NEW YORK – A bee-derived supplement known to have anti-inflammatory properties showed promise in potentiating the effect of levodopa in a rodent model of Parkinson’s disease, with biochemical and behavioral improvements seen that exceeded high-dose levodopa alone.
Levodopa (L-dopa) has long been a keystone in treatment for individuals with Parkinson’s disease (PD). However, its effectiveness wanes with time and long-term use is associated with significant undesirable side effects, including dyskinesias.
A dopamine precursor, L-dopa, once converted to dopamine, replaces the dopamine no longer made by the substantia nigra. Increasingly, neuroinflammation and oxidative stress are felt to play a role in the natural history of PD, said Azza Ali, PhD, who presented the findings at a poster session of the International Conference on Parkinson’s Disease and Movement Disorders. Whether mitigating these effects can alter the disease course for individuals with PD has not been well investigated, she added.
Dr. Ali and her research group at Al-Azhar University, Cairo, Egypt, where she heads the department of pharmacology and toxicology, are investigating several nutritional and supplement strategies to dampen inflammation. Among the substances she and her colleagues are investigating is propolis, a plant-derived product produced by bees and distinct from honey or beeswax.
Propolis has been shown to have antioxidant properties in addition to other reported health benefits.
Dr. Ali and her colleagues used a rodent model for PD: Rats were dosed with rotenone, which is known to induce a histologically verifiable parkinsonian syndrome. The investigators used six groups of rats; one group was the normal control, while the others all had rotenone-induced parkinsonism.
Of the remaining groups, one rotenone-dosed group was given neither L-dopa nor propolis. Two groups were treated with oral L-dopa alone, at 10 or 25 mg/kg per day. Another group was given an oral dose of 300 mg/kg per day of propolis, and the last group received propolis at that dose while also receiving the lower dose of L-dopa.
All groups were subject to behavioral assessments including a swim test, an open field test, a maze test, and other tasks designed to assess motor function and other aspects of behavior. Additionally, Dr. Ali and her collaborators assessed a variety of biochemical parameters that looked at oxidative stress and neuroinflammation in all rodent groups.
For most parameters, the rotenone-dosed rats that showed results most like normal controls were those who received both low-dose L-dopa and propolis. In particular, the rats receiving both L-dopa and propolis outperformed the other rotenone groups in the behavioral open field test and a grid test, where their performance neared the control group.
Levels of interleukin-1 beta fell for all treated rodents, but fell the most for those treated with the combination. Tissue dopamine levels were also lower for the rats who received combination treatment, and acetylcholinesterase and malondialdehyde levels also fell to near normal for rats receiving the combination treatment, but not for the other groups.
“Propolis is efficient in protection from PD development and represents a suitable adjuvant therapy, which can be translated to serious reduction of the long-term therapy side effects of the mainstay drug L-dopa,” wrote Dr. Ali and her coauthors. “Consequently, propolis could be recommended as a disease-modifying therapy of PD as well as a promising adjunct therapy with L-dopa especially when given early in the treatment course.”