Corticosterone is a 21-carbon steroid hormone

Steroid hormone

A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into five groups by the receptors to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestogens...

 of the corticosteroid

Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...

 type produced in the cortex of the adrenal gland

Adrenal gland

In mammals, the adrenal glands are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped...

s.

Roles

In many species, including amphibian

Amphibian

Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s, reptile

Reptile

Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s, rodents and birds, corticosterone is a main glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

, involved in regulation of fuel, immune reactions, and stress

Stress (medicine)

Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...

 responses.

However, in humans, corticosterone is produced primarily in the zona fasciculata

Zona fasciculata

The zona fasciculata constitutes the middle zone of the adrenal cortex, sitting directly beneath the zona glomerulosa. Constituent cells are organized into bundles or "fascicles"....

 of the adrenal cortex

Adrenal cortex

Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis.-Layers:Notably, the reticularis in...

. It has only weak glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

 and mineralocorticoid

Mineralocorticoid

Mineralocorticoids are a class of steroid hormones characterised by their similarity to aldosterone and their influence on salt and water balances.-Physiology:...

 potencies in humans and is important mainly as an intermediate in the steroidogenic pathway from pregnenolone

Pregnenolone

Pregnenolone is a steroid hormone involved in the steroidogenesis of progesterone, mineralocorticoids, glucocorticoids, androgens, and estrogens. As such it is a prohormone. Pregnenolone sulfate is a GABAA antagonist and increases neurogenesis in the hippocampus.-Chemistry:Like other steroids,...

 to aldosterone

Aldosterone

Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...

. Corticosterone is converted to aldosterone by aldosterone synthase

Aldosterone synthase

Aldosterone synthase is a steroid hydroxylase cytochrome P450 oxidase enzyme involved in the generation of aldosterone....

, found only in the mitochondria of glomerulosa cells. Glomerulosa cells are found in the Zona glomerulosa

Zona glomerulosa

The zona glomerulosa of the adrenal gland is the most superficial layer of the adrenal cortex, lying directly beneath the adrenal gland's capsule...

, which is the most superficial region of endocrine cells in the adrenal cortex

Adrenal cortex

Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis.-Layers:Notably, the reticularis in...

.

Release or generation mechanisms

One example of a release pathway relates to UV-B stimulation on the skins of certain amphibian

Amphibian

Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s such as the Rough-skinned Newt

Rough-skinned Newt

The rough-skinned newt is a North American newt known for its strong poison.- Toxicity :Many newts produce toxins to avoid predation, but the toxins of the genus Taricha are particularly potent...

, Taricha granulosa; this trigger seems to cause the internal generation of corticosterone in that species.