Neurohypophysial hormone
| Neurohypophysial hormones, N-terminal Domain | |||||||||
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| Neurohypophysial hormones, C-terminal Domain | |||||||||
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The neurohypophysial hormones form a
Most of the circulating oxytocin and vasopressin hormones are synthesized in
Oxytocin mediates contraction of the smooth muscle of the uterus and mammary gland, while vasopressin has antidiuretic action on the kidney, and mediates vasoconstriction of the peripheral vessels.[4] Due to the similarity of the two hormones, there is cross-reaction: oxytocin has a slight antidiuretic function, and high levels of AVP can cause uterine contractions.[5][6] In common with most active peptides, both hormones are synthesised as larger protein precursors that are enzymatically converted to their mature forms.
Members of this family are found in birds, fish, reptiles and amphibians (mesotocin, isotocin, valitocin, glumitocin, aspargtocin, vasotocin, seritocin, asvatocin, phasvatocin), in worms (annetocin, nematocin), octopuses (cephalotocin, octopressin), insects (locupressin, inotocin) and in molluscs (conopressins G and S).[7] Animals that lack a hormone from this family include fruit flies, and at least some mosquitos, silkworms, and honeybees.[8]