Editors' ChoiceNeuroscience

Conserved Behavioral Controller

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Sci. Signal.  30 Oct 2012:
Vol. 5, Issue 248, pp. ec279
DOI: 10.1126/scisignal.2003733

The related neuropeptides vasopressin and oxytocin control water homeostasis and mammalian reproductive behaviors, respectively. The role of related peptides in water balance is shared with invertebrates, but whether a role in regulating reproductive behaviors is also conserved is unclear. Using different approaches, two groups have identified the oxytocin- and vasopressin–related neuropeptide nematocin (NTC-1) and its receptors NTR-1 and NTR-2 in the nematode Caenorhabditis elegans. Both groups found that ntc-1 was expressed in thermosensory and mechanosensory neurons in both hermaphrodite and male worms, as well as in male-specific motor neurons that control mating behaviors. Similarly, ntr-1 and ntr-2 were expressed in various neurons of both sexes and in male-specific neurons and muscles involved in mating. Garrison et al. investigated the role of nematocin in male mating behaviors and found that whereas ntc-1, ntr-1, or ntr-2 mutant hermaphrodites showed normal locomotory and mating behavior, male mutants exhibited abnormal mating behaviors and reduced mating success. Having observed that ntc-1 was expressed in a gustatory neuron and in chemosensory neurons, Beets et al. explored the role of ntc-1 in salt (NaCl)–stimulated chemotaxis. ntc-1 mutants showed normal attraction to low concentrations of NaCl and avoidance of high concentrations of NaCl but were defective in salt-induced gustatory plasticity, which couples the NaCl response to food-seeking behavior. Wild-type worms are attracted to NaCl because it indicates the presence of food, but when worms arrive at an NaCl source and find no food, they subsequently show reduced or absent chemotaxis toward NaCl. ntc-1 and ntr-1 mutants showed reduced avoidance of NaCl after preexposure to NaCl in the absence of food. However, these mutants showed normal starvation-induced gustatory plasticity, indicating a specific defect in salt-induced gustatory associative learning. Genetic interaction experiments indicated that nematocin signaling cooperated with serotonergic and dopaminergic pathways in gustatory plasticity. A Perspective by Emmons considers the similarities between these reported roles for nematocin in mating and associative learning and the roles for oxytocin and vasopressin in regulating reproductive behaviors such as mating, pair-bonding, and parenting in mammals.

J. L. Garrison, E. Z. Macosko, S. Bernstein, N. Pokala, D. R. Albrecht, C. I. Bargmann, Oxytocin/vasopressin-related peptides have an ancient role in reproductive behavior. Science 338, 540–543 (2012). [Abstract] [Full Text]

I. Beets, T. Janssen, E. Meelkop, L. Temmerman, N. Suetens, S. Rademakers, G. Jansen, L. Schoofs, Vasopressin/oxytocin-related signaling regulates gustatory associative learning in C. elegans. Science 338, 543–545 (2012). [Abstract] [Full Text]

S. W. Emmons, The mood of a worm. Science 338, 475–476 (2012). [Abstract] [Full Text]

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