STUDIES ON AXONAL FLOW OF DOPAMINE β-HYDROXYLASE AND TYROSINE HYDROXYLASE IN SCIATIC NERVES BY IMMUNO-FLUORESCENT AND BIOCHEMICAL METHODS

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Abstract
The transport of dopamine .beta.-hydroxylase (DBH) and tyrosine hydroxylase (TH) in guinea pig sciatic nerves was studied by measuring the accumulation of these enzyme activities to a ligature. Axonal flow of DBH protein in rat sciatic nerves was also studied by immunofluorescence, and the anatomical results were compared with the biochemical results. The DBH immunofluorescence was increased in the proximal 3 mm segment of a ligature up to 48 h after ligation. The DBH activity accumulated in the proximal 3 mm segment until 48 h after ligation. Retrograde axonal flow of DBH or TH was observed in double ligation experiments at 5 h after ligation, but at 24 h the retrograde axonal flow apparently changed to the orthograde. The mean, or absolute axonal flow rate (millimeters/24 h) of DBH in guinea pig sciatic nerves was 100, or 180, while that of TH was 20, or 32, respectively. DBH and TH may be localized in different intracellular compartments; DBH may be transported at a fast flow rate as a particulate enzyme, while TH at an intermediate flow rate mostly as a cytoplasmic enzyme.