corticosterone

Corticosterone is a steroid hormone produced by the adrenal cortex of many vertebrates. In rodents and many other nonhuman mammals, it is the principal glucocorticoid and participates in regulating energy metabolism, immune responses, and the body's response to stress. In humans, cortisol is the dominant glucocorticoid, and corticosterone is present at lower concentrations; it also serves as a precursor in the biosynthesis of aldosterone, a mineralocorticoid.

Mechanism of action and distribution: Corticosterone acts by binding to glucocorticoid receptors (GR) and, in certain tissues, mineralocorticoid receptors (MR). Through GR signaling, it influences glucose and protein metabolism, fat distribution, and anti-inflammatory effects. In the brain, corticosterone is also classified as a neurosteroid, modulating stress responsiveness and cognition.

Regulation and physiology: Production is regulated by the hypothalamic-pituitary-adrenal (HPA) axis. CRH from the hypothalamus stimulates ACTH release from the pituitary, which in turn stimulates the adrenal cortex to synthesize corticosterone. Circulating levels exhibit diurnal variation and increase in response to stress. Negative feedback via GR reduces CRH and ACTH release to maintain homeostasis.

Synthesis, metabolism, and clinical notes: Corticosterone is synthesized from cholesterol through adrenal steroidogenesis. It is metabolized in the liver and excreted in urine, often after conjugation. In research and clinical contexts, corticosterone measurement is common in studies of HPA-axis activity in animals; in humans, cortisol is more frequently measured, but corticosterone can be quantified in certain settings and can serve as a substrate for aldosterone synthesis and interact with MR and GR.