The Effect of Octopamine on the Locust Stomatogastric Nervous System

Abstract

Octopamine (OA) is a prominent neuromodulator of invertebrate nervous systems, influencing multiple physiological processes. Among its many roles in insects are the initiation and maintenance of various rhythmic behaviors. Here, the neuromodulatory effects of OA on the components of the locust stomatogastric nervous system were studied, and one putative source of OA modulation of the system was identified. Bath application of OA was found to abolish the endogenous rhythmic output of the fully isolated frontal ganglion (FG), while stimulating motor activity of the fully isolated hypocerebral ganglion (HG). OA also induced rhythmic movements in a foregut preparation with intact HG innervation. Complex dose-dependent effects of OA on interconnected FG-HG preparations were seen: 10−5 M OA accelerated the rhythmic activity of both the HG and FG in a synchronized manner, while 10−4 M OA decreased both rhythms. Intracellular stimulation of an identified octopaminergic dorsal unpaired median neuron in the subesophageal ganglion was found to exert a similar effect on the FG motor output as that of OA application. Our findings suggest a mechanism of regulation of insect gut patterns and feeding-related behavior during stress and times of high energy demand.

Bio-Inspired Adaptive Locomotion Control System for Online Adaptation of a Walking Robot on Complex Terrains

“…Neurobiologists have hypothesized that neuromodulation and hormones seem to be integrated in the SEG (personal communication). Additionally, many reports have discussed neuromodulation in relation to a set of motor patterns that are very carefully orchestrated and controlled by different peptides acting as neurohormones or neuromodulators [43]- [45]. Our study also supports these findings and proposes an option for how hormones interact with motor control though neuromodulation (i.e., MI_H) in an artificial walking system, as illustrated in Fig.…”

The Functional Connectivity between the Locust Leg Pattern Generating Networks and the Subesophageal Ganglion Higher Motor Center

“…A potential candidate for the modulation of CPG-CPG interplay in insects is the 539 octopaminergic system (e.g. Rand et al, 2012;Rillich et al, 2013) and its prominent 540 members, the DUM neurons (for review: Libersat and Pflueger, 2004). Indeed, we found 541 that the activity of a descending SEG DUM neurons was correlated with the bilaterally 542 synchronized activity of the contralateral prothoracic CPGs (Fig.…”

Modulation of Low-Voltage-Activated Inward Current Permeable to Sodium and Calcium by DARPP-32 Drives Spontaneous Firing of Insect Octopaminergic Neurosecretory Cells

“…It is also well established that DUM neurons are an important component of different motor networks (Burrows and Pflüger, 1995 ; Baudoux et al, 1998 ; Mentel et al, 2008 ; Vierk et al, 2009 ). Although DUM neurons may be activated by sensory stimuli (e.g., Baudoux and Burrows, 1998 ; Field et al, 2008 ; Pflüger et al, 2011 ; Rand et al, 2012 ), they are defined by the absence of common somatic synaptic inputs from presynaptic neurons and by their uncommon intrinsic property allowing adequate beating pacemaker activity (Grolleau and Lapied, 2000 ; Wicher et al, 2001 ; Defaix and Lapied, 2005 ; Heidel and Pflüger, 2006 ; Lavialle-Defaix et al, 2006 ; Gautier et al, 2008 ). One of the most important key determinants of the DUM neuron excitability is the action potential threshold.…”