Growth hormone

From Ganfyd

Human Growth Hormone (light blue) bound to the dimer receptor proteins (Growth Hormone Binding Protein) (pink and green) of the growth hormone receptor necessary to activate its function at cellular level

Secreted by the anterior pituitary under stimulation from Growth hormone-releasing hormone(GHRH) and with feedback by Somatostatin, Ghrelin and IGF-I(insulin-like growth factor-I) it acts on adipose cell receptors directly to affect lipid metabolism but mainly acts by stimulating IGF-I secretion from tissues such as the liver. Growth hormone receptor is expressed most in the liver and cartilage. It is likely this mitigates growth hormone deficiency, either because of disease in the hypothalamus-pituitary axis or due to mutants of the hormone or GHRH that render it dysfunctional.

Deficiency

Lifetime deficiency states are manifest by:

• Short stature
• Growth retardation

Molecular model of GH alone in similiar configeration to that when bound to GH Binding Protein receptors

Phenotype can be variable and more complex than just this. Investigation of some GH mutations has revealed that abnormal GH can affect the production of other pituitary hormones and hence pituitary function. ^[1].

Although deficiency can be associated with the pathologies of early aging

• wrinkled skin
• obesity
• insulin resistance
• osteopenia

life span in man appears to be enhanced typically to ages of 80-90 years.^[2].

Excess

Leads to:

• Giantism
• Acromegaly

References