CHARACTERIZATION OF THE TYRAMINERGIC SYSTEM IN THE CENTRAL-NERVOUS-SYSTEM OF THE LOCUST, LOCUSTA-MIGRATORIA-MIGRATOIDES

Tyramine occurs in the central nervous system (CNS) of the migratory locust, Locusta migratoria migratoides. The distribution of tyramine within the CNS does not parallel that of octopamine. Tyramine is synthesised from tyrosine in the presence of tyrosine decarboxylase. A second decarboxylase in the CNS is active against 5HTP and DOPA. The locust ganglia incorporate tyramine by high- and low-affinity uptake processes that appear to be independent of dopamine and octopamine. Depolarisation of the locust ganglia by high potassium concentration results in calcium-dependent release of incorporated [H-3]tyramine.