Pituitary hormones and it's applied

1. Pituitary Hormones and their
control by Hypothalamus
Geeta Shamnani
MBBS, MD
King George’s Medical University

2. Gross Anatomy and Development of Pituitary
Gland
• Hypophysis Cerebri
• Wt: 0.5gms
• Diameter: 1cm
• Location: Hypophyseal fossa (Sella Turcica)
• Separated from Pituitary Gland by Diaphragmatic
Sellae

3. Location of Pituitary Gland

4. Structure and Relations of Pituitary Gland

5. Functional Anatomy of Pituitary Gland
Two parts
1. Anterior Lobe: Adenohypophysis
2. Posterior Lobe: Neurohypophysis

6. Development of Pituitary
Anterior Pituitary: from Rathke’s pouch
• Rathke’s Pouch: Embryonic invagination of
pharyngeal epithelium
• Epitheloid nature of cells
Posterior Pituitary:
• Neural tissue outgrowth from Hypothalamus
• Glial type of cells

7. Parts of Pituitary Gland
1. Adenohypophysis: About 80% of gland
a) Pars Distalis
b) Pars Intermedia
c) Pars Tuberalis
2. Neurohypophysis
a) Pars posterior-pars nervosa
b) Infundibular stem
c) Median Eminance

8. Pars Intermedia
 Rudimentary in human beings
 Secretion of Melanocyte Stimulating Hormone
(MSH)
 Control of change in colour in fish, reptiles,
amphibian
 In humans ACTH having MSH like activity
 Binding of ACTH to the melanotropin-1 receptors
over melanocyte

9. Histological structure of Pituitary Gland
 Chromatophobes: Agranular cells
 Chromatophils: Granular cells
50% of cells of anterior pituitary
Further classified into
1. Acidophilic cells (α cells): 35%
2. Basophilic cells (β cells): 15%

10. 1. Acidophilic cells (α cells):
• Somatotrophs: Secrete GH
• Mammotrophs or Lactotrophs: Produce
Prolactin
2. Basophilic cells (β cells):
• Corticotrophs: Produce ACTH
• Thyrotrophs: Produce TSH
• Gonadotrophs or δ cells: Produce FSH and LH

12. Histological structure of Pituitary Gland

13. Hypothalamic-Hypophyseal Portal System

14. Endocrinal aspects of Hypothalamus
• Functional Anatomy of Hypothalamus
 Master co-ordinator of hormonal actions
 location: Below Thalamus
 Close connection with the pituitary gland
 Control of anterior pituitary and posterior
pituitary function

15. Control of Anterior Pituitary Gland
• Control through various Hypothalamic-
Hypophysiotropic hormones
• Afferent tracts from Thalamus, The Reticular
Activating System, the eyes, Neocortex
• Through these inputs, the pituitary functions to
be influenced by pain, sleep, wakefulness,
emotions, fright, rage, olfactory sensations, light

16. Various Hypothalamic Releasing and
Inhibitory Hormones
• Growth Hormone Releasing Hormone (GHRH)
• Growth Hormone Inhibitory Hormone (GHIH)
• Corticotropin Releasing Hormone (CRH)
• Thyrotropin Releasing Hormone (TRH)
• Gonadotropin Releasing Hormone (GnRH)
• Prolactin Releasing Hormone (PRH)
• Prolactin Inhibiting Hormone (PIH)

17. Various Hypothalamic Hormones

18. Control of Posterior Pituitary Function
Formation of ADH by Supraoptic nuclei
Formation of Oxytocin by Paraventricular nuclei
Both the nuclei formed by large (Magnocellular)
neuron
Both the hormones reach posterior pituitary
through Hypothalamic- Hypophyseal tract

19. Control of Posterior Pituitary Function

20. Anterior pituitary hormones
• Growth hormone (Somatotropic Hormones)
• Thyroid Stimulating Hormone (TSH)
• Adrenocorticotropic hormone (ACTH)
• Follicle Stimulating Hormone (FSH)
• Luteinizing hormone (LH) in females
• Interstitial cell stimulating hormone(ICSH)
• Prolactin
• β Lipotropin and β Endorphin

21. Hormones from Anterior Pituitary

22. Growth Hormone (Somatotropin)
• Most important hormone for postnatal growth
• Small protein with 191 A.A. in single chain
• Molecular weight 22, 005

23. Metabolic actions of Growth Hormone
• Increase rate of protein synthesis in most of
cells
• Increase mobilization of fatty acids for
energy production
• Decrease rate of glucose utilization
throughout body

24. Effect on Protein Metabolism
Increase rate A.A. uptake by cells
Increase protein synthesis by Ribosome
Increase RNA synthesis
Decrease catabolism of protein and Amino-
acids

25. Effect on Fat Metabolism
• Enhancement of fat utilization for energy
• Increase circulating Free fatty acids
• FFA being source of energy during
hypoglycemia
• Ketogenic Effect: due to production of large
quantities of Acetoacetic acid

26. Effect on Carbohydrate Metabolism
• Decrease in carbohydrate utilization
• Decrease in glucose uptake by tissues such
as skeletal muscles and fat
• Increase glucose production by liver:
Gluconeogenesis
• Inhibition of Glycolysis
• Increase in glycogen stores

27. Effect on Cartilage and Bones
Promotion of linear growth of an individual
Stimulation of proliferation of chondrocytes
present in the epiphyseal end plates
Stimulation of osteoblastic activity
Action to be mediated by Somatomedins

28. Effect on Mineral Metabolism
• Promotion of bone mineralization in growing
children
• Mediated through Insulin Like Growth Factors
(IGF-1)
• Positive balance of calcium, phosphate and
magnesium

29. Effect on lactation
• Enhancement of milk production in lactating
animals
• Prolactin like effect of growth hormone

30. Mechanism of action of GH
• Receptors (Cytokine family) present on cell
membrane of target tissue
• Action to be mediated through Somatomedins
• Somatomedins to be formed in liver
• Effect of Somatomedins on growth being similar
to insulin: Insulin Like Growth Factors (IGF)
• Somatomedins: Strongly attach to carrier
protein

31. Factors affecting Growth Hormone Secretion
Stimulate GH secretion Inhibit GH secretion
Decrease blood sugar Increase blood sugar
Decreased blood FFA Increased blood FFA
Increase blood AA (Arginine) Aging
Starvation, Protein deficiency Obesity
Trauma, Stress, GHRH GHIH (Somatostatin)
Exercise, Excitement GH (Exogenous)
Testosterone, Estrogen, Ghrelin
Deep sleep (Stage II & IV)
Somatomedins (Insulin Like
Growth Factors)

32. Diurnal Variation in the Growth Hormone
Secretion

33. Abnormalities of Growth Hormone Secretion
Hyposecretion of Growth Hormone
• Pituitary dwarfism
• Panhypopituitarism
Hypersecretion of Growth Hormone
• Gigantism
• Acromegaly
• Acromegalic Gigantism

34. Pituitary Dwarfism
Reduced rate of development of all body parts
Proportionate development
Shortness of Stature
Normal mental activity
Plumpness (fatness)
Immature faces
Delicate extremities
Sexual immaturity

35. Pituitary Dwarf

36. Functional Tests
• Stimulation tests: Stimulation of GH secretion
by insulin induced hypoglycemia
• Gold standard test
• Insulin to be given 0.15U/Kg intravenously
• Samples to be taken 0, 30, 60, 90 and 120 min.
• Normal: Raise in GH level ˃ 20ng/ml
• GH deficiency: GH level ˂ 7ng/ml

37. Other causes of Dwarfism
Endocrinal causes:
1. GH deficiency
2. African pygmies
3. Laron dwarfism
4. Panhypopituitarism
5. Hypothyroid dwarf
6. Cushing Syndrome

38. Other causes of Dwarfism
Non-Endocrinal Causes
1. Familial dwarfism
2. Achondroplasia
3. Nutritional (Malnutrition, Malabsorption)
4. Chromosomal abnormalities (Turners
Syndrome)
5. Psychological dwarfism
6. Renal diseases

39. Gigantism
• Hypersecretion of GH before adolescence
• Before fusion of epiphysis
• Abnormal height (7-8 feet)
• Large hands and feet
• Coarse facial features (Thick lips, Macroglossia)
• Bilateral gynaecomastia
• Loss of libido, impotence
• Hyperglycemia, full blown DM

40. Gigantism

41. Features of Gigantism due to tumor mass
• Headache
• Cranial Nerve Palsies
• Visual field defect
• Enlargement of Pituitary Fossa

42. Acromegaly
Excess of GH in adults (after fusion of epiphysis)
Features:
Acromegalic face: Thick lips, Macroglossia, broad
and thick nose, prominent eyebrows, bossing of
forehead, thickened skin, coarse facial features
Prognathism: Elongation and widening of
mandible, increase spacing of teeth
Acral part abnormalities: Large spade like hands,
thick wide fingers, slanting of forehead, large
feet

43. Acromegalic Facies

44. Acromegalic Acral parts abnormalities

45. • Built: Height normal, built stout and stocky
• Kyphosis: due to improper vertebral growth
leading to hunched back
• Excessive growth of internal organs:
Cardiomegaly, Hepatomegaly, Splenomegaly,
Renomegaly
• Increase sympathetic activity: Increase
sweating, hypertension
• Poor gonadal function: due to
hyperprolactinaemia

46. Kyphosis

47. Biochemical features
1. Poor glucose tolerance
2. Frank diabetes: 15% cases
3. Hypertriglyceridaemia
4. Reduced lipoprotein lipase activity
5. Hypercalcaemia, Hyperphosphatemia
 Features due to tumor mass: similar to Gigantism

48. Functional tests for GH
1. Basal plasma GH level: High
2. Plasma Prolactin level: High
3. Glucose tolerance suppression test: 75 grams
of glucose to be given orally, GH and blood
glucose level to be measured 2 hourly
Normal: Suppression of GH by hyperglycemia
Acromegaly or gigantism: No suppression
4. Visual field defects: Due to pressure by pituitary
adenoma
5. CT scan skull

49. Treatment
Surgical
Careful removal of pituitary tumor
Medical
Bromocriptine:
• Stimulator of GH secretion in normal individual
• Suppression of GH in Acromegalic patient
Octreotide (Somatostatin Analogue):
• For long term Acromegaly