Leptin May Prevent Type 2 Diabetes
September 28, 2006 -- The appetite-controlling hormone leptin may offer new hope in battling the growing problem of type 2 diabetes in the US, according to a recent report. In animal studies, researchers were able to reverse type 2 diabetes in mice, using gene therapy.
The researchers demonstrated that, in diabetic mice, leptin in the hypothalamus maintains low insulin levels even with a constant high-fat diet. Such a diet over time often leads to or compounds symptoms of type 2 diabetes.
"We found that we were successful in keeping the blood levels of insulin low at the same time keeping blood glucose levels at a normal range," said Satya Kalra, PhD, a University of Florida professor of neuroscience and senior author. "In other words, we were able to correct diabetes in these animals under various challenges."
The researchers are hopeful that further testing will enable them more easily to treat people with type 2 diabetes.
Diabetes affects over 18 million people in the US, and 90% of these have type 2 diabetes (also called adult-onset diabetes), according to the Centers for Disease Control and Prevention. Type 2 diabetes is known to be caused in large part by overweight, overeating and lack of exercise.
If left untreated, type 2 diabetes can also cause cardiovascular disease, kidney disease and blindness.
Dr Kalra and colleagues injected a gene into the mice’s brains that increases leptin production in the hypothalamus.
Previous studies have confirmed leptin in the brain regulate appetite and weight, but this is the first time leptin has been shown independently to affect insulin secretion.
People who have type 2 diabetes can become resistant to their own insulin, which then builds up in the body. Gene therapy in this study resulted in blood sugar and insulin levels in mice return to normal levels – even when the mice ate a high-fat diet. In contrast, mice on a high-fat diet that received no gene therapy continued to have high insulin and blood sugar levels – markers for diabetes, according to Dr Kalra.
The study also showed that non-diabetic rats receiving leptin gene therapy produced less insulin.
"This was totally unexpected," said Dr Kalra. "Until now there was no evidence that leptin action in the hypothalamus had control on insulin secretion. [With leptin gene therapy] we can reimpose that control."
According to Dr Kalra, gene therapy would be an ideal treatment for diabetes because it can be administered in just one shot. Moreover, Dr Kalra believes drugs might be developed in a pill form that simulate leptin’s action and is easier to administer.
"What we have shown in animals is very effective," Kalra said. "It can be done.”
Leptin Could Combat Type 2 Diabetes, EMaxHealth, September 20, 2006.
Leptin transgene expression in the hypothalamus enforces euglycemia in diabetic, insulin-deficient nonobese Akita mice and leptin-deficient obese ob/ob mice. N Uenoc, et al. Peptides (online version), September 2006.
Posted: September 2006