium activated neutral protease to these operated muscles, resulted in a significantly greater maximal tetanic tension and motor unit size, when compared to untreated partially denervated muscles. This was achieved in the 4 - 6 day operated animals by an increased number of terminals and in the 17 - 19 day old animals by increased number of axonal sprouts that maintain contact with muscle fibres. In both groups of operated animals in the leupeptin treated muscles large numbers of motor units were able to maintain or achieve an expanded territory, whilst the size of the largest motor unit did not appear to be increased. It is proposed that leupeptin exerts its effect by inhibiting the degradative action of the neuronal calcium activated neutral protease on the axonal cytoskeleton. Such inhibition may act to prevent or decrease the degradation of cytoskeletal structures in the nerve terminal, and so provide protection for weak terminals at a synapse and growth cones of sprouting axons following partial denervation.

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“…The animals were anaesthetized with sterile chloral hydrate (Sigma; 3-5 % solution, 1 ml/100 g body weight i.P.). Using sterile precautions the L5 ventral ramus which contains the major neural input to soleus muscle was removed on one side (see Fisher et al 1989). Two days later, when the rats were 20 days old, some of the operated animals were anaesthetized as before and a second operation was performed using sterile precautions.…”

Section: Surgerymentioning

confidence: 99%

“…In muscles of neonatal animals, the size of the motor units is enlarged and each motoneurone has more branches and innervates a greater number of muscle fibres than in adults (Brown, Jansen & Van Essen, 1976;O'Brien, Ostberg & Vrbova, 1978). In the soleus muscle of the rat these excess terminal branches retract during the second and third week of life but partial denervation prevents this process and allows the remaining motor units to maintain an enlarged size (Thompson & Jansen, 1977;Lowrie, O'Brien & Vrbova, 1985;Fisher et al 1989;Vrbova' & Fisher, 1989). In this case only the maintenance of contacts between axon terminals and muscle fibres is influenced by the partial denervation and no new branches are produced.…”

Section: Introductionmentioning

confidence: 99%

Temporary loss of activity prevents the increase of motor unit size in partially denervated rat soleus muscles.

Connold

Vrbová

1991

The Journal of Physiology

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SUMMARY1. The effects of temporary short-term paralysis on changes of motor unit size and amount of sprouting after partial denervation of the rat soleus were studied.2. Two to ten months after section of the L5 ventral ramus combined with subsequent treatment with a-bungarotoxin (BTX) the tension developed by the operated muscle was 39±8 % (S.E.M., n = 8) of control unoperated soleus muscles. This is much less than the tension produced by partially denervated, NaCl-treated or untreated muscles which was 66+9% (S.E.M., n = 5) and 66+12% (S.E.M., n = 5) respectively. The smaller tension developed by the BTX-treated muscles was due to the relatively small size of their motor units.3. The mean increase of tension output of individual motor units after partial denervation and treatment with NaCl when compared with controls was 194 + 15 % (S.E.M., n = 4) while in the paralysed muscle this value was only 118+15% (S.E.M., n = 8). This reduced expansion of motor unit size in the BTX-treated soleus was not caused by a decrease of the size of the muscle fibres. Thus a brief temporary paralysis prevents the expansion of motor unit territory that normally occurs in partially denervated muscles.4. Examination of the innervation pattern and incidence of sprouting revealed that in partially denervated NaCl-treated muscles 24+4% (S.E.M., n = 4) of endplates was contacted by either terminal or collateral sprouts, whereas in the BTX-treated muscles only 5 + 2 % (S.E.M., n = 3) of endplates had been contacted by sprouts. Treatment with BTX alone, without partial denervation, did not affect the tension output of the muscles, but caused 8 + 5 % (S.E.M., n = 3) of the endplates to become innervated by collateral sprouts, as compared to only 3 + 2 % (S.E.M., n = 3) in controls.

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Partial denervation of the rat soleus muscle at two different developmental stages

Cited by 45 publications

References 16 publications

Regional differences in gene expression for calcium activated neutral proteases (calpains) and their endogenous inhibitor calpastatin in mouse brain and spinal cord

Regional differences in gene expression for calcium activated neutral proteases (calpains) and their endogenous inhibitor calpastatin in mouse brain and spinal cord

The Effect of Inhibiting the Calcium Activated Neutral Protease, on Motor Unit Size after Partial Denervation of the Rat Soleus Muscle

Temporary loss of activity prevents the increase of motor unit size in partially denervated rat soleus muscles.

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