A stomach hormone could be key to developing new medication for Parkinson’s disease, according to an article published by Yale researchers in the Nov. 11 issue of the Journal of Neuroscience.

The two-year study focused on the hormone ghrelin, which is produced by the stomachs of humans and other animals, Yale School of Medicine researcher Tamas Horvath said.

The death of brain nerve cells that produce the chemical dopamine causes the symptoms of Parkinson’s disease, which include shaking and impaired mobility, Horvath said. Mice deprived of ghrelin in the study lost dopamine-producing nerve cells more quickly than other mice.

“Essentially, by giving a chemical toxin that reduces ghrelin, we saw the same effects experienced by Parkinson’s patients,” Carleton University professor Alfonso Abizaid, who was a post-doctorate researcher at Yale during the study, said. Humans should have the same response to a lack of ghrelin, he added.

People with healthy lifestyles and high metabolisms typically produce more ghrelin — which signals hunger in the stomach — than other people, Abizaid said. This makes sense, Abizaid said, given that obese people are more likely to develop Parkinson’s disease.

“We do know that being overweight can make you vulnerable,” Abizaid said. “If we want long-term changes, we have to address certain social problems.”

Patients with Parkinson’s disease have already lost a significant number of dopamine nerve cells, Abizaid said. Because brain cells do not regenerate, the three main goals of Parkinson’s disease research are to slow down the progress of the disease, to find a way to replace dead nerve cells with stem cells and to discover the cause of the disease.

Abizaid said the causes behind most cases of Parkinson’s disease remain unknown.

“Over 99 percent of the cases — we have no idea what causes it,” Horvath said. “It is a shot in a dark.”

Currently, pharmaceutical companies are experimenting with compounds similar to ghrelin, Horvath said. The next step, Horvath said, is to determine the amount of ghrelin in people with Parkinson’s disease as compared to healthy people. With further research, these compounds could be adapted and sold as medicine, he said.

“Usually, there is a huge gap between academic research and clinical applicability,” Horvath said. “After reports come out, I get e-mails from patients saying that they get no benefit from all this wonderful research. Now, there is pressure for researchers to present more applicable results.”

The Michael J. Fox Foundation for Parkinson’s Research funded the study.