Growth Hormone


somatotrophin or growth hormone (GH)

Release

  • released from somatotrophs
  • regulated by GHRH (releases) and somatostatin (inhibits)
  • released during deep sleep, hypoglycaemia, stress
  • released in a pulsatile manner

Mechanism

  • works through intermediary - Insulin-like Growth Factor - 1 (IGF-I)

Effects

  • promotes growth of long bones, visceral organs, adipose and connective tissue, endocrine glands and striated muscle
  • decrease in blood amino acid concentrations
  • decrease in blood urea nitrogen
  • positive nitrogen balance
  • increase in RNA, DNA and protein synthesis.
  • elevated blood glucose
  • increased oxidation of fat
  • growth
  • stimulation and calcification of cartilage

Disorders

  • high doses can lead to diabetes mellitus in dogs and cats
  • in early life, hypersecretion leads to gigantism
  • hyposecretion leads to dwarfism -achondroplasia
  • in later life, once epiphyseal plates have fused, leads to acromegaly

 

14.2.3.2 growth hormone = somatotrophin (from somatotroph cells)

actions on growth: direct and indirect via IGFs; metabolic actions
control: via hypothalamic GHRH: metabolites; stress, sleep, exercise; pulsatile secretion
dysfunction: short and excess stature, acromegaly; diabetes mellitus
 

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