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"Investigators
also found relationships between plasma leptin levels, high-density lipoprotein
(HDL) cholesterol and the cholesterol saturation index. "
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Lipodystrophy And Leptin
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Investigators
have studied the actions and effects of the fat cell secreted hormone leptin
on obesity reduction and most recently on lipodystrophy. We know that people
with lipodystrophy have high levels of lipids in their blood and store
body fat in inappropriate places. Researchers at the National Institute
of Diabetes and Digestive and Kidney Diseases (NIDDK) and the University
of Texas Southwestern Medical Center report that people with lipodystrophy
are deficient in leptin, which is produced by and stored in fat cells.
(1,
2) Along with very low levels of leptin, people with lipodystrophy
have high levels of triglycerides, insulin resistance, and fatty liver.
Leptin may reduce insulin resistance and prevent redistribution of body
fat in the wrong places. (1)
It acts in the hypothalamus to inhibit appetite, reduce adiposity, and
promote weight loss and may be involved in the increased risk of cardiovascular
disease. (3, 4, 5) Matarese
and colleagues note leptin also affects thymocyte survival, proliferation
of naive T lymphocytes and the production of proinflammatory cytokines.
(6) Additionally, leptin
is associated with bone loss in females who starve themselves. (7)
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A number of investigators
have associated leptin levels with body fat. (1,
3, 8, 9)
Mark and colleagues suggest that evidence derived from studies of obese
mice with selective leptin resistance may have implications for human obesity.(4)
Increased plasma leptin levels in obese people with low energy expenditure
decrease along with body mass index after weight loss. (3)
Investigators also found relationships between plasma leptin levels, high-density
lipoprotein (HDL) cholesterol and the cholesterol saturation index.
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Study results suggest
that leptin deficiency may explain the insulin resistance in people with
lipodystrophy.
(1) A recent
four-month study of nine women with lipodystrophy showed that leptin can
reverse lipodystrophy in some diabetic patients.
(1,
2) Improvements to lipodystrophy-related metabolic abnormalities
were apparent with four months of leptin therapy as all of the women had
lower triglyceride levels, improved control of blood sugar, and smaller
livers. They ate less food and all but one patient lost weight. The eight
patients with diabetes were able to decrease or discontinue their diabetes
therapy with leptin treatment and all of the patients continue to receive
leptin-replacement therapy. Leptin treatment has also reversed
hepatic steatosis in three patients with severe lipodystrophy. Although
the participants in these studies were presumably HIV-negative, study results
are encouraging for people living with HIV/AIDS on highly active antiretroviral
therapy (HAART).
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