Growth hormone is a single chain peptide hormone that promotes growth in children and maintains protein synthesis, fat metabolism, and glucose regulation in adults. It acts through insulin-like growth factors to exert its effects. Conditions of excessive or deficient growth hormone levels can cause gigantism or dwarfism respectively. Growth hormone secretion is regulated by growth hormone-releasing hormone and somatostatin, while its effects are mediated by insulin-like growth factors. Prolactin similarly regulates breast development and lactation. Hyperprolactinemia can result from tumors or drugs and cause issues like galactorrhea or infertility.

1. Growth Hormone
Single chain peptide M.Wt.22000,191 Amino acids
Functions:
Promotes growth of all organs by inducing
hyperplasia
proportionate ↑size & mass of all parts of body –Except gonads, brain & eye
Promotes protein synthesis & N2 retention
↑ uptake of amino acids by tissues and results in +ve N2 balance
Promotes utilization of fat, lipolyisis in adipose
tissue.
 Promotes glycogenolysis- ↑ glucose output
from liver ,glucose uptake by muscles is ↓

2. • Growth promoting, nitrogen retaining and certain
metabolic actions of GH are exerted Indirectly
through the (1GF-1, IGF-2)- Somatomedins, or
insulin like growth factors ,extracellular mediators
of GH response.
• Liver is the main source of IGF1
• IGF1- promotes lipogenesis & glucose uptake by
muscles

3. Fasting,Hyp
oglycemia,
exercise,
Stress
Skeletal muscle, bones,
visceral muscle ,kidney
↑plsma FFA,
glucocorticoids
lGF-1,GH
Somatotrophs

4. Mechanism of action
GH acts on cell surface receptor (with out intrinsic enzyme)
- JAK-STAT protein kinase receptors
Binding of one GH molecule -
dimerisation
Recruitment of JAK (Janus kinase) –
then binds to STAT (signal transducer
and activation of transcription).
Phosphorylated STAT dimerises and
STAT dimer dissociate from the receptor
Migrate to the nucleus to induce gene
transcription

5. GROWTH HORMONE secretion
Secretion is high in the newborn, decreasing at 4
years to an intermediate level, which is then
maintained until after puberty, after which there is
a further decline.

6. Acromegaly
Excess production in adults, which
is usually the result of a benign
pituitary tumour
enlargement mainly of facial
structures and of the hands
and feet.
bromocriptine and
octreotide may mitigate
the condition, but
effective treatment
demands removal or
irradiation of the tumour.
Gigantism
An excessive
production of
growth hormone in
children
pituitary dwarfism
Lack of GHRF or a failure
of IGF generation or
action
Pathological involvement

7. GROWTH HORMONE inhibitors
SOMATOSTATIN
• Somatostatin is a peptide of 14 amino acid residues. It inhibits the
release of GH and TSH, thyrotrophin prolactin from the anterior
pituitary
• inhibits the release of insulin and glucagon from the pancreas
• inhibits the release of most of GI hormones, and reduces gastric
acid and pancreatic secretion.
Octreotide
• is a long-acting analogue of somatostatin .
• 40 times more potent in inhibiting the GH release
• used in secretory diarrhoeas associated with carcinoid, AIDS, cancerc
hemotherapy, diabetes.(inhibits the intestinal hormones)
• In the therapy of acromegaly
Use limited in acromegaly because short duration of action

8. PROLACTIN
• Prolactin is single chain peptide of MW 23000,
consisting of 199 AA
• Secreted from pituitary mamotrophs.
• These are abundant in the gland and increase in
number during pregnancy, under the influence of
oestrogen.

9. Physiological function
Prolactin (together with, estrogens, progesterone)
• Causes growth and development of breast during
pregnancy.
• It promotes proliferation of ductal as well as acinar cells
in the breast synthesis of milk proteins and lactose.
• After parturition, prolactin induces milk secretion,
because estrogen and progesterone level falls
• level ↑ during breast feeding – amenorrhoea- inhibits
GnRH- inhibits ovulation
• may affect immune response through action on T-
lymphocytes

10. Control of prolactin secretion
• PRIF -prolactin release-
inhibiting factor;
(predominant)
• PRF- possible factors ----
TRH, Oxytocin
• Prolactin levels low in
childhood, ↑ in girls at
puberty and
• High – during pregnancy
&lactation
• levels↓ on Discontinuation
of feeding

11. Pathological involvement
Hyperprolactinemia-
Causes –
Prolactin secreting tumours, hypothalamus disorder,
antidopaminergic drugs, hypothyroidism(↑TRH)
Symptoms-
galactorrhoea, amenorrhoea, infertility in women;
gynaecomastia and sterility in men
Treatment-
Prolactin inhibitors-Bromocriptine,Cabergoline