Growth Hormone - IN Flashcards
what is the structure of growth hormone
single chain polypeptide produced in anterior pituitary, T1/2 = 20 min
what causes gigantism
an excess in GH during childhood
what causes acromegaly
an excess in GH during adulthood
what causes dwarfism
a deficiency in GH
what are the 2 functions of GH
longitudinal growth/development, metabolism regulation
what causes pygmies
severe underexpression of GH RECEPTOR
where is GH regulated
Hypothalamoose
Stimulatory = GHRH
Inhibitory = Somatostatin
How does Ghrelin affect GH
stimulates release, Ghrelin secreted from stomach/pancreas
What actions stimulate GH
deep sleep, exercise, sex steroids, fasting, hypoglycemia, AAs, stress, a-adrenergic agonists, dopamine agonists
what actions inhibit GH
IGF-1, obesity, glucocorticoids, hyperglycemia, FFA, GH, B-adrenergic agonists
what are the temporal factors of GH regulation
pulses primarily at night, #pulses/day constant, larger pulse amplitude during puberty, strenuous exercise causes GH surge
what does GHRH do
increase GH gene transcription, promotes GH release, stimulates production of GHRH receptor, stimulates somatostatin release
what does somatostatin do
decreases pulse frequency and amplitude, no impact on GH synthesis, inhibits GHRH release
what does Ghrelin do, specifically
produced in stomach/pancreas, stimulates hunger, levels increase before meal and decrease after, acts on GH secretagogue receptor, more important for feeding behavior and energy regulation than GH secretion
what does GH do in animals that lack insulin or carbohydrates
does NOT induce growth
