In article <49a041$c02 at sun4.bham.ac.uk>, g0udm at g3iub.bham.ac.uk says...
>>I am a 1st year Medical Student, and I have been set an essay on the
>effects of the botulinum toxins. I have been able to gather some info
>from books, but what I am really lacking is info on what actually
>at the neuromuscular junction, and how this affects the muscle itself. I
>know that the toxin disables ACh release at the synapse, but I am not
>clear on how this affects the NMJ - is there Wallerian degeneration of
>the nerve fibre or something? Or is the effect felt in a different way?
>The other thing I would like to know (I know this is not strictly
>neuroscience, but I couldn't find any other newsgroups that seemed
>relevant) is what effects there are on the muscle itself. We have been
>asked to outline 'morphological and physiological changes in the muscle
>which occur if recovery takes place'. Can anyone give me any clues on
>>I would be very grateful for any replies!
>>Thanks in advance, James
>>>>If the muscle fiber does not receive stimulation, it undergoes a kind of
de-differentiation. ACh receptors start to appear all over the surface,
they are no longer clustered at the endplate region. They are also a
different type, with one of the subunits being an embryonal form. Also,
If a muscle does not receive stimulation, it will atrophy. There was a
Scientific American article about the nmj about 12 years ago. Sorry I
don't have anything more useful in front of me. Try looking in a
neurophysiology text. A recent literature search probably would not help,
you would need to go back a decade or two.
Jody K. Hirsh
Northwestern University, Chicago, IL. USA
jkh141 at nwu.edu