Journal of Neuroscience, Vol 6, 1712-1718, Copyright © 1986 by Society for Neuroscience
Consequences of partial axotomy for production of neurotransmitter vesicles and routing of rapidly transported membrane glycoproteins in the axonal tree
DJ Goldberg and RT Ambron
It was found previously that transection of one branch of the bifurcate
axon of a giant serotonergic neuron of Aplysia causes a proportionate
decrease in the export of transmitter storage vesicles from the cell body,
despite the ability of the remaining branch to transport all of the
vesicles normally exported (Aletta and Goldberg, 1982). We report here
evidence that this down-regulation is achieved by a decrease in the
production of vesicles, rather than a slowing of the processing of vesicles
for export from the cell body. Counts of serotonergic vesicles in the cell
body show that the size of the somal pool of vesicles is not increased at a
time when their rate of export has been halved. Also, transection of one or
both branches of the axon decreases the amount of 3H-fucose incorporated
during a short period into a putative vesicle membrane glycoprotein but not
into other glycoproteins. The results indicate that axotomy should be a
useful technique for studying the mechanism of regulation of the synthesis
of a secretory organelle. It was also previously shown that transection of
one branch of the axon far from the cell body does not impair the ability
of the injured branch to transport serotonergic vesicles, yet the majority
of vesicles that would normally enter that branch are nevertheless rerouted
into the uninjured branch. We have studied quantitatively the partitioning
between the 2 branches, after one has been transected distally, of 6
fucosyl glycoproteins, including the putative vesicle glycoprotein and a
glycoprotein whose transport moderately increases after
transection.(ABSTRACT TRUNCATED AT 250 WORDS)