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 |
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| dysfunction: short and excess stature, acromegaly;
diabetes mellitus |
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