Phenypressin

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Phenypressin
Phenypressin.svg
Names
IUPAC name
L-Cysteinyl-L-phenylalanyl-L-phenylalanyl-L-glutaminyl-L-asparagyl-L-cysteinyl-L-prolyl-L-arginyl-glycinamide (1→6)-disulfide
Other names
H-Cys(1)-Phe-Phe-Gln-Asn-Cys(1)-Pro-Arg-Gly-NH2
2-Phe-argipressin
Identifiers
3D model (JSmol)
PubChem CID
Properties
C46H65N15O11S2
Molar mass 1068.24 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Phenypressin (Phe2-Arg8-vasopressin) is an oxytocin neuropeptide belonging to the vertebrae vasopressin family and has similar pharmacological properties as arginine vasopressin. [1] The name phenypressin came about because there is a substitution of phenylalanine that makes it different from arginine vasopressin in the second residue and that is the only difference. [2] It belongs to the family, neurohypophysial hormones, named after the fact that they are secreted by the neurohypophysis (i.e. posterior pituitary gland) which is a neural projection from the hypothalamus. [3] It has mostly been found to be present is some species belonging to the family, Macropodidae, particularly eastern gray kangaroos[3] , red kangaroos, tammar wallaby, and the quokka wallaby. In other marsupial families, Phenypressin has not yet specifically been identified, but they do have other vasopressin-like peptides present. [1]

Oxytocin Peptide hormone and neuropeptide

Oxytocin (Oxt) is a peptide hormone and neuropeptide. Oxytocin is normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, sexual reproduction, childbirth, and the period after childbirth. Oxytocin is released into the bloodstream as a hormone in response to stretching of the cervix and uterus during labor and with stimulation of the nipples from breastfeeding. This helps with birth, bonding with the baby, and milk production.

Neuropeptide peptides released by neurons as intercellular messengers

Neuropeptides are small protein-like molecules (peptides) used by neurons to communicate with each other. They are neuronal signalling molecules that influence the activity of the brain and the body in specific ways. Different neuropeptides are involved in a wide range of brain functions, including analgesia, reward, food intake, metabolism, reproduction, social behaviors, learning and memory.

Vasopressin protein-coding gene in the species Homo sapiens

Vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travels down the axon of that cell, which terminates in the posterior pituitary, and is released from vesicles into the circulation in response to extracellular fluid hypertonicity (hyperosmolality). AVP has two primary functions. First, it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Second, AVP constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure.

Contents

Structure

Phenypressin was found to be less abundant in the marsupials compared to other vasopressin-like peptides. [1] It belongs to some marsupials [2] and has the polypeptide sequence: Cys-Phe-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2. [4] The neurohypophyseal hormones present in Australian marsupials are unique compared to the usual hormones found in placental mammals: oxytocin and arginine vasopressin.

Function

Phenypressin has very similar characteristics as arginine vasopressin, [1] so it is synthesized in the hypothalamus and travels to the posterior pituitary and is then released into the vesicles. Since the functions are similar to arginine vasopressin, we can assume that Phenypressin also has two main functions. Mainly, it increases the reabsorption of water in the kidneys. Secondly, it can also cause vasoconstriction, increasing the blood pressure. [5]

Experimental History

This neurohypophysial hormone was identified and characterized by scientists through amino acid composition, ion-exchange chromatography, and high pressure liquid chromatography. [6] Phenypressin differs from the common hormone, arginine vasopressin, because it has two phenylalanines and no tyrosine. A close look needs to be made in order to see the difference between arginine vasopressin and phenypressin because they have the same positions on the Amberlite CG-50 chromatograms and on paper chromato-electrophoresis. The differences in amino acids can be seen at residue 7. [6] The phenypressin discovery happened with two experiments which were carried out for two species: red kangaroo (9 and 14 glands) and the tammer (24 and 33 glands). After experimental preparation, the materials were examined through paper chromato-electrophoresis. These experiments helped show that Phenypressin was similar to arginine vasopressin, except the phenylalanine replaced the tyrosine at the second residue. [2]

Related Research Articles

Pituitary gland endocrine gland

In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The hypophysis rests upon the hypophysial fossa of the sphenoid bone in the center of the middle cranial fossa and is surrounded by a small bony cavity covered by a dural fold. The anterior pituitary is a lobe of the gland that regulates several physiological processes. The intermediate lobe synthesizes and secretes melanocyte-stimulating hormone. The posterior pituitary is a lobe of the gland that is functionally connected to the hypothalamus by the median eminence via a small tube called the pituitary stalk.

Hypothalamus part of diencephalon

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is the size of an almond. The hypothalamus is responsible for the regulation of certain metabolic processes and other activities of the autonomic nervous system. It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland. The hypothalamus controls body temperature, hunger, important aspects of parenting and attachment behaviours, thirst, fatigue, sleep, and circadian rhythms. The hypothalamus derives its name from Greek ὑπό, under and θάλαμος, chamber.

Thyrotropin-releasing hormone hormone

Thyrotropin-releasing hormone (TRH), is a hypophysiotropic hormone, produced by neurons in the hypothalamus, that stimulates the release of thyroid-stimulating hormone (TSH) and prolactin from the anterior pituitary.

Posterior pituitary posterior lobe of the pituitary gland

The posterior pituitary is the posterior lobe of the pituitary gland which is part of the endocrine system. The posterior pituitary is not glandular as is the anterior pituitary. Instead, it is largely a collection of axonal projections from the hypothalamus that terminate behind the anterior pituitary, and serve as a site for the secretion of neurohypophysial hormones directly into the blood. The hypothalamic–neurohypophyseal system is composed of the hypothalamus, posterior pituitary, and these axonal projections.

Supraoptic nucleus

The supraoptic nucleus (SON) is a nucleus of magnocellular neurosecretory cells in the hypothalamus of the mammalian brain. The nucleus is situated at the base of the brain, adjacent to the optic chiasm. In humans, the SON contains about 3,000 neurons.

Paraventricular nucleus of hypothalamus

The paraventricular nucleus is a nucleus in the hypothalamus. It is a group of neurons that can be activated by physiological changes including stress. Many PVN neurons project directly to the posterior pituitary where they release oxytocin into the general circulation. The supraoptic nucleus releases vasopressin. Both the PVN and the supraoptic nucleus do produce small amounts of the other hormone, ADH and Oxytocin respectively. Other PVN neurons control various anterior pituitary functions, while still others directly regulate appetite and autonomic functions in the brainstem and spinal cord.

Magnocellular neurosecretory cells are large neuroendocrine cells within the supraoptic nucleus and paraventricular nucleus of the hypothalamus. They are also found in smaller numbers in accessory cell groups between these two nuclei, the largest one being the nucleus circularis. There are two types of magnocellular neurosecretory cells, oxytocin-producing cells and vasopressin-producing cells, but a small number can produce both hormones. These cells are neuroendocrine neurons, are electrically excitable, and generate action potentials in response to afferent stimulation.

Neuroendocrine cells are cells that receive neuronal input and, as a consequence of this input, release message molecules (hormones) into the blood. In this way they bring about an integration between the nervous system and the endocrine system, a process known as neuroendocrine integration. An example of a neuroendocrine cell is a cell of the adrenal medulla, which releases adrenaline to the blood. The adrenal medullary cells are controlled by the sympathetic division of the autonomic nervous system. These cells are modified postganglionic neurons. Autonomic nerve fibers lead directly to them from the central nervous system. The adrenal medullary hormones are kept in vesicles much in the same way neurotransmitters are kept in neuronal vesicles. Hormonal effects can last up to ten times longer than those of neurotransmitters. Sympathetic nerve fiber impulses stimulate the release of adrenal medullary hormones. In this way the sympathetic division of the autonomic nervous system and the medullary secretions function together.

Neurophysin I is a carrier protein with a size of 10 KDa and contains 90 to 97 aminoacids. It is a cleavage product of preprooxyphysin. It is a neurohypophysial hormone that is transported in vesicles with oxytocin, the other cleavage product, along axons, from magnocellular neurons of the hypothalamus to the posterior lobe of the pituitary. Although it is stored in neurosecretory granules with oxytocin and released with oxytocin, its biological action is unclear.

Pituitary stalk

The pituitary stalk is the connection between the hypothalamus and the posterior pituitary. The floor of the third ventricle is prolonged downward as a funnel-shaped recess—the infundibular recess—into the infundibulum, where the apex of the pituitary is attached. It passes through the dura mater of the diaphragma sellae as it carries axons from the magnocellular neurosecretory cells of the hypothalamus down to the posterior pituitary where they release their neurohypophysial hormones, oxytocin and vasopressin, into the blood.

Neuroendocrinology is the branch of biology which studies the interaction between the nervous system and the endocrine system, that is how the brain regulates the hormonal activity in the body. The nervous and endocrine systems often act together in a process called neuroendocrine integration, to regulate the physiological processes of the human body. Neuroendocrinology arose from the recognition that the brain, especially the hypothalamus, controls secretion of pituitary gland hormones, and has subsequently expanded to investigate numerous interconnections of the endocrine and nervous systems.

Growth hormone–releasing hormone (GHRH), also known as somatocrinin or by several other names in its endogenous forms and as somatorelin (INN) in its pharmaceutical form, is a releasing hormone of growth hormone (GH). It is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus.

Vasotocin chemical compound

Vasotocin is an oligopeptide homologous to oxytocin and vasopressin found in all non-mammalian vertebrates and possibly in mammals during the fetal stage of development. Arginine vasotocin (AVT), a hormone produced by neurosecretory cells within the posterior pituitary gland (neurohypophysis) of the brain, is a major endocrine regulator of water balance and osmotic homoeostasis and is involved in social and sexual behavior in non-mammalian vertebrates. In mammals, it appears to have biological properties similar to those of oxytocin and vasopressin. It has been found to have effects on the regulation of REM sleep. Evidence for the existence of endogenous vasotocin in mammals is limited and no mammalian gene encoding vasotocin has been confirmed.

Neurophysin II cleavage product of the coding protein of AVP gene

Neurophysin II is a carrier protein with a size of 19,687.3 Da and is made up of a dimer of two virtually identical chains of amino acids. Neurophysin II is a cleavage product of the prepro-vasopressin. It is a neurohypophysial hormone that is transported in vesicles with vasopressin, the other cleavage product, along axons, from magnocellular neurons of the hypothalamus to the posterior lobe of the pituitary. Although it is stored in neurosecretory granules with vasopressin and released with vasopressin into the bloodstream, its biological action is unclear. Neurophysin II is also known as a stimulator of prolactin secretion.

Parvocellular neurosecretory cells are small neurons within paraventricular nucleus (PVN) of the hypothalamus. The axons of the parvocellular neurosecretory cells of the PVN project to the median eminence, at the base of the brain, where their neurosecretory nerve terminals release peptides into blood vessels in the hypothalamo-pituitary portal system. The blood vessels carry the peptides to the anterior pituitary gland, where they regulate the secretion of hormones into the systemic circulation.

Neurohypophysial hormone

The neurohypophysial hormones form a family of structurally and functionally related peptide hormones. Their main representatives are oxytocin and vasopressin. They are named after the location of their release into the blood, the neurohypophysis.

Copeptin is a 39-amino acid-long peptide derived from the C-terminus of pre-pro-hormone of arginine vasopressin, neurophysin II and copeptin. Arginine vasopressin (AVP), also known as the antidiuretic hormone (ADH), is involved in multiple cardiovascular and renal pathways and abnormal level of AVP are associated with various diseases. Hence measurement of AVP would be useful, but is not commonly carried out in clinical practice because of its very short half-life making it difficult to quantify. In contrast, copeptin can be immunologically tested with ease and therefore can be used as a vasopressin surrogate marker.

Howard Sachs (scientist)

Howard Sachs, was a biochemist who helped pioneer the study of neuroendocrinology. His discoveries concerning the production of the hormone vasopressin laid the foundation for the field of hormone biosynthesis.

References

  1. 1 2 3 4 Chauvet, M.T.; Colne, T.; Hurpet, D.; Chauvet, J.; Acher, R. (1983-08-01). "Marsupial neurohypophysial hormones: Identification of mesotocin, lysine vasopressin, and phenypressin in the quokka wallaby (Setonix brachyurus)". General and Comparative Endocrinology. 51 (2): 309–315. doi:10.1016/0016-6480(83)90086-2. ISSN   0016-6480.
  2. 1 2 Chauvet, M. T.; Hurpet, D.; Chauvet, J.; Acher, R. (1980-10-16). "Phenypressin (Phe2-Arg8-vasopressin), a new neurohypophysial peptide found in marsupials". Nature. 287 (5783): 640–642. doi:10.1038/287640a0. ISSN   0028-0836. PMID   7432483.
  3. ↑ Burbach, J. Peter H.; Luckman, Simon M.; Murphy, David; Gainer, Harold (2001). "Gene Regulation in the Magnocellular Hypothalamo-Neurohypophysial System". Physiological Reviews. 81 (3): 1197–1267. doi:10.1152/physrev.2001.81.3.1197. PMID   11427695.
  4. ↑ Pubchem. "Phenypressin". pubchem.ncbi.nlm.nih.gov. Retrieved 2018-11-08.
  5. ↑ "Oxytocin and Vasopressin: Genetics and Behavioral Implications" (PDF).
  6. 1 2 Hurpet, D.; Chauvet, M. T.; Chauvet, J.; Acher, R. (April 1982). "Marsupial hypothalamo-neurohypophyseal hormones. The brush-tailed possum (Trichosurus vulpecula) active peptides". International Journal of Peptide and Protein Research. 19 (4): 366–371. doi:10.1111/j.1399-3011.1982.tb02617.x. ISSN   0367-8377. PMID   7118406.
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