Johns Hopkins scientists report success in
significantly suppressing levels of the "hunger
hormone" ghrelin in pigs using a minimally invasive means
of chemically vaporizing the main vessel
carrying blood to the top section, or fundus, of the
stomach. An estimated 90 percent of the body's
ghrelin originates in the fundus, which can't make the
hormone without a good blood supply.
"With gastric artery chemical embolization, called
GACE, there's no major surgery," said
Aravind Arepally, clinical director of the Center for
Bioengineering Innovation and Design and
associate professor of
radiology and
surgery at the School of Medicine. "In our study in
pigs, this
procedure produced an effect similar to bariatric surgery
by suppressing ghrelin levels and
subsequently lowering appetite."
Reporting on the research in the Sept. 16 online
edition of Radiology, Arepally and his team note
that for more than a decade efforts to safely and easily
suppress ghrelin have met with very limited
success.
Bariatric surgery — involving the removal,
reconstruction or bypass of part of the stomach or
bowel — is effective in suppressing appetite and
leading to significant weight loss, but it carries
substantial surgical risks and complications. "Obesity is
the biggest biomedical problem in the country,
and a minimally invasive alternative would make an enormous
difference in choices and outcomes for
obese people," Arepally said.
Arepally and colleagues conducted their study over the
course of four weeks using 10 healthy
growing pigs; after an overnight fast, the animals were
weighed and blood samples were taken to
measure baseline ghrelin levels. Pigs were the best option,
he said, because of their humanlike anatomy
and physiology.
Using X-ray for guidance, members of the research team
threaded a thin tube up through a
large blood vessel near the pigs' groins and then into the
gastric arteries supplying blood to the
stomachs. There, they administered one-time injections of
saline in the left gastric arteries of five
control pigs and, in the other five, one-time injections of
sodium morrhuate, a chemical that destroys
the blood vessels.
The team then sampled the pigs' blood for one month to
monitor ghrelin values. The levels of
the hormone in GACE-treated pigs were suppressed up to 60
percent from baseline.
"Appetite is complicated because it involves both the
mind and body," Arepally said. "Ghrelin
fluctuates throughout the day, responding to all kinds of
emotional and physiological scenarios. But
even if the brain says, 'Produce more ghrelin,' GACE
physically prevents the stomach from making the
hunger hormone."
The research was funded by the National Institutes of
Health.
Authors on the paper are Brad P. Barnett, Tarek T.
Patel, Valerie Howland, Racy C. Boston, Dara
L. Kraitchman, Ashkan A. Malayeri and Arepally, all of
Johns Hopkins.
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