Equine insulin receptor and insulin-like growth factor-1 receptor expression in digital lamellar tissue and insulin target tissues.
Authors: Kullmann A, Weber P S, Bishop J B, Roux T M, Norby B, Burns T A, McCutcheon L J, Belknap J K, Geor R J
Journal: Equine veterinary journal
Summary
# Editorial Summary Hyperinsulinaemia represents a significant risk factor for endocrinopathic laminitis, yet the mechanistic basis remains incompletely understood, particularly regarding how different insulin and insulin-like growth factor-1 receptors are expressed across equine tissues. Kullmann and colleagues investigated mRNA expression patterns of insulin receptor isoforms (InsR-A and InsR-B), IGF-1R, and hybrid receptors in digital lamellar tissue alongside metabolic target tissues from horses varying in body type and dietary carbohydrate exposure. The research revealed tissue-specific receptor expression profiles, with lamellar tissue demonstrating distinct InsR and IGF-1R isoform distributions compared to classical insulin-target tissues, and notable variation in receptor expression according to body condition and dietary composition. These findings suggest that lamellar tissue responds to systemic hyperinsulinaemia through unique receptor mechanisms that may not be fully captured by studying metabolic tissues alone, highlighting the importance of understanding lamella-specific insulin signalling pathways when evaluating laminitis risk in obese or dysmetabolic horses. For practitioners, this underpins the rationale for aggressive dietary management and weight control in predisposed individuals, as interventions reducing circulating insulin may modulate pathological signalling cascades specific to lamellar tissue that differ fundamentally from systemic metabolic effects.
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Practical Takeaways
- •Understanding tissue-specific insulin receptor expression patterns may help explain why some horses are more susceptible to hyperinsulinaemia-related laminitis
- •Dietary carbohydrate management and body condition assessment should consider individual variation in insulin receptor expression across tissues
- •Knowledge of receptor isoforms and hybrid receptors provides mechanistic basis for managing insulin-related laminitis prevention strategies
Key Findings
- •Study investigates mRNA expression of insulin receptor isoforms (InsR-A, InsR-B), IGF-1 receptor, and hybrid receptors in equine digital lamellar tissue and other insulin target tissues
- •Research examines influence of body type and dietary carbohydrate intake on receptor expression patterns in horses
- •Hyperinsulinaemia is implicated in pathogenesis of endocrinopathic laminitis through multiple insulin receptor signalling pathways