Hypothalamic-pituitary-adrenal axis activity and vascular function in healthy adults

Area of Science:

• Endocrinology
• Cardiovascular Physiology
• Metabolic Health

Background:

• The hypothalamic-pituitary-adrenal (HPA) axis plays a crucial role in stress response and metabolic regulation.
• Vascular function and insulin sensitivity are key indicators of cardiovascular health.
• Understanding the interplay between HPA axis activity, vascular function, and insulin sensitivity is vital for assessing cardiovascular risk in healthy individuals.

Purpose of the Study:

• To investigate the relationship between hypothalamic-pituitary-adrenal (HPA) axis activity and vascular function in healthy adults.
• To determine if insulin sensitivity is associated with HPA axis activity and vascular function.
• To explore the contribution of endothelial dysfunction to the link between HPA hyperactivity and cardiovascular risk.

Main Methods:

• An observational study involving 30 healthy adults.
• HPA axis activity was assessed by measuring serum cortisol levels post-ACTH stimulation, categorizing participants into low and high responders.
• Vascular function was evaluated using the reactive hyperaemia index (RHI), and insulin sensitivity was assessed via the Matsuda index.

Main Results:

• High HPA axis responders exhibited significantly lower reactive hyperaemia index (RHI) values compared to low responders (p=0.04).
• A negative association was observed between RHI and peak cortisol levels post-ACTH stimulation (β=-0.56, p<0.01).
• No significant differences in insulin sensitivity (Matsuda index) were found between high and low HPA responders.

Conclusions:

• In healthy adults, heightened HPA axis activity is associated with impaired endothelial function.
• Endothelial dysfunction may mediate the link between HPA hyperactivity and increased cardiovascular risk.
• The observed endothelial dysfunction is not primarily a consequence of insulin resistance.