Anti-diuretic hormone (Vasopressin)

Neuropeptide syntheised in the cell bodies of the supraoptic and paraventricular nuclei of the hypothalamus. transport down their axons to the posterior lobe of the pituitary gland, from which it is secreted. there are at east 3 types of vasopresin receptor, all of whicg are G-protein coupled.

Effects:

• Renal water retention. Increased adenylate cyclase activity and cAMP levels increase the permeability of the collecting ducts, allowing water to be reabsorbed into the renal interstitium.
• Vasoconstriction - Direct effect on vascular smooth muscle.
• Increases circulating factor VIII

Release is stimulated by:

• Increases in plasma osmolality as detected by osmoreeptors in the anterior hypothalamus.
• Reduction in ECF detected by the barorecptors
• Stress
• Soe drugs - e.g. morphine and barbiturates
• Angiotensin II