Plasma amino acid concentrations during experimental hyperinsulinemia in 2 laminitis models

Abstract

Background: Endocrinopathic laminitis develops in association with insulin dysregulation, but the role of insulin in the pathogenesis remains unclear.Hyperinsulinemia can cause hypoaminoacidemia, which is associated with integumentary lesions in other species and therefore warrants investigation as a potential mechanism in laminitis.Objective: Evaluate plasma amino acid concentrations in the euglycemichyperinsulinemic clamp (EHC) and prolonged glucose infusion (PGI) laminitis models.

Plasma Amino Acids in Horses Suffering from Pituitary Pars Intermedia Dysfunction

“…These are not only influenced by the type of cancer, but also by the cancer stage [ 32 , 33 , 34 , 35 , 36 , 37 ]. The plasma amino acid profile seems to undergo specific changes during different diseases, not only in humans, but also in animals, which was previously shown in horses suffering from equine metabolic syndrome [ 38 , 39 ] or in experimentally-induced hyperinsulinemia [ 21 ].…”

“…Previous research has suggested that the increased endogenous glucocorticoid concentrations may be responsible for laminitis, since these are known to be associated with systemic insulin resistance [ 12 , 13 , 14 , 15 , 16 , 17 ]. The suspected mechanism is that binding of insulin to the insulin-like growth factor 1 receptor (IGF-1R) has an effect in the lamellar tissue of the hoof [ 18 , 19 , 20 ] and also that insulin can directly trigger laminitis even through mechanisms that have not yet been identified [ 21 ]. In addition to its effects on the glucose metabolism, insulin is an important regulator of protein metabolism.…”

Plasma Amino Acid Concentration in Obese Horses with/without Insulin Dysregulation and Laminitis

“…The development of laminitis in horses is often associated with an endocrine disease (equine metabolic syndrome = EMS; pituitary pars intermedia dysfunction = PPID), in which insulin dysregulation occurs (EMS) or can occur (PPID) [ 1 , 2 , 3 ]. The suspected pathomechanism of endocrinopathic laminitis is hyperinsulinemia, but the mechanism by which hyperinsulinemia can cause laminitis remains unclear [ 4 ]. Based on the results of previous studies, it is suggested that insulin has an effect in the lamellar tissue of the hoof via the insulin-like growth factor 1 receptor (IGF-1R) [ 5 , 6 , 7 ], and also that insulin can directly trigger laminitis even through mechanisms that have not yet been identified [ 4 ].…”

“…The suspected pathomechanism of endocrinopathic laminitis is hyperinsulinemia, but the mechanism by which hyperinsulinemia can cause laminitis remains unclear [ 4 ]. Based on the results of previous studies, it is suggested that insulin has an effect in the lamellar tissue of the hoof via the insulin-like growth factor 1 receptor (IGF-1R) [ 5 , 6 , 7 ], and also that insulin can directly trigger laminitis even through mechanisms that have not yet been identified [ 4 ]. In addition to its effects on the glucose metabolism, insulin is an important regulator of protein metabolism.…”

“…Since hoof horn is an appendix to the epidermis, the changes that occur in laminitis could also be influenced by an altered amino acid concentration. A recently published study in healthy horses showed that horses with euglycemic, hyperinsulinemic clamps for 48 h and glucose infusion for 66 h, had a reduction in blood plasma amino acids and the clinical signs of laminitis [ 4 ]. Furthermore, altered postprandial levels of citrulline, histidine, isoleucine, leucine, methionine, ornithine, tyrosine, and valine in horses with EMS, were described previously [ 17 ].…”