The effects of ghrelin and melatonin on experimental cataract model

Cataract is the most common cause of blindness worldwide and its incidence is likely to increase with age. The aim of this study is to investigate whether melatonin and ghrelin have protective effects on experimental cataract model formed by sodium selenite in rats. In this study, thirty-five Spraque Dawley rat pups were randomly assigned to form five groups. Subcutaneous sodium selenite injection was applied to all the newborn rats except the group I (control) on postpartum tenth day and between postnatal days of 8 and 15; pups in group II (sham I) were administered 2 mg/kg /day saline solution, pups in group III (sham II) were administered %1 ethanol-salin solution, pups in group IV were administered 10 µg/g/day melatonin and pups in group V were administered 20 ng/kg/day ghrelin intraperitoneally. Cataract grading was made and the lenses were extracted with capsules. Glutathion (GSH), malondialdehyde (MDA), total antioxidant ( TAS), total oxidant (TOS) and total nitrit (TN) levels were analyzed in the samples of lens. The mean cataract levels in the sham I, sham II, melatonin and ghrelin group were found as 1.71±1.06, 1.78±1.12, 0.35±0.39, 1.64±1.21. The mean cataract level in the melatonin group was found to be significantly lower than the other groups except control group (p<0.05). The mean lens GSH, TAS and TN levels in the melatonin group were found significantly higher than the other group levels; and the mean lens MDA and TOS levels were found significantly lower than sham I-II and ghrelin groups (p<0.05). Protective effect of ghrelin on the cataract was found similer to sham groups (p>0.05). In melatonin group, lower levels of lens MDA and TOS and higher levels of lens GSH, TAS and TN supports the protective effect of melatonin on cataract. However, ghrelin failed to produce the protective effect. Further studies using different doses are needed to determine the effective dose of ghrelin on cataracts. Keywords: Sodium selenite, experimental cataract, melatonin, ghrelin