Tweaking Mouse Genes May Help Opiate Dependency

Researchers at the University of California at San Francisco say that have been able to prevent mice from becoming dependent on morphine by altering a trait on the surface of neurons.

Acting on a hunch that dependence is caused by the failure of receptors for endorphins -- the body's natural painkillers -- to withdraw from the surface of neurons, the researchers bred mice with the ability to withdraw their receptors -- a process called endocytosis -- in the resence of morphine. They found that these mice enjoyed the painkilling benefits of morphine but did not become dependent upon the drug.

"As more pain medications are being removed from the market, new strategies to overcome chronic pain become crucial," said lead researcher Jennifer Whistler, Ph.D. "If new opiate drugs can be developed with morphine's pain killing properties but also with the ability to promote endocytosis, they could be less likely to cause the serious side effects of tolerance and dependence."

The study was published in the Jan. 17, 2008 issue of the journal Current Biology.