Paraventricular nucleus of hypothalamus
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/* Centrally-projecting neurons */ Made link of "interneuron."
{{Infobox Brain|
Name = {{PAGENAME}} |
Latin = nuclei paraventricularis hypothalami |
GraySubject = |
GrayPage = |
Image = PVNss.jpg |
Caption = Human paraventricular nucleus (PVN) in this coronal section is indicated by the shaded area. Dots represent [[vasopressin]] (AVP) neurons (also seen in the [[supraoptic nucleus]], SON). The medial surface is the 3rd ventricle (3V), with more lateral to the left. |
Image2 = Gray1181.png |
Caption2 = Magnocellular neurons of the PVN and SON project to the posterior "lobe" of the pituitary |
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Artery = |
Vein = |
Acronym = |
BrainInfoType = hier |
BrainInfoNumber = 370 |
MeshName = Paraventricular+hypothalamic+nucleus |
MeshNumber = A08.186.211.730.385.357.342.400 |
DorlandsPre = n_11 |
DorlandsSuf = 12582324 |
}}
The '''paraventricular nucleus''' (PVN) is an aggregation of neurons in the [[hypothalamus]] which produces many [[hormones]].
==Location==
The paraventricular nucleus lies adjacent to the [[third ventricle]], from which it derives its name, "paraventricular" meaning "alongside a ventricle."
It does lie within the periventricular zone and must not be confused with the [[periventricular nucleus]], which occupies a more medial position, beneath the [[third ventricle]].
The PVN is highly vascularised and is protected by the [[blood-brain barrier]], although its [[Neuroendocrinology | neuroendocrine]] neurons extend to sites (in the [[median eminence]] and in the [[posterior pituitary]]) beyond the blood-brain barrier.
==Neurons==
The PVN contains [[magnocellular neurosecretory cell]]s whose axons extend into the [[posterior pituitary]], parvocellular neurosecretory cells that project to the [[median eminence]], and several populations of [[peptide]]-containing cells that project to many different brain regions.
===Magnocellular neurosecretory neurons===
The [[magnocellular]] cells in the PVN elaborate and secrete two peptide [[hormones]], [[oxytocin]] and [[vasopressin]].
These hormones are packaged into large vesicles, which are then transported down the [[axon]]s of the cells and released from neurosecretory nerve terminals residing in the [[posterior pituitary gland]].
Similar magnocellular neurons are found in the [[supraoptic nucleus]].
===Parvocellular neurosecretory neurons===
The axons of the [[parvocellular]] neurosecretory neurons 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. The parvocellular neurosecretory cells include those which make
* [[Corticotropin-releasing hormone]] (CRH), which regulates [[ACTH]] secretion from the [[anterior pituitary gland]],
* [[Vasopressin]], which also regulates ACTH secretion (vasopressin and CRH act synergistically to stimulate ACTH secretion), and
* [[Thyrotropin-releasing hormone]] (TRH), which regulates [[TSH]] and [[prolactin]] secretion.
===Centrally-projecting neurons===
As well as neuroendocrine neurons, the PVN contains [[interneuron]]s and populations of neurons that project centrally (i.e., to other brain regions). The centrally-projecting neurons include
* Parvocellular oxytocin cells, which project mainly to the [[brainstem]] and [[spinal cord]] and are involved, respectively, in gastric reflexes and penile erection,
* Parvocellular vasopressin cells, which project to many points in the hypothalamus and [[limbic system]], as well as to the brainstem and spinal cord (these are involved in blood pressure and temperature regulation), and
* Parvocellular CRH neurons, which are thought to be involved in stress-related behaviors.
==Afferent inputs to the PVN==
The PVN receives afferent inputs from many brain regions.
Among these, inputs from neurons in structures adjacent to the anterior wall of the third ventricle (the "AV3V region") carry information about the electrolyte composition of the blood, and about circulating concentrations of such hormones as [[angiotensin]] and [[relaxin]], to regulate the magnocellular neurons.
Inputs from the brainstem (the [[nucleus of the solitary tract]]) and the ventrolateral medulla carry information from the heart and [[stomach]]. Inputs from the [[hippocampus]] to the CRH neurones are important regulators of stress responses.
Inputs from [[neuropeptide Y]]-containing neurons in the [[arcuate nucleus]] co-ordinate metabolic regulation (via TRH secretion) with regulation of energy intake.
==References==
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==External links==
* [http://www.painresearch.utah.edu/cancerpain/ch06f2.html Diagram of location in brain at painresearch.utah.edu]
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[[Category:Neuroscience]]
[[Category:Neuroendocrinology]]
[[de:Nucleus paraventricularis]]
[[he:Paraventricular nucleus]]