On 24 Oct 1995, Stephan Anagnostaras wrote:
> > Glutamate agonists may be neurotoxic via both NMDA and non-NMDA receptors
> > if given i.c.v. The evidence that glutamate is neurotoxic following oral
> > administration in man (including neonates) is lacking. This has been
> > convinvingly demonstrated only in neonatal rodents. The August 1995 FASEB
> > (FDA) report on all aspects of the safety of MSG concluded that orally
> > administered glutamate was wholly safe, although there may be a very small
> > subgroup of individuals who show some sensitivity and exhibit peripheral
> > (not CNS effects). Furher research has been indicated in a small number of
> > asthmatics who may show sensitivity. Glutamate basically does not enter
> > the brain, or rather, there is no net accumulation. Compounds like domoic
> > acid from contaminated mussels, do cross the bbb to activate kainate/AMPA
> > receptors and produce neurotoxic sequelae.
> > Peter Roberts
>> Sure, but under normal physiological conditions I don't think AMPA
> receptors contribute much to neurotoxic damage, because they depotentiate
> rapidly when rapidly overstimulated. This is why the whole brain doesn't
> die during hypoxia but just places where there are lots of NMDA receptors.
> So the system overall is pretty conservative; NMDA receptors won't be
> activated unless there are already lots of AMPA receptors activated
> and these are usually going to depotentiate rapidly.
>[stuff deleted]
this is not completely true--there is a small subset of ampa receptors
that mediate Ca2+ entry into the cell. cells that have these special
receptors are particularly vulnerable to neurotoxic insults. jh weiss
does a lot of work on these receptors/cells--do a medline search on him
if interested, i think most of his papers are on this issue.
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-neal prakash
aka shrapnel
http://meded.com.uci.edu:80/~nprakash/neal.html
"In addition they seemed to spend a great deal of time eating and drinking
and going to parties, and Frensic, whose appearance tended to limit his
sensual pleasures to putting things into himself rather then into other
people, was something of a gourmet. (tom sharpe, 1977)
