Drug discovery for depression promising

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SAN ANTONIO, July 9 (UPI) -- In a study using mice, U.S. researchers found a hormone with anti-diabetic properties also reduces depression-like symptoms.

Senior author Xin-Yun Lu of the Barshop Institute for Longevity and Aging Studies at the University of Texas Health Science Center San Antonio said all types of current antidepressants, including tricyclics and selective serotonin re-uptake inhibitors, increase the risk for type 2 diabetes.

The hormone adiponectin is secreted by fat tissue and sensitizes the body to the action of insulin, the hormone that lowers blood sugar.

"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," Lu said in a statement.

The mice were exposed to 14 days of repeated social defeat stress -- each male mouse was introduced to the home cage of an unfamiliar, aggressive resident mouse for 10 minutes and was physically defeated.

After the defeat, the resident mouse and the intruder mouse each were housed in half of the cage separated by a perforated plastic divider to allow visual, olfactory and auditory contact for the remainder of the 24-hour period. Mice were exposed to a new resident mouse cage and subjected to social defeat each day. Plasma adiponectin concentrations were determined after the last social defeat session.

The study found the defeated mice displayed lower plasma adiponectin levels, Lu said.

"Adiponectin, with its anti-diabetic activity, would serve as an innovative therapeutic target for depression treatments, especially for those individuals with diabetes or pre-diabetes and perhaps those who fail to respond to currently available antidepressants," Lu said.

The findings were published in this week's Proceedings of the National Academy of Sciences.