Secretagogues, Sex Hormones, and Belly Fat Independently Control Cortisol Release

The body's stress response, mediated by the hormone cortisol, is crucial for survival but chronic dysregulation can lead to serious health issues like metabolic syndrome, obesity, and cardiovascular disease. Cortisol secretion is tightly controlled by the hypothalamic-pituitary-adrenal (HPA) axis, stimulated by various secretagogues (substances that induce secretion). However, the precise and individual contributions of secretagogue type, sex-steroid hormones, and abdominal visceral adiposity to cortisol secretion have remained incompletely understood.

The study revealed distinct and independent influences on cortisol secretion. ACTH stimulation consistently resulted in a 2.5-fold higher peak cortisol response compared to CRH stimulation (p<0.001), indicating a more potent direct adrenal stimulus. Furthermore, the sex-steroid milieu played a significant role: higher endogenous estrogen levels in women were associated with a 15% blunted cortisol peak following secretagogue administration compared to men or women in the luteal phase (p=0.02). High abdominal visceral adiposity was identified as the strongest independent predictor, leading to a 43% greater overall cortisol area under the curve (AUC) compared to individuals with low visceral fat (p<0.001), suggesting a heightened HPA axis sensitivity. This exaggerated response in individuals with more belly fat was observed irrespective of the secretagogue type, highlighting a fundamental alteration in HPA axis regulation. Conversely, higher testosterone levels in men correlated with a 10% lower baseline cortisol secretion (p=0.04).