Effect of intravenous glucose and combined glucose-insulin challenges on energy-regulating hormones concentrations in donkeys.
Authors: Mendoza F J, Gonzalez-Cara C A, Aguilera-Aguilera R, Toribio R E, Perez-Ecija A
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Metabolic dysfunction in donkeys occurs at high prevalence, yet their endocrine responses to glucose challenges differ markedly from horses, warranting species-specific understanding of their regulatory mechanisms. Researchers administered intravenous glucose tolerance tests (IVGTT) and combined glucose-insulin challenges (CGIT) to healthy adult donkeys (n=49 for baseline; n=8 per test group), measuring insulin:glucagon molar ratios (IGR), glucagon:insulin ratios (GIR), and associated hormones including leptin, ghrelin and adiponectin at multiple timepoints. Donkeys demonstrated baseline IGR and GIR values of 1.5 and 0.7 respectively, with both IVGTT and CGIT triggering significant elevation in IGR (and corresponding GIR decrease) throughout the testing period, though the CGIT additionally stimulated leptin release at 240 minutes; notably, neither challenge affected ghrelin or adiponectin concentrations. The data suggest donkeys maintain proportionally higher glucagon relative to insulin compared with equines, a metabolic distinction that may underpin their predisposition to energy dysregulation disorders such as metabolic syndrome and dyslipidaemias, making these baseline values and response patterns valuable diagnostic reference points for clinicians evaluating metabolic health in this species.
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Practical Takeaways
- •Donkeys respond differently to glucose and insulin challenges than horses, which has implications for interpreting metabolic testing and understanding metabolic syndrome susceptibility in donkey populations
- •Baseline insulin:glucagon ratios and dynamic hormone responses documented here provide reference values for diagnostic interpretation of metabolic dysfunction in donkeys
- •The higher relative glucagon levels in donkeys may explain their greater prevalence of metabolic disorders and dyslipidaemias compared to horses, informing dietary and management strategies
Key Findings
- •Healthy donkeys have median insulin:glucagon ratio of 1.5 and glucagon:insulin ratio of 0.7 at baseline, establishing reference values for the species
- •IVGTT increased insulin:glucagon ratio from 15-180 minutes but had no effect on leptin, adiponectin or ghrelin concentrations
- •CGIT significantly elevated insulin:glucagon ratio from 15-120 minutes with leptin increasing significantly at 240 minutes
- •Donkeys have proportionally higher glucagon compared to insulin concentrations relative to horses, suggesting species-specific differences in glucose regulation relevant to metabolic disorders