Category: endocrine_axis
Magnocellular neurons in supraoptic + paraventricular nuclei synthesize oxytocin + arginine vasopressin (AVP, ADH), package them in vesicles, and release into the systemic circulation at the posterior pituitary. AVP: V1A (vasoconstriction), V1B (ACTH release), V2 (renal collecting duct aquaporin-2 insertion → water reabsorption). Oxytocin: uterine contraction at parturition + breast myoepithelial milk ejection + social-bonding CNS effects. Therapeutic: oxytocin (IV for labor induction + postpartum hemorrhage); desmopressin (DDAVP — V2-selective for central DI + bedwetting + von Willebrand disease); vasopressin (IV pressor in vasodilatory shock + cardiac arrest historical).