Abstract
Purpose :
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 (3 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. Systemic effects on physiology were examined by meauring locomotor responses to touch and heart rates.
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 4.12 µm in 0.05% DMSO controls to 5.69 µm in the 20 µg/ml CSE-treated larvae (p≤0.0001). 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% DMSO controls (205.1 µm). Larvae exposed to CSE had significantly higher numbers of RPE phagosomes compared to vehicle controls (p=0.0002). 20 µg/ml CSE-treated larvae had an average of 0.1425 ± 0.009287 phagosomes/um RPE (n=4), a value ~50% higher than larvae treated as the vehicle control (0.093 ± 0.009 phagosomes/um RPE, n=3)
Conclusions :
Zebrafish larvae with a developed visual system display defects in visual behaviour and retinal biology after acute exposure to CSE, enabling a valuable in vivo model to investigate ocular disorders related to cigarette smoke.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.