Fluoxetine Exposure Negatively Affects Wounding Healing in Spinal and Cardiac
Regions in Daphnia magna
Daphnia magna are small aquatic invertebrates with open circulatory systems and complex immune systems. D. magna carapace wounds usually heal in hours or days. Fluoxetine (Prozac) is an antidepressant that belongs to a group of medicines known as Selective Serotonin Reuptake Inhibitors (SSRIs), and has been found polluting aquatic ecosystems. This study aims to explore the effects of fluoxetine on D. magna wound healing. We hypothesized that exposure to fluoxetine would increase the rate of wound healing of D. magna based on studies in mammalian model systems. In the present study, half of the organisms were exposed to an environmentally-relevant concentration (1μg/L) of fluoxetine. In each group of control, or exposed, animals, half were inflicted with a wound near their heart (cardiac wound) and half near their apical spine (spinal wound). Animals were imaged, allowed to recover for one week, then imaged again, and fixed for fluorescence microscopy. During recovery, offspring produced by the animals (neonates) were counted. We found that there were no significant differences in rate of wound healing of cardiac vs spinal wounds in either control or exposed animals; however, animals treated with fluoxetine exhibited a significantly reduced rate of wound healing in general (p = 0.037). Animals exposed to fluoxetine produced more neonates, but the differences were not significant. Based on our findings, exposure to environmentally-relevant concentrations of fluoxetine decreases rates of wound healing in D. magna. Our results deepen our understanding of how fluoxetine affects invertebrates.