Metabolic impact of weight variations in Icelandic horses

Abstract

Background Insulin dysregulation (ID) is an equine endocrine disorder, which is often accompanied by obesity and various metabolic perturbations. The relationship between weight variations and fluctuations of the insulin response to oral glucose tests (OGT) as well as the metabolic impact of ID have been described previously. The present study seeks to characterize the concomitant metabolic impact of variations in the insulin response and bodyweight during repeated OGTs using a metabolomics approach. Methods Nineteen Icelandic horses were subjected to five OGTs over one year and their bodyweight, insulin and metabolic response were monitored. Analysis of metabolite concentrations depending on time (during the OGT), relative bodyweight (rWeight; defined as the bodyweight at one OGT divided by the mean bodyweight across all OGTs) and relative insulin response (rAUCins; defined accordingly from the area under the insulin curve during OGT) was performed using linear models. Additionally, the pathways significantly associated with time, rWeight and rAUCins were identified by rotation set testing. Results The results suggested that weight gain and worsening of ID activate distinct metabolic pathways. The metabolic profile associated with weight gain indicated an increased activation of arginase, while the pathways associated with time and rAUCins were consistent with the expected effect of glucose and insulin, respectively. Overall, more metabolites were significantly associated with rWeight than with rAUCins.

Palatability, glycemic, and insulinemic responses to various carbohydrate formulations: Alternatives for the diagnosis of insulin dysregulation in horses?

“…Eighteen Icelandic Horses with variable insulinemic status were available for study 2. These research horses have been continuously endocrinologically characterized and monitored as part of several research projects 23‐26 . The median age of the Icelandic Horses was 20 (10‐26) years.…”

“…These research horses have been continuously endocrinologically characterized and monitored as part of several research projects. 23 , 24 , 25 , 26 The median age of the Icelandic Horses was 20 (10‐26) years. There were 10 mares, 7 geldings, and 1 stallion.…”

“…The enrolled horses had been continuously monitored for their insulinemic responses in oral GCs (tube-GTs) performed longitudinally over 1.5 years. [23][24][25][26] Based on these results, the horses were retrospectively classified ID: P = .02). In non-ID individuals, the GC pellets provoked significantly higher insulin concentrations at 120 and 240 min compared to the tube OGT (P = .03 and P = .002, respectively).…”

Associations of plasma sphingolipid profiles with insulin response during oral glucose testing in Icelandic horses

“…However, the impact of an acute OGT challenge on sphingolipid metabolism in horses has been characterized only for a limited number of sphingolipids, mainly SM. 19 , 20 , 21 The correlation between sphingolipids and insulin response has not yet been well established. We hypothesized that the OGT would alter plasma sphingolipid profiles, specifically that the acute activation of the insulin signaling pathway by an OGT would downregulate ceramide biosynthesis.…”

“…If this insulin resistance is caused by increased ceramide concentrations, it could explain the link between alteration in sphingolipid metabolism and ID. However, the impact of an acute OGT challenge on sphingolipid metabolism in horses has been characterized only for a limited number of sphingolipids, mainly SM 19‐21 . The correlation between sphingolipids and insulin response has not yet been well established.…”