Midterm 2 - Importance of Growth Hormone Flashcards
where does GH originate from
cells of the anterior pituitary
what does GH promote
tissue and body growth in young animals
what does GH especially promote
longitudinal growth until skeleton is complete
what does GH mainly control in adults
metabolism
does GH stimulate growth in fetal life
no - IGF1 and 2
what does protein sequence differ a lot between
species (poor cross reactivity)
what regulates GH
GHRH and GHIH
what increases GH secretion
high aa and low glucose content in plasma
exercising and stress
sex steroids
why does GH increase during sleep
it follows a circadian pattern
what type of eating will increase GH
high protein diet
long fasting
what happens at puberty due to GH
burst of growth
what is IGF1 responsible for
negative feed back on GH secretion
does GH have a short or long half life
short (about 20 min)
what does GH affect
most cells in the body
what type of hormone is GH
anabolic - promotes synthesis of protein (like insulin)
while being anabolic, what else is GH
a catabolic hormone - conversely to insulin GH stimulates lipolysis and reduces lipogenesis in adipose tissue
what does lipolysis increase
fatty acid production
what does GH decrease
glucose utilization in most tissue… in turn increasing glucose concentration in blood
what does GH do its indirect roles
via IGFs
what does GH stimulate
synthesis of IGF1 and its binding proteins in the liver
aside from GH stimulation, where are small amounts of IGFs produced
locally in muscle and adipose tissue
what is IGF1
a polypeptide chain with a sequence similar in human, porcine, and bovine
what is a main difference between GH and IGF1
IGF1 has a much longer half-life than GH due to being bound to carrier proteins
how does IGFs act
via its own tyrosine kinase receptors
what does IGF1 stimulate
chondrocytes
satellite cells
aa uptake and protein synthesis
does GH have any major role in mammary gland development
no
how are GH effects on milk production mainly mediated
via metabolism, and partitioning nutrients to mammary gland for milk synthesis
what does insulin normally direct nutrients towards
lipogenesis in adipose tissue - GH has opposite effect
what can boost milk production
Bovine GH (bST)
how much can bovine GH boost milk production by
10 and 40% in early and late lactation
is overproduction of GH common in animals
no - rare
what is overproduction of GH called before puberty (before skeleton is formed)
gigantism - increased longitudinal growth
what is overproduction of GH after puberty (no more longitudinal growth)
acromegaly, increased bone width and density, diabetes
what can be the cause of GH overproduction in old dogs and cats
pituitary tumor
what is the result of a lack of GH production
dwarfism
what causes dwarfism
mostly genetic defects of GH or GH receptor genes
how can dwarfism be treated
injection of recombinant GH and IGF1
what happens to dogs with dwarfism
they keep their puppy coat for a long time due to lack of IGF1 action on hair follicle differentiation
what does GHRH do
stimulates GH
what does GHIH (somatostatin) do
inhibits GH
what does GH do with IGF1
stimulates IGF1 production by liver –> IGF1 stimulates cartilage and bone growth and milk production
what does GH regulate
lipid and protein metabolism
what family is GH receptor a member of
the interleukin (cytokin) family
