Researchers in
Florida University have successfully used gene therapy to control weight
gain and appetite in animal models. Though human studies are far away, still
there is some hope that some day a single injection may be a
viable option for treating obesity.
Scientists
injected mice and rats with genes that increased the production of two
appetite-controlling compounds already existing in the body-leptin
and ciliary neurotrophic factor, or CNTF.
Leptin is a
protein produced by fat cells that inhibits appetite and
increases energy expenditure. It
signals the brain, affecting its secretion of appetite-regulating
signals. Such signals
include neuropeptide Y, a chemical that researchers found stimulates
appetite. This process is thought to be faulty in most obese
people so that even high levels of leptin fail to turn off the hunger
signal. The concept is that if you can turn off the production of
neuropeptide Y and other appetite-stimulating signals by increasing
leptin levels, it is possible to control body weight.
Researchers
injected leptin-producing genes into obese mice that did not produce
the protein. Once inside the mice, the
genes integrated into their cells and acted like small factories,
producing increased levels of leptin. The result was weight loss in
less than three weeks. Normal, lean rats given the leptin genes
maintained their body weight for three months, the duration of the
experiment.
Research team also experimented with an alternative
appetite-suppressing protein, CNTF. After six weeks, researchers
observed a decrease in body weight similar to that in the mice treated
with the leptin gene.
Clinical
studies of CNTF and leptin gene therapy in humans will not be approved
until researchers can prove that these gene treatments are safe.


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