Leptin, a hormone considered critical in body weight regulation and obesity, also might play a role in diabetic eye disease, a study by Yale researchers shows.
Leptin is known to exist in fatty tissue, in the placenta, ovaries, mammary glands, gastric mucosa, and in the liver, as well as other tissues. The Yale study of 73 patients with and without severe diabetic eye disease also found leptin in the eye tissue of patients with diabetic retinopathy.
"We measured the amount of leptin inside the vitreous humor and found leptin was highly elevated in patients with advanced eye disease compared with patients who don't have the disease," said Ray Gariano, M.D., assistant professor of ophthalmology at Yale School of Medicine. His study was published in the journal Investigative Ophthalmology & Visual Science.
A co-author of the study, Maria Rocio Sierra-Honigmann, M.D., formerly an associate research scientist in the pathology department at Yale, discovered a few years ago that leptin causes blood vessels to grow.
"We hypothesized that perhaps leptin is involved in diabetic eye disease since abnormal blood vessel growth occurs in more advanced stages of diabetic eye disease," said Gariano. "Our results support that proposition."
The research group found that leptin was highest in the group of patients with proliferative retinopathy; intermediate in the group with primary or recurrent retinal detachment, and lowest in the group with mild diabetic retinopathy or a variety of non-diabetic eye diseases.
Gariano said it is not yet clear how this finding could be used to minimize severe eye disease in diabetics since there are currently no drugs that inhibit leptin or block its actions.
Leptin regulates body weight, promotes satiety, decreases appetite, decreases the degree to which the body synthesizes fat and increases the body's ability to burn fat. Like diabetics who have a surplus of insulin that their bodies fail to secrete properly, some people who are overweight or obese may have a surplus of leptin that is not functional in regulating body weight.
"Finding a drug to inhibit leptin is a major challenge in obesity research," Gariano said. "But there are some other techniques being tried to inhibit or antagonize leptin's actions, which could be therapeutically beneficial for the eye."
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