title: Silver nanoparticles alter learning and memory formation in an aquatic organism, Lymnaea stagnalis.
abstract: We tested the effect of silver nanoparticles (AgNPs) on the ability of the pond snail, Lymnaea stagnalis, to learn and form long-term memory (LTM) following operant conditioning of aerial respiration. We hypothesized that the AgNPs would act as a stressor and prevent learning and LTM formation. We tested snails exposed for either 72 h or only during training and testing for memory (i.e. 0.5 h) and found no difference between those treatments. We found that at a low concentration of AgNPs (5 μg/L) neither learning and nor memory formation were altered. When we increased the concentration of AgNPs (10 μg/L) we found that memory formation was enhanced. Finally, at a higher concentration (50 μg/L) memory formation was blocked. To determine if the disassociation of Ag+from the AgNPs caused the effects on memory we performed similar experiments with AgNO3and found similar concentration-dependent results. Finally, we found that snails perceive the AgNPs differently from Ag+ as there was context specific memory. That is, snails trained in AgNPs did not show memory when tested in Ag+and vice-versa. We believe that changes in memory formation may be a more sensitive determination of AgNPs on aquatic organisms than the determination of a LC50.
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Austin
authors.initials: A
authors.lastname: Young
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Protheroe
authors.affiliation: Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada. Electronic address: lukowiak@ucalgary.ca.
authors.forename: Ken
authors.initials: K
authors.lastname: Lukowiak
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D003216:Conditioning, Operant; D007858:Learning / Q000187:drug effects; D008195:Lymnaea / Q000187:drug effects / Q000502:physiology*; D008568:Memory / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity*; D012834:Silver / Q000633:toxicity*; D012908:Snails; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D012834:Silver
keywords: AgNO(3); Long-term memory; Lymnaea; Silver nanoparticles; Stress