Studies on biogenic amines and their metabolites in nervous tissue and hemolymph of adult male cabbage looper moths—I. Quantitation of photoperiod changes

Abstract

HPLC with electrochemical detection was used to quantify levels of 5-hydroxytryptamine, octopamine, dopamine, tryptophan, tyramine, tyrosine, 5-hydroxytryptophan, 5-hydroxyindolacetic acid, 3,4-dihydroxyphenylacetic acid, N-acetyl-5-hydroxytryptamine, N-acetyloctopamine, and N-acetyldopamine in optic lobes, corpora allata/corpora cardiaca compex, thoracic ganglia, supraesophageal-subesophageal ganglion complex (or brain) and hemolymph in individual male cabbage looper moths, Trichoplusia ni, at five times in the photoperiod. Levels of amines remained unchanged throughout the photophase, but decreased in some tissues during scotophase. In the hemolymph, levels of octopamine increased during the initial part of the dark period, whereas levels of dopamine remained unchanged, and 5-hydroxytryptamine was not detected. Levels of tryptophan, tyrosine, 5-hydroxytrytophan and tyramine did not change significantly over the photoperiod. Levels of N-acetyloctopamine, N-acetylserotonin and N-acetyldopamine in each tissue increased corresponding to the observed decreases in octopamine, 5-hydroxytryptamine, or dopamine. No evidence was found for catabolic activity involving monoamine oxidase. Within individuals, there was no correlation between decreased levels of octopamine and 5-hydroxytryptamine in the brain, or with levels of either of these amines in the thoracic ganglia. However, decreases in octopamine in the thoracic ganglia paralleded decreases in dopamine. The results are discussed with respect to the proposed modulatory action of amines on male moth locomotor activity and response to sex pheromone.