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Old 07-15-2011
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Question Neurophysin

in FA official updates p. 288, it says that neurophysins carry ADH & oxytocin in circulation is incorrect.
Hoever, in UW it says that neurophysins along with ADH & oxytocin are secreted together from the posterior pituitary into the hypophysial vein.

So, this means that after posterior pituitary. neurophysin just "accidentally" goes the same way with ADH & oxytocin but does not carry them anymore??

Can someone please tell me whether I am right or wrong?

Thank you!!
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This is from FA errata on www.firstaidteam.com -

" 288 - Pituitary gland
Neurophysins carry ADH and oxytocin only from their site of
synthesis (hypothalamus) to their site of release (posterior
pituitary). The notation that they carry hormones in circulation is
incorrect"

This basically states that Neurophysins do carry ADH & oxytocin but only from the hypothalamus to the posterior pituitary- not in the circulation or blood stream to make them available to other organs.

As for UW, can you please quote the exact statement? Hypophyseal veins are different than hypothalamic-hypophyseal portal veins (which run from hypothalamus to posterior pituitary). The neurophysins along with oxytocin & ADH are secreted in that system.
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Neurophysins are produced in hypothalamus along with the ADH and Oxytocin and along with them goes into the post pituitary and are carriers of ADH and Oxytocin in circulation. That's a little review from what says in FA 2011 and UW.
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Quote:
Originally Posted by evavar View Post
Neurophysins are produced in hypothalamus along with the ADH and Oxytocin and along with them goes into the post pituitary and are carriers of ADH and Oxytocin in circulation. That's a little review from what says in FA 2011 and UW.
Yup, but if you look at the errata, it says that neurohypophysins DO NOT go into "circulation" with ADH & Oxytocin. "The notation that they carry hormones in circulation is incorrect". They simply carry them from hypothalamus to posterior pituitary.
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I just check it out again from UW, cause I have a question on it 2 days ago. It says that neurophysins along with ADH and OXYtocin are secreted (remember is secreted, not produced) from post pituitary to the hypophyseal vein and then into the circulation.
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Neurophysins are carrier proteins which transport the hormones oxytocin from the paraventricular nucleus of the hypothalamus and vasopressin from the supraoptic nucleus to the posterior pituitary, the site of their secretion. Neurophysins are secreted along with their passenger hormones, though their physiological roles are unknown.

From wikipedia.
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Quote:
Originally Posted by evavar View Post
I just check it out again from UW, cause I have a question on it 2 days ago. It says that neurophysins along with ADH and OXYtocin are secreted (remember is secreted, not produced) from post pituitary to the hypophyseal vein and then into the circulation.
Ah ok.. well FA Errata says "The notation that they carry hormones in circulation is incorrect" so to summarize it Id say - Neurohypophysins are secreted in circulation but do not carry vasopressin & Oxytocin in circulation. They only carry ADH & oxytocin from hypothalamus to posterior pituitary. Correct ?
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Well, I'm going to do a little bit more of research about that topic and I will posted here.
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Neurophysin-neurophysin.jpeg

Synthesis, processing, and transport of preprovasopressin. Human ADH (also called arginine vasopressin or AVP) is synthesized in the hypothalamic magnocellular cell bodies and packaged into neurosecretory granules. During intraaxonal transport of the granules down the infundibular process to the pars nervosa, provasopressin is proteolytically cleaved into the active hormone (AVP = ADH), neurophysin (NP), and a C-terminal glycoprotein (GP). NP arranges into tetramers that bind five AVP molecules. All three fragments are secreted from axonal termini in the pars nervosa (posterior pituitary) and enter the systemic blood. Only AVP (ADH) is biologically active.
(Modified from Larsen PR et al [eds]: Williams Textbook of Endocrinology, 10th ed. Philadelphia, Saunders, 2003.)

Koeppen & Stanton: Berne and Levy Physiology, Updated Edition, 6th ed.
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From a question I had in UW. Neurohyphysins are carrier proteins which carry the Post pituitary hormones from their site of synthesis from the hypothalamic neurons to the post pituitary for their secretion. get released from post pituitary with their hormones. Neurohypophysin 2 is a protein which carries ADH through ER, into golgi and into the neurosecretory granules for release. Point mutation in neurohypophysin 2 leads to abnormal protein folding and removal from ER along with bound vasopressin - decreased vasopressin available for secretion. sorry dont have the question ID but i had written this down in my FA from UW!
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