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
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.
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