A study conducted with a rat model of Parkinson's disease showed that an anti-inflammatory drug, when injected subcutaneously, or under the skin, could decrease motor impairments and protect neurons from neurodegeneration.

Previous studies with the same drug in animal models used direct injections into the brain, but this study found that the drug had a beneficial effect when administered under the skin.

The drug, XPro1595, was tested at Emory University School of Medicine. By directly affecting inflammation, XPro1595 address what previous, compelling research suggested was the main cause of progression of Parkinson's disease. Tumor necrosis factor (TNF) is a chemical involved in the inflammatory process, and is the main target of XPro1595, which is designed to specifically distinguish the soluble form of TNF. Since this drug is so specific, the risk of hindering the body's immunity to potential infections, a risk that comes with other anti-TNF drugs, is not a problem.

The researchers induced Parkinson's in rats with an injection that reproduces certain symptoms of the disease. Dopaminergic neurons (neurons that produce the chemical dopamine) died as a result, impairing movement.

Three days later, the researchers administered XPro1595. Five weeks later, they found that only 15 percent of the dopaminergic neurons died. They also found that the more dopamine neurons died, the worse the degree of motor impairment.

When they administered the drug two weeks after inducing Parkinson's, 44 percent of the neurons died, suggesting that the drug needs to be administered early after symptoms arise.

"Recent clinical studies indicate there is a four or five year window between diagnosis of Parkinson's disease and the time when the maximum number of vulnerable neurons are lost," says Dr. Malu Tansey, associate professor of physiology at Emory. "If this is true, and if inflammation is playing a key role during this window, then we might be able to slow or halt the progression of Parkinson's with a treatment like XPro1595."

The study was published in the Journal of Parkinson's Disease.

Parkinson's disease affects movement via the nervous system. Onset is gradual, and often begins with a slight hand tremor, but can also cause stiffness or slow movement. Symptoms of the disease worsen with time -- speech becomes slurred and facial expressions are difficult to form. While there is no cure for the disease, there are medications to alleviate symptoms, as well as brain surgeries. XPro1595 will be tested in clinical trials to gauge the efficacy in human-based Parkinson's and, if successful, will be able to slow the worsening of symptoms and substantially increase quality of life.