Exposure to SSRI-type antidepressants increases righting time in the marine snail Ilyanassa obsoleta

Abstract

Exposure to human antidepressants has been shown to disrupt locomotion and other foot-mediated mechanisms in aquatic snails. We tested the effect of three selective serotonin reuptake inhibitor (SSRI)- and one selective serotonin-norepinephrine reuptake inhibitor (SNRI)-type antidepressants on the righting response in the marine snail, Ilyanassa obsoleta. All four antidepressants (fluoxetine, sertraline, paroxetine, venlafaxine) significantly increased righting time compared with controls with an exposure time as short as 1 h. Dose responses were nonmonotonic with effects seen mainly at the lowest exposure concentrations and shortest duration. The lowest concentration to show an effect was 3.45 μg/L fluoxetine with a 2-h exposure period and is about 3.71 times higher than environmental concentrations. Our results highlight rapid disruption of another foot-mediated behavior in aquatic snails by SSRI-type antidepressants. We discuss these and other reported nonmonotonic dose responses caused by antidepressants in terms of the various possible physiological mechanisms of action in nontarget aquatic species.

Serotonin in Animal Cognition and Behavior

“…This includes flatworms [58], cnidarians [59], nematodes [60], annelids [61,62], arthropods (insects and crustaceans, [63][64][65]), and mollusks [66][67][68][69]. Part of our knowledge comes from studies investigating the ecological/toxicological consequences of SSRIs used as antidepressants, released in sanitary water, and finally spread in rivers [63,65,[70][71][72]. It also comes from studies stimulated by the need to develop new ecological intervention to decrease or eradicate associated pathologies to promote human health [58,73].…”

Impacts of ammonia and temperature on freshwater snail behavior and physiology.

“…Thus, increased righting time is used as an indicator of stress in gastropods and other aquatic groups (e.g. Burger 1998;Fong et al 2017;Zhang et al 2017).…”

“…These pre-tests were done at room temperature (20°C) to provide a baseline righting time for each snail before the treatment groups were exposed to elevated temperatures. Pre-tests also helped to account for potential differences in righting time related to size, age, sex, or other factors (Fong et al 2017). However, age was controlled to some degree as only adult snails were included in this study.…”

“…Increased righting time is used as an indicator of stress in various gastropods (e.g. Weldon and Hoffman 1979;Fong et al 2017) because snails that are flipped upside down, with the aperture, or shell opening, exposed, may be more vulnerable to predators (Orr et al 2007, Lemmnitz et al 1989) and cannot carry out normal activities like mating or foraging. Several factors have been found to impact righting behavior in gastropods.…”

“…Average snail sizes (±SE) were 11.7 ± 0.07 mm for fine-ridged elimia and 12.0 ± 0.07 mm for Shawnee rocksnails. Each snail's righting time was tested before and after exposure to NH3 to account for differences in righting time related to size, age, or other individual differences (Fong et al 2017). Before the pre-exposure righting test, snails were allowed to acclimate to their beakers overnight in 150 mL reconstituted fresh water and were fed ad libitum on TetraMin® tropical flakes.…”