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| Pharmaceutical product: Human Growth Hormone: Definition, Growth hormone receptor, Biological effects, rHGH, Therapeutic uses of rHGH |
Pharmaceutical
product: Human Growth Hormone: Definition, Growth hormone receptor, Biological
effects, rHGH, Therapeutic uses of rHGH
Definition:
Growth hormone is a polypeptide hormone
synthesized in the anterior pituitary.
Mature human growth hormone contains 191
amino acids and has a molecular mass of 22 kilo Dalton.
It also contains two intra-chain disulfide
linkages.
Growth
hormone synthesis and release from the pituitary is regulated by two peptide
hypothalmic factors -
a) Growth
hormone releasing factor (GHRF/ Somatorelin)
b) Growth
hormone release inhibiting hormone (GHRIH/ Somatostatin)
Human growth hormone undergo alternate
splicing, forming a shortened GH molecule of 20 kDa, which is indifferent from
22 kDa in biological activity.
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| Overview of the mechanism by whice GH induces its biological effects and how it's secretion is regulated; Figure by Sadia Akhtar |
Growth
hormone receptor and its action:
The biological effects of growth hormone are
induced by binding to a cell surface receptor, known as Growth hormone
receptor.
The growth hormone receptor is a single chain
transmembrane polypeptide containing 620 amino acids. It is a member of the
hematopoietic receptor superfamily.
Soluble GH - binding proteins (GHBPs) are
found in the circulation. In human, the
GHBPs are generated by enzymatic cleavage of the integral membrane receptor,
releasing the GH - binding extracellular domain.
In serum,growth hormone binds to two GHBPs inducing an action that
provides hormone plasma half-life.
Biological
effects of growth hormone:
Growth hormone expresses anabolic activity.
It stimulates the growth of bones, muscles and cartilage.
Binding of growth hormone to its hepatic
receptor results in the synthesis and release of IGF - 1 (Insulin like Growth
Factor 1 / Somatomedin C).
Growth
hormone has these anabolic effects:
1. Increased
body growth, specially bones and skeletal muscles.
2.
Stimulation of protein synthesis in tissues.
3. Elevation
of blood glucose effects or anti - insulin effects.
4. Increase
of muscles and cardiac glycogen storages.
5. Increased
kidney size and enhanced renal functions.
6.
Reticulocytosis (Increased reticulocytes production in bone marrow).
7.
Mobilization of deposited lipids from adipose tissues.
Recombinant
Human Growth Hormone (rHGH):
Recombinant Human Growth Hormone or
somatotropin was first produced in early 1980s using Escherichia coli.
Its amino acid sequence is similar to natural human growth hormone.
The recombinant preparation is different from
the native human growth hormone in that it contains an extra methionine residue
to the AUG start codon inserted at the beginning of the gene.
Use of recombinant human growth hormone may
cause cancers.
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| Production of rhGH in E Coli, Figure By Sadia Akhtar |
Therapeutic
uses of growth hormone:
Major applications of the recombinant human
growth hormone for medical use are -
a)
Genotropin, Neutropin and Biotropin - used for hGH deficiencies in children.
b)
Neutropin AQ - growth failure, Turner's Syndrome.
c)
Serostim - treatment of AIDS - associated catabolism.
d)
Omnitrop and Valtropin - treatment of
children
and adults with certain types of
growth
failure.
e)
Somavert - treatment of patients of acromegaly.
"Pharmaceutical
product: Human Growth Hormone: Definition, Growth hormone receptor, Biological
effects, rHGH, Therapeutic uses of rHGH."
Written By
Sadia
Akhtar
Student of
Department of Microbiology
Jagannath
University.
Email-
sadiabd810@yahoo.com
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