A/E are caused by accidental transection of pituitary stalk:

A i.e. Diabetes mellitus - ADH is formed primarily in supraoptic nucleiQ, whereas oxytocin is formed mainly in paraventricular nucleiQ of hypothalamus. Both hormones are secreted in free form or loosely bound to neurophysin (II & I respectively but then immediately gets detached) to circulate in blood as free hormone formsQ. - Hyperosmolarity is the greatest stimulator for ADH secretionQ. So injection of hyperosmolar (concentrated) electrolyte solution in aery supplying hypothalamus (supraoptic nucleus mainly) cause release of ADH. - Neurosecretion of posterior pituitary hormone ADH (antidiuretic hormone or vaspression) mainly from supraoptic nuclei of hypothalamus is increased with increased plasma osmolality (hyperosmolality) and is decreased with decreased plasma osmolality. Surgery, exercise, stress, pain also increaseADH secretionQ. ADH increases the permeability of distal tubule & collecting ducts to waterQ therefore retaining water in excess of solute. - Vasopressin (ADH) has 3 receptor - receptor in vascular smooth musclesQ, (causing vasoconstriction), liver (glycogenolysis) and area postrema of brain (decreasing cardiac output); V113 or V3 receptor in anterior pituitaryQ (increasing ACTH secretion); and V2 receptor in principal cells of collecting ductsQ (augmenting movement of water through water channel aquaporin-2). - Milk secretion (ejection or let down) a neuroendocrinal reflexQ is caused by oxytocin secreted from posterior pituitaryQ. Oxytocin, whose secretion is affected by emotionsQ & genital stimulation, cause contraction of myoepithelial cellsQ that lie outside the alveoli and hence lit milk ejection. - Diabetes mellitus results from complete or absolute lack of insulin d/t reduction in )3 -cell mass of pacreaseQ. It has nothing to do with pituitary.