Somatomammotropic hormones Flashcards
Three somatomammotropic hor,omes
Growth hormone (GH)
Prolactin (PRL)
Placental lactogen (PL)
Actions of GH
Promotes overall growth
Indirect action via IGF’s
Diverse metabolic actions, usually opposite to insulin (protein, carb, lipid metabolism)
Protein metabolism changes of GH
Amino acid uptake into cells
Synthesis of RNA
synthesis of enzymes important in protein synthesis
Carbohydrate metabolism actions of GH
Decreased carb breakdown
Incresed plasma glucose levels by inhibiting glucose transport into cells and decreasing peripheral glucose utilisation
Lipid metabolism actions of GH
Promotes breakdown of stored triglycerides
When is growth not dependent on GH?
During foetal and neonatal time
IGFs are also called
somatomedins
GH is secreted in which manner?
Pulsatine manner
What 2 hypothalamic peptides control GH secretion?
Stimulates: GHRH
Inhibits: Somatostatin
GHRH secretion is stimulated by (3)
Acetylcholine
Noradrealine
Dopamine
GHRH is inhibited by (1)
adrenaline
Where is Ghrelin produced?
Mainly in fundus
What is Ghrelin?
Hunger stimulating peptide
Levels increase before meals
Administration increases feed intake
In youn dogs ghrelin is more important GH stimulant than GHRH
What is weird about dogs and GH secretion?
They can also produce GH in mammary gland
Induced by progestins
Not released in pulsatile manner
Not inhibited by somatostatin
Three types of dwarfism of hormonal origin
-Hypothalamic disorder
-Primary pituitary disease
-Liver does not respond to GH –> low levels of IGFs
