Effect of nicotine exposure during gestation on neonatal rat crystalline lenses

Purpose To assess histologically the influence of maternal nicotine exposure during gestation in vivo on crystalline lenses in neonatal rats using different dosages of the test compound simulating the range of low, moderate, and heavy smokers in humans. Methods Experimentally naive, adult female Wistar-albino rats ( 200 - 250 g) were mated with adult male rats over 2 days for copulation in the proportion of two females for every male animal. After confirming pregnancy with vaginal smear method, 40 gravid rats ( dams) were then randomly assigned into four equal groups ( three experimental and one control; n = 10 in each). Groups 1, 2, and 3 experimental dams were treated with intraperitoneal (i.p.) (-)- nicotine tartrate at doses of 0.5, 1, and 2 mg/kg body weight/day, respectively, during pregnancy from gestational days 9 through 21. Group 4 control dams were given i.p. saline solution daily for the same period. After normal delivery, the eyes were removed at postnatal day 1 or day 30 for macroscopic and histopathologic investigation of the lenses. Results Control and group 1 litters had normal anterior lens capsules with a single layer of anterior cuboidal epithelial cells, regularly orientated cortical and nuclear lens fibres, and a clear posterior lens capsule with no lining epithelial cells behind the equator. On the other hand, some lenses in groups 2 and 3 litters had mature or immature cataract macroscopically at postnatal 30th day. Histopathologic findings suggesting cataractogenesis included cortical lens fibre cell swelling and liquefaction, prominent epithelial cells lining the posterior lens capsule behind the equator, and the retention of lens nuclei into the deeper and central area. Moreover, some lenses were immature developmentally, indicating arrested lenticular embryogenesis at vesicle stage. Conclusions Nicotine exposure during pregnancy has teratogenic and cataractogenic effects on developing crystalline lenses in neonatal rats both macroscopically and histopathologically. If appropriate dose of nicotine can be identified, nicotine-induced cataract formation may possibly be used as a new experimental cataract model in animal studies. Therefore, future studies are needed in this respect.