The enteroinsular axis (EIA) comprises intestinal factors (incretins) that promote insulin release and suppress glucagon secretion. Glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) are the main incretins. EIA alterations could contribute to energy dysregulation in critically ill foals.
The EIA has been evaluated in horses, however, information is lacking in healthy and sick newborn foals. Our study sought to evaluate GLP-1 (total and active), GIP, and insulin response to fasting and dextrose (oral and intravenous) administration in healthy newborn foals.
Oral and intravenous glucose tolerance tests were performed in 17 healthy Standardbred foals < 72 hours old. Following 1 hour of fasting, a bolus of dextrose (300 or 500 mg/kg) was administered orally or intravenously. Blood incretin and insulin concentrations were measured at 0, 5, 10, 15, 30, 45, 60, 90, 120, 150, and 180 minutes by immunoassay.
GIP concentrations decreased steadily following dextrose (300 and 500 mg/kg) regardless of route of administration by 68-75% of baseline values (P < 0.05). GLP-1 total and active concentrations showed a steady decrease of 52-70% of baseline values (P < 0.05). Mild but not significant GLP-1 elevations were noted at 5-15 minutes.
In foals allowed to nurse, incretin concentrations increased above baseline within 15 minutes of nursing. Minimal incretin response with oral dextrose but rapid incretin release after nursing indicates that 500 mg/kg was insufficient for a strong EIA stimulation, that higher dextrose dosing is required, or that factors in milk may be important to activate the EIA in newborn foals.
Resident - Equine Internal Medicine
The Ohio State University College of Veterinary Medicine
Thursday, June 14
2:15 PM – 2:30 PM
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