Supraoptic nucleus

Supraoptic nucleus
Human supraoptic nucleus (SON, dorsolateral and ventromedial components) in this coronal section is indicated by the shaded areas. Dots represent vasopressin (AVP) neurons (also seen in the paraventricular nucleus, PVN). The medial surface is the 3rd ventricle (3V), with more lateral to the left.
Details
Identifiers
Latin	nucleus supraopticus
MeSH	A08.186.211.730.385.357.342.650
NeuroNames	hier-368
NeuroLex ID	Supraoptic nucleus
TA	A14.1.08.912
FMA	62317
Anatomical terms of neuroanatomy []

The supraoptic nucleus (SON) is a nucleus of magnocellular neurosecretory cells in the hypothalamus of the mammalian brain. The nucleus is situated at the base of the brain, adjacent to the optic chiasm. In humans, the SON contains about 3,000 neurons.

The cell bodies produce the peptide hormone vasopressin, which is also known as anti-diuretic hormone (ADH). This chemical messenger travels via the bloodstream to its target cells in the papillary ducts in the kidneys, enhancing water reabsorption.

In the cell bodies, the hormones are packaged in large, membrane-bound vesicles that are transported down the axons to the nerve endings. The secretory granules are also stored in packets along the axon called Herring bodies.

Similar magnocellular neurons are also found in the paraventricular nucleus.

Each neuron in the nucleus has one long axon that projects to the posterior pituitary gland, where it gives rise to about 10,000 neurosecretory nerve terminals. The magnocellular neurons are electrically excitable: In response to afferent stimuli from other neurons, they generate action potentials, which propagate down the axons. When an action potential invades a neurosecretory terminal, the terminal is depolarised, and calcium enters the terminal through voltage-gated channels. The calcium entry triggers the secretion of some of the vesicles by a process known as exocytosis. The vesicle contents are released into the extracellular space, from where they diffuse into the bloodstream.

Vasopressin (antidiuretic hormone, ADH) is released in response to solute concentration in the blood, decreased blood volume, or blood pressure.