Analysis of Retina and Erythrocyte Glycerophospholipid Alterations in a Rat Model of Type 1 Diabetes

Abstract

A n automated tandem mass spectrometryebased analysis using precursor ion and neutral loss scans in a triple quadrupole (QqQ) mass spectrometer has been used to identify and quantify changes in the abundances of glycerophospholipids extracted from retina and erythrocytes in a rat streptozotocin model of type 1 diabetes, 6 and 36 weeks after the induction of diabetes, compared with age-matched nondiabetic controls. The utility of an ''internal standard'' method compared with an ''internal standard free'' method for quantification of differences in the abundances of specific lipid ions was evaluated in both retina and erythrocyte lipid extracts. In retina, equivalent results were obtained by using the internal standard and internal standard free methods for quantification. In erythrocytes, the two methods of analysis yielded significantly different results, suggesting that factors intrinsic to particular sample types may influence the outcome of label-free lipidome quantification approaches.Overall increases (w25e35%) in the abundances of major retina glycerophospholipid classes were demonstrated in rats at 6 weeks of diabetes, relative to control animals. However, at 36 weeks of diabetes, subsequent overall decreases in retina glycerophosphatidylcholine (GPCho) and glycerophosphatidylethanolamine (GPEtn) abundances of 16% and 33%, respectively, were observed. Additionally, retina and erythrocyte GPCho lipids at both 6 and 36 weeks of diabetes exhibited increased incorporation of linoleic acid (18:2n6) and a decrease in docosahexaenoic acid (DHA (22:6n3) ) content. Finally, an approximately fivefold increase in the abundances of specific glycated GPEtn (Amadori-GPEtn) lipids were observed in the retina of 36-week diabetic rats, with a corresponding 1.6-fold increase of Amadori-GPEtn lipids in diabetic erythrocytes. (JALA 2009;14:383-99)

A monophasic extraction strategy for the simultaneous lipidome analysis of polar and nonpolar retina lipids

“…6A and Fig. 6B , respectively), the relative distributions of lipids observed from the gold standard Folch lower phase lipid extract and the monophasic lipid extract were found to be virtually identical, and in both cases were in good agreement with previously published descriptions of rat retina phospholipid content by us and others ( 9,15,53 ). Minor differences in phospholipid molecular species distribution between this and previous studies of rat retina are most likely due to differences in the strains, ages, and diets of the rats used in the experiments.…”

“…including diabetic retinopathy (8)(9)(10)(11)(12), Stargardt-like macular dystrophy ( 13 ), age-related macular degeneration ( 14 ), Smith-Lemli-Opitz syndrome ( 15 ), and retinopathy of prematurity ( 16 ). In some retinal disorders, particularly diabetic retinopathy, all of these metabolic defects may be present simultaneously (8)(9)(10)(11)(12).…”

“…In some retinal disorders, particularly diabetic retinopathy, all of these metabolic defects may be present simultaneously (8)(9)(10)(11)(12). Unfortunately, analysis of structurally diverse lipid species such as sphingolipids, fatty acids, and phospholipids that span a wide range of polarities, degree of unsaturation, and abundance within a given tissue remains analytically prohibitive, particularly given the small amount of retinal tissue that may be obtained when using rodent models of retinal disease.…”

Is the omega-3 index a valid marker of intestinal membrane phospholipid EPA+DHA content?

“…Lipid extraction was performed using a modified version of the Rose and Oaklander method [14], which utilizes a mixture of 2-propanol:chloroform (11:7 v/v) to minimize heme interferences within erythrocytes or heme-contaminated tissues [15]. To ensure uniform sampling from each tissue, lipid extraction was preceded by pulverizing frozen tissue (100–200 mg tissue/sample) using a mortar/pestle on dry ice.…”

The role of dyslipidemia in diabetic retinopathy

“…However, during diabetic conditions where insulin levels are low or in cases of insulin resistance, plasma lipids levels as well as the composition of fatty acids, are dramatically altered (33-37). Altered plasma fatty acid composition can contribute to both retinal, and bone-marrow-derived inflammatory as well as progenitor cell membrane composition and function(15, 38-40). …”