Vasopressin and Oxytocin are neurohormones produced by the neuro secretory cells of hypothalamus reach the pituitary through the axon terminals of the secretory neurons as secretory granules bound to neurophysin proteins.
Vasopressin or Antidiuretic hormone (ADH) :
This hormone has two main functions. it stimulates the reabsorption of water in the distal convoluted tubules, collecting tubules and collecting ducts in the kidneys and decreases the loss of water by reducing urine secretion. It stimulates the contraction of smooth muscles of the blood vessels and thus increases the blood pressure, hence its name vasopressin.
Deficiency of ADH reduces reabsorption of water and increase urine output, causing excessive thirst. This disorder is called diabetes insipidus. No glucose is lost in the urine of such a patient.
Oxytocin (Pitocin): It is released in the blood when the hypothalamic neurons are stimulated by widening of uterus at the time of uterus at the time of delivery or sucking of the breast by the child. It stimulates contraction of uterine muscles during the birth of the young one and contraction of myoepithelial cells of the mammary glands to initiate ejection or release of milk during sucking by the child. Because of its role, oxytocin is called birth hormone and milk ejecting hormone.
Vasopressin vs OxytocinVasopressin
1. It is a vasoconstrictor.
2. It tends to increase blood pressure.
3. It helpful in concentration of urine.
4. It functions in both sexes.
5. Its secretion is stimulated by reduced quantity of body fluids.
6. Target cells: Cells of kidney
1. It is a vasodilator
2. It tends to decrease blood pressure
3. It has no such activity.
4. Its function is known only in females.
5. Its secretion is stimulated by distension of uterus and suckling of breast.
6. Target cells: Cells of mammary glands