Adrenocorticotropic Hormone (ACTH)

Define ACTH and Its Functions

Hormones are steroidal substances that are secreted from different organs. These biochemical substances are developed to control and manage various biological functions. Most human hormones are secreted by the pituitary gland present in the lower portion of the human brain. It is also called the master gland that controls the functions of other organs. One such hormone produced by the pituitary gland is adrenocorticotropic hormone (ACTH). In this section, we will study the ACTH function elaborately and the disorders caused by its abnormal levels.


What is ACTH Hormone?

Adrenocorticotropic Hormone (ACTH) is a steroidal substance that acts as a hormone. It is produced in the anterior section of the pituitary gland located under the human brain. This hormone is commonly called adrenocorticotrophin, arginine vasopressin, corticotropin, or serum adrenocorticotropic hormone.


This hormone is required for the functioning of the adrenal glands. As you can easily understand by its name, the prime ACTH hormone function is to maintain the vital functions of this pair of glands. These glands are responsible for the production and secretion of cortisol or stress hormones. These hormones are produced in the cortex region of these glands.


How ACTH is Synthesized?

The first stage is the production and release of the Corticotrophin-releasing hormone. This hormone acts as the precursor of the synthesis and release of ACTH. ACTH, after synthesis and release, reaches the bloodstream to reach the adrenal glands. These glands are present on the top of both kidneys. The cortisols are then synthesized in the cortex of these glands. These hormones then reach the hypothalamus of our brain to signal and stop the synthesis of ACTH.


Now that we have understood the answer for what is ACTH hormone, we need to go deeper into the synthesis and control of the ACTH level in our body. It is obvious that the hormone travels through the bloodstream and reaches the adrenal glands for action. It has been observed that the level of this hormone is the highest when you wake up in the morning. Eventually, it reduces throughout the day and is the lowest before you go to sleep. The level is controlled but three crucial organs of our body. They are the hypothalamus, adrenal glands, and pituitary gland.


We have learned that the level of this hormone is controlled by the cortisol or stress hormones present in the bloodstream. We also know that the lowest level of ACTH occurs during the night time when we are about to hit the bed. This proves that working relentlessly and taking stress release cortisol in the bloodstream. These stress hormones then reach the hypothalamus telling it to shut down the production. The ACTH hormone levels then significantly fall over the day in due course of time and action. This rhythmic synthesis and reduction of the ACTH hormone level during the daytime are called the diurnal or circadian rhythm.


Functions of ACTH Hormone

The list of ACTH functions is given below:

  • Resorption of bones

  • Protein catabolism

  • Anabolic effects of this hormone can be seen on bones and muscles

  • Proper stimulation and beginning of spermatogenesis

  • Proper metabolism of glucose, lipolysis, hyperglycemia, androgens, and immuno-suppression.

What Happens When the ACTH Level Drops?

When the ACTH hormone levels drop significantly, it can cause anomalies that are related to the functioning of the adrenal glands. It can happen due to hypopituitarism or the low functioning of the master gland. Cushing’s syndrome can also increase the level of cortisol that affects the synthesis of ACTH causing such issues.


What Happens When the ACTH Hormone Levels Increase?

The ATH level can significantly increase due to hyperpituitarism, Cushing’s disease, adrenal insufficiency (low cortisol levels), adrenal hyperplasia in the congenital condition, etc. Due to the increased ACTH level, it can cause Addison’s disease.


What are the ACTH Hormone Disorders?

When there is an improper level of ACTH in the bloodstream, it can indicate the presence of an anomaly in the physiology of the brain, the adrenal glands, etc. It can happen due to tumours present in the pituitary gland, Cushing’s disease, adrenal insufficiencies such as Addison’s disease, or congenital adrenal hyperplasia.


Conclusion

The definition of this hormone depicts the ACTH hormone function that is crucial for the proper functioning and development of the human body. It indicates the adrenal glands develop and promotes their functions. Indirectly, the functions of the adrenal glands are controlled by this hormone. The hormones produced in these glands are aldosterone, cortisol, noradrenaline, and adrenaline. These hormones function to control metabolism, blood sugar levels, water-slat balance, blood pressure, pregnancy, puberty, sexual characteristics development, balancing the sex hormones, etc.

FAQs (Frequently Asked Questions)

1. What Do You Mean by ACTH Hormone?

Ans: The full form of ACTH is Adrenocorticotropic Hormone. This hormone is produced by the pituitary gland, also called the master gland present in the hypothalamus of the human brain. Its prime aim is to promote the synthesis of functions and secretion of different hormones in the adrenal glands. The level of this hormone is maintained by the hypothalamus, the pituitary gland, and the adrenal gland. This proves an intricate system of hormones that control each other and maintain an excellent hormonal balance for promoting the right functions at the right time.

2. What are the Hormones that Control the Level of ACTH in the Blood?

Ans: As per the physiology of the master gland, the ACTH level is maintained by the level of cortisol in the bloodstream. We have studied that the ACTH level is highest during the daytime. It eventually reduces when the cortisol levels increase. This shows that the cortisol level signals the hypothalamus to stop producing ACTH in the pituitary gland. It also means that the ACTH hormone function also recedes. In fact, its level reduces to the lowest during bedtime.

3. What Affects the Level of ACTH in the Bloodstream?

Ans: Hypopituitarism, hyperpituitarism, autoimmune disease, Cushing syndrome, congenital adrenal hyperplasia, fluctuating cortisol levels, etc affect the level of ACTH in the bloodstream. The improper functioning of the pituitary gland and the adrenal glands are also the cause.