Monoamines and peptides interact to inhibit glutamatergic signaling in Caenorhabditis elegans
Year: 2010
Type: article
Abstract: Monoamines and peptides modulate neuronal plasticity and interact to define behavioral state.However, little is known about specific interactions between monoaminergic and peptidergic signaling due in large part to the complexity of the mammalian nervous system.Therefore, we have examined the monoaminergic/peptidergic modulation of simple behaviors using the well characterized and genetically-tractable Caenorhabditis elegans model system.Octopamine (OA), often considered the invertebrate equivalent to noradrenaline, inhibits key behaviors in C. elegans and often acts antagonistically to serotonin (5-HT).However, virtually nothing is known about the individual OA receptors or neuronal circuits involved in this modulation.In the present study, tyramine (TA) and OA each independently abolish 5-HT dependent increases in aversive responses mediated by a single pair of nociceptive ASH sensory neurons.Octopaminergic inhibition of ASH-mediated aversive responses iv involves three α -adrenergic-like OA receptors, OCTR-1, SER-6 and SER-3, depending on the intensity of the initiating stimulus.At low levels of stimulation, OCTR-1 inhibits signaling in the ASHs directly through a Gα o dependent pathway and at increasing ASH stimulation a second OA receptor, SER-6, signals the release of inhibitory peptides from the ADL, AWB and ASI sensory neurons through a Gα s/q -dependent pathway.In addition, SER-3 opposes the action of OCTR-1 in the ASHs at higher exogenous OA concentrations.Specifically, the OA and SER-6 -dependent release of peptides encoded by nlp-7 and 8 from the ADLs, nlp-9 from the AWBs and nlp-6, 7 and 9 from the ASIs is essential for maximal OA inhibition of aversive responses to 100% octanol.These studies highlight the complexity of octopaminergic/peptidergic interactions in the translation of nutritional state to the modulation of aversive behavior and suggest that the OA modulation of ASH-mediated aversive behavior may be an excellent model to examine the mechanism(s) that prevent the overstimulation of sensory mediated circuits.
Author: Rachel T. Wragg
Institution: University of Toledo
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2226760499