A hormone known for its anti-diabetic properties can also lower depression-like symptoms, a new study says.

Studies conducted on mice models demonstrated that adiponectin, a hormone that sensitizes the body to the action of insulin, can help reduce stress that occurs as a result of social defeat.

Previous studies have shown that higher levels of adiponectin result in lower risk of type 2 diabetes and lower heart disease risk. According to researchers using this hormone to treat depression would be beneficial for people who have diabetes.

"The finding offers a novel target for treating depression, and would be especially beneficial for those depressed individuals who have type 2 diabetes or who are at high risk for developing it," said, Xin-Yun Lu, PhD, associate professor of pharmacology and psychiatry at University of Texas Health Science Center at San Antonio and the study's senior author.

For the study, researchers introduced a large aggressive male mouse and kept it with each of the study mice for 10 minutes per day for 14 days. During this exposure time, the smaller mice were socially defeated. After each session, both sets of mice, the aggressive mouse and the defeated mice, were kept in cages that had a perforated plastic divider. Each defeated mouse stayed with social defeat stress continuously for the next 14 days.

Adiponectin levels were checked at regular intervals. Defeated mice had lower adiponectin levels than mice that were victiorious.

"We showed that adiponectin levels in plasma are reduced in a chronic social defeat stress model of depression, which correlates with the degree of social aversion," Dr. Lu said.

Mice that were genetically altered to stop producing the hormone displayed more helplessness when socially defeated.

"These findings suggest a critical role of adiponectin in the development of depressive-like behaviors and may lead to an innovative therapeutic approach to fight depression," Dr. Lu said.

The researchers even induced obesity and diabetes in the mice by keeping them on a high fat diet. The hormone, when administered worked effectively in keeping them from being stressed due to social defeat.

Currently available anti-depressants increase risk of type 2 diabetes. Researchers say that using this hormone could lower stress without increasing diabetes risk.

"The prevalence of depression in the diabetic population is two to three times higher than in the non-diabetic population. Unfortunately, the use of current antidepressants can worsen the control of diabetic patients. Adiponectin, with its anti-diabetic activity, would serve as an innovative therapeutic target for depression treatments, especially for those individuals with diabetes or prediabetes and perhaps those who fail to respond to currently available antidepressants," Dr. Lu said.

The study was published in the Proceedings of the National Academy of Sciences.

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