In vitro occurrence of m-octopamine in the cultured cephalic ganglion of Locusta migratoria L. after L-dopa administration.

Cephalic ganglia of the locust Locusta migratoria L. were cultured in the presence of L-DOPA and inhibitors of dopa decarboxylase or dopamine beta hydroxylase. The addition of L-DOPA to the culture medium resulted in a marked increase of m-octopamine, following higher levels of dopamine. L-DOPA produced an increase of m-tyramine. RO 44602 considerably reduced the levels of p and m-octopamines, m-tyramine, dopamine and noradrenaline while fusaric acid reduced only those of p and m-octopamines, m-tyramine and noradrenaline. Though not normally found in the locust nervous system, m-octopamine appears to be closely related to catecholamines and to be produced via their biosynthesizing enzymes through a hypothetical dehydroxylation step.