Early life tributyltin exposure has long term physiological effects on the zebrafish (Danio rerio) visual system

Tributyltin (TBT) is an antiestrogenic endocrine disrupting compound used in the production of plastic, timber, and aquatic antifouling paints. Previous studies focusing on short-term effects of TBT exposure have identified immediate detrimental effects. Here, we evaluate whether a transient (24 h) exposure to TBT during development can cause persistent effects that remain after removal from treatment. Zebrafish (Danio rerio) larvae were exposed to environmentally relevant concentrations of TBT (0.04 and 0.4 μg/L) when they were either 3- or 7-days post-fertilization (dpf). After exposure, larvae were returned to recovery conditions and assessed 2-weeks, 4-weeks, or > 5 months postexposure. Exposure to 0.4 μg/L TBT at 3 dpf decreased total and distal retinal thicknesses. Adult (>5 month) photopic electroretinograms revealed physiological changes to photoreceptor a-wave and ON-bipolar cell b-wave components, with greater deficits in the 0.4 μg/L group. TBT exposure at 7 dpf significantly increased retinal inner plexiform layer thickness at 2-weeks, an effect that persisted to adulthood. Adult electroretinograms were also altered, with 0.04 μg/L TBT increasing and delaying a-wave and OFF-bipolar d-wave responses and increasing b-wave amplitude. Thus, the impact of TBT exposure depends on both concentration and exposure age, with retinal sequelae characterized by early anatomical and later physiological deficits. These data suggest that TBT exposure during critical periods of visual system development causes persistent age- and concentration-dependent deficits that are specific to the retina, revealing a previously unknown effect of this compound.