Journal of Neuroscience, Vol 2, 934-941, Copyright © 1982 by Society for Neuroscience
Axonal transport of muscarinic cholinergic receptors in rat vagus nerve: high and low affinity agonist receptors move in opposite directions and differ in nucleotide sensitivity
MA Zarbin, JK Wamsley and MJ Kuhar
The presence and transport of muscarinic cholinergic binding sites have
been detected in the rat vagus nerve. These binding sites accumulate both
proximal and distal to ligatures in a time-dependent manner. The results of
double ligature and colchicine experiments are compatible with the notion
that the anterogradely transported binding sites move by fast transport.
Most of the sites accumulating proximal to ligatures bind the agonist
carbachol with high affinity, while most of the sites accumulating distally
bind carbachol with a low affinity. Also, the receptors transported in the
anterograde direction are affected by a guanine nucleotide analogue
(GppNHp), while those transported in the retrograde direction are less, or
not, affected. The bulk of the sites along the unligated nerve trunk bind
carbachol with a low affinity and are less sensitive to GppNHp modulation
than the anterogradely transported sites. These results suggest that some
receptors in the vagus may undergo axonal transport in association with
regulatory proteins and that receptor molecules undergo changes in their
binding and regulatory properties during their life cycle. These data also
support the notion that the high and low affinity agonist form of the
muscarinic receptor represent different modulated forms of a single
receptor molecule.