ACTH Full Form

The anterior pituitary gland produces and secretes a tropic polypeptide hormone known as adrenocorticotropic hormone (ACTH; sometimes adrenocorticotropin, corticotropin). It’s also utilised as a diagnostic tool and a medication. ACTH, a hormone produced by the hypothalamic-pituitary-adrenal axis in response to biological stress, is a key component (along with its precursor corticotropin-releasing hormone from the hypothalamus). Many creatures’ circadian rhythms are also influenced by ACTH.

ACTH full form

The full form of ACTH is Adrenocorticotropic Hormone.

The anterior or front pituitary gland in the brain produces a hormone called adrenocorticotropic hormone (ACTH). The steroid hormone cortisol is secreted from the adrenal gland, and ACTH regulates its levels. Other names for ACTH include: 

• Adrenocorticotropic Hormone

• Serum Adrenocorticotropic Hormone

• Highly-sensitive ACTH

• Corticotropin

• Cosyntropin, which is a pharmacological version of ACTH, is a highly sensitive Adrenocorticotropic Hormone.

These disorders may be caused by one or more of the following factors:

1. An adrenal or pituitary gland

2. Malfunction

3. A tumours of the pituitary

4. A tumours of the adrenals

5. A pulmonary adenocarcinoma

Production and regulation of ACTH

In response to the hormone corticotropin-releasing hormone (CRH) released by the hypothalamus, corticotropic cells in the anterior lobe (or adenohypophysis) of the pituitary gland secrete POMC, ACTH, and -lipotropin. Pre-pro-opiomelanocortin is used to make ACTH (pre-POMC).

The 241-amino-acid polypeptide POMC is produced when the signal peptide is removed during translation. It then goes through a series of post-translational modifications like phosphorylation and glycosylation before being proteolytically cleaved by endopeptidases to yield various polypeptide fragments with varying physiological activity. 

Many chemicals released within this axis exhibit slow/intermediate and quick feedback-loop action in order to regulate ACTH secretion.

Glucocorticoids released by the adrenal cortex inhibit CRH secretion by the hypothalamus, which reduces ACTH secretion by the anterior pituitary.

Structure of ACTH

The first 13 amino acids (counting from the N-terminus) of ACTH can be cleaved to create -melanocyte-stimulating hormone (-MSH) (this common structure is responsible for abnormally browned skin in Addison’s illness). ACTH is a cleaved into-melanocyte-stimulating hormone (-MSH) and CLIP, a peptide of unclear action in humans, after a short time. The molecular weight of ACTH in humans is 4,540 atomic mass units.

Functions of ACTH

• ACTH stimulates the release of glucocorticoids from adrenal cortex cells, notably in the zona fasciculata.

• ACTH operates by binding to ACTH receptors on cell surfaces, which are predominantly present on the adrenal cortex’s adrenocortical cells.

• The ACTH receptor spans seven membranes and is a G protein-coupled receptor. In response to ligand binding, the receptor undergoes conformational changes that stimulate the enzyme adenylyl cyclase. 

• ACTH has a short-term as well as a long-term effect on steroid hormone secretion.

• One of ACTH’s rapid functions is to promote cholesterol delivery to the mitochondria, where the P450scc enzyme is situated.

• ACTH also stimulates lipoprotein absorption into cortical cells. This increases cholesterol bioavailability in adrenal cortex cells.

• In the long run, ACTH increases the transcription of genes encoding steroidogenic enzymes such as P450scc and steroid 11-hydroxylase, as well as their related electron transfer proteins. 

How the ACTH test is performed

Before your test, your doctor may advise you not to take any steroid medications. These factors may have an impact on the accuracy of the results. Typically, the test is performed first thing in the morning. When you first wake up, your ACTH levels are at their highest. The test will most likely be scheduled very early in the morning by your doctor. A blood sample is used to determine ACTH levels. Blood is drawn from a vein, generally on the inside of the elbow, to obtain a sample.

The steps for taking a blood sample are as follows: 

1. To kill germs, a healthcare provider cleans the site with an antiseptic.

2. An elastic band will then be wrapped over your arm. The vein swells as a result of this.

3. A needled syringe will be gently inserted into your vein, and your blood will be collected in the syringe tube.

4. The needle is removed after the tube is filled. To halt the bleeding, the elastic band is removed and the puncture site is wrapped with sterile gauze.

Why is the ACTH test performed?

If you have symptoms of too much or too little cortisol, your doctor may prescribe an ACTH blood test. These symptoms vary greatly from person to person and are frequently an indicator of other health issues.

If one’s cortisol level is high, he may experience

1. obesity

2. a rounded appearance

3. weak muscles, frail skin, and purple lines on the belly

6. acne and 7-an increase in body hair

8. excessive blood pressure

9. potassium deficiency

10. high bicarbonate concentration

11. elevated glucose levels

12. diabetes

Low cortisol causes the following symptoms

1-muscle weakness

2-fatigue

3-weight reduction

5-a decrease in appetite 4-increased skin pigmentation in places not exposed to the sun

6-hypotension (low blood pressure)

7-Low blood glucose levels 

8 sodium deficiency

9 excessive potassium levels

10-extremely high calcium levels 

Conclusion

ACTH is a pituitary hormone that promotes adrenal cortex growth and development as well as glucocorticoid synthesis. 

ACTH’s major job is to keep the glucocorticoid (steroid) hormone cortisol in check. The adrenal gland produces cortisol. Blood pressure, blood sugar, the immune system, and stress responses are all regulated by it. This test can assist in determining the source of some hormone issues.