Impact of atenolol on oyster hemocytes: a model for assessing pharmaceutical immunotoxicity

The Eastern oyster Crassostrea virginica is a filter feeder that is exposed to a variety of anthropogenic contaminants including pharmaceuticals in the seawater within its natural habitat. Atenolol, a β-adrenergic antagonists, is frequently detected in the marine environment. However, the impacts of atenolol on marine organisms have been understudied. This study aims to broaden our knowledge of the impact of pharmaceuticals on marine invertebrates by evaluating the impact of the β-adrenergic antagonist atenolol on oysters hemocytes and assessing the use of C. virginica hemocytes as a screening tool. Results indicate atenolol is sub-lethal with no impact on viability. However, apoptosis temporarily increased for hemocytes exposed to 266 µg/L of atenolol. Furthermore, differences in response by agranulocytes and granulocytes were observed, supporting the need to evaluate hemocyte subpopulations along with the whole population. These findings suggest oyster hemocytes may be a useful tool in addressing the gap of knowledge in ecotoxicological impacts of emerging contaminants on marine organisms and can serve as a preliminary assessment of immunotoxicity of these contaminants prior to in-vivo experiments.