Long-term exposure to bisphenol S damages the visual system and reduces the tracking capability of male zebrafish (Danio rerio)

Bisphenol S (BPS) is widely detected in aquatic environments and in human bodies. BPS has reproductive and thyroid disrupting effects, but its effect on the visual system remains unknown. In the present study, zebrafish embryos were exposed to BPS at concentrations of 1, 10, 100 and 1000g l(-1) until 120days post-fertilization in a semistatic system, and the effect of BPS on the visual behavior was examined using the optokinetic response and the optomotor response tests in male zebrafish. The retinal histology, mRNA expression of photoreceptor opsin genes (zfrho, zfblue, zfgr1, zfred and zfuv) and apoptosis-related genes (bax and bcl-2) were also assessed. Long-term BPS exposure decreased the tracking capability of male zebrafish, consistent with structural damage to the retina. BPS induced different amounts of vacuoles in the retinal pigment epithelium, and 1000g l(-1) BPS exposure decreased the length of the inner plexiform layer, ganglion cell layer and retina, and induced an irregular arrangement of photoreceptor cells. The expression levels of the opsin genes (zfred, zfgr1 and zfrho) were significantly elevated, indicating an enhanced spectral sensitivity to red, green and dim light to compensate for the reduction of the optomotor response. Together, the results showed for the first time that long-term exposure to BPS damaged the structure of male zebrafish retina and reduced their tracking capability. This study aimed to examine the effect of bisphenol S (BPS) on the visual system in male zebrafish. Zebrafish embryos were exposed to BPS at concentrations of 1, 10, 100 and 1000 g l(-1) until 120 days post-fertilization in a semi-static system. Results showed that long-term BPS exposure damaged the retinal structure, decreased their tracking capability and stimulated the transcription of opsin genes in the eyes, suggesting a severe deficiency in the visual system in male zebrafish.