Environmental toxins and Parkinson's disease: what have we learned from pesticide-induced animal models?

Parkinson's disease (PD) is a common neurodegenerative disorder largely of idiopathic nature with the exceptions of rare familial forms, and is characterized by both motor and non-motor disturbances. Pathologically, most motor features are the result of a dramatic loss of ventral tier mesencephalic dopaminergic neurons and thus dopamine content at their target sites. Although the exact etiology of the disease remains to be elucidated, it is thought to be multifactorial, with a critical role for environmental factors, such as pesticides, that may act on genetically predisposed individuals. Arising from consideration of the potential environmental triggers of PD, in vivo animal models of the disease utilizing these compounds are increasingly reported in the literature. Here, we review recent advances in the predominant models employing the insecticide Rotenone, the herbicide Paraquat and the fungicide Maneb, discuss their scientific merit and evaluate their relevance in the study of PD pathogenesis.