Serotonin Mediates a Learned Increase in Attraction to High Concentrations of Benzaldehyde in Aged "C. elegans"

Autor/inn/en	Tsui, David; van der Kooy, Derek
Titel	Serotonin Mediates a Learned Increase in Attraction to High Concentrations of Benzaldehyde in Aged "C. elegans"
Quelle	In: Learning & Memory, 15 (2008) 11, S.844-855 (12 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	1072-0502
DOI	10.1101/lm.1188208
Schlagwörter	Animals; Associative Learning; Animal Behavior; Age Differences; Cognitive Processes; Learning Processes + Suchen Sie Ihr Suchwort? Animal; Tier; Tiere; Tierverhalten; Age; Difference; Age difference; Altersunterschied; Cognitive process; Kognitiver Prozess; Learning process; Lernprozess
Abstract	We utilized olfactory-mediated chemotaxis in "Caenorhabditis elegans" to examine the effect of aging on information processing and animal behavior. Wild-type (N2) young adults (day 4) initially approach and eventually avoid a point source of benzaldehyde. Aged adult animals (day 7) showed a stronger initial approach and a delayed avoidance to benzaldehyde compared with young adults. This delayed avoidance is due to an increased attraction rather than a decreased avoidance to benzaldehyde because (1) aged "odr-3" mutants that are defective in odor attraction showed no delayed benzaldehyde avoidance, and (2) the delay in avoidance was also observed with another attractant diacetyl, but not the repellent octanol. Interestingly, the stronger expression of attractive behavior was only observed at benzaldehyde concentrations of 1% or higher. When worms were grown on nonbacterial growth media instead of "Escherichia coli", thus removing the contingency between odors released from the food and the food itself, the increase in attraction to benzaldehyde disappeared. The increased attraction recovered after reinitiating the odor-food contingency by returning animals to "E. coli" food or supplementing axenic media with benzaldehyde. Moreover, serotonin-deficient mutants showed a deficit in the age-enhanced attraction. These results suggest that the increased attraction to benzaldehyde in aged worms is (1) serotonin mediated, (2) specific to high concentration of odorants, and (3) dependent on a learned association of odor metabolites with the presence of food. We propose that associative learning may selectively modify pathways at or downstream from a low-affinity olfactory receptor. (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10