Evidence for octopaminergic modulation of an insect visceral muscle
Article first published online: 11 OCT 2004
Copyright © 1985 John Wiley & Sons, Inc.
Journal of Neurobiology
Volume 16, Issue 3, pages 171–181, May 1985
How to Cite
Orchard, I. and Lange, A. B. (1985), Evidence for octopaminergic modulation of an insect visceral muscle. J. Neurobiol., 16: 171–181. doi: 10.1002/neu.480160303
- Issue published online: 11 OCT 2004
- Article first published online: 11 OCT 2004
- Manuscript Revised: 15 NOV 1984
- Manuscript Received: 21 SEP 1984
Two dorsal unpaired median neurons (DUMOV1 and DUMOV2) lying in the posterior region of the VIIth abdominal ganglion of Locusta migratoria have axons which project to the muscles of the oviducts. This study reports the presence of octopamine within isolated DUMOV cell bodies, as well as in the oviducal nerve and innervated oviducal muscle. Individual cell bodies were pooled and found to contain about 0.34 pmol of octopamine per cell body giving an approximate value of 1.27 mM octopamine. Octopamine is concentrated within the area of oviducal muscle which receives DUMOV axons.
Pharmacological studies reveal that the amplitude of neurally-evoked contractions of the oviducal muscle is reduced in a dose-dependent manner by octopamine, with threshold lying between 5 × 10−10M and 7 × 10−9M. The receptors for this response show a specificity for octopamine and synephrine, with an order of potency being octopamine = synephrine > metanephrine > tyramine > dopamine.
The presence of octopamine throughout this neural pathway, coupled with the demonstration of octopaminergic modulation of muscular contraction, supports the hypothesis that octopamine serves a physiological role in this visceral system.