Age-Related Conjunctival P2Y2 Receptor Alterations in the Cu, Zn-Superoxide Dismutase-1 (Sod1)-Knockout Dry Eye Model Mice.

PURPOSE: To investigate the effects of aging on the conjunctival P2Y2 receptors, tear functions, and corneal epithelial status from 10 to 50 weeks in the Sod1 in comparison with the wild-type mice.

METHODS

Eight eyes of 4 Sod1 male mice and 8 eyes of 4 C57BL6 strain wild-type male mice were examined at 10 and 50 weeks in this study. Tear film breakup time (BUT) and corneal epithelial damage by fluorescein staining were evaluated. Phenol red-impregnated cotton threads were performed without topical anesthesia to measure aqueous tear quantity. Anterior segment photography was also performed at 10 and 50 weeks. Conjunctival specimens underwent immunohistochemistry stainings with anti P2Y2 antibodies. P2Y2 receptor mRNA expression in the bulbar conjunctiva was investigated by using quantitative real-time polymerase chain reaction.

RESULTS

The mean tear quantity and BUT scores significantly declined, and the mean fluorescein staining scores significantly increased in both strains of mice from 10 to 50 weeks. % mRNA expression for P2Y2 receptors significantly increased in both mice strains from 10 to 50 weeks.

CONCLUSION

The tear stability, quantity, and ocular surface health decline with aging as evidenced by the decrease in tear BUT, tear quantity, and the increase in ocular surface staining. Conjunctival P2Y2 receptor mRNA was upregulated from 10 to 50 weeks, which we believe is a compensation for the decline of tear functions with aging.