Prolactin

introduction
pituitary gland hormone
factor affecting secretion
function
regulation of secretion of prolactin
causes and symptoms of hypoprolactinaemia
causes and symptoms of hyperprolactinaemia
diagnosis
treatment


mechanism of prolactin
role of prolactin
uses

1. Prolactin By: Khushboo Thakur M.Pharm Sem II Pharmacology

2. Introduction Human prolactin is a single- chain polypeptide of 199 amino acids. It has a molecular weight of 23 kDa. Prolactin is synthetized in and secreted from specialized cells of the anterior pituitary gland, the lactotroph cells. The pituitary gland (also called as the master gland) is an endocrine gland about the size of a pea (weighing 0.5 g) and located at the base of the brain (just below the hypothalamus).

3. The pituitary gland has two parts – the anterior lobe and posterior lobe – that have two separate functions. The pituitary gland secrets hormones regulating homeostasis, including tropic hormones that stimulate other endocrine glands.

4. PITUITARY GLAND HORMONES

5. Factors affecting secretion Factors increasing prolactin secretion: Prolactin releasing hormone (PRH) Estrogen (during stimulates lactotropes to secrete prolactin) Oxytocin (causes muscle contractions to expel milk) Vasoactive intestinal peptide (VIP) Thyrotropin releasing hormone (TRH) Breast feeding Stress Sleep Dopamine antagonists (eg., antipsychotic drugs) Chest wall trauma Factors inhibiting prolactin secretion: Dopamine (also called prolactin inhibiting hormone) Bromocryptine (Dopamine agonist)

6. function Prolactin is responsible of: Primarily, initiating and sustaining lactation and Stimulation of breast development along with Estrogen during pregnancy. Other function of prolactin: Reproductive; inhibition of ovulation by decreasing secretion of LH and FSH during pregnancy. Regulation of immune system; by stimulating T cell functions. Osmoregulation; transporting fluid, Na, Cl and Ca across epithelial intestinal membrane and promoting Na, K and water retention in the kidney. Metabolism; essential in fat cell production, differentiation and regulation.

7. Regulation of secretion Breast feeding is the major stimulus of prolactin production. Triggered by the prolactin releasing hormone (PRH) Inhibited by prolactin inhibiting hormone (PIH), dopamine, acting on the D2 receptors present on the lactotroph cells. In male, the influence of PIH predominates. In female, prolactin levels increase and decrease in accordance with Estrogen blood levels: Low Estrogen levels stimulate PIH release. High Estrogen levels promote release of PRH and thus prolactin. Blood level increase toward the end of pregnancy. When the mother no longer needs to produce milk, dopamine inhibits prolactin by signaling the hypothalamus to stop.

8. Cause And Symptoms Of Hypoprolactinaemia Hypoprolactinaemia - decreased prolactin hormone secretion by the anterior pituitary gland. Common causes of Hypoprolactinaemia: Sheehan’s syndrome (caused by ischemic necrosis of the pituitary gland due to blood loss during or after child birth) Hypopituitarism Excess dopamine Autoimmune disease Growth hormone deficiency Head injury Infection (eg., tuberculosis)

9. Symptoms: Ovarian diseases, delayed puberty and infertility. Impotence and abnormal spermatogenesis.

10. Causes And Symptoms Of Hyperprolactinaemia Hyperprolactinaemia – increased prolactin hormone secretion by the anterior pituitary gland. Common causes of Hyperprolactinaemia: Stress Medications (e.g, Antipsychotic drugs) Primary hypothyroidism: prolactin is stimulated by the increase of TRH. Pituitary gland tumour Prolactinoma: a non-cancerous tumour of the pituitary cell secreting prolactin.

11. Idiopathic hypersecretion: eg., due to impaired secretion of dopamine. Other : Chest wall lesion Chronic renal failure.

12. Symptoms: Women: Oligomenorrhoea Amenorrhoea Galactorrhoea Infertility Hirsutism Osteoporosis Men (late onset): Gynaccomastia Impotence Osteoporosis In both sexes, tumour mass effects may cause visual- field defects and headache.

13. Diagnosis and treatment Diagnosis: History (medication, oligomenorrhoea, hirsutism) Physical examination (Galactorrhoea) Laboratory Pregnancy test Prolactin Macroprolactin (inactive, large complex of serum prolactin with an IgG antibody) TSH, Free T4 U& Es Tes , LH and FSH

14. MRI scan (Prolactinaemia) Visual field tests (optic nerve)

15. Treatment : Hyper Prolactinaemia: dopamine agonists (e.g., Bromocryptine or Cabergoline ) Surgery removal and/or radiation therapy (large pituitary tumours) Thyroid abnormalities: thyroid hormone replacement (e.g., levothyroxine ) Ovarian insufficiency: hormonal therapy (e.g., Estrogen and progestins)