Journal of Neuroscience, Vol 5, 2018-2027, Copyright © 1985 by Society for Neuroscience
Dendritic transport. II. Somatofugal movement of neuronal lysosomes induced by colchicine: evidence for a novel transport system in dendrites
C Gorenstein and CE Ribak
The effect of colchicine injections on the ultrastructural localization of
dipeptidyl peptidase II (Dpp II) was studied in the mitral cells of the rat
olfactory bulb. In control animals, electron-dense reaction product
representing Dpp II activity was observed in lysosomes, lipofuscin
granules, short cisternae located close to the granular endoplasmic
reticulum, and dense granules. Lysosomes and lipofuscin granules were the
most intensely stained organelles. Dpp II-containing organelles were
localized mainly to the cell body and were randomly distributed in the
perikaryal cytoplasm. Twenty-four hours after a 100- micrograms
intracerebroventricular colchicine injection, the distribution of Dpp
II-containing organelles was drastically altered. Short cisternae and dense
granules containing Dpp II reaction product were noticeably absent in these
preparations. Lysosomes and lipofuscin granules were depleted from the
perikaryal cytoplasm and were concentrated in dendrites. Lysosomes were
observed to extend for considerable distances in dendrites where they
acquired elongated and dumbbell shapes. The shapes of some of these labeled
lysosomes gave the impression that they were actively being "pulled" into
the dendrites. These results indicate that microtubules sequester lysosomes
to the perikaryal cytoplasm and suggest the presence of a novel transport
system responsible for the movement of lysosomes from the cell body to the
dendrites.