Journal of Neuroscience, Vol 5, 965-969, Copyright © 1985 by Society for Neuroscience
Retrograde axonal transport of endogenous phospholipids in rat sciatic nerve
R Armstrong, A Toews, RB Ray and P Morell
Anterograde axonal transport of phospholipids occurs at a rate of several
hundred millimeters per day. However, although labeled precursors are
incorporated into phospholipids in the neuronal cell bodies within several
hours, these newly synthesized phospholipids are committed to transport
over a much longer period of time. Thus, maximal accumulation of
radioactive lipids in axons and nerve endings does not occur for several
days (e.g., 4 to 7 days in rat optic tract and sciatic nerve). We have now
investigated the retrograde axonal transport of endogenous phospholipid
molecules in sensory neurons of rat sciatic nerve. Labeled phospholipids
were delivered to axons and nerve endings of these cells by anterograde
axonal transport following injection of [2-3H] glycerol into the L5 dorsal
root ganglion. At various times following precursor injection two
ligatures, 9 mm apart, were applied to the mid-thigh region of the sciatic
nerve. Animals were sacrificed 3 to 48 hr after nerve ligation, nerves were
dissected and sectioned into 5-mm segments, and phospholipid radioactivity
in each segment was determined. The time-dependent accumulation of labeled
phospholipids distal to the distal ligature demonstrated their retrograde
axonal transport. The time course of retrograde transport for these
phospholipids was more prolonged and peaked several days later than the
time course for the anterograde transport phase. Further information
regarding the relationship between radioactive phospholipids arriving at
the nerve endings by anterograde transport, and their subsequent
"turn-around" and retrograde transport back to the nerve cell bodies, was
obtained by analyzing the phospholipid class label distribution of both of
these transport phases at various times following precursor
injection.(ABSTRACT TRUNCATED AT 250 WORDS)