neurohormone
{{Short description|Hormone released by neuroendocrine cells}}
A neurohormone is any hormone produced and released by neuroendocrine cells (also called neurosecretory cells) into the blood.{{cite book | last1 = Purves | first1 = William K. | first2 = David | last2 = Sadava | first3 = Gordon H. | last3 = Orians | first4 = H. Craig | last4 = Heller | name-list-style = vanc | title = Life: The Science of Biology | publisher = Sinauer Associates | edition = 6th | year = 2001 | location = Massachusetts | page = [https://archive.org/details/isbn_9780716738732/page/718 718] | url = https://archive.org/details/isbn_9780716738732/page/718 | isbn = 978-0-7167-3873-2 | url-access = registration }}Nelson. 2005 An Introduction To Behavioral Endocrinology, Third Edition By definition of being hormones, they are secreted into the circulation for systemic effect, but they can also have a role of neurotransmitter or other roles such as autocrine (self) or paracrine (local) messenger.Purves et al. p. 714.
The hypothalamus releasing hormones are neurohypophysial hormones in specialized hypothalamic neurons which extend to the median eminence and posterior pituitary. The adrenal medulla produces adrenomedullary hormones in chromaffin cells, cells which are very similar in structure to post-synaptic sympathetic neurons, even though they are not neurons they are derivatives of the neural crest.{{cite journal | vauthors = Unsicker K, Huber K, Schütz G, Kalcheim C | title = The chromaffin cell and its development | journal = Neurochemical Research | volume = 30 | issue = 6–7 | pages = 921–5 | date = Jun–Jul 2005 | pmid = 16187226 | doi = 10.1007/s11064-005-6966-5 }}
Enterochromaffin and enterochromaffin-like cells, both being enteroendocrine cells, are also considered neuroendocrine cells due to their structural and functional similarity to chromaffin cells, although they are not derivatives of the neural crest.{{cite journal | vauthors = Andrew A | title = Further evidence that enterochromaffin cells are not derived from the neural crest | journal = Journal of Embryology and Experimental Morphology | volume = 31 | issue = 3 | pages = 589–98 | date = June 1974 | pmid = 4448939 }} Other neuroendocrine cells are scattered throughout the body. Neurohormone are released by neurosecretory cells
Releasing hormones
Releasing hormones also known as hypophysiotropic or hypothalamic hormones are synthesized by different kinds of specialized neurons in the hypothalamus. They are then transported along neuronal axons to their axon terminals forming the bulk of the median eminence, where they are stored and released into the hypophyseal portal system. They then rapidly reach the anterior pituitary where they exert their hormonal action. The residual hormones pass into the systemic circulation where they are diluted, degraded and have comparatively little effects. The synthesis, control, and release of those hormones is co-regulated by hormonal, local and synaptic signals (neurotransmitters).{{cite journal | vauthors = Meites J, Sonntag WE | title = Hypothalamic hypophysiotropic hormones and neurotransmitter regulation: current views | journal = Annual Review of Pharmacology and Toxicology | volume = 21 | pages = 295–322 | date = April 1981 | pmid = 6112966 | doi = 10.1146/annurev.pa.21.040181.001455 }}{{cite journal | vauthors = Nillni EA | title = Regulation of the hypothalamic thyrotropin releasing hormone (TRH) neuron by neuronal and peripheral inputs | journal = Frontiers in Neuroendocrinology | volume = 31 | issue = 2 | pages = 134–56 | date = April 2010 | pmid = 20074584 | pmc = 2849853 | doi = 10.1016/j.yfrne.2010.01.001 }} The neurons secreting various hormones have been found to discharge impulses in burst, causing a pulsatile release which is more efficient than a continuous release.{{cite book|last=Brown|first=A. G. | name-list-style = vanc | title=Nerve cells and nervous systems : an introduction to neuroscience|year=2001|publisher=Springer|location=London|isbn=978-3-540-76090-0|pages=200}} Hypophysiotropic hormones include:
Neurohypophysial hormones
Neurohypophysial hormones are synthesized in the magnocellular secretory neurons of the hypothalamus. They are then transported along neuronal axons within the infundibular stalk to their axon terminals forming the pars nervosa of the posterior pituitary, where they are stored and released into the systemic circulation. The synthesis, control, and release of those hormones is co-regulated by hormonal, local and synaptic signals.{{cite journal | vauthors = Burbach JP, Luckman SM, Murphy D, Gainer H | title = Gene regulation in the magnocellular hypothalamo-neurohypophysial system | journal = Physiological Reviews | volume = 81 | issue = 3 | pages = 1197–267 | date = July 2001 | pmid = 11427695 | url = http://physrev.physiology.org/content/81/3/1197.full | doi=10.1152/physrev.2001.81.3.1197}} Neurohypophysial hormones include:
This is through this pathway that the vast majority of oxytocin and vasopressin hormones reach the systemic circulation.
Adrenomedullary hormones
Adrenomedullary hormones are catecholamines secreted from the adrenal medulla by chromaffin cells, neurosecretory cells connected to the central nervous system.{{cite journal | vauthors = Chung KF, Sicard F, Vukicevic V, Hermann A, Storch A, Huttner WB, Bornstein SR, Ehrhart-Bornstein M | title = Isolation of neural crest derived chromaffin progenitors from adult adrenal medulla | journal = Stem Cells | volume = 27 | issue = 10 | pages = 2602–13 | date = October 2009 | pmid = 19609938 | doi = 10.1002/stem.180 | doi-access = free }} The synthesis, storage (in chromaffin cells) and release of catecholamines is co-regulated by synaptic input from their respective pre-synaptic sympathetic neurons, as well as hormonal and local inputs.{{cite journal | vauthors = Gasman S, Chasserot-Golaz S, Bader MF, Vitale N | title = Regulation of exocytosis in adrenal chromaffin cells: focus on ARF and Rho GTPases | journal = Cellular Signalling | volume = 15 | issue = 10 | pages = 893–9 | date = October 2003 | pmid = 12873702 | doi = 10.1016/S0898-6568(03)00052-4 }}{{cite journal | vauthors = Bornstein SR, Ehrhart-Bornstein M | title = Ultrastructural evidence for a paracrine regulation of the rat adrenal cortex mediated by the local release of catecholamines from chromaffin cells | journal = Endocrinology | volume = 131 | issue = 6 | pages = 3126–8 | date = December 1992 | pmid = 1446648 | doi = 10.1210/endo.131.6.1446648 }} The adrenomedullary hormones are:
Enteric neurohormones
Enterochromaffin cells in the epithelia lining the lumen of the digestive tract secrete serotonin, while enterochromaffin-like cells at the stomach glands secrete histamine. Their synthesis, storage, and release of hormones is co-regulated by hormonal, local and nervous inputs.{{cite journal | vauthors = Prinz C, Zanner R, Gerhard M, Mahr S, Neumayer N, Höhne-Zell B, Gratzl M | title = The mechanism of histamine secretion from gastric enterochromaffin-like cells | journal = The American Journal of Physiology | volume = 277 | issue = 5 Pt 1 | pages = C845-55 | date = November 1999 | pmid = 10564076 }}{{cite journal | vauthors = Rhee SH, Pothoulakis C, Mayer EA | title = Principles and clinical implications of the brain-gut-enteric microbiota axis | journal = Nature Reviews. Gastroenterology & Hepatology | volume = 6 | issue = 5 | pages = 306–14 | date = May 2009 | pmid = 19404271 | doi = 10.1038/nrgastro.2009.35 | pmc=3817714}}{{cite journal | vauthors = Haas HL, Sergeeva OA, Selbach O | title = Histamine in the nervous system | journal = Physiological Reviews | volume = 88 | issue = 3 | pages = 1183–241 | date = July 2008 | pmid = 18626069 | doi = 10.1152/physrev.00043.2007 | url = http://physrev.physiology.org/content/88/3/1183.full }}{{cite journal | vauthors = Rodriguez-Diaz R, Dando R, Jacques-Silva MC, Fachado A, Molina J, Abdulreda MH, Ricordi C, Roper SD, Berggren PO, Caicedo A | title = Alpha cells secrete acetylcholine as a non-neuronal paracrine signal priming beta cell function in humans | journal = Nature Medicine | volume = 17 | issue = 7 | pages = 888–92 | date = June 2011 | pmid = 21685896 | pmc = 3132226 | doi = 10.1038/nm.2371 }}{{cite journal | vauthors = Sandor A, Kidd M, Lawton GP, Miu K, Tang LH, Modlin IM | title = Neurohormonal modulation of rat enterochromaffin-like cell histamine secretion | journal = Gastroenterology | volume = 110 | issue = 4 | pages = 1084–92 | date = April 1996 | pmid = 8612997 | doi = 10.1053/gast.1996.v110.pm8612997 | doi-access = free }}