Metabotropic Pathways

James Teo james at teoth.fsnet.co.uk
Fri Jan 18 21:49:30 EST 2002

On 16 Jan 2002 15:28:01 -0800, mats_trash at hotmail.com (mat) wrote:

>"yan king yin" <y.k.y@(dont spam)lycos.com> wrote in message news:<PVd18.935$na5.123627 at news.xtra.co.nz>...
>> There could be two types of diffusion. One is retrograde, from
>> postsynaptic to presynaptic. Another type is from one postsynaptic
>> site to another postsynaptic site nearby (inside the same dendrite).
>> Im suggesting this latter form might lead to some interesting learning
>> rules.
>There is actually spillover of transmitter itself at some synapses. 
>Another thing you might want to investigate for your learning rules is
>the role of Glial cells.  THey are not passive structural cells but
>actually participate in transmitter uptake from synpases etc. further
>a system of 'volume transmission' of molecules such as NO over broad
>areas of the brain has been found to be due to glia.  Its role in
>higher function is unclear though.

And on the topic of glia, I can tell you that they are very active
cells in neurotransmission. I did some work on glial metabotropic
glutamate receptors 3 years ago, and I found that mGlu agonists
increase glutamate release from glial cells and mGluR5 antagonists
inhibited this process. Now there are loads of neurotransmitter
receptors (ionotropic and metabotropic) on glial cells so it is not
surprising if they somehow modulate synaptic transmission in some way.
Someone (Nerdergaard is his name I believe) has done a lot of work on
this area and has postulated a new view of the synapse: the synapse as
a tripartite connection. 

Glia makes for a complex additional pathway for retrograde synaptic
transmission other than simple molecules like NO and CO.

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