STUDIES ON BIOGENIC-AMINES AND METABOLITES IN NERVOUS-TISSUE AND HEMOLYMPH OF MALE CABBAGE-LOOPER MOTHS .3. FATE OF INJECTED OCTOPAMINE, 5-HYDROXYTRYPTAMINE AND DOPAMINE

Adult male cabbage looper moths, Trichoplusia ni, were injected with two dosages of octopamine, or 5-hydroxytryptamine, or dopamine. The dosages were 1 and 10 mu g, the latter a dosage that was previously shown to induce changes in nocturnal locomotor activity (5-hydroxytryptamine) and sensitivity to sex pheromone (octopamine). Injections were made into the hemolymph in the head capsule dorsal to the supraesophageal ganglion. Males were injected 1 hr prior to the onset of scotophase, and then brains + optic lobes, thoracic ganglia and hemolymph were analyzed at five time intervals over the following 6 hr. Levels of the three amines and their N-acetylated metabolites were quantified using HPLC with electrochemical detection. With the 1 mu g dosage of the three amines, there was a significant increase in hemolymph values, but no changes in levels in the nervous system. With the 10 mu g dosage, significant increases in each amine were found in the hemolymph, thoracic ganglia and brain + optic lobes. Levels of injected amines then rapidly decreased from hemolymph and nervous tissue. Within 2.5 hr following injections, levels of octopamine and dopamine in the brain + optic lobes and thoracic ganglia stabilized at twice the level in saline injected controls, 5-hydroxytryptamine levels were below control levels and hemolymph levels of each amine were not significantly different from controls. Decreases in amine levels were accompanied by significant increases in the N-acetylated form of each amine. In no instance did we observe a measurable peak for metabolites that would suggest the presence of MAO activity.