The document discusses growth hormone (GH), including its molecular structure, physiological effects, regulation and abnormalities. Some key points: - GH is a protein made up of 191 amino acids with a molecular weight of 22,124 daltons. It stimulates growth and has direct effects on tissues and indirect effects via stimulating IGF-1. - GH secretion is regulated by GHRH and somatostatin from the hypothalamus as well as ghrelin from the stomach. It is secreted in pulses, with the largest pulse an hour after sleep onset. - Physiological effects of GH include promoting linear growth, increasing lipolysis and protein synthesis while decreasing glucose utilization. - Abnormal

1. 1
Growth Hormone
The genes for human growth hormone are closely related
to human chorionic somatomammotropin (also known as
placental lactogen)
GH, human chorionic somatomammotropin, and prolactin
(PRL) are a group of homologous hormones with growth-
promoting and lactogenic activity.

2. 2
Growth Hormone cont’d
• Molecular structures
• The human growth hormone, also known as
somatotropic hormone, is a protein made up of
191 amino acids
• has a molecular weight of 22,124 daltons.
• The structure includes four helices necessary for
functional interaction with the GH receptor.
• Despite marked structural similarities between
growth hormone from different species, only
human and primate growth hormones have
significant effects in humans.

3. 3
Plasma level binding, metabolism
• GH binding protein-GHBP binds GH in plasma
and protects it from degradation.
• GHBP is equivalent to extracellular portion of
GH receptors
• About 50% of total is bound
• Metabolism takes place in the liver

4. 4
Growth Hormone cont’d
Physiologic Effects of Growth Hormone
 human growth hormone has two distinct types of effects
 Direct effects are the result of growth hormone binding to its
receptors on target cells.
 Indirect effects via IGF-1

5. 5
Growth Hormone cont’d
• Direct effects are the result of growth hormone
binding its receptor on target cells.
• for example Fat cells (adipocytes),
• GH stimulates them to break down triglycerides
and ↑circulating lipids.

6. 6
Growth Hormone cont’d
• Indirect effects are mediated primarily by a insulin-like growth
factor-1 (IGF-1), a hormone that is secreted from the liver,
chondrocytes, kidney, muscle, pituitary, gastrointestinal tract in
response to GH stimulation.
• Majority of the growth promoting effects of GH is actually due
to IGF-1 acting on its target cells.

7. 7
GH-Molecular action
• HG binds with receptors- member of cytokine
receptor of phosphorylated signal transducer
and activator of transcription (STAT) into the
nucleus →gene transcription →activation of
IGF-1 and super family →activation of JAK2
→self-phosphorylation →phosphorylation of
STAT→entering others →cellular biological
responses

8. 8
Growth Hormone cont’d
 Physiologic effects of GH
 Promotes linear growth of the body, ↑chondrogenesis &
mitogenic activities
 Metabolic role of GH
 On CHO metabolism
↓Glucose utilization
↑Gluconeogenesis ↑BGC ( Hyperglycaemic
↑Glycogenolysis hormone)
On protein metabolism (protein anabolic)
↑aa transport through the cell membrane
↑DNA transcription
↑RNA translation (protein synthesis)
↓Protein catabolism

9. 9
Physiologic effects of GH (cont’d)
On Fat metabolism
↑Lipolysis
↑FFA in plasma
↑Ketogenesis
↑β-oxidation
On Electrolytes
↑Absorption of Na+, K+ and Ca2
Other Roles of GH
↑RBC formation
↑MR, thermogenic
Decreases insulin secretion (Diabetogenic effect of GH)
↑Secretion of Somatomedin-C

10. 10
Control of Growth Hormone Secretion
 Production of growth hormone is modulated by many factors,
including stress, exercise, nutrition, sleep and growth
hormone itself.
 However, its primary controllers are two: hypothalamic
hormones (GHRH) & (SS) and one hormone from the
stomach (Ghrelin)
 Growth hormone-releasing hormone (GHRH) stimulates
both the synthesis and secretion of growth hormone.
 Somatostatin (SS) inhibits growth hormone release
 Ghrelin is a peptide hormone secreted from the stomach that
stimulates secretion of growth hormone by binding to its
receptors on somatotrophs.

11. 11
Control of Growth Hormone
Secretion
GH

12. 12
Regulation of GH secretion
OC MB
+
_
Somatotrops
GH
GH
SS
Cortisol
IGF-1
Stress
Surgical trauma
Anaesthesia
Haemorrhage
Excitement
Hormones
-Glucagon
-Androgens
-Estrogens
-Insulin
-T3/T4, PRL
+
+
_
Fasting
Exercise
+
Hypoglycemia
↓FFA
Deep sleep
AAs (arginine)
L-Dopa
+

13. 13
Secretion patterns
 Most of the physiologically important secretion occurs as
several large pulses or peaks of GH release each day.
 The plasma concentration during these peaks may range
from 5 to even 45 micg/mL.
 Peaks typically last from 10 to 30 minutes before returning
to basal levels
 The largest and most predictable of these GH peaks occurs
about an hour after onset of sleep
 Basal GH levels are low, usually less than 5 micg/mL for
most of the day and night.

14. 14
Growth Pattern
 With the life cycle the rate
of growth is not even.
 Infancy has the highest
rate decreasing until of
spurt of growth caused by
sexual maturity.

15. 15
Factors affecting growth
Growth
promoting
hormones
Insulin PRL
GH
Tissue growth factors
T3/T4
Androgens
Estrogens
Progesterone
Other factors affecting growth
Hereditary factors (genetic factors)
Nutritional factors
Environmental factors

16. 16
 Growth Rates differ
according to the time of the
life cycle.
 Growth hormone and
Thyroxin are the most
active.
 Sex hormones govern
growth spurt at sexual
maturity.

17. 17
Health benefits of HGH products
 HGH promotes the growth of every tissue especially bone
(Increases calcium retention, and strengthens and increases
the mineralization of bone), of a human mainly in the growth
period.
 Additionally causes
 stimulation of amino acid uptake and protein synthesis
 inhibition of protein decomposition
 acceleration of neutral lipid metabolism
 acceleration of sugar metabolism
 promotion of retention of electrolytes such as Na+, K+,
etc.

18. 18
health benefits of HGH products
 Administration of HGH products has been shown to
increase the rate of growth, weight gain and meat
production in animals.
 Additional benefits of HGH therapy have included reduction
in LDL, cholesterol and improved Psychological well-being.
 Human growth hormone supplementation has been shown
to be an effective treatment for GH deficiencies and their
related disease states in humans.
 Studies have uncovered that HGH supplementation may be
useful in combating aging in humans.

19. 19
health benefits of HGH products
 Elevated growth hormone levels have been shown to result in
increased lean muscle mass.

 As people age, the body fat percentage of the body increases
while the important lean muscle mass decreases.
 A Stanford University School of Medicine survey of clinical
studies on the subject showed that the application of GH on
healthy elderly increased lean muscle by about 2 kg and
decreased body fat by the same amount
 The maintenance of lean muscle mass is considered extremely
important as the loss of muscle strength is directly related to
limited mobility and physical performance
 Therefore, HGH is regarded as an anti-aging products and
bodybuilding supplements.

20. 20
Abnormalities of GH secretion
A. Hyposecretion (deficiency) of GH
B. Hypersecretion (excess)
C. Hyposecretion (deficiency) of GH
 Clinical features of Dwarfism
 Stunted growth
 Short stature
 Immature face, small for age
 Physical retardation
 Accelerated aging
 Causes of GH deficiency
 Panhypopituitarism
 Chromophob adenoma
 Craniopharyngioma (suprasellar cyst)
 Surgical removal of adenohypophysis

21. 21
Causes of dwarfism
The following are the various causes of
dwarfism
 Pituitary dwarfism (GH deficiency)
 Lorain dwarfism ( GH receptor defect)
 African pygmies dwarfism (Somatomedin-C
defect)
 Chromosomal defect (Turner's syndrome)
 Cretinism (Hypothyroidism)
 Hypoinsulinism
 Deficiency of gonadotropic hormones
 Under nutrition

22. 22
Abnormalities of GH secretion (cont’d)
B. Hyper secretion: Excessive
GH secretion
Causes:
1. Acidophilic hyperplasia
2. Acidophilic adenoma
3. Chromophob adenoma
4. Ectopic GH secretion
Classification:
1. Gigantism
2. Acromegaly
Rx: Surgery
Radiotherapy
Drugs: SS

23. 23
Characteristic Features of Acromegaly
Coarsening of the face due to excessive deposition of
connective tissue. e.g. Thickening of lip
Enlargement of nose and ear due to excessive growth of
cartilages
Protrusion of the lower jaw ( prognatism)
Prominent eye brow and long face
Enlargement and broadening of hands and feet
Kyphosis and osteoarthritis due to excessive thickening of
vertebral bones
Generalized pronounced enlargement of internal organs
(liver, heart, kidneys, endocrine disorders such as
hyperglycaemia, diabetes mellitus, hypertension,

24. 24
Acromegaly
Prior
Early
Onset
Full
Development
Progression of untreated
acromegly
irregular bone growth
continues

25. 25
Hands
Feet
Jaws