VASOPRESSIN AND OXYTOCIN HORMONE .ppt.pptx

Introduction to hormone
Mechanism of action of hormone
Biological action of hormone
Disorders of hormone

1. VASOPRESSIN & OXYTOCIN Dr. S. ASHA , M.Sc., M.Phil., Ph.D., SET, Assistant professor, Department of Biochemistry, D.K.M. College for Women, Sainathapuram, Vellore -1.

2. VASOPRESSIN (or) (ADH)- ANTIDIURETIC HORMONE

3. INTRODUCTION Secreted by supra optic nuclei of hypothalamus. Octa peptide hormone with molecular weight 1100 daltons . Made up of 8 amino acids STIMULATING FACTORS 1. Blood osmotic pressure 2. Blood volume 3. Hypotension 4. Nausea and emotional stress 5. Drugs

4. BIOLOGICAL ACTIONS OF VASOPRESSIN ANTIDIURETIC EFFECT : Increases reabsorption of water in kidney tubules. Acts on distal convoluted renal tubules and renal collecting tubules of nephrons and increses water permeability this leads to increased reabsorption of water from glomerular filtrate. Secretion is regulated by osmoregulatory can be present in hypothalamus. If osmotic pressure of blood increases ADH secretion increases in turn water reabsorption is increased.

5. Decreased osmotic pressure in blood reduced ADH secretion and subsequently leads to decreased reabsorption of water in tubules and leads to more diluted urine excretion EFFECT OF BLOOD VESSELS: ADH causes contraction of peripheral arterio venous capillaries, as a result blood pressure increases. Due to this effect vasopressin is named. This effect is called pressor effect.

6. Phosphorylation of other enzymes Hormone + Receptor = Hormone Receptor complex Activation of Adenylate cyclase cAMP Activates protein kinase Increased permeability MECHANISM OF ACTION IN RENAL COLLECTING DUCTS

7. DISORDERS Deficiency or reduced amount of ADH leads to decreased water reabsorption in kidney tubules leading to formation of dilute urine. Patient with this disorder excrete more amount of diluted urine ( polyuria ) and frequently intake more amount of water ( polydipsia ). This conditions is termed as diabetes insipidus . This can be overcome by the administration of vasopressin.

8. OXYTOCIN (or) PITOCIN

9. Oxytocin is a octapeptide hormone. Molecular weight is 1000 daltons . Synthesized by Para ventricular nucleus of hypothalamus. BIOLOGICAL ACTIONS OF OXYTOCIN EFFECT ON UTERUS (Smooth muscles) Oxytocin causes contraction of uterus. Secreted in moderate quantity during latter part of pregnancy and larger quantity at the time of parturition. Helps in expulsion of baby from uterus at the time of delivery.

10. EFFECT ON MAMMARY GLAND Stimulates contraction of smooth muscles in mammary glands and myoepithelial cells surrounding alveoli and induces milk expulsion. This effect is called as galactogogue effect. Mammary glands receptors and uterine receptors regulates the oxytocin secretion. Estrogen increases the number of receptors while progesterone decreases the number of receptors in mammary glands and myoepithelial cells.