changes in synaptic number

caudle at irp.nidr.nih.gov caudle at irp.nidr.nih.gov
Thu Dec 29 15:40:19 EST 1994


On 28 Dec 1994 17:24:27 GMT, 
Thomas Chimento  <chimento at ursa.arc.nasa.gov> wrote:

>I have been looking for references on changes in the number of synaptic
>connections resulting from an alteration in the input or environment of an
>organism. I have done all the Medline searches under synaptic plasticity
>and read numerous review articles on synapses, but I am unable to find an
>example of anatomical, quantitative  changes in the number of synaptic
>sites anywhere in the nervous system caused by changing the input to that
>part of the nervous system. I am not toaking about dendritic spine numbers,
>but the synaptic sites within existing neurons. 
>
>The reason I am searching for this information is that our experiments in
>the vestibular endorgan have demonstrated a change in the number of
>synaptic sites within hair cells when the gravitational environment is
>altered. In a hypergravity environment produced on a 24' centrifuge (2-g)
>the number of synaptic sites decreases whereas an opposite effect occurs
>when the animals (rats) are placed in microgravity aboard the Space
>Shuttle. I am hesitant to state that this is the only such case
>demonstrated, but have not been able to find any others. Any help would be
>greatly appreciated. Suggestions of key words for a search, books,
>articles, or specific investigators names all would be very helpful. 
>Thanks
>
>Thomas


Interesting..... How do you count the synapses?  What statistical methods 
do you employ? How long must the rats be exposed to altered gravity to 
demonstrate a change? How large is the change? How long does it take the 
rats to return to normal synaptic numbers. How do you control for the 
accelerations to and from the test gravity (Shuttle launch g>>1, Shuttle 
reentry g<<1)? 

I ask these questions because there were a group of studies presented at 
the Society for Neuroscience a few years ago about ultrasound causing 
changes synapses.  I believe these studies died a horrible death before 
publication. However, some may have slipped through.  If you search medline 
with "ultrasound" you may find them.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Robert M. Caudle                                      "If I had my life to
NAB, NIDR, NIH                                         live over, I'd be a
Bldg. 49, Rm 1A-11                                     plumber."
9000 Rockville Pike                                        A. Einstein
Bethesda, MD 20892

Caudle at yoda.nidr.nih.gov
or
Caudle at irp.nidr.nih.gov
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