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Nina Riddell, Melanie J Murphy, Sheila Gillard Crewther; GC/MS metabolomics in chick myopia and hyperopia models. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5889.
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© ARVO (1962-2015); The Authors (2016-present)
Exploratory transcriptome and proteome studies have identified shifts in metabolic pathways (particularly those related to cellular respiration) in the widely used chick refractive error model. Little is known about corresponding metabolite profiles. Thus, this study used gas chromatography mass spectrometry (GC/MS) to profile metabolite abundance in the chick retina/RPE following 6 and 48hrs of defocus-induced myopia and hyperopia.
Chicks were raised from post-hatch day 5 with monocular +10 Diopter (D) or -10D lenses, or no lens. Following 6 and 48hrs, eight chicks per lens group were anesthetized and biometric measures were collected. Retina/RPE sections were then removed from the experimental eye and prepared for GC/MS analysis of polar metabolites at Metabolomics Australia. Metabolites were identified using Agilent MassHunter software based on retention time and fragmented ion patterns relative to the in-house GC/MS library. The targeted data matrix was filtered, median normalized, and log2 transformed in MetaboAnalyst 4.0. One-way ANOVAs were then conducted to compare the effect of lens group on metabolite abundance at 6 and 48hrs (FDR <0.05). Post hoc analyses were conducted using Tukey's HSD.
Biometrics showed 3.88D (±0.23 SEM) and 7.81D (±0.31) of refractive compensation (RC) to +10D defocus after 6 and 48hrs respectively, while RC to -10D lenses was -3.54D (±0.52) and -9.69D (±0.38) at the same times. Three TCA cycle intermediates (succinic acid, citric acid and isocitric acid) and the amino acid L-aspartate were down-regulated following 6hrs of positive and negative lens-wear. The neurotransmitter gamma-aminobutyric acid (GABA) and hydroxyproline (a major component of collagen) were down-regulated in the positive lens group only. No statistically significant changes in metabolite abundance were identified at 48hrs.
These results suggest that the initial hours of lens induced myopia and hyperopia are characterised by a decrease in TCA cycle activity with potential implications for ATP availability. This finding is consistent with our previous proteomic study in a subset of the same samples showing a decrease in the expression of mitochondrial ADP/ATP translocases and ATP-dependent ion transporters (including Na/K-ATPase subunits) following 6hrs of lens wear.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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