DOPA-decarboxylase activity in sciatic nerves of the rat after constriction

Abstract

The DOPA-decarboxylase activity in rat sciatic nerve was estimated at different times after constriction. In the part proximal to the lesion a rapid increase of enzyme activity to about 5 times the normal level was observed during the second day. A reduction from this high level was observed after seven days, and after 14 days the values were almost normal. Below the constriction the changes in DOPA-decarboxylase activity were smaller, but after 4 days an increase of activity to 2.5 times normal was obtained. In rats which had been lumbar sympathectomized the activity of unligated nerves was about half of that of nerves of normal animals. No increase in enzyme activity was observed after ligation in these symphathectomized rats and it was therefore concluded that the increase in enzyme activity observed in normally innervated rats after ligation occurred within the sympathetic postganglionic nerve fibres. The increase in DOPA-decarboxylase activity proximal to a constriction differed from that of noradrenaline with respect to time course and magnitude. The lack of correspondence between these two curves indicates that DOPA-decarboxylase is not localized within the amine storage granules.