September 12, 2011

Lack of Dopamine can lead to Parkinson’s

(Ivanhoe Newswire) — Dopamine is more than just for pleasure!  The lack of the brain chemical dopamine can rewire the interaction between two groups of brain cells and lead to symptoms of Parkinson´s disease.

The discovery, made by Anatol Kreitzer, PhD, a scientist at Gladstone Institute, identified how the loss of dopamine alters the wiring of a small group of brain cells, kicking off a chain of events that eventually leads to difficulties controlling movement–a hallmark of Parkinson´s disease.
More than a half-million people suffer from Parkinson´s in the United States, including the boxer Muhammad Ali and the actor Michael J. Fox.

“The development of truly effective and well-tolerated therapies for Parkinson´s has proved difficult,” Lennart Mucke, MD, director of neurological disease research at the Gladstone Institute and professor of neurology and neuroscience at the University of California,  San Francisco,  a Gladstone affiliate, was quoted as saying.  Dr. Mucke also added that he hopes the new discovery will lead to the development of more effect medicines.

To better understand Parkinson´s and the relationship between dopamine and medium spiny neurons, also known as MSNs that work together to coordinate body movement, , Dr. Kreitzer artificially removed dopamine from the brains of laboratory mice in which the mice began to experience motor symptoms of the disease, including tremors, problems with balance and slowed movement.

Not only did the decrease dopamine levels throw off the balance between the two types of MSNs, but they also changed the interaction between MSNs and another group of neurons called fast-spiking neurons, or FSNs.

Dr.Kreitzer´s experiments showed that under normal circumstances, FSNs connect to both types of MSNs in a similar way; however, without dopamine, the signaling between the FSN circuits gets rewired and the neurons begin to target one type of MSN over the other.

“Our research has uncovered how an entirely different group of neurons can play a role in the development of Parkinson´s disease symptoms,” Dr. Kreitzer, who is also an assistant professor of physiology and neurology at UCSF was quoted saying.  “We hope to target the changes among these neurons directly with drug therapies, in order to help relieve some of Parkinson´s most debilitating symptoms.”

SOURCE: Neuron, published online September 2011