Posted on December 27, 2018
Parkinson’s disease researchers are studying how a natural compound found in some plants protects dopaminergic neurons.
In trials performed on mice, researchers found that the compound, arbutin, which is found in plants such as bearberry leaves and pear trees, helped to prevent damage to these cells, as well as lessen the behavioral deficits and oxidative stress of Parkinson’s disease.
Parkinson’s disease is a progressive, neurodegenerative condition that affects more than 10 million people worldwide. In the United States, 1 million people are living with the condition, with 60,000 new cases diagnosed each year, according to statistics from the Parkinson’s Foundation.
The average age of onset for Parkinson’s disease is 60, although some people are diagnosed as young as 40.
Parkinson’s disease causes the decline and death of dopaminergic neurons. The death and damage to dopaminergic neurons causes neurological effects, including tremors, amnesia, muscle stiffness and rigidity, loss of balance, and difficulty moving.
There is some evidence that Parkinson’s disease also caused mild cognitive impairment. Some individuals living with the condition also experience urinary and digestive problems.
The molecular triggers that cause dopaminergic neurons to become damaged or die are unknown. One theory is that oxidative stress plays a role in how the disease progresses.
Increasing evidence shows that oxidative stress is an important factor that contributes to disease progression.
Oxidative stress is a situation created in cells when there is an imbalance of free radicals and the body’s ability to neutralize the effects of these free radicals with antioxidants.
When free radicals reign in cells, they can cause damage to vital cell molecules, including DNA. They can also affect cell proteins that transmit information between and inside cells, which can negatively affect cell function and survival.
“There is no cure for Parkinson’s disease,” said Dr. Joel Singer, a New York physician.
Conventional treatments for the condition include anti-tremor treatments and antidepressants, but these medications can cause unwanted and uncomfortable side effects. Thus, the desire to identify potential new treatments for the condition is critical.
“Some patients have seen a reduction in the side effects of Parkinson’s disease with regenerative medical treatments,” Singer said.
In the arbutin study, the effects of the compound were observed in laboratory mice. Researchers divided the mice into three groups: a control group that received a harmless saline injection; a second group that received an injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, or MPTP, a compound that induces Parkinson’s symptoms similar to those observed in human patients; and a third group that received an arbutin injection before being injected with MPTP.
On the 14th day of the study, the researchers assessed the behavioral changes of the mice to analyze locomotion, or the ability to move from one place to another, as well as forepaw stride length. The blood and brain tissue of the mice were also analyzed. They also examined the animals’ blood and brain tissue.
The mice in the arbutin-treated group showed improvements in their locomotion and great forepaw step distance compared to the control (saline and MPTP) groups.
The arbutin-treated group also saw lower levels of free radicals associated with oxidative stress, including nitric oxide, a gas known to cause the death of dopaminergic neurons. Another indicator of oxidative stress, thiobarbituric acid reactive substance (TBARS), was also reduced in the arbutin-treated animals.
The researchers believe these findings support the potential for arbutin to help reduce the effects of oxidative stress and the stress of free radicals on dopaminergic neurons. They are also working to identify how this protection happens through molecular mechanisms inside the cell.
Parkinson’s News Today. Plant Compound, Arbutin, Eases Some Symptoms in Parkinson’s Mouse Model, Study Shows. 29 November 2018.