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

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.

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.

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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