See articles on 'Long-term potentiation' for the supposed role of NO as a
retrograde messenger in Hebbian responses (synaptic strengthening). As for
its role in dendritic sprouting, I've haven't as yet come across any
evidence for it. Note: 'nerve growth factor' belongs to a class of trophic
factors known as NEUROTROPHINS and also includes neurotrophin 3/4 and
neurotrophin 5, in man. Thus, if it IS true(???), NO acts as a neurotrophin.
T.L.S.
TonyJeffs2 <tonyjeffs2 at aol.comTonyJ> wrote in message
news:20000630031043.06267.00001789 at nso-fo.aol.com...
> In article <395BA0E9.E12EC8BF at nospam.com>, rh <rh at nospam.com> writes:
>> >
> >As I understand it, as neural pathways are used
> >the spines grow and become more numerous.
> >
> >My question is: why? Why do they get bigger? Also, do they multiply,
> >or are they just changing shape?....what accounts for this new form that
> >they take?
> >
> >Thanks.
>> I am not an expert, but think that this is caused by 'retrograde
messengers'.
> When a neurotransmitter conveys a message accross a synapse, the neuron on
the
> receiving end sends back a reply in the form of a retrograde messenger.
For
> example the gas NO is a type of retrograde messenger. It has a very short
life,
> and when it is released from the post-synaptic membrane, itdiffuses into
the
> surrounding area. The more activity there is at the synapse, the more NO
is
> released. The NO also acts as a' nerve growth factor' , and the more
there
> is, the more it stimulates the growth of new branches from nearby neurons.
>> That is the way I understand it.
>> Tony
>
