Adrenocorticotropic hormone: definition, functions and pathologies

The human body works just like a production line does. To obtain a final result (in this case a physical or bodily response) a series of prior reactions must first occur. For example, when we perceive stress symptomsBefore, there have already been a series of chain reactions inside our body.

One of the agents that make this chain reaction possible is the adrenocorticotropic hormone. A complex-functioning hormone with a multitude of functions that we will talk about throughout this article.

What is adrenocorticotropic hormone?

Also known as ACTH, adrenocorticotropic or corticotropin, this hormone secreted by the pituitary It is part of the category of tropic polypeptide hormones and although it is mainly related to the stress processes and reactions is also used as a medicine and a diagnostic factor for a large number of conditions organic.

Discovered in 1933 by the American biochemist Evelyn M. Anderson, this hormone has been the object of study of countless investigations, due to the large number of functions and effects that it has in the body, as well as its complex form of performance.

At the moment we know that adrenocorticotropic hormone is one of the main agents involved in the functioning of the hypothalamic-pituitary-adrenal axis and its production has traditionally been associated with a stress response biological.

In addition, this hormone has a fundamental role in the regulation and release of other hormones known as steroids. By stimulating the activity of the adrenal and adrenal glands, ACTH promotes the release of hormones such as adrenaline and norepinephrine.

However, as we mentioned previously, the main function of the corticotropic hormone is to increase the cortisol levels and corticosterone in the blood. This occurs as a response to stress and its main effect on the body is related to the metabolism of fats, carbohydrates, proteins and blood pressure.

In addition, the role of the adrenocorticotropic hormone is closely related to the circadian rhythms of our body. It functions differently throughout the day, generating higher ACTH peaks. in the mornings, especially when waking up, and that are declining throughout the day. This is known as the adrenocorticotropin diurnal rhythm.

Regarding the possible therapeutic effects of adrenocorticotropin, this is usually used in the treatment of inflammation. Made in the form of an anti-inflammatory drug, it is administered in cases of inflammatory conditions such as rheumatoid arthritis, lupus erythematosus, and ulcerative colitis.

Production and regulation

The synthesis of adrenocorticotropic hormone takes place in the anterior lobe of the pituitary gland, also known as the adenohypophysis. However, the regulation and control of its release is linked to three regions interconnected parts of our body: the hypothalamus, the pituitary gland and the glands adrenals. This structure is known as the hypothalamic-pituitary-adrenal axis.

When ACTH levels in the blood are lower than usual, the small group of cells in the hypothalamus release a hormone known as a hormone. corticotropin-releasing agent, which stimulates the pituitary gland to secrete more adrenocorticotropin into the stream blood.

However, when the adrenal glands detect an excess of this hormone, which causes an increase in the levels of cortisol in the blood, it is automatically produces a decrease in corticotropin-releasing hormone, whereby the amount of adrenocorticotropin in the stream begins to diminish. This is what is known as a negative feedback loop..

Pathologies associated with ACTH

Due to its role in a large number of activities and functions of our body, abnormal levels of adrenocorticotropic hormone can lead to a host of diseases and clinical conditions.

These ACTH-related diseases vary significantly depending on whether they are caused by an increase of the levels of this hormone in the blood or, conversely, if its cause is a deficiency of adrenocorticotropin.

1. ACTH excess in blood

The effects of an excess of adrenocorticotropic hormone are a direct consequence of increased levels of cortisol in the blood. Although this increase in corticosteroid hormones is not necessarily a health hazard, abnormally high levels are often associated with the following conditions:

• Cushing's disease: This condition is caused by a cancerous tumor or adenoma located in the pituitary gland and is usually related to abnormal levels of ACTH.
• Tumor formations located outside the pituitary gland known as ectopic adrenocorticotropic hormone tumor.
• Addison's disease: characterized by abnormally low cortisol levels but excessively high ACTH levels.
• Congenital adrenal hyperplasia: a genetic disorder distinguished by inadequate production of cortisol and / or aldosterone.

2. ACTH deficiency

On the contrary, it may happen that the person experiences a deficiency of adrenocorticotropic hormone due to also to the appearance of tumor formations or as a side effect of radiotherapy or surgery in the pituitary.

In this case, the main conditions associated with this deficit are:

• Suprarrenal insufficiency: The adrenal glands stop producing ACTH properly, which causes a decrease in adrenal androgens.
• Cushing's disease: In addition to an excess of ACTH, it can also be related to a deficit of this.
• Clinical conditions of the pituitary gland such as hypopituitarism.

Although these are the main clinical diseases related to adrenocorticotropin, there is a large list of other conditions in which this hormone plays a special role. Among them we find:

• Small cell carcinoma
• Nelson syndrome
• West syndrome or infantile spasms
• Posttorgasmic disease syndrome

Bibliographic references:

• Backers A, Stevenaert A, Foidart JM, Hennen G and Frankenne F (1991). Placental and Pituitary growth hormone secretion during pregnancy in acromegazic women. J Clin Endocrinol Metab 71: 725.

• Guyton-Hall (2001). Treaty of Medical Physiology, 10th ed., McGraw-Hill-Interamericana.