Effects of octopamine, dopamine, and serotonin on production of flight motor output by thoracic ganglia of Manduca sexta

Abstract

Effects of biogenic amines on a centrally generated motor pattern in Manduca sexta were examined by pressure injecting nanomole to micromole amounts of octopamine, dopamine or serotonin into thoracic ganglia. Motor output was recorded extracellularly from a pair of antagonistic flight muscles and their motor neurons. The monoamines were found to alter production of a motor pattern that produces rhythmic wing flapping (10 Hz) and exhibits phase relationships similar to those in the flight pattern of intact moths. In mesothoracic ganglia with sensory nerves intact, octopamine (4 X 10(-9) mol) injected into lateral regions evoked regular firing of a single motor neuron, whereas a higher dose (4 X 10(-8) mol) often elicited the flight motor pattern. In the absence of sensory input, these doses of octopamine had little effect. Low doses (10(-10) mol) greatly enhanced motor responses to electrical stimulation of a wing sensory nerve. Dopamine (2 X 10(-10) mol) injected into the medial region of the mesothoracic ganglion elicited the flight motor pattern in the presence or absence of sensory input. Rhythmic output induced by dopamine (5 X 10(-10) mol) was suppressed by injecting serotonin (5 X 10(-10) mol) into the same region. These findings demonstrate that dopamine, octopamine, and serotonin have different effects on motor output in Manduca and suggest that these amines are involved in initiating, maintaining and terminating flight behavior, respectively. Octopamine may elicit flight production by enhancing the efficacy of sensory transmission thereby increasing excitability or arousal. Dopamine may act on interneurons involved in generating the flight motor pattern.

Loss of Flight and Associated Neuronal Rhythmicity in Inositol 1,4,5-Trisphosphate Receptor Mutants ofDrosophila

“…In addition, the observation of partial loss of flight and associated physiology in DdCGAL4/UAS-TNT flies suggests that there is a requirement for DdCGAL4 neurons in the acute control of flight in adult Drosophila. This idea is supported by studies in Manduca sexta where biogenic amines have been shown to play a role in initiating, maintaining, and terminating flight behavior (Claassen and Kammer, 1986). At this stage, our experiments cannot directly address the requirement for the InsP 3 R in adult DdCGAL4 neurons.…”

Flight Initiation and Maintenance Deficits in Flies with Genetically Altered Biogenic Amine Levels

“…Although acute application of OA is sufficient to elicit flight in a number of different insect preparations (Sombati and Hoyle, 1984;Claassen and Kammer, 1986;Stevenson and Kutsch, 1987;Duch and Pflueger, 1999), OA is not necessary for the initiation of flight in Drosophila but modulates flight initiation and maintenance. Even flies without any OA/TA-containing neurons can fly.…”

“…In principle, both could be controlled by aminergic action on the CPG and/or on the fly's sensory system. It is well established that OA acts on the CPG in a number of insect species (Sombati and Hoyle, 1984;Claassen and Kammer, 1986;Stevenson and Kutsch, 1987), but central actions of TA are not known. OA has also been reported to increase the responsiveness of flight-associated sensory cells in insects (Ramirez and Orchard, 1990), and TA could conceivably reduce excitability of sensory neurons as Drosophila TARs activate chloride currents (Cazzamali et al, 2005).…”

Serotonin modifies the sensitivity of the male silkmoth to pheromone

“…Serotonin affects the central nervous system as well as the sensory periphery and the neuromuscular junction (Evans, 1980;Mercer and Menzel, 1982;Claassen and Kammer, 1986;Nässel, 1988;Casagrand and Ritzmann, 1992;Erber et al, 1993;Menzel et al, 1999).…”