Hormones vasopressin

Hemophilia -blood for treatment of pRACTIONATION, BLOOD - PLASMA FRACTIONATION] (Vol 11) -use of vasopressin [HORMONES - POSTERIORPITUITARYHORMONES] (Vol 13)... 

DU VIGNEAUD, VINCENT (1901-1978). An American biochemist who won the Nobel prize lor chemistry in 1955. His work involved Ihe study of the metabolism of biologically significant sulfur compounds, which led to the finding of transmethylation in mammalian metabolism. He isolated and proved the structure of Ihe vitamin biotin, and synthesized penicillin, oxytocin, and the vasopressin hormone of the posterior pituitary. His education was at Rochester. Yale. St. Louis, and George Washington Universities. 

The principal hormones of the human posterior pituitary include the two nonapeptides, oxytocin [50-56-6] and arginine vasopressin [11000-17-2] (antidiuretic hormone, ADH). Many other hormones, including opioid peptides (see Opioids, endogenous), cholecystokinin [9011-97-6] (CCK) (see Hormones, BRAIN oligopeptides), and gastrointestinal peptides, also have been located in mammalian neurohypophysis (6), but are usually found in much lower concentrations (7). Studies have demonstrated that oxytocin and vasopressin are synthesized in other human organs, both centrally and peripherally, and there is considerable evidence for their role as neurotransmitters (see Neuroregulators) (8). 

Fig. 3. Processing steps of rat and bovine prepro-vasopressin lea ding to the hormone vasopressin and its carrier protein, neurophysin (14). (a) Putative signal peptide (b) vasopressin (c) neurophysin (d) glycopeptide. CHO = carbohydrate.

In humans, the hypothalamic-derived protein and the hormone noncovalent complexes are packaged in neurosecretory granules, then migrate along axons at a rate of 1 4 mm/h until they reach the posterior pituitary where they are stored prior to release into the bloodstream by exocytosis (67). Considerable evidence suggests that posterior pituitary hormones function as neurotransmitters (68) vasopressin acts on the anterior pituitary to release adrenocorticotropic hormone [9002-60-2] (ACTH) (69) as well as on traditional target tissues such as kidneys. Both hormones promote other important central nervous system (CNS) effects (9,70). 

Oxytocin and Vasopressin Receptors. The actions of oxytocin and vasopressin are mediated through their interactions with receptors. Different receptor types as well as different second messenger responses help explain their diverse activities in spite of the hormones stmctural similarities. Thus oxytocin has at least one separate receptor and vasopressin has been shown to have two principal receptor types, and V2. Subclasses of these receptors have been demonstrated, and species differences further compHcate experimental analysis. It is apparent that both oxytocin and receptors function through the GP/1 phosphoHpase C complex (75), while the V2 receptors activate cycHc AMP (76). 

Vasopressin and Oxytocin. Arginine -vasopressin (AVP, vasopressia also known as antidiuretic hormone, ADH) (342) is a nonapeptide amide that functions both as a neuroregulator and a hormone (84,85). Oxytocia (OT) (343) is a nonapeptide amide related to AVP. 

Stmctural defects at the receptor level are determinant for a number of receptor diseases. In nephrogenic diabetes insipidus, where patients void large volumes of dilute urine even in the presence of vasopressin (antidiuretic hormone) (105), the disease is linked to mutations in three discrete regions of the G-protein-linked vasopressin (V2) receptor (106,107). 

A disulfide bond between cysteine residues in different peptide chains links the otherwise separate chains together, while a disulfide bond between cysteine residues in the same chain forms a loop. Such is the case, for instance, with vasopressin, an antidiuretic hormone found in the pituitary gland. Note that the C-terminal end of vasopressin occurs as the primary amide, -CONHz, rather than as the free acid. 

The natural polymers known as proteins make up about 15% by mass of our bodies. They serve many functions. Fibrous proteins are the main components of hair, muscle, and skin. Other proteins found in body fluids transport oxygen, fats, and other substances needed for metabolism. Still others, such as insulin and vasopressin, are hormones. Enzymes, which catalyze reactions in the body, are chiefly protein. 

Vasopressin (antidiuretic hormone [ADH]) secretion increases in response to decreased blood volume and/or reductions in effective blood volume via a decrease in inhibitory tone from both low-pressure and high-pressure baroreceptors to the hypothalamus. The neuronal pathways that mediate hemodynamic regulation of... 

Vasopressin 8-arginine-vasopressin (AVP) Antidiuretic hormone (ADH) Lysipressin Oxytocin (OT) 8-leucine-vasotocin... 

X-linked nephrogenic diabetes insipidus (NDI) is caused by mutations in the gene for the vasopressin V2 receptor leading to an insensitivity of the kidney for the antidiuretic hormone arginine vasopressin (AVP). The main symptom of the disease is diuresis, i.e., the production of a large amount of diluted urine. Due to the massive loss of water, the patients suffer from thirst and are in danger of dehydration. The disease usually becomes evident shortly after birth. 

There may be a decreased resistance and inability to The posterior pituitary gland produces two hormones localize infection. The nurse observes the skin daily for vasopressin (antidiuretic hormone) and oxytocin (see localized signs of infection, especially at injection sites Chap. 53). Posterior pituitary hormones are summarized or IV access sites. Visitors are monitored to protect the in the Summary Drag Table Anterior and Posterior patient against those witii infectious illness. Pituitary Hormones. 

Vasopressin (Rtressin Synthetic) and its derivatives, namely lypressin (Diapid) and desmopressin (DDAVP), regulate the reabsorption of water by the kidneys. Vasopressin is secreted by the pituitary when body fluids must be conserved. An example of this mechanism may be seen when an individual has severe vomiting and diarrhea with little or no fluid intake. When this and similar conditions are present, die posterior pituitary releases the hormone vasopressin, water in die kidneys is reabsorbed into die blood (ie, conserved), and die urine becomes concentrated. Vasopressin exhibits its greatest activity on die renal tubular epithelium, where it promotes water resoqition and smooth muscle contraction throughout die vascular bed. Vasopressin has some vasopressor activity. 

Vasopressin and its derivatives are used in die treatment of diabetes insipidus, a disease resulting from die failure of the pituitary to secrete vasopressin or from surgical removal of die pituitary. Diabetes insipidus is characterized by marked increase in urination (as much as 10 L in 24 hours) and excessive tiiirst by inadequate secretion of die antidiuretic hormone or vasopressin. Treatment with vasopressin therapy replaces die hormone in the body and restores normal urination and thirst Vasopressin may also be used for die prevention and treatment of postoperative abdominal distention and to dispel gas interfering with abdominal roentgenography. 

Figure 25-7. Metabolism of adipose tissue. Hormone-sensitive lipase is activated by ACTH, TSH, glucagon, epinephrine, norepinephrine, and vasopressin and inhibited by insulin, prostaglandin E, and nicotinic acid. Details of the formation of glycerol 3-phosphate from intermediates of glycolysis are shown in Figure 24-2. (PPP, pentose phosphate pathway TG, triacylglycerol FFA, free fatty acids VLDL, very low density lipoprotein.)...

Otfier fiormones accelerate tfie release of free fatty acids from adipose tissue and raise tfie plasma free fatty acid concentration by increasing the rate of lipolysis of the triacylglycerol stores (Figure 25—8). These include epinephrine, norepinephrine, glucagon, adrenocorticotropic hormone (ACTH), a- and P-melanocyte-stimulat-ing hormones (MSH), thyroid-stimulating hormone (TSH), growth hormone (GH), and vasopressin. Many of these activate the hormone-sensitive hpase. For an optimal effect, most of these lipolytic processes require the presence of glucocorticoids and thyroid hormones. These hormones act in a facilitatory or permissive capacity with respect to other lipolytic endocrine factors. 

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