Neonatal glucocorticoid overexposure programs pituitary-adrenal function in ponies

Area of Science:

• Endocrinology
• Animal Physiology
• Veterinary Medicine

Background:

• The hypothalamic-pituitary-adrenal (HPA) axis regulates the stress response.
• Neonatal exposure to glucocorticoids can have long-term effects on HPA axis function.
• Understanding these effects is crucial for animal health and welfare.

Purpose of the Study:

• To investigate if neonatal overexposure to glucocorticoids alters HPA axis reactivity in ponies.
• To assess the HPA axis response to stress at 1 and 2 years of age following neonatal treatment.
• To determine the long-term consequences of early-life cortisol elevation on HPA axis function.

Main Methods:

• Newborn foals received either saline or long-acting adrenocorticotropic hormone (ACTH) for five days to elevate cortisol levels.
• At 1 and 2 years of age, HPA axis function was tested using ACTH and insulin challenges.
• Plasma ACTH and cortisol concentrations were measured at regular intervals after drug administration.

Main Results:

• No significant differences were observed in basal ACTH or cortisol levels, or in the cortisol response to exogenous ACTH.
• Ponies treated with ACTH neonatally showed a greater ACTH increment in response to insulin-induced hypoglycemia at 60 minutes.
• Neonatal cortisol overexposure did not alter the cortisol response to hypoglycemia but affected ACTH response.

Conclusions:

• Neonatal cortisol overexposure alters the functioning of the HPA axis in adult ponies.
• The study demonstrates a lasting impact of early-life stress on the HPA axis regulation.
• These findings highlight the sensitivity of the developing HPA axis to glucocorticoid levels.