Anti-diuretic hormone regulates the quantity of water and hence the concentration of urine discharged by the kidney to maintain blood pressure, blood volume, and tissue water content. Specific nerve cells in the hypothalamus, which lies towards the base of the brain, produce anti-diuretic hormone. The hormone is transported by nerve cells through their nerve fibers (axons) to the posterior pituitary gland, where it is released into the circulation. By acting on the kidneys and blood arteries, anti-diuretic hormone helps to manage blood pressure. Its main purpose is to keep body hydrated by reducing the quantity of water send out in urine.