Corticosterone, also known as 17-deoxycortisol and 11β,21-dihydroxyprogesterone,
is a 21-carbon
steroid hormone
A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Wit ...
of the
corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...
type produced in the cortex of the
adrenal gland
The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer adrenal corte ...
s. In the very rare case of
congenital adrenal hyperplasia due to 17α-hydroxylase deficiency cortisol production is blocked.
Roles
In many species, including
amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s,
reptile
Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...
s,
rodents and
birds
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
, corticosterone is a main
glucocorticoid
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...
,
involved in regulation of energy,
immune reactions, and
stress responses.
However, in
humans
Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...
,
cortisol
Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone.
Cortisol is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal corte ...
is the primary glucocorticoid that is produced primarily in the
zona fasciculata of the
adrenal cortex. Corticosterone has only weak
glucocorticoid
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...
and
mineralocorticoid
Mineralocorticoids are a class of corticosteroids, which in turn are a class of steroid hormones. Mineralocorticoids are produced in the adrenal cortex and influence salt and water balances (electrolyte balance and fluid balance). The primary ...
potencies in humans and is important mainly as an intermediate in the
steroidogenic pathway from
pregnenolone to
aldosterone
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays ...
. Corticosterone is converted to aldosterone by
aldosterone synthase, found only in the mitochondria of glomerulosa cells. Glomerulosa cells are found in the
zona glomerulosa, which is the most superficial region of endocrine cells in the
adrenal cortex.
Corticosterone is the precursor molecule to the mineralocorticoid aldosterone, one of the major homeostatic modulators of sodium and potassium levels in vivo.
Release or generation mechanisms
One example of a release pathway relates to
UV-B stimulation on the skins of certain
amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s such as the
Rough-skinned Newt, ''
Taricha granulosa''; this trigger seems to cause the internal generation of corticosterone in that species.
Corticosterone in birds
A sizable amount of research has been done on the effects of corticosterone in
birds
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
. A brief survey of this research is below.
Corticosterone both inhibits
protein synthesis and degrades
proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...
. Birds with increased levels of corticosterone will have slower
feather
Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and an exa ...
growth during their molting period and an extended period of poor flight. As a result, many birds have reduced levels of corticosterone when they
moult so as to prevent the degradation of their new feathers. Interestingly, higher levels of corticosterone are also associated with a wider range of exploration, despite beforementioned inhibited feather growth.
Corticosterone has further developmental effects on birds. Increased levels of corticosterone in chicks leads to increased begging for food and
aggressiveness. In the short term this leads to higher chance of obtaining food, but in the long term, increased corticosterone in early life compromises the birds cognitive functioning (
problem solving
Problem solving is the process of achieving a goal by overcoming obstacles, a frequent part of most activities. Problems in need of solutions range from simple personal tasks (e.g. how to turn on an appliance) to complex issues in business an ...
, association of visual cue with food, etc.).
Parental response to increased begging by chicks is an increased time
foraging for food. This leaves the nest of chicks without protection for increased durations of time. To counter this, during extended periods of food shortage, chicks of some species may suppress corticosterone activity and thus reduce the negative effects elevated corticosterone induces.
Effect on memory
Corticosterone has multiple effects on
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...
. The main effects are seen through the impact of
stress on emotional memories as well as
long term memory (LTM).
With emotional memories, corticosterone is largely associated with
fear
Fear is an unpleasant emotion that arises in response to perception, perceived dangers or threats. Fear causes physiological and psychological changes. It may produce behavioral reactions such as mounting an aggressive response or fleeing the ...
memory recognition. Studies have shown that when fear memories are reactivated or consolidated, levels of corticosterone increased. The increase in corticosterone is linked to anxiety relief. This finding depends on the time at which the administration of corticosterone took place as compared to when the fear conditioning took place; corticosterone can either facilitate or interrupt
conditioned fear.
Not only does corticosterone have effects on emotional memories but memory
recognition and
consolidation as well.
With respect to recognition and long term memories, corticosterone has variable effects. Studies show that the modification of certain chemical and brain processes that affect corticosterone levels can also impact stress effects on memory. In studies on rats, the fluctuations of corticosterone concentration are shown to prevent stress' impairment of recognition memory in lower amounts. These lower levels seem to be linked to the rescue of stress-induced attenuation of CA1 long-term
potentiation. When researchers looked at stress effects on LTM, they found many outcomes. In multiple studies, the formation of LTM (tested 24 h later) was found to be enhanced by corticosterone in some studies, while the persistence of LTM (tested at least 1 wk later) was only assisted by corticosterone in the late phase of memory consolidation and
reconsolidation.
[S. Moore et al. 2013. Conversion of short-term to long-term memory in the novel object recognition paradigm. Neurobiology of Learning and Memory. 105: 174-185.][C. Yang et al. 2013. Stress within a Restricted Time Window Selectively Affects the Persistence of Long-Term Memory. PLoS One. 8(3): e59075.] Stress facilitates the consolidation but disrupts the reconsolidation of emotional memory. As mentioned previously, the persistence of LTM is selectively enhanced when stress and corticosterone are administered during the late phase after acquisition, but it is disrupted when stress and corticosterone are administered during the late phase after retrieval of memory.
With regards to the persistence of LTM, there is a restricted time window between acquisition and retrieval where persistence is affected. These studies found that while persistence of LTM is selectively affected based on stage of memory, the formation of LTM is left intact after a certain length of time. Up to this point, studies have not agreed as to whether or not these processes are dependent on corticosterone or what even happens based on corticosterone in these processes and how memory is ultimately affected.
In the end, corticosterone affects many processes in terms of memory as well as different types of memories themselves.
Additional images
File:Steroidogenesis.svg, Steroidogenesis
File:11-Deoxycorticosterone.svg, Deoxycorticosterone
File:Aldosterone-2D-skeletal.svg, Aldosterone
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays ...
See also
*
11-Deoxycortisol
*
11-Deoxycorticosterone
*
Cortisol
Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone.
Cortisol is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal corte ...
References
External links
Corticosterone MS Spectrum
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Biological activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...
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{{Mineralocorticoid receptor modulators
{{Glucocorticoid receptor modulators
{{Xenobiotic-sensing receptor modulators
Corticosteroids
Pregnane X receptor agonists
Pregnanes