Text 1121, 81 rader
Skriven 2004-12-20 21:47:00 av R Norman (1:278/230)
Ärende: Re: Question regarding th
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On Mon, 20 Dec 2004 05:39:52 +0000 (UTC), tomhendricks474@cs.com
(TomHendricks474) wrote:

>Someone mentioned neurons and it made me think of this quote.
>
>"Miles (Herkenham) has estimated that counter to the collective wisdom of the
>neuropharmacologists and neuroscientists, less than 2 persent of neuronal
>communication actually occurs at the synapse.  It was so radical an idea that
>for several years his observation of the mismatches was ignored and attributed
>to artifacts of the mapping techniques. In fact, the way in which peptides
>circulate through the body, finding their target receptors in regions far more
>distant than had every previously been thought possible, made the brain
>communication system resemble the endocrine system, whose hormones can travel
>the length and breadth of our bodies. The brain is like a bag of hormones. Our
>view of the brain, and the metaphors we used to describe it, were permanently
>altered."
>- Candace Pert.
>
>
>Had others heard of this new idea
>that only 2 % at the synapse?
>

Miles Herkenham is a neuroimmunologist at NIH -- see their web site at
  http://neuroscience.nih.gov/Lab.asp?Org_ID=165
which says: "Dr. Herkenham's laboratory explores the molecular,
cellular, and intercellular bases for immune signaling in the brain in
several animal models of inflammation and disease."

See also his lab website at
  http://intramural.nimh.nih.gov/lcmr/sfn/
which says: "Our group uses the tools of modern neuroanatomy to define
and map out regulatory events that occur in animals when they respond
to immune challenges, drug administration, emotional challenges, or
stress. "

It is true that the brain, like all organs of the body, responds to a
variety of challenges generally called "stress" which is mediated
through the immune system.   Neuroimmunology is a very challenging and
difficult field about which far too little is known.

Still, it is a bit of a stretch to claim that only 2% of the
"informational processing" capability of the brain is mediated through
synapses.  What Dr. Herkenham is referring to is the fact that neurons
are living breathing cells that respond to all kinds of factors.
Processing information is only one aspect of what they do.  It is now
well established that there are complex signaling processes between
cells that mediate all sorts of cellular functions.  The immune
system, the endocrine system, and the nervous system use this
signaling system in different ways for different purposes.  However,
in the end, the target cell integrates all the influences that play on
it, whether immune, endocrine, or synaptic, to determine just what it
does.

The signals studied by Dr. Herkenham's lab are more involved in
controlling metabolic pathways and regulating gene expression and
protein synthesis in the neuron than in determining whether or not the
cell is going to produce an action potential or release synaptic
transmitter, the traditional role of the synapse.  However, there does
exist a tremendous overlap in systems.  Metabotropic synapses mediate
neuromodulatory events by controlling metabolic and gene transcription
pathways. Immune and endocrine signaling mediates electrical signaling
by controlling the synthesis of proteins essential for bioelectric
events.

I am not familiar with the 2% quote you cite nor of any particular
controversy about claims from Dr. Herkenham.  It is true, though, that
the realization of the primacy of cell signaling and the recognition
of the enormous role of neuromodulation did take some time to become
accepted.  However it is now quite routine in cell biology courses to
discuss synaptic transmission in the same context as hormone action
and immune system function.
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