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Title: Differential changes in neuromuscular junction morphology after divergence of activity pattern in rat slow and fast skeletal muscles
Author: Jawaid, S.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2000
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The morphology of NMJ was quantified in soleus and EDL muscles during postnatal development. Differences were extensively quantified in adults by measuring various parameters (e.g. junctional area, terminal area, width/length ratio, fragmentation of the terminal, shape coefficient). The fluorescent marker FMI-43 was used to label the presynaptic synaptic vesicles in the terminals, and postsynaptic acetylcholine receptors were labelled with fluorescent Rh α-bungarotoxin. Fibre type proportions and fibre diameter were also studied to see if there is any relation between NMJ morphology and fibre type proportion of fibre diameter. Fibre types in both muscles were studied by using histochemistry and immunohistochemistry. The results demonstrate that NMJ morphologies are very similar initially, except for shape coefficient. Marked changes in NMJ morphological parameters occur in the third postnatal week, when both muscles diverge from their common neonatal activity pattern. Fibre type proportion, initially were slow in both muscles. After onset of the adult activity pattern, the rearrangement in fibre proportions makes soleus predominantly slow- and EDL a fast-twitch muscle. Fibre diameter is always greater in soleus. Fibre diameter increased in both muscles but only after the onset of adult activity. Soleus fibres were wider but have longer synapses. Finally, width/length ratio was found to be a major discriminator between NMJ morphologies in the two muscles. In soleus muscle, but not EDL, a reasonable correlation between width/length ratio of NMJ morphology and fibre types was found. All differences appeared after the establishment of adult activity pattern, supporting the hypothesis. Comparison with other studies, however, suggests the effects of activity are probably indirect, via changes in fibre diameter.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available