Control of alternative behavioral states by serotonin in Caenorhabditis elegans.
Serotonin has been implicated in the regulation of a wide range of brain functions involving alternative behavioral states, including the control of mood, aggression, sex, and sleep. Here, we report that in the nematode Caenorhabditis elegans, serotonin controls a switch between two distinct, on/off states of egg-laying behavior. Through quantitative analysis of the temporal pattern of egg-laying events, we determined that egg laying can be modeled as a novel random process, in which animals fluctuate between discrete behavioral states: an active state, during which eggs are laid in clusters, and an inactive state, during which eggs are retained. Single-cell ablation experiments indicate that two pairs of motor neurons, HSNL/HSNR and VC4/VC5, can induce the active phase by releasing serotonin. These neurons also release acetylcholine, which appears to trigger individual egg-laying events within the active phase. Genetic experiments suggest that determination of the behavioral states observed for C. elegans egg laying may be mediated through protein kinase C-dependent (PKC-dependent) modulation of voltage-gated calcium channels.
Department of Biology, University of California, San Diego, La Jolla 92093, USA.
L E
LE
Waggoner
G T
GT
Zhou
R W
RW
Schafer
W R
WR
Schafer
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D005260:Female; D008954:Models, Biological; D010058:Oviposition / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D013269:Stochastic Processes
D012701:Serotonin; D000109:Acetylcholine