Stresshormone

Stresshormone, in a broad sense, refers to chemical messengers released by the body in response to stress. The primary stress hormones are adrenaline (epinephrine) and noradrenaline (norepinephrine) released by the adrenal medulla, and cortisol released by the adrenal cortex. The release is regulated by two major systems: the sympathetic-adrenal-medullary (SAM) axis and the hypothalamic–pituitary–adrenal (HPA) axis. In acute stress, the SAM axis triggers rapid secretion of adrenaline and noradrenaline, increasing heart rate, blood pressure, and glucose availability to muscles, and preparing the body for “fight or flight.” The HPA axis stimulates the hypothalamus to release CRH, which triggers ACTH release from the pituitary, and in turn stimulates cortisol secretion from the adrenal cortex. Cortisol helps sustain energy by promoting gluconeogenesis, mobilizing fatty acids, and modulating immune and inflammatory responses. Cortisol also influences mood, cognition, and memory through central receptors.

Action at target tissues occurs via specific receptors: adrenergic receptors for catecholamines; glucocorticoid and mineralocorticoid receptors for cortisol. Effects can be rapid or occur over hours to days. Acute effects differ from chronic exposure: chronic stress can lead to elevated baseline cortisol levels, blood pressure changes, insulin resistance, suppression of certain immune functions, and mood disturbances.

Clinical and research notes: The term stress hormone is often used to refer to cortisol and catecholamines. Measurement can be through blood, saliva, or urine. Regulation is complex and influenced by sleep, nutrition, exercise, and disease.