(a) Rat ex vivo eye cup preparations were placed at the bottom of an acrylic cylinder filled with aCSF, and incubated at 30°C for 24 hours. Hydrostatic pressure was calculated to be 10, 35, and 75 mm Hg when the height of aCSF liquid column was 13.5, 47.3, and 101.2 cm, respectively. Allopregnanolone, finasteride, and picrotoxin were added to the aCSF buffer during some experiments. (b) Measurement of allopregnanolone in the retinal extracts using LC-MS/MS. Allopregnanolone levels significantly increased at 75 mm Hg compared to lower pressure (10 or 35 mm Hg) or incubation with 1 μM finasteride (Fin), 1 μM dutasteride (Duta), and 50 μM APV. At 75 mm Hg, administration of 1 μM finasteride significantly depressed the increase of allopregnanolone. Administration of 1 μM dutasteride inhibited allopregnanolone levels more effectively than finasteride. Administration of 50 μM APV also significantly inhibited allopregnanolone levels at 75 mm Hg. P values are calculated by unpaired Student's t-test compared to 75 mm Hg (*P < 0.001, **P < 0.0001).