Pinus densiflora bark extract prevents selenite-induced cataract formation in the lens of Sprague Dawley rat pups

PURPOSE: Rat pups treated with sodium selenite are typically used as an in vivo model to mimic age-related nuclear cataract. Reactive oxygen species (ROS) production, lipid peroxidation, reduction of antioxidant enzymes, crystalline proteolysis, and apoptosis are considered factors that contribute to pathogenesis of age-related nuclear cataract. In the present study, we investigated whether Pinus densiflora bark extract has potential to prevent cataract formation and elucidated the underlying mechanism. METHODS: Sprague Dawley rats were divided into six groups (n=10). Group 1 rat pups (the control) were treated with only normal saline. The rat pups in groups 2 to 6 were given a subcutaneous injection with sodium selenite (18 μmol/kg bodyweight) on postnatal (P) day 10. Group 3 rat pups (the positive control) were given gastric intubation with curcumin (80 mg/kg bodyweight) on P9, P10, and P11. The rat pups in groups 4 to 6 were given gastric intubation with P. densiflora bark extract 40 mg/kg, 80 mg/kg, and 120 mg/kg, respectively, on P9, P10, and P11. RESULTS: This study showed that P. densiflora bark extract dose-dependently prevented cataract formation. Water-soluble protein, glutathione, superoxide dismutase, glutathione peroxidase, and catalase activity levels were found to be high, and conversely, water-insoluble protein, malondialdehyde, and Ca(2+)-ATPase were found to be low in the groups treated with P. densiflora bark extract compared to group 2. Real-time PCR analysis showed αA-crystalline, lens-specific m-calpain (Lp84), lens-specific intermediates (filensin and phakinin), and antiapoptotic factor (Bcl-2) were downregulated, and the apoptotic factors (caspase-3 and Bax) and plasma membrane Ca(2+)-ATPase (PMCA-1) were upregulated in group 2 compared to group 1. P. densiflora bark extract regulated the imbalance of these genes. The increased cleavage form of caspase-3 was lowered in the groups treated with P. densiflora bark extract. In conclusion, P. densiflora bark extract prevented selenite-induced cataract formation via regulating antioxidant enzymes, inhibiting m-calpain-induced proteolysis, and apoptosis, and thus, maintained the transparency of the lens. CONCLUSIONS: These results suggested that P. densiflora bark extract could be a new agent for preventing age-related nuclear cataract.