Editing Paraventricular nucleus (section)

== Neurons ==
The PVN contains [[magnocellular neurosecretory cell]]s whose [[axon]]s extend into the [[posterior pituitary]], [[parvocellular neurosecretory cell]]s that project to the [[median eminence]], ultimately signalling to the [[anterior pituitary]], and several populations of other cells that project to many different brain regions including parvocellular preautonomic cells that project to the [[brainstem]] and [[spinal cord]].{{cn|date=May 2022}}

=== Magnocellular neurosecretory neurons ===
[[File:Gray1181.png|thumb|Magnocellular neurons of the PVN and SON project to the [[posterior pituitary]]]]

The [[magnocellular neurosecretory cell|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 [[Myelin|unmyelinated]] axons of the cells and released from neurosecretory nerve terminals residing in the posterior pituitary gland.{{cn|date=May 2022}}

Similar magnocellular neurons are found in the [[supraoptic nucleus]] which also secrete vasopressin and a smaller amount of oxytocin.{{cn|date=May 2022}}

=== Parvocellular neurosecretory neurons ===

The axons of the [[parvocellular neurosecretory cell|parvocellular]] neurosecretory neurons of the PVN project to the median eminence, a neurohemal organ at the base of the brain, where their neurosecretory nerve terminals release their hormones at the primary capillary plexus of the [[hypophyseal portal system]]. The median eminence contains fiber terminals from many hypothalamic neuroendocrine neurons, secreting different neurotransmitters or neuropeptides, including vasopressin, corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), growth hormone-releasing hormone (GHRH), dopamine (DA) and somatostatin (growth hormone release inhibiting hormone, GIH) into blood vessels in the hypophyseal 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 that 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)
* [[Thyrotropin-releasing hormone]] (TRH), which regulates [[Thyroid-stimulating hormone|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]]. These neurons are thought to have a role in gastric reflexes and penile erection,<ref name="pmid11477488">{{cite journal | vauthors = Giuliano F, Allard J | title = Dopamine and sexual function | journal = International Journal of Impotence Research | volume = 13 Suppl 3 | pages = S18-28 | date = August 2001 | pmid = 11477488 | doi = 10.1038/sj.ijir.3900719 | doi-access = free }}</ref><ref name="pmid16043278">{{cite journal | vauthors = Argiolas A, Melis MR | s2cid = 24929538 | title = Central control of penile erection: role of the paraventricular nucleus of the hypothalamus | journal = Progress in Neurobiology | volume = 76 | issue = 1 | pages = 1–21 | date = May 2005 | pmid = 16043278 | doi = 10.1016/j.pneurobio.2005.06.002 }}</ref>
* 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 [[Brown adipose tissue|brown fat]] [[thermogenesis]].
* Parvocellular CRH neurons, which are thought to be involved in stress-related behaviors.