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 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 bark extract 40 mg/kg, 80 mg/kg, and 120 mg/kg, respectively, on P9, P10, and P11.

RESULTS

This study showed that 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-ATPase were found to be low in the groups treated with bark extract compared to group 2. Real-time PCR analysis showed αA-crystalline, lens-specific m-calpain (), lens-specific intermediates (filensin and phakinin), and antiapoptotic factor () were downregulated, and the apoptotic factors (caspase-3 and Bax) and plasma membrane Ca-ATPase () 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 bark extract. In conclusion, bark extract prevented selenite-induced cataract formation via regulating antioxidant enzymes, inhibiting -calpain-induced proteolysis, and apoptosis, and thus, maintained the transparency of the lens.

CONCLUSIONS

These results suggested that bark extract could be a new agent for preventing age-related nuclear cataract.