Even though the first hint of nonsynaptic neuronal communication
was published in 1969 (Paton & Vizi), this form of neuronal
communication still seems radical to some. Since then much work
has provided evidence for its existence (see Vizi & Labos, 1991;
Vizi, 1984 for reviews).
In brief, nonsynaptic neuronal communication involves release of a
neuromodulator (this could be a peptide or noradrenaline,
acetylcholine, etc.) from a varicosity or axon terminal devoid of
synaptic specialization, which then diffuses some distance (on
the order of 1-3 micrometers) to have its effect at a target cell
via receptors. The receptors are (usually) presynaptic and are
(usually) heteroreceptors (e.g. alpha2 receptors on cholinergic
As one can see, both nonsynaptic neuronal communication and heteroreceptors
increase the complexity of the nervous system tremendously.
My question is this: nonsynaptic neuronal communication implies
that this form of neurotransmission does not have a reuptake
mechanism, doesn't it? That is, in order for the neuromodulator
to make it to the target cell(s) a reuptake mechanism must not be present.
Replies from anyone interested/doing research in this area would
be greatly appreciated. In addition, anyone who would like
to discuss this topic further please reply also.
Post to bionet or direct:
Behavioral Neuroscience Research Group
University of Calgary
jdbecker at acs.ucalgary.ca