Abstract
Purpose:
To determine the differential profiles of cholesterol and their quantitative differences between aqueous humor (AH) derived from ocular normotensive and hypertensive DBA/2J mice.
Methods:
Experiments were performed in accordance with the ARVO statement for the use of animal in ophthalmic and vision research. DBA/2J breeding pairs from Jackson Laboratory were maintained in our animal facility. IOP was measured using a TONOLAB. Aqueous was extracted with a syringe post euthanasia. Mice with IOP ≤ 15 mmHg (3-6 months of age) were treated as normotensive and those with IOP of 25-36 mmHg were treated as hypertensive (8-9 months of age), n=40 animals were used per group for each gender. Lipids were extracted using a modified Bligh and Dyer method with the aqueous phase subjected to the Bradford method for protein quantification. Cholesterols were analyzed on a TSQ Quantum Access Max mass spectrometer using infusion with a Triversa Nanomate with the Chipsoft 8.3.3 software with optimal spray parameters for cholesterols. Analyses were performed in positive ion mode with a daughter mass of 97.1 m/z at collision energy = 22 eV for optimal cholesterol identification. Ratiometric quantification was performed using an internal standard and in-house macros. Identification was done using MZmine 2.9 software and a database derived from LipidMaps.
Results:
We identified 4 cholesterol species as unique in normotensive males, 5 in normotensive females, 7 in hypertensive males, and 5 in hypertensive females. 71 species were common between male normotensive and hypertensive mice, and 71 species were common between female normotensive and hypertensive mice. Further studies are required for understanding the relationship between cholesterol species metabolism and IOP elevation.
Conclusions:
The vast majority of species were common between normotensive and hypertensive phases. The uniquely identified species will lead to further investigation in the effect of cholesterols on IOP elevation.
Keywords: 583 lipids •
427 aqueous