The effect of different types of axonal trauma on the synthesis and transport of amine storage granules in rat sciatic nerves.

In crushed sciatic nerves of rat the accumulation of noradrenaline (NA), proximal to a ligation, proceeds approximately linearly up to 48 hr after operation, as was earlier reported. After 48 hr the NA in the Proximal portion ceases to increase. The reasons for this arrest in N.A-accumulation have been studied in the present investigation. Rat sciatic nerves were cut, ligated, or crushed at a low level 1–23 days prior to sacrifice. Two hours before death, the nerves were crushed at a level of about 2 cm proximal to the initial operations. Using a histochemical fluorescence method, the relative accumulation of NA above the second high crush was studied. In previously cut or ligated nerves, the NA accumulation observed was very low or zero by 7–9 days, and remained low during the observation period. In previously crushed nerves the NA accumulation was also decreased to rather low levels by 7–9 days. At 15 days, however, the NA accumulation was larger again, and histochemically normal accumulation was observed 17–23 days after the initial crush operation. The results may indicate that axonal trauma causes a depression in the synthesis and transport of amine stronge granules in the adrenergic neurons. Furthermore, the degree and duration of depression seemed to vary with the type of trauma performed. Crushing the nerves, which leaves the connective tissues sheaths uninterrupted, facilitating thus regeneration, appeared to cause a less marked and shorter-lasting depression than cutting or ligating the nerves.