Sphingolipids and ceramides of mouse aqueous humor: Comparative profiles from normotensive and hypertensive DBA/2J mice.

To identify the sphingolipid and ceramide species and their quantitative differences between normotensive and hypertensive intraocular pressure states in DBA/2J mouse aqueous humor (AH). Normotensive and hypertensive AH was sampled from mice by paracentesis. Lipid extraction was performed using modifications of the Bligh and Dyer method. Protein concentration was estimated using the Bradford colorimetric assay. Sphingolipids and ceramides were identified and subjected to ratiometric quantification using appropriate class specific lipid standards on a TSQ Quantum Access Max triple quadrupole mass spectrometer. The comparative profiles of normotensive and hypertensive DBA/2J mouse AH showed several species of sphingomyelin, sphingoid base, sphingoid base-1-phosphate (S1P) and ceramides common between them. A number of unique lipids in each of the above lipid classes were also identified in normotensive AH that were absent in hypertensive AH and vice versa. A number of sphingolipid and ceramide species were found to be uniquely present in normotensive, but absent in hypertensive AH and vice versa. Further pursuit of these findings is likely to contribute towards expanding our understanding of the molecular changes associated with increased intraocular pressure (IOP) and glaucoma.