Transcript Growth Hormone_________ JESSSSSSSSSSSSSSSSSSSSSSSICA

Growth Hormone
Jessica crownover
GROWTH HORMONE IS…
• is a peptide hormone that stimulates growth, cell
reproduction and regeneration in humans and
other animals. Growth hormone is a 191-amino
acid, single-chain polypeptide that is
synthesized, stored, and secreted by the
somatotroph cells within the lateral wings of the
anterior pituitary gland. Somatotropin (STH)
refers to the growth hormone 1 produced
naturally in animals, whereas the term
somatropin refers to growth hormone produced
by recombinant DNA technology,1 and is
abbreviated "HGH" in humans.
Gene Iocus
• Genes for human growth hormone, known as
growth hormone 1 and 2, are localized in the
q22-24 region of chromosome 1734 and are
closely related to human chronis
somatomammotropin genes. GH, human
chorionic somatomammotropin, and proclantin
belong to a group of hormones with growthpromoting and lactogenic activity.
STRUCTURE
• The major isoform of the human growth
hormone is a protein of 191amnio acids and a
molecular weight of 22,124 daLTONS. The
structure includes four helices necessary for
functional interaction with the GH receptor. It
appears that, in structure, GH is evolutionarily
homologous to prolactin and chorionic
somatomammotropin. Despite marked structural
similarities between growth hormone from
different species, only human and monkey
growth hormones have significant effects on.
Normal functions of GH
• Effects of growth hormone on
the tissues of the body can
generally be described as
anabolic (building up). Like
most other protein hormones,
GH acts by interacting with a
specific receptor on the
surface of cells.
• Increased height during
childhood is the most widely
known effect of GH. Height
appears to be stimulated by at
least two mechanisms:
Problems caused by too much of
GH…
• The most common disease of GH excess is a pituitary tumor
composed of somatotroph cells of the anterior pituitary. These
somatotroph adenomas are benign and grow slowly, gradually
producing more and more GH. For years, the principal clinical
problems are those of GH excess. Eventually, the adenoma may
become large enough to cause headaches, impair vision by
pressure on the optic nerves, or cause deficiency of other pituitary
hormones by displacement.
• Prolonged GH excess thickens the bones of the jaw, fingers and
toes. Resulting heaviness of the jaw and increased size of digits is
referred to as acromegaly. Accompanying problems can include
sweating, pressure on nerves, muscle weakness, excess sex
hormone-binding globulin (SHBG), insulin resistance or even a rare
form of type 2 diabetes, and reduced sexual function.
TREATMENTS
• Treatment with exogenous GH is indicated only
in limited circumstances,31 and needs regular
monitoring due to the frequency and severity of
side-effects. GH is used as replacement therapy
in adults with GH deficiency of either childhoodonset (after completing growth phase) or adultonset (usually as a result of an acquired pituitary
tumor). In these patients, benefits have variably
included reduced fat mass, increased lean
mass, increased bone density, improved lipid
profile, reduced cardiovascular risk factors, and
improved psychosocial well-being.
NON-MEDICAL USE USED IN
ATHLETES
• Athletes in many sports have used human
growth hormone in order to attempt to enhance
their athletic performance. Some recent studies
have not been able to support claims that
human growth hormone can improve the athletic
performance of professional male athletes.
Many athletic societies ban the use of GH and
will issue sanctions against athletes who are
caught using it. In the United States, GH is
legally available only by prescription from a
medical doctor.
EFFECTS
•
•
Direct effects are the result of
growth hormone binding its
receptor on target cells. Fat cells ,
for example, have growth
hormone receptors, and growth
hormone stimulates them to break
down triglyceride and supresses
their ability to take up and
accumulate circulating lipids.
Indirect effects are mediated
primarily by a growth factor a
hormone that is secreted from the
liver and other tissues in response
to growth hormone. A majority of
the growth promoting effects of
growth hormone is actually due to
IGF-I acting on its target cells
Too much GH can result in this…
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