Glucagon, insulin, adrenocorticotropic hormone, and cortisol in response to carbohydrates and fasting in healthy neonatal foals.

The research examines how energy regulation hormones react to fasting and carbohydrate intake in healthy newborn foals. It concludes that factors in milk besides carbohydrates strongly stimulate these hormones.

Objective and Methodology

The objective of the research was to evaluate how glucagon, insulin, adrenaline and cortisol — hormones crucial to maintaining energy balance — react to fasting and carbohydrate administration in neonatal foals. The research was conducted on twenty-two healthy Standardbred foals that were no more than four days old.

These foals were divided into four groups: subjected to fasting, intravenous glucose, orally administered glucose, and orally administered lactose. The team frequently collected blood samples for a period of 210 minutes. The foals were allowed to nurse from 180 to 210 minutes. The concentrations of glucagon, ACTH (the hormone that produces adrenaline), insulin and cortisol were measured using immunoassays.

Results

• The concentration of glucagon in the plasma decreased relative to the baseline at 45, 90, and 180 minutes during the oral lactose test. No changes were observed in the other test groups. However, nursing stimulated an increase in plasma glucagon, insulin, and glucose concentrations in all test groups.
• The concentration of ACTH (Adrenocorticotropic Hormone responsible for releasing adrenaline) increased relative to baseline at 180 minutes during fasting and the oral lactose test. No changes were observed in other test groups. However, nursing resulted in decreased plasma ACTH concentrations in all test groups.
• There was an increase in serum cortisol concentration during the oral lactose test at 180 minutes relative to the baseline. No changes were noticed in other test groups. Nevertheless, nursing led to decreased serum cortisol concentrations in all test groups.

Conclusions

While the study concludes that the endocrine response to carbohydrates administered both enterally (via the gastrointestinal tract) and parenterally (outside of the digestive tract, typically through intravenous injection) stimulates glucagon, insulin, adrenaline and cortisol, it also suggests that nursing has a greater impact on these hormones. The research found that factors in milk other than carbohydrates are strong stimulators, either directly or indirectly, of the endocrine pancreas (the portion of the pancreas that produces and secretes hormones into the bloodstream) and the hypothalamic-pituitary-adrenal axis (an interaction between the hypothalamus, pituitary gland, and adrenal glands that regulates things like mood, energy usage, and the body’s response to stress).