Serotonergic modulation of feeding behavior in Caenorhabditis elegans and other related nematodes.

Serotonin is a conserved neuromodulator that controls feeding behavior in response to environmental inputs in a wide range of species, including the nematode, Caenorhabditis elegans. To understand the detailed mechanism and evolution of serotonergic neuromodulation, the feeding behaviors of C. elegans and related species have been studied intensively because of their simple neural anatomy and genetic manipulability. C. elegans shows patterned movements of a feeding structure called the pharynx, and serotonin modulates feeding rhythms via several serotonin receptors expressed in pharyngeal motor neurons and muscles. Environmental inputs and physiological states like food signals, starvation, and heat affect the activity of serotonergic neurons and downstream neural pathways. We focus on serotonergic neural pathways in the feeding behavior of C. elegans and other nematodes, neuromodulation between environmental inputs and behavioral outputs, and their evolutionary path.