Introduction: Cigarette smoking adversely affects multiple aspects of human health including eye disorders such as age-related macular degeneration, cataracts and dry eye disease. However, there remains a knowledge gap in how constituents of cigarette smoke affect vision and retinal biology. We used zebrafish to assess effects of short-term acute exposure to cigarette smoke extract (CSE) on visual behaviour and retinal biology.
Methods: Zebrafish larvae with a developed visual system at three days post-fertilization (dpf) were exposed to CSE for 4, 24 or 48 hours. Visual behaviour, hyaloid vasculature morphology, retinal histology, oxidative stress gene expression and outer segment phagocytosis were investigated using visual behavioural optokinetic and visual motor response assays (OKR and VMR), microscopy (light, fluorescence and transmission electron microscopy), and real-time PCR.
Results: In zebrafish larvae, 48 hours of CSE treatment resulted in significantly reduced visual behaviour. Larvae treated with 10, 15 or 20 μg/mL CSE showed an average of 13.7, 10.7 or 9.4 saccades per minute, respectively, significantly lower compared with 0.05% DMSO controls (p=0.0093, p=0.0004 and p<0.0001, respectively) that exhibited 19.7 saccades per minute. The diameter of intraocular vessels increased from 4.833 μm in 0.05% DMSO controls to 5.885 μm in the 20 μg/mL CSE-treated larvae (p=0.0333). Biometry analysis highlighted a significant axial length elongation in 20 μg/mL CSE-treated larvae (216.9 μm, p<0.0001) compared to 0.05% dimethyl sulfoxide (DMSO) controls (205.1 μm). Larvae exposed to 20 μg/mL CSE had significantly (p=0.0002) higher numbers of RPE phagosomes compared to vehicle controls (0.1425 and 0.093 phagosomes/μm RPE, respectively).
Conclusions: Zebrafish larvae with a developed visual system display apparent defects in visual behaviour and retinal biology after acute exposure to CSE, establishing a valuable in vivo model to investigate ocular disorders related to cigarette smoke.
Keywords: Smoking; oxidative stress; retina; visual behaviour; zebrafish.
This study investigates the effects of cigarette smoke on the visual system of zebrafish larvae. We exposed the larvae to cigarette smoke extract for 4, 24, or 48 hours and assessed their eye movements, retina morphology and oxidative stress gene expression. Exposure to cigarette smoke extract for 48 hours reduced eye movements behaviour in the zebrafish larvae and led to changes in the morphology of their hyaloid vasculature present in the lens and the number of phagosomes in their retinal pigment epithelium. When exposure was shortened to 4 or 24 hours, eye movements were still reduced and oxidative stress was affected. These results suggest that zebrafish larvae can be used as a valuable model to investigate ocular disorders related to cigarette smoke.
Copyright: © 2023 Gómez Sánchez A et al.