Arcuate nucleus 760165 220813426 2008-06-21T18:35:49Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{dablink|This article is about the hypothalamic structure. For the structure in the medulla oblongata, see [[Arcuate nucleus (medulla)]].}} {{Infobox Brain| Name = {{PAGENAME}} | Latin = nucleus arcuatus hypothalami | GraySubject = | GrayPage = | Image = HypothalamicNuclei.PNG | Caption = Arcuate nucleus is 'AR', at bottom center, in green. | Image2 = | Caption2 = | IsPartOf = [[Hypothalamus]]| Components = | Artery = | Vein = | Acronym = | BrainInfoType = hier | BrainInfoNumber = 378 | MeshName = Arcuate+nucleus | MeshNumber = A08.186.211.730.385.357.352.081 | DorlandsPre = n_11 | DorlandsSuf = 12580380 | }} The '''arcuate nucleus''' (or infundibular nucleus<ref>[http://www.onderzoekinformatie.nl/en/oi/nod/onderzoek/OND1289935/ onderzoekinformatie.nl - Project: Does activation of neurons in the infundibular nucleus in menopause prevent the occurrence of Alzheimer changes?]</ref>) is an aggregation of [[neuron]]s in the mediobasal [[hypothalamus]], adjacent to the [[third ventricle]] and the [[median eminence]]. The arcuate nucleus includes several important populations of neurons, including: ==Neuroendocrine neurons== * [[Neuroendocrinology |Neuroendocrine neurons]] with nerve endings in the median eminence, which release [[dopamine]] into the hypophysial portal blood. These are sometimes called the "tuberoinfundibular dopamine" (TIDA) neurons. In lactating females, TIDA neurons are inhibited by the stimulus of suckling. Dopamine released from their nerve endings at the median eminence is transported to the [[anterior pituitary gland]], where it regulates the secretion of [[prolactin]]; dopamine inhibits prolactin secretion, so, when the TIDA neurons are inhibited, there is increased secretion of prolactin, which stimulates [[lactogenesis]] (milk production). Prolactin acts in a short-loop negative feedback manner to decrease its levels by stimulating the release of dopamine. Dopaminergic neurons of the arcuate also inhibit the release of [[gonadotropin-releasing hormone]], explaining in part why lactating (or otherwise [[hyperprolactinemia|hyperprolactinemic]]) women experience oligomenorrhea or amenorrhea (infrequency or absence of menses). * Neuroendocrine neurons, mainly in the ventrolateral part of the nucleus, that make [[growth hormone-releasing hormone]] (GHRH). Like the TIDA neurons, these neurons have nerve endings in the median eminence. GHRH released into the hypophysial portal blood is transported to the anterior pituitary gland, where it regulates the secretion of [[growth hormone]]; GHRH stimulates growth hormone secretion. These neurons are inhibited by [[somatostatin]]. The reciprocal relationship between the electrical activity of GHRH neurons and somatostatin neurons leads to pulsatile secretion of growth hormone, a pattern of secretion that is important for its biological effectiveness. ==Centrally-projecting neurons== * Centrally-projecting neurons that contain [[neuropeptide Y]] (NPY), [[agouti-related protein]] (AGRP), and the inhibitory neurotransmitter [[GABA]]. These neurons, in the most ventromedial part of the nucleus, project strongly to the [[lateral hypothalamus]] and to the [[paraventricular nucleus]] of the hypothalamus, and are important in the regulation of [[appetite]]. When activated, these neurons can produce ravenous eating. These neurons are regulated (inhibited) by circulating concentrations of [[leptin]] and [[ghrelin]]. * Centrally-projecting neurons that contain [[peptide]] products of [[pro-opiomelanocortin]] (POMC), and cocaine-and-amphetamine-regulating transcript (CART). These neurons have widespread projections to many brain areas, including to all nuclei in the hypothalamus. These cells are also important in the regulation of [[appetite]], and, when activated, they inhibit feeding. These neurons are also regulated (activated) by circulating concentrations of [[leptin]] and [[ghrelin]], and they are directly innervated by the NPY neurons. POMC neurons that project to the medial preoptic nucleus are also involved in the regulation of [[sexual behavior]] in both males and females. The expression of POMC is regulated by gonadal steroids. The release of a POMC product, beta-endorphin is regulated by NPY. * Centrally-projecting neurons that make somatostatin; the neurosecretory somatostatin neurons that regulate growth hormone secretion are a different population, located in the periventricular nucleus. ==Other== * A small population of neurons that synthesise [[ghrelin]]. The role of this population is not known; many neurons in the arcuate nucleus express receptors for ghrelin, but these are thought to be respond mainly to blood-borne ghrelin. The arcuate nucleus also contains a population of specialized [[ependymal cells]], called [[tanycytes]]. ==Footnotes== <references/> ==References== * {{cite journal |author=Kawano H, Daikoku S |title=Somatostatin-containing neuron systems in the rat hypothalamus: retrograde tracing and immunohistochemical studies |journal=J. Comp. Neurol. |volume=271 |issue=2 |pages=293–9 |year=1988 |pmid=2897982 |doi=10.1002/cne.902710209}} {{Neuroscience-stub}} {{Diencephalon}} [[Category:Nervous system]] [[Category:Neuroendocrinology]]