The Hypothalamic Pituitary Adrenal (HPA) axis is a critical neuroendocrine system that plays a central role in the body's response to stress. Comprising the hypothalamus, pituitary gland, and adrenal glands, the HPA axis regulates hormonal responses to various stressors, ensuring adaptive responses to both physical and psychological challenges. The HPA axis functions through a tightly regulated feedback loop, starting with the release of corticotropin-releasing hormone (CRH) from the paraventricular nucleus of the hypothalamus. CRH stimulates the anterior pituitary gland to release adrenocorticotropic hormone (ACTH) into the bloodstream. ACTH, in turn, targets cells of the adrenal cortex, promoting the secretion of glucocorticoid hormones, primarily cortisol in humans. Cortisol, the primary effector hormone of the HPA axis, plays several crucial functions in the body. For example, cortisol levels help the body cope with stress by mobilizing energy reserves, by increasing alertness, and by suppressing non-essential functions, such as digestion and immune responses. In acute stress situations, cortisol temporarily suppresses immune responses, aiming to redirect energy towards the stress response. However, chronic stress and sustained high cortisol levels can itself weaken the immune system, making individuals more susceptible to infections and inflammatory conditions. For example, cortisol inhibits the function of immune cells, such as T cells and natural killer (NK) cells, which are critical for detecting and eliminating infected or abnormal cells. High cortisol levels can lead to a decrease in the number and activity of these immune cells, impairing the body's ability to defend against infections. Additionally, cortisol can downregulate the production of pro-inflammatory cytokines, which mediate many immune responses. Cortisol also influences glucose metabolism, acting to increase blood sugar levels during times of stress. This effect is vital to provide the body energy to cope with the stressor. However, chronically elevated cortisol levels can also lead to insulin resistance and contribute to metabolic disorders such as diabetes and obesity. Cortisol levels typically follow a diurnal pattern, peaking in the morning to promote wakefulness and gradually declining throughout the day to facilitate sleep onset. Disruptions in this pattern, such as elevated cortisol at night due to chronic stress, can lead to sleep disturbances and insomnia. Cortisol also influences memory consolidation and cognitive function. Moderate cortisol levels are associated with improved memory performance, but excessive or chronic stress-related cortisol release can impair memory and cognitive abilities. Finally, cortisol interacts with brain regions involved in emotion regulation, such as the amygdala and prefrontal cortex. In response to stress, cortisol can modulate emotional responses, helping individuals adapt to challenging situations. Again however, persistent stress and cortisol dysregulation may contribute to mood disorders such as anxiety and depression. Overall, the HPA axis and cortisol, play a crucial role in regulating the body's stress response and maintaining physiological balance. Whilst the stress response is essential for survival, chronic activation of the HPA axis can have detrimental effects on physical and mental health, with dysregulation of the HPA axis implicated in various stress-related disorders, major depressive disorder, and certain metabolic diseases. We offer a wide product catalogue of research reagents for investigating the hypothalamic pituitary adrenal axis, including ACTH antibodies, Luteinizing Hormone antibodies, 5HT1A Receptor antibodies, POMC ELISA Kits, and Luteinizing Hormone ELISA Kits. Explore our full hypothalamic pituitary adrenal axis product range below and discover more, for less.