Effects of long-term passive smoking on the vascular endothelial growth factor and apoptosis marker expression in the retina and choroid: an experimental study
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Aim: To investigate the effects of smoking, reported as a risk factor for age related macular degeneration (ARMD), on the vascular endothelial growth factor (VEGF) expression and apoptosis in the retina and choroid of rats. Materials and methods: This experimental study included 38 Sprague-Dawley rats. The rats were randomly assigned into 4 groups. Groups 1 (males) and 2 (females) were exposed to smoke beginning on day 21 after birth, whereas groups 3 (males) and 4 (females) were not exposed to smoke. At the end of the fourth month, the right eyes of all of the rats were enucleated. Immunohistochemical analysis was performed in the enucleated eyes in terms of the VEGF and apoptosis markers, namely caspase-3, Bcl-X, and p53. Comparisons between the groups were performed using the Mann-Whitney U test. Results: The VEGF expression in the retina and choroid increased significantly in rats exposed to smoking. This significant difference did not change between the sexes. There were no significant differences in terms of Bcl-X and p53 expressions between the groups; however, the caspase-3 expression increased significantly in the photoreceptor layer in rats exposed to smoking. Conclusion: Our findings show that smoking significantly increases the VEGF expression in many of the retinal layers and choroid. Smoking also increases caspase-3 expression only in the photoreceptor layer. According to these findings, smoking may be a risk factor for retinal vascular disease such as exudative ARMD, via stimulating the VEGF.