Equine metabolic syndrome: Role of the enteroinsular axis in the insulin response to oral carbohydrate.

The research article discusses the role of the enteroinsular axis (EIA) in inducing insulin responses after carbohydrate consumption in horses, leading to equine metabolic syndrome, primarily hyperinsulinaemia and laminitis. The article explores components of the EIA such as glucagon-like peptide-1 and 2 and their influence on insulin secretion, while also highlighting the need for further research on other potential EIA peptides and their function.

Understanding Equine Metabolic Syndrome and Insulin Dysregulation

• The study sheds light on the syndrome of Equine Insulin Dysregulation (ID), which is characterized by an amplified insulin response to ingested carbohydrates, insulin resistance, or a combination of both.
• These conditions result in a state of sustained or recurrent hyperinsulinaemia (overproduction of insulin) in horses.
• Hyperinsulinaemia is a significant health issue for horses due to its direct linkage with the risk of laminitis, a painful inflammatory condition of the tissues (laminae) that bond the hoof wall to the pedal (coffin) bone in the horse’s hoof.

Role of the Gastrointestinal Tract in Insulin Secretion

• Post-meal hyperinsulinaemia is a common form of ID, which is usually identified and diagnosed using tests that incorporate an assessment of the gastrointestinal tract (GIT) in horses.
• The GIT houses numerous factors that either directly or indirectly boost the secretion of insulin from the endocrine pancreas, a combination of these factors is known as the enteroinsular axis (EIA).

Incretin Peptides and the Enteroinsular Axis

• The research discusses key components of the EIA, particularly incretin peptides such as glucagon-like peptides 1 and 2, investigating their role in the pathophysiology of ID in horses.
• All incretins that have been studied till now have been found to enhance insulin responses to orally ingested carbohydrates through one or more mechanisms.
• However, the biological role and existence of many potential EIA peptides of importance, such as glicentin and oxyntomodulin, remain largely underexplored in equine medicine.

Discussing Future Research Directions

• The study highlights the relevance of conducting more dedicated research on the EIA in horses to better understand ID, comparing the existing knowledge derived from similar but extensive studies performed on other species.
• The researchers suggest that future studies should aim to bridge the current knowledge gaps in understanding the interplay between the components of the EIA and their influence on equine insulin regulation.