Prolactin is a 199-amino acid polypeptide hormone produced in the anterior pituitary gland, essential for lactation and regulating various body functions like immune response and metabolism. Its secretion is influenced by factors such as breastfeeding, estrogen, and stress, while inhibited by dopamine. Disorders of prolactin levels include hypoprolactinaemia and hyperprolactinaemia, leading to various reproductive and health issues, and can be diagnosed through medical history, lab tests, and imaging, with treatment options including medications and surgery.

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)