2015 ACVIM Forum Research Abstract Program

Mean insulin concentrations during the OST were significantly higher in ID when compared to CON ponies at baseline (mean AE SD; ID 15.4 AE 5.6 mU/L, CON 4.0 AE 2.6 mU/L) and at 75 minute (ID 112.7 AE 29.1 mU/L, CON 16.3 AE 8.3 mU/L) whereas mean glucose concentrations did not differ between groups at baseline (ID 73.0 AE 8.3 mg/dL, CON 73.4 AE 6.7 mg/dL) or at 75 minute (ID 108.3 AE 12.4 mg/ dL, CON 106.4 AE 23.7 mg/dL). The serum metabolomic profile comprised 646 biochemical compounds, of which 506 were of known identity. Statistically significant differences between ID and CON were identified for >130 biochemicals, particularly metabolites involved in the tricarboxylic acid (TCA) cycle, fatty acid metabolism, and branched-chain amino acid (BCAA) oxidation. Mannose, produced by enzymatic isomerization of glucose, was higher (P < 0.05) in ID than in CON at baseline. In both groups fructose, pyruvate and mannose were significantly higher at 75 minute when compared to baseline. Citrate, fumarate and malate, metabolites associated with the mitochondrial use of pyruvate, were lower in ID than in CON at 75 minute, suggesting lower TCA cycle activity in ID ponies. Several long-chain fatty acids (e.g. palmitoleate, eicosapentanoate) and acylcarnitines (e.g. palmitolycarnitine, laurylcarnitine) were 2-to-3-fold higher in ID vs. CON at baseline and at 75 minute. In addition, intermediates in BCAA metabolism including 4-methyl-2-oxopentanoate, 3-methyl-2-oxoalerate and isovalerylglycine were significantly higher in ID when compared to CON ponies, suggesting reduced BCAA oxidation in ID ponies.