Growth hormones Flashcards
Where are growth hormones/ somatotropin produced?
Somatotropes in anterior pituitary
What is the function of GH and IGF-1?
Long-term: Promotes growth, Protein synthesis
Short-term: Starvation response, Lipolysis, Insulin resistance
How does the growth response promote protein synthesis
Increases nuclear transcription (DNA→RNA) and translation (RNA→proteins)
Increases amino acid transport through cell membrane and decreases catabolism of proteins and amino acids
What are the stimuli for GH release?
Decreased blood glucose
Decreased blood free fatty acids
Decreased protein
Trauma, stress, excitement
What does the GH response cause?
Rapid catabolic actions → hyperglycemia
Protein within minutes it increases rate of protein synthesis
Within hours it increases lipolysis and fat use
How does the growth response promote hyperglycemia?
Decreasing glucose transport across cell membranes
Increasing insulin antagonism
Increasing gluconeogenesis
What do insulin like growth factors do and what stimulates their release?
Mimic effects of insulin on growth
Stimulated by GH
Where are IL growth factors produced?
Produced by different tissues; mainly liver
What is the half life of insulin like growth factor and GH?
IGF t½ = 20 hours
GH t½ = 20 minutes
Where is IGF-1 produced?
Liver
What does IGF-1 do?
Increase chondrogenesis and growth as the cartilage mineralises
Name some clinical signs of pituitary dwarfism
Proportionate growth retardation
Soft woolly hair coat
Become lethargic, have a decrease in appetite, and appear systemically ill
In Males it produces Uni/bilateral crytorchidism(retained testis/es)
In Females it presents a persistent oestrus or failure to ovulate due to low progesterone
Animals with pituitary dwarfism will have what?
Decreased GH and decreased IGF-1
Cats with acromegaly are nearly always…
Males
Dogs with acromegaly are always..
Female
Caused by: Induction of GH gene in mammary glands
Mammary GH identical to pituitary GH
