This hormone regulates the reabsorption of water molecules and therefore promotes fluid retention.
Hormones are chemical compounds that, when released by the endocrine glands into the blood or the nervous system of living beings, exert modulating effects on the functions of other cells and body structures.
One of the most relevant and well-known human hormones is vasopressin or antidiuretic hormone, which is essential for fluid retention or the stress response, among other phenomena. In this article we will discuss the properties and functions of vasopressin.
What is vasopressin?
Vasopressin is also known as “argipressin”, “arginine vasopressin” and “antidiuretic hormone”. As this last name suggests, this hormone fulfills functions related to the reabsorption of water molecules through the kidneys and to the reduction of the amount of urine accumulated in the body.
It is an oligopeptide, that is, a molecule composed of the union of a small number of amino acids, specifically 9. By contrast, polypeptides are groups of between 10 and 100 amino acids, while we speak of “proteins” to refer to to clusters of more than 100 molecules of this type.
Specifically, vasopressin contains an amino group (-NH2), cysteine (Cys), tyrosine (Tyr), phenylalanine (Phe), glutamine (Gln), asparagine (Asn), proline (Pro), arginine (Arg) and a carboxyl group (-COOH).
Vasopressin is secreted by the neurohypophysis, the posterior lobe of the pituitary gland, in response to changes in osmotic concentration and blood volume. Although most of the vasopressin we produce is released into the bloodstream, its effects on the brain also explain some of its functions.
Other pituitary hormones
The pituitary gland or pituitary gland is one of the main endocrine glands. It fulfills an intermediary function between the hypothalamus, which initiates the secretion of hormones, and the rest of the endocrine system by sending biochemical signals.
This structure is made up of two lobes: the anterior or adenohypophysis and the posterior or neurohypophysis. While the posterior pituitary gland stores the hormones vasopressin and oxytocin (related to motherhood and orgasm), the anterior pituitary secretes thyrotropin, corticotropin, gonadotropin, and growth hormone-releasing hormones.
Functions of this hormone
The main functions of vasopressin are associated with its ability to regulate kidney activity; however, this hormone also has effects on other body systems, including the cardiovascular and central nervous systems.
1. Retention and reabsorption of liquids
Vasopressin increases the permeability of kidney cells, increasing the amount of water they absorb; this function is called “antidiuresis”. This process also implies an increase in the urine concentration due to the lower availability of fluid in the excretory system.
On the other hand, the antidiuretic hormone also reabsorbs urea, the main chemical compound in urine, made up of waste products from the body. This prevents the frequency of urination from being excessive.
2. Maintenance of homeostatic balance
Homeostasis (self-regulation of the internal environment of organisms) depends on a large number of factors; among these is the activity of vasopressin. Failure of homeostatic mechanisms can lead to problems such as dehydration and acidosis.
This hormone helps to maintain the electrolyte balance of the bloodstream by retaining and reabsorbing adequate amounts of water, glucose and sodium, among other chemical compounds relevant to the functioning of the body.
3. Increase in blood pressure
Another of the most prominent effects of vasopressin is the increase in blood pressure. This function occurs as a consequence of the vasoconstrictive properties of this hormone, which have a moderate intensity. The potentiating role of vasopressin on stress- related hormones and neurotransmitters is also important to explain this effect.
4. Modulation of the stress response
Although scientific research has not yet fully confirmed this, there is strong evidence that vasopressin has a modulating effect on the body’s response to stressful (or anxiety) situations.
Antidiuretic hormone regulates the release of corticotropin-releasing hormone, also called “adrenocorticotropic hormone-releasing hormone.” This compound promotes the secretion of corticosteroids such as aldosterone and cortisol, mainly associated with vasoconstriction and the stress response, by the adrenal gland.
5. Reduction of pain sensation
In recent years, the role of vasopressin in the modulation of pain sensations has been studied . It is believed that this hormone could act as a pain reliever ; this would imply that, when released under certain conditions, vasopressin would have reinforcing effects due to the positive sensations associated with its secretion.
6. Formation of sexual and social ties
Studies with rodents suggest that the release of vasopressin also acts as an enhancer of social bonds, especially those of a couple. In humans, these effects have been found mainly in men and are related to the direct release of antidiuretic hormone in the reward circuits of the central nervous system.