Environmental toxins called proteasome inhibitors cause a Parkinson’s disease-like movement disorder in rats, according to new research. The findings suggest that these natural toxins may contribute to the development of Parkinson’s in humans. Proteasome inhibitors are produced by bacteria and fungi. Humanmade proteasome inhibitors also find their way into the environment.
“These results suggest that we should determine how widespread these toxins are in the environment, how humans are exposed to them, and how such exposures correlate with the incidence of Parkinson’s disease,” study lead author Kevin St. P. McNaught, of Mount Sinai School of Medicine in New York , said in a prepared statement.
The study appears in the online edition of the Journal Annals of Neurology. In humans and other animals, proteasomes act like a garbage disposal system by eliminating abnormal proteins from cells. There’s growing evidence that people with Parkinson’s have defective proteasomes. In this study, McNaught and his colleagues used both man-made and naturally occurring proteasome inhibitors to interfere with proteasomes in laboratory rats. Imaging of the rats’ brains showed types of changes identical to that seen in Parkinson’s disease. They began to display Parkinson’s-like symptoms such as slowness of movement, tremors, and rigidity.
“These symptoms gradually worsened over a period of months, and could be reversed with drugs that are used to treat Parkinson’s patients,” McNaught said. At autopsy, the rats’ brains showed a reduction in levels of the brain chemical dopamine, which undergoes a similar decline in Parkinson’s patients. Autopsy also revealed a pattern of nerve cell loss that closely resembled Parkinson’s.