Orthograde and retrograde axonal transport of labeled protein in motoneurons
1976; Elsevier BV; Volume: 50; Issue: 3 Linguagem: Inglês
10.1016/0014-4886(76)90032-7
ISSN1090-2430
Autores Tópico(s)Pesticide Exposure and Toxicity
ResumoAfter injection of 3H-l-leucine into the vicinity of rat lumbosacral motoneurons, a wave of labeled protein traveled along the sciatic nerve with a velocity of 428 mm/day. Subsequent events were followed by crushing the sciatic nerve at intervals after injection and measuring the accumulation of label at crushes over a 3-hr period. The 3-hr accumulation at the proximal side of a crush declined rapidly over the first 10 hr after precursor administration. Over the period 10 to 99 hr proximal accumulations declined more slowly. Three hour accumulations at the distal side of a crush were initially low but rose to a peak at 44 to 47 hr, when distal accumulation was 180% of proximal accumulation. Thereafter distal accumulation declined. After intravenous injection of leucine, accumulations of activity which occurred at nerve crushes were only 3 to 6% of the accumulation observed when leucine was injected into the lumbosacral cord. Injury currents were not responsible for conveying material to the crush region. It was concluded that accumulation represented the damming-up of material derived from the motoneuron and in transit along the axon. The pattern of accumulation at the nerve crushes was interpreted thus: after precursor administration there was a 6-hr phase of orthograde protein transport containing large amounts of activity, followed by a more sustained phase containing smaller amounts of activity. Some of the transported protein was returned to the cell body after spending about 30 hr in the terminals. During the period 4 to 99 hr after precursor administration, the quantity of label returning to the cell body was half the amount transported into the axons.
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