Contacts: Karen
McNulty Walsh, (631) 344-8350 or Peter
Genzer, (631) 344-3174
The following news release was issued by the Society
of Nuclear Medicine (SNM) regarding a talk given at their 58th
annual meeting by Brookhaven Lab researcher Gene-Jack Wang. Society
of Nuclear Medicine media contact: Susan Martonik, smartonik@snm.org,
703-652-6773.
Molecular Imaging Finds Link Between Obesity
and Low Estrogen Levels
San Antonio, Texas (June 6, 2011) — A new study presented
at SNM’s 58th Annual Meeting could throw open the door to a
recently established area of obesity research. Investigators have
developed a novel molecular imaging agent that targets estrogenic
mechanisms in the brain to find out what effect an enzyme called
aromatase has on body mass index (BMI), a measurement of body fat
based on height and weight. Aromatase is crucial for the production
of estrogen in tissues throughout the body, including the
brain.
According to the World Health Organization, worldwide obesity
has more than doubled since 1980. As of 2008, an estimated 1.5
billion adults were overweight, and in 2010 nearly 43 million
children under the age of five were overweight.
“We used this imaging agent to evaluate the amount of aromatase
activity in the brain regions related to eating behaviors, such as
the hypothalamus and amygdala, in both overweight and normal weight
subjects. We were really surprised to see the highest correlation
between aromatase availability and BMI happening in the amygdala,
which controls emotional memory,” says Gene-Jack Wang, MD, senior
scientist and chair of the medical department at Brookhaven
National Laboratory, Upton, N.Y. “Our eating is not only controlled
by the hunger centers in the brain. It is also related to memory,
and that could have a big impact on a person’s eating behavior.
This agent could potentially translate into a number of new studies
evaluating estrogen and obesity, food intake and appetite
suppression.”
For this study, five healthy overweight subjects and 13
normal-weight subjects of the same age were chosen to undergo
positron emission tomography, a molecular imaging technique that
provides digital representations of physiological functions of the
body. Subjects were injected before imaging with the novel imaging
agent (C-11)vorozole, which is composed of a medical isotope bound
with an aromatase inhibitor that binds strongly with the active
sites of the enzyme in the brain. This allowed investigators to
track and quantify the availability of this enzyme to selected
areas of the brain associated with hunger and feeding behavior.
A significant correlation was found between high BMI of subjects
and decreased uptake of the aromatase inhibitor. Imaging agent
uptake was decreased in the hypothalamus (25 percent less),
thalamus (27 percent less) and amygdala (30 percent less) in
subjects with high BMI. This means that there was less availability
of the enzyme in these selected brain regions. There was also a
strong inverse correlation between low BMI and imaging agent uptake
in the amygdala, meaning BMI was less in subjects showing higher
aromatase availability. These findings suggest that there is
decreased availability of aromatase in the brains of overweight
subjects, conceivably leading to reduced availability of estrogen
and potentially less control over appetite and food intake,
resulting in weight gain; however, further studies need to be
conducted to validate the relationship between estrogen synthesis
and high BMI.
Future studies could be introduced to screen eating behaviors of
obese subjects in order to further validate the correlation between
BMI and estrogen availability in the brain. Based on the current
research, theoretically the less estrogen available to the brain,
the less control patients may have over their appetite. Studies
moderating estrogen and feeding behavior could result in novel
drugs for appetite suppression and perhaps even reduction of BMI.
This is just the first step toward discovering the mechanisms
behind appetite, BMI and estrogen availability.
Scientific Paper 340: G. Wang, A. Biegon, F. Telang, J. Logan,
S. Won Kim, M. Jayne, N. Volkow, J. Fowler, Brookhaven National
Laboratory, Upton, N.Y.; National Institute on Alcohol Abuse and
Alcoholism, Bethesda, MD; “Decreased brain aromatase availability
in overweight humans,” SNM’s 58th Annual Meeting, June 4-8, 2011,
San Antonio, TX.
Number: 11-1291 | BNL Media &
Communications Office
