Changes in brain octopamine levels during metamorphosis of the moth, Mamestra configurata Wlk

Abstract

During metamorphosis, the amount of octopamine in the brain of Mamestra configurata increased by almost 30-fold, from 0.45 pmoles per brain in the pupa to 12.6 pmoles per brain in the adult. When increases in brain weight were taken into account, the change was more than ten-fold, from 9.8 pmoles per mg dry brain weight to 110 pmoles per mg dry brain weight. The rise in the level of octopamine occurred rapidly during the last ten days of metamorphosis and paralleled increases in the activity of octopamine-sensitive adenylate cyclase both in time and in relative magnitude of change. The highest concentration of octopamine and the highest specific activity of octopamine-sensitive adenylate cyclase occur in the optic lobes of the adult brain. These observations support a neurotransmitter or neuromodulator role for octopamine in the optic lobes. The low concentration of octopamine and weak activity of octopamine-sensitive adenylase cyclase in the pupal brain of M. configurata appear to be correlated with the low level of sensory input and limited behavioural range of the dormant pupa overwintering in the soil in darkness at sub-zero temperatures. The development of an enhanced octopaminergic system during brain ontogeny may be required to process and/or modulate the greatly increased sensory input of the volant adult, and in particular, to modulate input from the compound eyes.