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Scientists find potential
protein biomarkers for growth hormone
SAN FRANCISCO – Ohio University scientists have
identified several proteins in mice that might act
as biomarkers for growth hormone. The research could
be the first step to finding a more reliable way to
detect recombinant human growth hormone (rhGH),
which some athletes and teenagers use illegally to
boost muscle and reduce fat.
 At
the Endocrine Society annual meeting in San
Francisco on Tuesday
June 17, scientists John Kopchick and Juan Ding
presented a new study
that pinpointed four proteins
that significantly decreased or increased in the
blood after exposure to bovine growth hormone, which
is similar to human growth hormone.
The researchers injected six 6-month-old male mice
with growth hormone
for seven days. They studied blood samples from the
mice and compared the results to six control
animals. Kopchick and Ding scanned hundreds of
plasma proteins and found four—apoA1, transthyretin,
clusterin and albumin—that showed a strong reaction
to growth hormone.
“They’re in the blood, but we don’t know if they’re
coming from liver, fat, muscle or the kidneys,” said
Kopchick, Goll-Ohio Professor of Molecular Biology
with Ohio University’s Edison Biotechnology
Institute and Heritage College of Osteopathic Medicine.
Kopchick and Ding, a graduate student in biological
sciences, are hopeful that the proteins could be
viable biomarkers for growth hormone activity in
humans as well.
“In mice we can control the variables and the
environment, but humans are genetically diverse and
have different lifestyles that impact growth
hormone. So the results may point to future study in
humans, but may not necessarily apply to humans
yet,” said Ding, who also is studying how to
identify protein biomarkers for human aging.
Growth hormone is hard to detect because it has a
serum half life of only 15 minutes. RhGH, an
approved drug for individuals with growth hormone
deficiency, also is identical to human growth
hormone. The current method of detecting growth
hormone, analyzing levels of insulin-like growth
factor (IGF-1), isn’t always accurate, the
researchers said, as it is age and gender sensitive.
“If you have an 18-year-old Olympic athlete and a
38-year-old athlete, the IGF-1 values may look very
different,” said Kopchick, whose research is funded
by the National Institutes of Health, World
Anti-Doping Agency, Ohio Eminent Scholars program
and Ohio University’s Edison Biotechnology
Institute.
Because identification of rhGH misuse or abuse has
high stakes – it can make or break an athletic
career – the current method has too many variables
to depend on, he said.
It’s still early to tell whether these protein
markers have the same age limitations, as the mice
in the study live to only 2 years. But the markers
may have longer half lives of several days, which
would offer a wider testing window, he said.
Kopchick already is exploring how to detect rhGH in
human blood and tissues through a project with
Danish scientist J.O. Jorgensen. The team received a
three-year grant from the World Anti-Doping Agency
to look for protein markers in blood and tissues of
human subjects exposed to rhGH or exercise, as well
as patients with growth hormone disorders.
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