Researchers have shown in experiments with mice that blocking calcium channels in adult dopaminergic neurons coaxes them back into a more juvenile state, thereby protecting them against the progression of Parkinson's disease.

Loss of dopaminergic neurons (nerve cells), which are the major source of dopamine in the central nervous system, is a prominent feature of Parkinson's disease.

Calcium channel blockers are drugs that prevent calcium from entering the muscle cells of the heart and the arteries. If calcium gets into these cells, the heart will contract and the arteries will narrow. By blocking the entry of calcium, decreases contraction of the heart and widens the arteries.

These findings point to a potential new therapeutic strategy to slow or halt the progression of Parkinson's disease, according to the team's report in the journal Nature published online.

"We made three key observations," Dr. D. James Surmeier of Northwestern University, Chicago, told Reuters Health. The first observation, he explained, was that dopaminergic neurons that die in Parkinson's disease change in a way as they age that makes them more vulnerable to toxins and stress.

"Specifically, we found that these neurons increase their reliance upon calcium channels to drive their...activity. Calcium ions are essential for normal cellular function, but in excess can kill," Surmeier explained.

The second observation was that blocking these calcium channels in adult dopaminergic neurons causes them to revert to a juvenile form...that does not rely upon calcium. "After this 'rejuvenation', neurons became much more resistant to toxins and stress," Surmeier told Reuters Health.

The third observation was that the blockade of these calcium channels and the rejuvenation could be accomplished with the calcium entry blocker, dihydropyridine isradipine, which has been used for decades to treat high blood pressure.

In essence, Surmeier said, "we have identified a drug that you could take with your coffee in the morning that might slow or stop the progression of Parkinson's disease."

Data from a recent study of patients with high blood pressure provides further evidence that dihydropyridine isradipine treatment may lower the incidence of Parkinson's disease by 30 percent to 50 percent, the authors note in their report.

"Because isradipine is approved for human use, the path between where we are now and clinical practice is potentially very short," Surmeier said. The next step is a phase III clinical trial to determine whether isradipine slows the progression of the disease in humans. A proposal to conduct this trial will be submitted this fall, Surmeier said.