The regulation of feeding and metabolism in response to food deprivation in Caenorhabditis elegans

Abstract

This review considers the factors involved in the regulation of feeding and metabolism in response to food deprivation using Caenorhabditis elegans as a model organism. Some of the sensory neurons and interneurons involved in food intake are described, together with an overview of pharyngeal pumping. A number of chemical transmitters control feeding in C. elegans including 5-hydroxytryptamine (5-HT, serotonin), acetylcholine, glutamate, dopamine, octopamine, and tyramine. The roles of these transmitters are modified by neuropeptides, including FMRFamide-like peptides (FLPs), neuropeptide-like protein (NLPs), and insulin-like peptides. The precise effects of many of these neuropeptides have yet to be elucidated but increasingly they are being shown to play a role in feeding and metabolism in C. elegans. The regulation of fat stores is complex and appears to involve the expression of a large number of genes, many with mammalian homologues, suggesting that fat regulatory signalling is conserved across phyla. Finally, a brief comparison is made between C. elegans and mammals where for both, despite their evolutionary distance, classical transmitters and neuropeptides have anorectic or orexigenic properties. Thus, there is a rationale to support the argument that an understanding of the molecular and genetic basis of feeding and fat regulation in C. elegans may contribute to efforts aimed at the identification of targets for the treatment of conditions associated with abnormal metabolism and obesity.

Modulation of appetite and feeding behavior of the larval mosquito Aedes aegypti (L.) by the serotonin-selective reuptake inhibitor paroxetine: shifts between distinct feeding modes and the influence of feeding status.

“…Received 31 July 2013; Accepted 5 November 2013 Luedtke et al, 2010;Gaudry and Kristan, 2012). We investigated these pathways further using the serotonin-selective reuptake inhibitor (SSRI) paroxetine (Paxil TM ).…”

“…As in vertebrates, serotonergic pathways inhibit appetite and feeding behavior in insects (Gillette, 2006;Halford et al, 2007). In both insects and vertebrates, feedback to feeding centers reflecting overall energy and nutrient balance is provided by peptide hormones and neurotransmitters including neuropeptide Y and insulin-like peptides (Gruninger et al, 2007;Nässel and Wegener, 2011;Tecott, 2007;Luedtke et al, 2010).…”

Two Forms of Learning following Training to a Single Odorant in Caenorhabditis elegans AWC Neurons

“…As such, the presence of food (E. coli OP50) or exogenous serotonin, a food signal (Luedtke et al, 2010), obviates the adaptive response in a manner consistent with the properties of associative learning. This suggested a serotonergic mechanism acts on a food-sensitive step in Bnz adaptation to block memory formation (Nuttley et al, 2002).…”

Caenorhabditis elegans: An Emerging Model System for Pesticide Neurotoxicity

“…For example, dopamine signaling facilitates the response of C. elegans to environmental changes by modulating locomotion. Well-fed wild-type nematodes slow their movements when they encounter a food source, a process requiring dopamine release [76,77]. Nematodes that have their dopaminergic neurons ablated fail to exhibit this "slowing" process, further supporting the supposition that these neurons are mechanosensory and that slowing is likely caused by physical stimuli [78].…”

“…For example, a food-deprived nematode will come to a complete stop upon entering a bacterial lawn versus a well-feed nematode that will just slow [61]. Serotonin signaling helps ensure that food-deprived nematodes do not leave a food source, while dopamine signaling encourages nematodes to stay within that source [61,76,80]. Synthesis of serotonin occurs in neurosecretory motor neurons (NSMs) that have sensory endings located in the lumen of the pharynx.…”