In 1922, a teenager with diabetes Toronto became the first person to be rescued by an insulin treatment, and since then, the injections have suffered millions of diabetics who do not do their own hormone. But there are alternatives to a lifetime of insulin therapy? A new study suggests that an anorectic hormone called leptin is just as effective as insulin to control diabetes in mice.
The discovery of insulin diabetes type 1 transformed from a fatal to a chronic disease. In this type of diabetes, the body destroys the insulin-producing cells in the pancreas, which leads to high levels of glucose in the blood. (The most common form of type 2 diabetes occurs when the body does not respond properly to its own insulin.) But the insulin treatment is not perfect. Get the insulin dose is just hard, and despite all their efforts to manage their disease, many people with diabetes suffer from serious complications, including kidney failure, blindness and limb amputation.
Diabetes researchers are considering various replacements for insulin injections: Transplanting new pancreatic islet cells that make insulin, cuddly patient's own islets to regenerate or treating diabetics early in the disease with immunosuppressive therapies to prevent their bodies to destroy the rest of their pancreatic islets. Some studies have also examined leptin; such as insulin, the hormone helps the body lower glucose levels. Last year, researchers reported that mice with a form of diabetes recovered after receiving leptin gene therapy directly into the brain.
diabetes researcher Roger Unger of the University of Texas Southwestern Medical Center at Dallas became interested in leptin by chance. He was performing transplants of islets in diabetic rodents and found that treatment of animals with leptin helped make the transplants more effective. Unger and his colleagues then tried to give leptin solo and glucose levels in the blood of animals returned to normal, as if they had obtained new islets. "We do not believe at first," he said.
To study the effect in more detail, the Unger group took 15 diabetic mice and implanted a pump near their shoulder blades that bring high levels leptin for 12 days. They compared these animals with those treated only with insulin pumps. glucose levels returned to normal in both groups, the researchers report online today in the Acts the national Academy of sciences .
Unger and his colleagues found that leptin curbs production glucagon, a hormone that is essentially the opposite of insulin. glucagon stimulates the liver to . glucose release into the blood removing glucagon with leptin had the same effect on mice that produce insulin. it reduced glucose levels in the blood
"he is insulin substitution, "agrees Satya Kalra, a neuroscientist at the University of Florida in Gainesville who did the work of gene therapy earlier with leptin. "In type 1 diabetes, if you have more leptin, it should help." Unger believes that leptin actually has advantages over insulin, since it appears to reduce sugar fluctuations in the blood that people with diabetes struggle with.
The efficacy of leptin to combat diabetes in these animals may have been due to heavy doses given, says Laura McCabe, a physiologist at Michigan State University in East Lansing. In a study published last year with one of his graduate students, Katherine Motyl, it tests whether leptin could help ward off mice bone loss that can accompany diabetes type 1. It did not. But they found that much lower doses than those used Unger causing glucose levels to drop, but not back to normal. Unger, however, said he has had success with lower doses, too.
McCabe and Kalra agree that leptin, which was used as a treatment for certain rare metabolic diseases, would probably not have serious side effects, although weight loss is a concern: Leptin dampens significantly appetite, and mouse Unger ate 50% less than normal. (In the long run, Unger said, the mice leptin are lighter than those who receive insulin, but they have more lean body mass and less body fat.) It is also unclear whether leptin has immune effects. Unger's team and some colleagues are now preparing to test a combination of leptin and insulin in a clinical trial to determine if people with diabetes do as well as his mouse.
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