Vasopressin (væsoʊprɛsən / vaso + -in + pressure), also known as antidiuretic hormone (ADH) has a molecular weight of 1228 kDa and is formed by the following sequence of nine amino acids: cysteine - tyrosine - phenylalanine - glutamate - aspartate - cysteine - proline - arginine - glycine. The presence of a disulfide bridge between the cysteines in position 1 and 6, gives it a ring-shaped structure. In most species, the 8th position of the molecule is occupied by arginine and due to that, ADH is therefore also called arginine vasopressin or argipressin (AVP). Lysine vasopressin has a lysine in the traditional arginine position. In 1955, Du Vigneaud won the Nobel Prize in Chemistry, in part, by the discovery of vasopressin and oxytocin, a hormone related to vasopressin. In kidney, vasopressin increases the permeability of the renal tubule cells to water. As a result, it allows the body to retain water, increasing urine concentration and decreasing its volume. For this reason it is called antidiuretic hormone (ADH). 
Also, it promotes arteriolar vasoconstriction, increasing consequently the peripheral resistance and blood pressure. For this reason it is also called vasopressin. It also has other functions such as regulation of circadian rhythms, homeostasis and different social behaviors.This hormone is produced by the neurohypophysis, but can also be produced by the hypothalamus at the supraoptic and paraventricular levels of the core. The production of vasopressin begins with the activation of the gene responsible for its biosynthesis. This gene is located on chromosome 20 and has 3 exons separated by 2 introns. Each exon codes for one of the three domains of the precursor molecule of vasopressin.
Under enzymatic action, this precursor loses the signal peptide and is stored in vesicles at the Golgi complex, and then is transported from the cell body of the neuron to the nerve endings. This transport takes approximately 12 to 24 hours. During this time, several cleavages occur, giving rise to ADH molecules, neurophysin and copeptin. ADH is excreted by the neurohypophysis briefly in response to decreases in plasma volume (detected by barorrecetores), potential increases in osmotic plasma (detected by osmorecetores veins, arteries, and other vessels) and also in response to cholecystokinin (excreted by small intestine).
The diseases associated with vasopressin normally give a deficiency or excess in its production or in its effect. Disability can cause polyuria, excessive excreted urine which is hypotonic and when combined with hypernatremia (excess sodium in the blood) may be a sign of diabetes insipidus. The term diabetes refers to water loss, which is insipidus due to the absence of sweetnessin the urine. Diabetes insipidus arises from the lack of production of the hormone ADH. The excess of ADH is characterized by fluid retention and can lead to hyponatremia. It often happens in drops in blood pressure, reduced blood volume (amount of circulating blood) or dehydration. The excess of ADH also occurs by inadequate secretion of vasopressin syndrome, caused by disorders in the central nervous system, cancer, lung disease, and HIV medications and not by pressure drops and any of the other factors.
Under enzymatic action, this precursor loses the signal peptide and is stored in vesicles at the Golgi complex, and then is transported from the cell body of the neuron to the nerve endings. This transport takes approximately 12 to 24 hours. During this time, several cleavages occur, giving rise to ADH molecules, neurophysin and copeptin. ADH is excreted by the neurohypophysis briefly in response to decreases in plasma volume (detected by barorrecetores), potential increases in osmotic plasma (detected by osmorecetores veins, arteries, and other vessels) and also in response to cholecystokinin (excreted by small intestine).
The diseases associated with vasopressin normally give a deficiency or excess in its production or in its effect. Disability can cause polyuria, excessive excreted urine which is hypotonic and when combined with hypernatremia (excess sodium in the blood) may be a sign of diabetes insipidus. The term diabetes refers to water loss, which is insipidus due to the absence of sweetnessin the urine. Diabetes insipidus arises from the lack of production of the hormone ADH. The excess of ADH is characterized by fluid retention and can lead to hyponatremia. It often happens in drops in blood pressure, reduced blood volume (amount of circulating blood) or dehydration. The excess of ADH also occurs by inadequate secretion of vasopressin syndrome, caused by disorders in the central nervous system, cancer, lung disease, and HIV medications and not by pressure drops and any of the other factors.
Text written by:
Luís Alves
Pedro Silva
Ricardo Praia
Tiago Fernandes
Tiago Borges
.
No comments:
Post a Comment