IUBio

why study neurology?

Brian zhil at online.no
Tue Jan 15 15:29:04 EST 2002


"mat" <mats_trash at hotmail.com> skrev i melding
news:43525ce3.0201151220.2911afcb at posting.google.com...
> Of course :) synpatic plasticity miust be involved in memory, but the
> function of memeory itself may not be reducible to individual synapse
> but higher level networks

Right.

> > Im wondering if the metabotropic receptors have secondary
> > messengers that diffuse to nearby synapses and cross-talk with
> > their pathways, thus modifying those synapses. This might give rise
> > to some interesting learning rules. Thats just my guess and I have
> > to study it more thoroughly.
> >
> Well it depends what you mean...  For example, the activation of
> Phospholipase A2 by diacylglycerol, and the subsequent liberation of
> arachidonic acid which may cross synapses has been postualted as a
> messenger to regulate LTP/LTD, particularly in the gluatmatergic
> system.  Other second messengers (cAMP, IP3) due to the very nature of
> their function have to be hydrophilic to be soluble in the cytosol and
> diffuse to their targets.  Therefore, they would likely find it
> difficult to escape through the cells' plasma membrane effectively
> without some sort of channeling (Arachidonate is lipophilic and
> doesn't suffer this problem).  You might conceive of a leaky membrane
> I suppose, but then this offers little ability to regulate the
> response as you would need to coordinate any useful function.
> Further, second messengers are usually broken down very rapidly after
> receptor activation otherwise they would actually be of no use as
> signalling molecules.  All in all I don't think it very likely for
> cAMP or IP3 etc.. the current literature on arachidonic acid is very
> confused

What about Nitrogen-oxides ?
I've read that it might be one way to give a 'feedback' across synapses.......

Brian





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