The Pesticide Connection - Medical mystery jump-starts investigation of the link between PARKINSON’S DISEASE and crop-protecting chemicals

The rats in a room at the University of Pittsburgh regularly get hit with doses of pesticide. But the researchers in J. Timothy Greenamyre’s lab don’t expose the rodents because of an infestation problem. They give the neurotoxin to the animals to learn more about Parkinson’s disease. After receiving a low daily dose of the pesticide rotenone for a week or two, rats in Greenamyre’s lab begin to lose mobility in ways similar to Parkinson’s patients. The rodents move at a glacial pace, they have trouble keeping their balance, and their limbs become impossibly stiff. Even the animals’ brains develop classic signs of the nervous system disorder: Nerve cells in a region called the substantia nigra accumulate clumps of the protein α-synuclein and die. It’s not unusual to use animal models such as these to probe the molecular causes of Parkinson’s, which affects 7 million to 10 million people worldwide, and to test treatments. But their use also raises a question: If a chemical gives lab rats Parkinson’s symptoms, might it do the same to humans exposed in the real world?

A number of population studies have reported that people living in rural areas and people who work with pesticides have a higher incidence of Parkinson’s disease. In the past five years, some investigations have even associated the use of specific pesticides, such as rotenone, with a higher risk of having the disorder. And most recently, researchers have been investigating whether specific people might be vulnerable to pesticides because of their genes: People are at greater risk if they have mutated versions of enzymes or protein pumps that protect cells against damaging substances.
On the basis of these results, many in academia say the link between pesticides and Parkinson’s is clear. But others, including pesticide industry representatives, argue that these studies are fraught with bias, and other research has not shown a Parkinson’s-pesticide tie-in. One thing these two camps agree upon, though, is that the story of how scientists connected pesticides to Parkinson’s is a medical mystery worthy of the big screen.

Source:
LAUREN K. WOLF, C&EN WASHINGTON - The Pesticide Connection. Medical mystery jump-starts investigation of the link between PARKINSON’S DISEASE and crop-protecting chemicals. CEN.ACS.ORG 11-15, November 25, 2013
http://cen.acs.org/articles/91/i47/Pesticide-Connection.html