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So I'm Derek LeRoith, Chief of the
Division of Endocrinology, Diabetes, and
Bone Diseases at
Mount Sinai School of Medicine.
And today, my discussion is going
to be on "The Growth Hormone and
Insulin-Like Growth Factor-1 Axis
in Health and Disease".
So in discussing growth hormone IGF-I
axis, today what we want to cover is
the normal physiology of the axis,
disorders of the growth hormone IGF axis,
including disorders like acromegaly,
growth retardation and aging.
And then finally,
we'll discuss growth hormone and
IGF-I axis in conditions such as diabetes,
tumor hypoglycemia and
in general, forms of cancer.
So let's talk firstly about
the normal physiology of
the growth hormone IGF-I axis.
This slide shows the hypothalamus and
And as you can see,
there are hypothalamic-releasing and
hypothalamic inhibitory hormones,
which reach the pituitary gland and
stimulate the release of prolactin, growth
hormone, thyrotropin or TSH, luteinizing
hormone, follicular-stimulating hormone,
And there are specific cells
as shown here, the lactotroph,
the thyrotroph, the gonadotroph, and
each of which release these hormones.
But the hormone that we'll be dealing
with today is growth hormone.
So this slide shows how
the growth hormone,
IGF axis works under normal
As you can see, stress, sleep,
exercise, etc affect the hypothalamus
to release the growth hormone-releasing
hormone, which reaches the anterior
pituitary to stimulate growth
hormone released to the periphery.
Once it reaches the liver, muscle,
adipose, or bone, it then stimulates
the synthesis and release of
insulin-like growth factor-1, or IGF-I,
which then reaches the circulation, and
has a positive effect on target tissues.
IGF-I, on the other hand, has a negative
feedback to the hypothalamus and
the pituitary, to inhibit growth hormone.
And this is the normal negative
feedback regulation so
well-known in the endocrine system.