METHODS

All procedures in this study were approved by our Institutional Animal Care and Use Committee, and followed the guidelines of the Institute for Laboratory Animal Research. We obtained 170 C57BL/6J and 60 CBA/CaJ young adult mice (8-12 weeks of age, about 25 g) from the Jackson Laboratory (Bar Harbor, ME). All mice were entrained to a daily 12 h diurnal/light (6 AM to 6 PM) and 12 h nocturnal/dark cycle for at least two weeks before the experiments. Food and water were freely available and the housing air temperature was constant at 21 C.

Sixty light-dark entrained C57BL/6J mice were used to establish the 24 h pattern of aqueous humor protein under standard light-dark conditions. At each of six times: 8 AM, noon, 4 PM, 8 PM, midnight, and 4 AM, 10 mice were sacrificed using CO2 exposure. In the dark period, a dim photo-safe red light (< 5 lux) was used to assist the procedure. A euthanized mouse was laid on its side with its right eye facing up. The ocular surface was thoroughly washed with sterile saline and tapped dry with filter paper. Under a dissecting microscope, the eye was proptosed and the central cornea was carefully punctured with a 30 gauge needle. Aqueous humor exited in-