CorpusHuman Anatomy
EndocrineBrain region

Paraventricular nucleus

Nucleus paraventricularis hypothalami

Also known as: PVN

A wing-shaped nucleus in the wall of the third ventricle that contains magnocellular oxytocin/ADH neurons, parvocellular CRH and TRH neurons, and pre-autonomic neurons — the hub of the stress response.

Show on body map Hypothalamic–Pituitary Axis

Overview

The paraventricular nucleus lies in the dorsal part of the anterior hypothalamus, immediately beside the third ventricle. It is functionally three nuclei in one. Its magnocellular division makes mainly oxytocin (and some ADH) and projects to the posterior pituitary with the supraoptic fibres. Its parvocellular division makes CRH and TRH (and co-expresses ADH, which potentiates CRH at corticotrophs) and projects to the median eminence, releasing these into the portal circulation. Its pre-autonomic neurons project to the dorsal motor nucleus of the vagus, nucleus of the solitary tract and the intermediolateral cell column of the spinal cord.

It thus coordinates the hormonal (HPA axis) and autonomic (sympathoadrenal) limbs of stress, and relays the suprachiasmatic clock to the pineal gland and the cortisol rhythm.

Location

Anterior hypothalamus, in the wall of the third ventricle, dorsal to the supraoptic nucleus.

Function

  • Releases CRH (and ADH) into the portal system — drives the HPA axis.
  • Releases TRH — drives the HPT axis.
  • Synthesises oxytocin for the posterior pituitary (labour, milk ejection).
  • Controls sympathetic outflow, including the pathway to the pineal gland.
Regulation

Cortisol inhibits CRH neurons (long-loop negative feedback); T3 (generated locally by tanycyte type 2 deiodinase) inhibits TRH neurons. Stressors (pain, hypoglycaemia, haemorrhage, psychological stress) via brainstem and limbic inputs override feedback.

Clinical significance

Prader–Willi and PVN development

Reduced oxytocin neurons in the PVN have been described in Prader–Willi syndrome and may contribute to its hyperphagia; congenital PVN hypoplasia (SIM1 mutations) also causes severe obesity.

Test yourself

Light suppresses melatonin secretion through which pathway?
  1. Optic nerve → lateral geniculate body → visual cortex → pineal
  2. Retina → retinohypothalamic tract → suprachiasmatic nucleus → paraventricular nucleus → spinal cord → superior cervical ganglion → pineal
  3. Retina → superior colliculus → posterior commissure → pineal
  4. Retina → oculomotor nucleus → ciliary ganglion → pineal

Answer: Retina → retinohypothalamic tract → suprachiasmatic nucleus → paraventricular nucleus → spinal cord → superior cervical ganglion → pineal

Melanopsin-containing retinal ganglion cells signal the SCN, which via the PVN and upper thoracic preganglionic neurons controls postganglionic sympathetic fibres from the superior cervical ganglion. Norepinephrine on pinealocyte β1 receptors (in darkness) drives AANAT and melatonin synthesis.

More endocrine system questions

Compiled from standard anatomy and physiology references — see the Endocrine System sources. For education only; not medical advice.