Effect of blood-retinal barrier development on formation of selenite nuclear cataract in rat.

Selenite cataract, as an experimental animal model of nuclear cataract to mimic human senile cataract, is produced only when overdose selenite is injected to neonatal rats before eyelid opening. To clarify the cause of age differences on selenite cataract formation in rats, mRNA expression of GPx1, MsrA and MsrB1, as well as GPx activity in Wistar rat lens at different ages were assayed, level of lipid peroxidation, extent of lens damage induced by sodium selenite and barricade function of blood-retinal barrier (BRB) were investigated. The results showed that mRNA expressions and activity of antioxidant enzymes in neonatal rat lens before eyelid opening were the highest and then decreased with age, and revealed by transmission electron microscopy (TEM) using lanthanum hydroxide as tracer that higher selenite content entering eyes injured lens and resulted in cataract formation for immature BRB before eyelid opening, moreover, a little selenite content entering eyes was not enough to induce cataract formation after eyelid opening because of mature BRB.