MONOAMINE OXIDASE ACTIVITY IN RAT SCIATIC NERVES AFTER CONSTRICTION

The activity of monoamine oxidase (MAO) above and below a ligature of rat sciatic nerve has been studied with biochemical and histochemical methods. In the proximal part of the nerve an increase of enzyme activity to a level of 240% of normal was observed after seven days. At three weeks the values were almost in the normal range. In animals which gad undergone lumbar sympathectomy beforehand, the increase in MAO activity after seven days was significantly lower than in normal animals. After two weeks the sympathectomized group reached a peak activity of 215%, and was normal at three weeks. It is suggested that the earlier accummulation of MAO activity observed in normal nerves at seven days is due to a small but relatively fast-moving MAO pool (probably the mitochondria) within the adrenergic axons. In the distal part there was a decrease in enzyme activity after two or three weeks both normally and after lumbar sympathectomy. Thus, the behaviour of the MAO activity is quite different from that of noradrenaline, dopamine-β-hydroxylase activity and dihydroxyphenylalanine-decarboxylase activity after nerve ligation. © 1969.