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[Neuroscience] Re: Can a single neuron release multiple neurotransmitters?

John H. via neur-sci%40net.bio.net (by j_hasenkam At yahoo.com.au)
Mon Jan 29 08:28:09 EST 2007



On Jan 21, 7:22 am, "Zachary  Tong" <polyfrac... At gmail.com> wrote:
> Thanks again to everyone who replied to me.  This is thoroughly
> interesting and I find the material fascinating (despite only being an
> undergrad just getting into this work).
>
> >>Can't be sure but know of one example that highlights what you're
> >>driving at. CB 1 receptors - cannabinoid receptor. Cannabinoid
> >>consumption slowly leads to the retraction of these receptor from the
> >>cell surface. In one study the degree of cannabinoid tolerance was
> >>found to be directly related to the loss of these receptors(mice). It
> >>has been suggested that these receptors are then degraded and never
> >>find their way back to the cell membrane, thus requiring gene
> >>transcription to create new receptors. Hence, long continual pot
> >>smoking radically alters the number of CB 1 receptors. Cessation, will,
> >>hopefully, restore the receptor balance but that could take weeks if
> >>not months.

Thats exactly the idea I was thinking.  I wasn't sure, however, if it
> the loss of sensitivity was a "choice" of the neuron, or if it was
> because of molecular actions.  Based off your comment about the CB1
> receptors, it appears that it is based in molecular limitations.  Then
> again, it appears that the brain has evolved to use these limitations
> to its advantage, so perhaps its not a limitation as I first assumed.


Never think about choice, even in parentheses. Remove all such 
thinking from your mind. The reason for the change is because the 
animal must still interact with its environment and the changes in 
receptor levels mediated by exogenous agents require adjustments in 
order to maximise beneficial behavior. Now there will be more to it 
than that but never forget that trying to understand the brain without 
reference to its function in the world is like trying to study 
aerodynamics on the moon.


> >>I doubt there would be a way to select between the transmitters for
> >>release - after all an action potential is an action potential.  However
> >>I could imagine that secondary transmitters leaking back across the
> >>synaptic cleft could influence the releasability of presynaptic vesicles
> >>of different kinds.  That's just a guess though.This makes sense.  The interplay of secondary transmitters and reuptake
> of primary neurotransmitters with the presynaptic end probably adds
> another layer of complexity to the brain, allowing for complex
> behaviors to arrise from a fairly simplistic subunit (relatively
> speaking of course, the neuron is fascinatingly complex in its own
> right)
>
> >>For example, SSVs (containing e.g.,
> >>ACh, glutamate, GABA) are released after single spikes, whereas high
> >>frequency trains are required to mobilize and release LDCVs containing
> >>peptides.Thats really interesting stuff.  The fast and slow actions of the
> different vesicles add yet another layer of complexity.  I'd imagine
> that, despite being complex, each neuron fires its various transmitters
> in a predicatable manner depending on the input.  I'd assume the key to
> understanding higher cognitive function is understanding the complex
> firing patters, which in turn would mean knowing the exact reasons for
> various neurotransmitter release.
>
> Thanks for the papers, I'm about to go read them.  They look
> fascinating :)
>
> Lastly, I was curious on the technicalities of conducting "research".
> I'm a comp. sci major, but have been highly interested and motivated in
> learning about neuroscience.  I've been drafting a prototype brain
> simulation, based off of brain structure (particularly the neocortex)
> and theories of how the the neocortex works (collection of several
> authors).  Anyhow, it should be "functional" (although entirely
> possible it not useful) soon, and I'm curious how I should go about
> documenting my results.  Take lots of data and date all material?
> Should I record observations in a formal manner?
>
> Basically, should I stumble across something publication worthy, how
> should I go about documenting my work so that if that time comes, I'm
> ready?  Thanks.
>
> -Zachary Tong



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